Potential Impact of Sex and BMI on Response to Therapy in Psoriatic Arthritis: Post Hoc Analysis of Results From the SEAM-PsA Trial

Objective. In this post hoc analysis, we examined the potential impact of sex and BMI on response in the Study of Etanercept and Methotrexate in Combination or as Monotherapy in Subjects with Psoriatic Arthritis (SEAM-PsA) trial (NCT02376790), a 48-week, phase III, randomized controlled trial that compared outcomes with methotrexate (MTX) monotherapy, etanercept (ETN) monotherapy, and MTX+ETN combination therapy in patients with psoriatic arthritis (PsA) who were naïve to MTX and biologics. Methods. We evaluated key outcomes at week 24 stratified by sex (male vs female) and BMI (kg/m2; ≤ 30 vs > 30), including the American College of Rheumatology 20 (ACR20) criteria, minimal disease activity (MDA), very low disease activity (VLDA), and Psoriatic Arthritis Disease Activity Score (PASDAS). We analyzed data using descriptive statistics, normal approximation, logistic model, and analysis of covariance. Results. A total of 851 patients completed the SEAM-PsA trial. Higher proportions of men than women who received MTX+ETN combination therapy achieved ACR20 (71.5% vs 58.3%; P = 0.02), MDA (45.8% vs 25.2%; P = 0.0003), and VLDA (19.1% vs 9.5%; P = 0.03), and men achieved better PASDAS (-3.0 vs -2.3; P = 0.0004). Patients with BMI ≤ 30 generally had better outcomes than those with BMI > 30 in some treatment arms for ACR20, MDA, VLDA, and PASDAS; however, there was no consistent pattern regarding the treatment arm in which the difference occurred. Conclusion. Improved outcomes were observed more in men than in women for MDA and PASDAS with MTX+ETN combination therapy. Patients with BMI ≤ 30 had better outcomes than those with BMI > 30, with no clear pattern regarding treatment received. These findings suggest that contextual factors such as sex and BMI may affect response to PsA therapy.