Clinically Important Changes in Short Form 36 Health Survey Scales for Use in Rheumatoid Arthritis Clinical Trials: The Impact of Low Responsiveness
Article first published online: 24 NOV 2014
Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Arthritis Care & Research
Volume 66, Issue 12, pages 1783–1789, December 2014
How to Cite
Ward, M. M., Guthrie, L. C. and Alba, M. I. (2014), Clinically Important Changes in Short Form 36 Health Survey Scales for Use in Rheumatoid Arthritis Clinical Trials: The Impact of Low Responsiveness. Arthritis Care Res, 66: 1783–1789. doi: 10.1002/acr.22392
- Issue published online: 24 NOV 2014
- Article first published online: 24 NOV 2014
- Accepted manuscript online: 30 JUN 2014 01:48PM EST
- Manuscript Accepted: 24 JUN 2014
- Manuscript Received: 14 APR 2014
- Intramural Research Program
- NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases
Despite wide use of the Short-Form 36 (SF-36) health survey in clinical trials of rheumatoid arthritis (RA), estimates of minimum clinically important improvement (MCII) for its scales are not well-established. We estimated MCIIs for SF-36 scales in patients with active RA.
In this prospective longitudinal study, we studied 243 patients who had active RA and who completed the SF-36 before and after treatment escalation. We first assessed responsiveness with standardized response means (SRMs). For scales with adequate responsiveness (SRM ≥0.50), we used patient judgments of improvement in arthritis status as anchors for estimating MCIIs. We used receiver operating characteristic curve analysis to identify the MCIIs as the change associated with a specificity of 0.80 for improvement.
Patients had substantial improvement in RA activity with treatment. However, among SF-36 scales, only the physical functioning and bodily pain scales and the physical component summary had adequate responsiveness. Using 0.80 specificity for improvement as the criterion, the MCIIs were 7.1 for the physical functioning scale, 4.9 for the bodily pain scale, and 7.2 for the physical component summary.
Low responsiveness precluded estimation of valid MCIIs for many SF-36 scales in patients with RA, particularly the scales assessing mental health. Although the SF-36 has been included in many clinical trials to broaden the assessment of health status, low responsiveness limits the interpretation of changes in its mental health–related scales.