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

PURPOSE: If newer, more aggressive treatment strategies in 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 computed 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, adjusting for age, sex, race, education, clinical center, disease duration, follow-up, and attrition. We used two regression approaches: ordinary and generalized least squares.
RESULTS: Average disability declined by about 2% to 3% per calendar year of disease onset (2.7% to 2.8% per year [P <0.001] in univariable models and 2.0% to 2.1% per year [P <0.001] in multivariable models). This trend was consistent by age, sex, race, disease duration, clinical center, and baseline disability.
CONCLUSION: After accounting for potential confounders, average disability levels in rheumatoid arthritis have declined by approximately 40% in the 20+ years since 1977. This decline is consistent with a beneficial effect of the associated changes in treatment strategies.