Abstract
Objective. The Rasch measurement model provides robust analysis of the internal construct validity of outcome measures. We reviewed the application of Rasch analysis in musculoskeletal medicine as part of the work leading to discussion in a Special Interest Group in Rasch Analysis at Outcome Measures in Rheumatology 11.
Methods. A systematic literature review of SCOPUS and MEDLINE was performed (January 1, 1985, to February 29, 2012. Original research reports in English using “Rasch” or “Item Response Theory” in musculoskeletal diseases were assessed by 2 independent reviewers. The topics of focus and analysis methodology details were recorded.
Results. Of 212 articles reviewed, 114 were included. The number of publications rose from 1 in 1991–1992 to 23 in 2011–February 2012. Disease areas included rheumatoid arthritis (28%), osteoarthritis (16.6%), and general musculoskeletal disorders (43%). Sixty-six reports (57.9%) evaluated psychometric properties of existing scales and 35 (30.7%) involved development of new scales. Nine articles (7.9%) were on methodology illustration. Four articles were on item banking and computer adaptive testing. A majority of the articles reported fit statistics, while the basic Rasch model assumption (i.e., unidimensionality) was examined in only 57.2% of the articles. An improvement in reporting qualities with Rasch articles was noted over time. In addition, only 11.4% of the articles provided a transformation table for interval scale measurement in clinical practice.
Conclusion. The Rasch model has been increasingly used in rheumatology over the last 2 decades in a wide range of applications. The majority of the articles demonstrated reasonable quality of reporting. Improvements in quality of reporting over time were revealed.
