Background/Purpose: Several prior studies have demonstrated poor clinical responses and reduced likelihood of achievement of remission among women with rheumatoid arthritis (RA). We aimed to determine if this observation represents a biologic effect versus a bias in the performance of clinical disease activity measures and their components. Specifically, we compared rates of treatment response in men and women based on different clinical composite and component scores as well as by MRI definitions of low activity in two large clinical trials.

Methods: This is an ancillary study of patients who completed the 52-week MRI sub-studies of two large clinical trials of golimumab. MRI of the dominant hand was performed and RAMRIS synovitis scores were determined at baseline, and at week 52. Standard clinical assessments and patient-reported measures were recorded at all time-points and composite scores were determined including the DAS28(ESR), DAS28(CRP), and CDAI. Remission was defined according to standard thresholds and using Boolean criteria for individual components. A low synovitis score on MRI was defined according to prior published thresholds (<3). Multivariable logistic regression models assessed relationships between sex and achievement of remission or MRI low inflammatory activity by 52 weeks adjusting for age, race, study and treatment group.

Results: Men (N=58) and women (N=295) had similar DAS28(CRP) and CDAI at baseline, but women had higher DAS28(ESR) and higher patient global and tender joint counts (Table 1). Women were less likely to achieve remission by 52 weeks when remission was defined by the DAS28(ESR) or CDAI (Table 2). However, there was not a significant difference in the achievement of remission between men and women for DAS28(CRP). Among component scores, women were less likely to reach a low patient global score and a low ESR (<30 mm/hr) and tended to be less likely to reach a low tender joint count (p=0.056). Men and women were equally likely to achieve low CRP, a low swollen joint count, and a low evaluator global score. Men and women also achieved low MRI synovitis scores with similar frequency.

Conclusion: Although women were less likely to achieve DAS28(ESR) and CDAI remission, they were equally likely to achieve a low CRP, swollen joint count, and low MRI synovitis. These findings suggest that there is not a biologic difference in treatment response in men and women, but that differences in the performance of subjective clinical measures of disease activity and expected sex differences in ESR may explain differences in observed response rates.