Sex Differences in the Achievement of Remission and Low Disease Activity in Rheumatoid Arthritis

Objective: In rheumatoid arthritis, whether women are less likely to achieve low disease activity is unclear. We evaluated sex differences in remission and low disease activity, comparing different clinical and imaging measures. Methods: We used data from the Veterans Affairs Rheumatoid Arthritis (VARA) registry and from 2 clinical trials. Remission and low disease activity were defined using composite scores, individual items (tender joints, swollen joints, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP] level, and evaluator/patient global assessment), and magnetic resonance imaging (MRI). In the VARA registry, we assessed the likelihood of point remission at any time during follow-up using logistic regression, and time to sustained remission (2 consecutive visits) using Cox proportional hazards models. In the clinical trials, logistic regression models evaluated the likelihood of low clinical and MRI activity at 52 weeks. Results: Among 2,463 patients in VARA, women (10.2%) were less likely to be in Disease Activity Score in 28 joints (DAS28)–ESR remission in follow-up (odds ratio [OR] 0.71 [95% confidence interval (95% CI) 0.55–0.91]; P < 0.01) and had a longer time to sustained DAS28-ESR remission. This difference was not observed for DAS28-CRP, Clinical Disease Activity Index, or Routine Assessment of Patient Index Data 3. Women were more likely to achieve favorable individual components except for an ESR <30 mm/hour (OR 0.72 [95% CI 0.57–0.90]; P < 0.01). Among 353 trial participants (83.7% women), women had reduced rates of DAS28-ESR remission (OR 0.39 [95% CI 0.21–0.72]; P = 0.003) but similar rates of low MRI synovitis and osteitis. Conclusion: The comparison of remission rates between men and women varies based on the disease activity measure, with sex-specific differences in ESR resulting in reliably lower rates of remission among women. There were no differences in MRI measures.