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Clinically Important Changes in Short Form 36 Health Survey Scales for Use in Rheumatoid Arthritis Clinical Trials: The Impact of Low Responsiveness
Author(s) -
Ward Michael M.,
Guthrie Lori C.,
Alba Maria I.
Publication year - 2014
Publication title -
arthritis care and research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.032
H-Index - 163
eISSN - 2151-4658
pISSN - 2151-464X
DOI - 10.1002/acr.22392
Subject(s) - rheumatoid arthritis , medicine , physical therapy , clinical trial , mental health , scale (ratio) , sf 36 , receiver operating characteristic , clinical psychology , physical medicine and rehabilitation , psychiatry , health related quality of life , physics , disease , quantum mechanics
Objective 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. Methods 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. Results 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. Conclusion 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.