RESPONSIVENESS OF HEALTH-STATUS INSTRUMENTS TO CHANGES IN ARTICULAR STATUS AND PERCEIVED HEALTH IN PATIENTS WITH PSORIATIC-ARTHRITIS

Objective. To compare the responsiveness of the Health Assessment Ques tionnaire (HAQ), Arthritis Impact Measurement Scale 2 (AIMS2), and Med ical Outcome Study Short Form Health Survey (SF-36) to changes in arti cular status and perceived health in outpatients with psoriatic arthri tis (PsA). Methods. The 3 health status instruments were administered in random order on 2 occasions, about 12-18 months apart, to 70 patien ts attending the University of Toronto psoriatic arthritis clinic. Sta ndardized assessments of disease activity, disease severity, and gener al health perceptions were also performed at each clinic visit. To ass ess responsiveness we used: (1) linear regression analyses to relate c hange scores for perceived health, the number of actively inflamed, an d damaged joints to change scores for selected dimensions of the HAQ, AIMS2, and SF-36; (2) logistic regression analyses to relate both impr ovement in disease activity and disease progression to health status c hange scores; and (3) standardized response means (SRM). Results. Ther e were 43 men and 27 women with a mean age of 46 years and arthritis d uration of 13 years. Univariate regression analyses showed that the in dividual instruments were responsive to perceived changes in health, b ut relatively insensitive to detect changes in articular status. Multi variate regression analyses, in which the common dimensions of the ins truments were jointly entered, indicated the SF-36 was equally or more responsive to changes in number of actively inflamed joints, clinical improvement in disease activity and perceived health than the HAQ and AIMS2. The SRM analysis also suggested that the SF-36 was the most re sponsive. Conclusion. The SF-36 proved equally or more responsive to s hort term changes in perceived health and inflammatory disease activit y; however, none of the instruments showed responsiveness to disease p rogression.