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Volume 2010 (2010), Article ID 416796, 8 pages
Research Article

Item Response Theory Analysis of Two Questionnaire Measures of Arthritis-Related Self-Efficacy Beliefs from Community-Based US Samples

1Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
2Department of Allied Health Science, Division of Physical Therapy, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
3Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
4Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, NC 27599, USA
5Departments of Medicine, Orthopedics, and Social Medicine, University of North Carolina, Chapel Hill, NC 27599, USA

Received 23 November 2009; Accepted 2 March 2010

Academic Editor: George D. Kitas

Copyright © 2010 Thelma J. Mielenz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Using item response theory (IRT), we examined the Rheumatoid Arthritis Self-efficacy scale (RASE) collected from a People with Arthritis Can Exercise RCT (346 participants) and 2 subscales of the Arthritis Self-efficacy scale (ASE) collected from an Active Living Every Day (ALED) RCT (354 participants) to determine which one better identifies low arthritis self-efficacy in community-based adults with arthritis. The item parameters were estimated in Multilog using the graded response model. The 2 ASE subscales are adequately explained by one factor. There was evidence for 2 locally dependent item pairs; two items from these pairs were removed when we reran the model. The exploratory factor analysis results for RASE showed a multifactor solution which led to a 9-factor solution. In order to perform IRT analysis, one item from each of the 9 subfactors was selected. Both scales were effective at measuring a range of arthritis SE.