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 Questionnaire (HAQ), Arthritis Impact Measurement Scale 2 (AIMS2), and Medical Outcome Study Short Form Health Survey (SF-36) to changes in articular status and perceived health in outpatients with psoriatic arthritis (PsA).


METHODS
The 3 health status instruments were administered in random order on 2 occasions, about 12-18 months apart, to 70 patients attending the University of Toronto psoriatic arthritis clinic. Standardized assessments of disease activity, disease severity, and general health perceptions were also performed at each clinic visit. To assess responsiveness we used: (1) linear regression analyses to relate change scores for perceived health, the number of actively inflamed, and damaged joints to change scores for selected dimensions of the HAQ, AIMS2, and SF-36; (2) logistic regression analyses to relate both improvement in disease activity and disease progression to health status change scores; and (3) standardized response means (SRM).


RESULTS
There were 43 men and 27 women with a mean age of 46 years and arthritis duration of 13 years. Univariate regression analyses showed that the individual instruments were responsive to perceived changes in health, but relatively insensitive to detect changes in articular status. Multivariate regression analyses, in which the common dimensions of the instruments 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 responsive.


CONCLUSIONS
The SF-36 proved equally or more responsive to short term changes in perceived health and inflammatory disease activity; however, none of the instruments showed responsiveness to disease progression.
Husted
J A
JA
Centre for Prognosis Studies in the Rheumatic Diseases and the Psoriatic Arthritis Clinic, The Toronto Hospital, ON, Canada.
Gladman
D D
DD
Cook
R J
RJ
Farewell
V T
VT
D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000503:physiopathology* / Q000523:psychology*; D018450:Disease Progression; D005069:Evaluation Studies as Topic; D005260:Female; D006304:Health Status; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D007596:Joints / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012649:Self Concept; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D013997:Time Factors