Objective: To investigate the evolution of functional capacity, disease activity, and joint destruction over time in a 12-year prospective cohort of rheumatoid arthritis (RA) patients, and to study the relative contribution of disease activity and joint destruction to the loss of functional capacity.
Methods: One hundred thirty-two female patients with recent-onset RA were assessed at 0, 3, 6, and 12 years of followup for functional capacity (Health Assessment Questionnaire [HAQ] score), disease activity (Disease Activity Score [DAS]), and joint destruction (Sharp score of radiologic damage).
Results: The Sharp score deteriorated steadily over time, while the HAQ score and DAS showed a variable course. The DAS correlated strongly with the HAQ score throughout the disease course. The correlation between the Sharp score and the HAQ score was weak at study start, but became strong after 12 years. After 12 years of followup, disease activity was the main determinant of the HAQ score when entered in a multivariate analysis.
Conclusion: Functional capacity is strongly influenced by disease activity throughout the course of RA. Even in longstanding RA, disease activity proves to be the main determinant of the HAQ score for functional capacity.