Abstract
Objective. To determine the extent to which instruments that measure core outcome domains in acute gout fulfill the Outcome Measures in Rheumatology (OMERACT) filter requirements of truth, discrimination, and feasibility.
Methods. Patient-level data from 4 randomized controlled trials of agents designed to treat acute gout and 1 observational study of acute gout were analyzed. For each available measure, construct validity, test-retest reliability, within-group change using effect size, between-group change using the Kruskall-Wallis statistic, and repeated measures generalized estimating equations were assessed. Floor and ceiling effects were also assessed and minimal clinically important difference was estimated. These analyses were presented to participants at OMERACT 11 to help inform voting for possible endorsement.
Results. There was evidence for construct validity and discriminative ability for 3 measures of pain [0 to 4 Likert, 0 to 10 numeric rating scale (NRS), 0 to 100 mm visual analog scale (VAS)]. Likewise, there appears to be sufficient evidence for a 4-point Likert scale to possess construct validity and discriminative ability for physician assessment of joint swelling and joint tenderness. There was some evidence for construct validity and within-group discriminative ability for the Health Assessment Questionnaire as a measure of activity limitations, but not for discrimination between groups allocated to different treatment.
Conclusion. There is sufficient evidence to support measures of pain (using Likert, NRS, or VAS), joint tenderness, and swelling (using Likert scale) as fulfilling the requirements of the OMERACT filter. Further research on a measure of activity limitations in acute gout clinical trials is required.
Footnotes
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Supported with resources and use of facilities at the Birmingham VA Medical Center, Alabama, USA (J.A.S. and D. Redden). N. Dalbeth has received consulting fees from Ardea Biosciences, Metabolex, Novartis, and Takeda. Her institution has received funding from Fonterra, and she is a named inventor on a patent related to milk products and gout. H.R. Schumacher has been a consultant for Regeneron, Novartis, Pfizer, Savient, Ardea, Metabolex, and BioCryst, and he has received a grant from Takeda. N.L. Edwards has received consultant fees from Novartis, Takeda Pharmaceutical, Savient Pharmaceutical, Ardea Biosciences, Regeneron Pharmaceuticals, Metabolex Pharmaceuticals, and BioCryst Pharmaceuticals. L.L. Simon has served on the board of directors for Savient Pharmaceuticals, and has consulted for Takeda. M.R. John is employed by Novartis and sometimes owns shares in the company. M.N. Essex is employed by Pfizer and owns shares in the company. D.J. Watson is an employee of and owns stock in Merck & Co. Inc.; the marketing authorization holder for etoricoxib and sponsor of the etoricoxib clinical trials that contributed data for this work. R. Evans is employed by Regeneron and owns shares of stock. J.A. Singh has received research grants from Takeda and Savient and consultant fees from Savient, Takeda, Ardea, Regeneron, Allergan, URL Pharmaceuticals and Novartis. He is a member of the executive of OMERACT, an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies; a member of the American College of Rheumatology’s Guidelines Subcommittee of the Quality of Care Committee; and a member of the Veterans Affairs Rheumatology Field Advisory Committee.
