To determine if disease duration and number of prior disease-modifying antirheumatic drugs (DMARDs) affect response to therapy in patients with established rheumatoid arthritis (RA).
Associations between disease duration or number of prior DMARDs and response to therapy were assessed using data from two randomised controlled trials in patients with established RA (mean duration, 11 years) receiving adalimumab+methotrexate. Response to therapy was assessed at week 24 using disease activity outcomes, including 28-joint Disease Activity Score based on C-reactive protein (DAS28(CRP)), Simplified Disease Activity Index (SDAI) and Health Assessment Questionnaire Disability Index (HAQ-DI), and proportions of patients with 20%/50%/70% improvement in American College of Rheumatology (ACR) responses.
In the larger study (N=207), a greater number of prior DMARDs (>2 vs 0-1) was associated with smaller improvements in DAS28(CRP) (-1.8 vs -2.2), SDAI (-22.1 vs -26.9) and HAQ-DI (-0.43 vs -0.64) from baseline to week 24. RA duration of >10 years versus <1 year was associated with higher HAQ-DI scores (1.1 vs 0.7) at week 24, but results on DAS28(CRP) and SDAI were mixed. A greater number of prior DMARDs and longer RA duration were associated with lower ACR response rates at week 24. Data from the second trial (N=67) generally confirmed these findings.
Number of prior DMARDs and disease duration affect responses to therapy in patients with established RA. Furthermore, number of prior DMARDs, regardless of disease duration, has a limiting effect on the potential response to adalimumab therapy.