How does the short form 36 health questionnaire (SF-36) in rheumatoid arthritis (RA) relate to RA outcome measures and SF-36 population values? A cross-sectional study

Abstract

The aim of the study was to show that the SF-36 is a practical tool for use on outpatients with RA, to examine the relationship between the SF-36 and indices of outcome in RA, and to compare the results with population norms and other disease states. Eighty-six consecutive RA patients attending the Haywood Hospital in Stoke-on-Trent and starting or changing second-line therapy were enrolled. Disease outcome was assessed using the American College of Rheumatology core set and all subjects completed the SF-36 health questionnaire. The cohort had moderately active disease (median ESR 46) and appreciable disability (median HAQ 1.875). Impairment of health status was moderate to marked by the SF-36, with significant differences from population norms and chronic disease states such as low back pain. Good correlations were observed between HAQ and physical function (r>0.75, p<10(-6)) and HAQ and social function (r>0.61, p<10(-6)). In contrast, SF-36 scales for physical and emotional role showed no association with activity measures. We concluded that, SF-36 is a practical tool for use in patients with RA. HAQ is associated with its physical and social function scales. Other SF-36 scales, such as physical and emotional role, are not associated with activity core set measures; this suggests different information is involved. RA has a considerable impact on health status compared to other diseases.