Identifying Provisional Generic Contextual Factor Domains for Clinical Trials in Rheumatology: Results from an OMERACT Initiative

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.

From the Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen; The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital; Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; Clinical Epidemiology Program, Ottawa Hospital Research Institute; Children’s Hospital of Eastern Ontario Research Institute; Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa, Ottawa; Institute for Work and Health, Department of Occupational Science and Occupational Therapy, Rehabilitation Sciences Institute and the Institute for Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; Department of Epidemiology and Biostatistics; Amsterdam Rheumatology and Immunology Center; Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam; Department of Rheumatology, and Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden; Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre; Care and Public Health Research Institute, Maastricht University, Maastricht; University of Twente, Department of Psychology, Health and Technology, Enschede, the Netherlands; Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles; Division of Immunology/Rheumatology, Stanford University, Palo Alto, California; Medicine Service, VA Medical Center, Birmingham; Department of Medicine, School of Medicine, University of Alabama, and Division of Epidemiology, School of Public Health, University of Alabama, Birmingham, Alabama; Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, Burlington, Vermont; University of Washington, Seattle, Washington, USA; Swiss Paraplegic Research, Nottwil, Switzerland; Université de Lorraine, EA 4360 Approches Épidémiologiques et Psychologiques (APEMAC), Nancy, France; University of Florence, Florence, Italy; Division of Rheumatology, Department of Medicine 3, Medical University of Vienna, Vienna, Austria; European Medicines Agency, London, UK; Faculty of Medicine and Health University of Sydney and Department of Rheumatology, Royal North Shore Hospital, Sydney, Australia. JAS is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies. AB received research grants to her department from Celgene and AbbVie. The views expressed in this article are personal views and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties. S.M. Nielsen, MSc, Biostatistics and Clinical Epidemiology Fellow, Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital and The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark; P. Tugwell, MD, Division of Rheumatology, Department of Medicine, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, and Clinical Epidemiology Program, Ottawa Hospital Research Institute; M.P. de Wit, PhD, OMERACT patient research partner, and Amsterdam University Medical Centre, Department of Medical Humanities, Amsterdam Public Health; M. Boers, MD, PhD, Professor of Clinical Epidemiology, Amsterdam UMC, Vrije Universiteit Amsterdam; D.E. Beaton, BscOT, PhD, Associate Professor, Occupational Science and Occupational Therapy, University of Toronto, and Senior Scientist, Institute for Work and Health; T.G. Woodworth, MD, Visiting Clinical Researcher, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine, UCLA; R. Escorpizo, PT, DPT, MSc, Clinical Associate Professor, Department of Rehabilitation and Movement Science, College of Nursing and Health Sciences, University of Vermont, and Adjunct Senior Research Scientist, Swiss Paraplegic Research; B. Shea, PhD, Clinical Investigator and Adjunct Professor, Ottawa Hospital Research Institute, and School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; K. Toupin-April, PhD, Scientist, Children’s Hospital of Eastern Ontario Research Institute, and Assistant Professor, Department of Pediatrics and School of Rehabilitation Sciences, University of Ottawa; F. Guillemin, MD, PhD, Université de Lorraine, EA 4360 APEMAC, Nancy, and INSERM CIC 1433, University Hospital; V. Strand, MD, MACR, FACP, Adjunct Clinical Professor, Division of Immunology/Rheumatology, Stanford University; J.A. Singh, MBBS, MPH, Professor of Medicine and Epidemiology, Department of Medicine at the School of Medicine, University of Alabama at Birmingham; M. Kloppenburg, MD, PhD, Professor of Rheumatology, Leiden University Medical Center; D.E. Furst, MD, David Geffen School of Medicine, Division of Rheumatology, UCLA, and University of Washington, and University of Florence; G.A. Wells, PhD, School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa; J.S. Smolen, MD, Division of Rheumatology, Department of Medicine 3, Medical University of Vienna; R. Veselý, MD, Head of the Rheumatology, Respiratory, Gastroenterology and Immunology Office, Scientific and Regulatory Management Department, European Medicines Agency; A. Boonen, MD, Professor of Rheumatology, Department of Internal Medicine, Division of Rheumatology, Maastricht University Medical Centre+, and Care and Public Health Research Institute, Maastricht University; H. Storgaard, MSc student, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, and Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital; M. Voshaar, MSc, PhD student at University of Twente, Department Psychology, Health and Technology; L.M. March, PhD, Liggins Professor of Rheumatology and Musculoskeletal Epidemiology University of Sydney, Head of Department of Rheumatology, Royal North Shore Hospital; R. Christensen, PhD, Professor of Biostatistics and Clinical Epidemiology, The Rheumatology Research Unit, Department of Rheumatology, Odense University Hospital and University of Southern Denmark, and Head of Musculoskeletal Statistics Unit, The Parker Institute, Bispebjerg and Frederiksberg Hospital. Address correspondence to Dr. R. Christensen, The Parker Institute, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Copenhagen F, Denmark. E-mail: Robin.Christensen@regionh.dk. Accepted for publication November 30, 2018.