Reduction in long-term functional disability in rheumatoid arthritis 1977-1998: longitudinal study of 3035 patients

rheumatoid arthritis are more effective, long-term outcomes in rheumatoid arthritis should be improving substantially. We therefore assessed trends in disability over time in a large cohort of patients with rheumatoid arthritis. METHODS: We examined functional disability data from 3035 patients with rheumatoid arthritis whose disease onset was from 1977 to 1998. Disability data were collected semiannually with the Health Assessment Questionnaire disability index. We then estimated average disability for each patient. We also com-puted mean disability for each calendar year by averaging the values from all patients in that year. We examined the relation of successive annual cohorts and subsequent disability, adjust-ing for age, sex, race, education, clinical center, disease dura-tion, follow-up, and attrition. We used two regression ap-proaches: ordinary and generalized least squares