Potential Impact of Sex and Body Mass Index on Response to Therapy in Psoriatic Arthritis: Post-hoc Analysis of Results From the SEAM-PsA Trial.

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The Journal of rheumatology


washington; swedish; seattle


Objective: In this post-hoc analysis, we examined the potential impact of sex and body mass index (BMI) on response in the SEAM-PsA trial (NCT02376790), a 48-week, phase 3, randomized controlled trial that compared outcomes with methotrexate monotherapy, etanercept monotherapy, and methotrexate+etanercept combination therapy in patients with psoriatic arthritis (PsA) naïve to methotrexate and biologics.

Methods: We evaluated key outcomes at Week 24 stratified by sex (male vs female) and BMI (≤30kg/m2 vs >30kg/m2), including the American College of Rheumatology 20 (ACR20), 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 methotrexate+etanercept combination therapy achieved ACR20 (71.5% vs 58.3%; P=0.0194), MDA (45.8% vs 25.2%; P=0.0003), and VLDA (19.1% vs 9.4%; P=0.0273), and men achieved better PASDAS (-3.0 vs -2.3; P=0.0004). Patients with BMI≤30kg/m2 generally had better outcomes than those with BMI>30kg/m2 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 methotrexate+etanercept combination therapy. Patients with BMI≤30kg/m2 had better outcomes than those with BMI>30kg/m2 with no clear pattern regarding treatment received. These findings suggest that contextual factors such as sex and BMI may affect response to PsA therapy.

Clinical Institute

Orthopedics & Sports Medicine