To examine whether disease duration is an independent predictor of achieving remission in rheumatoid arthritis (RA) patients initiating therapy.
RA patients in the Consortium of Rheumatology Researchers of North America registry newly prescribed a nonbiologic disease-modifying antirheumatic drug (DMARD) or anti--tumor necrosis factor (anti-TNF) with at least one followup visit were identified. Achievement of remission was defined using the Clinical Disease Activity Index (CDAI; score ≤2.8) and 28-joint Disease Activity Score (DAS28; score <2.6) at any followup visit within one year; sustained remission was defined as remission during any two successive visits. Likelihood of remission was examined through logistic regression based on 5-year increments of disease duration, adjusting for baseline covariates.
Among the 1,646 nonbiologic DMARD initiators, CDAI remission occurred in 21.3% of those with ≤5 years of disease duration, 19.6% with 6-10 years, and 13.5% with ≥11 years (P < 0.001); sustained remission occurred in 10.2%, 8.8%, and 2.5%, respectively (P < 0.001). Results were similar among the 3,179 anti-TNF initiators (CDAI remission in 22.3%, 17.7%, and 12.8%, respectively [P < 0.001]; CDAI sustained remission in 9.7%, 9.5%, and 4.2%, respectively [P < 0.001]). DAS28 results were similar in both groups. In adjusted analyses, an increase of disease duration by 5 years was associated with a reduced likelihood of CDAI remission in nonbiologic DMARD (odds ratio [OR] 0.91, 95% confidence interval [95% CI] 0.83-0.99) and anti-TNF initiators (OR 0.88, 95% CI 0.83-0.94). A similar result was seen for sustained remission using the CDAI (nonbiologic DMARD: OR 0.61, 95% CI 0.48-0.76; anti-TNF: OR 0.85, 95% CI 0.75-0.97).
Earlier treatment was associated with a greater likelihood of remission.