2691: Understanding the Impact of Overweight and Obesity on Treatment Response in Psoriatic Arthritis: Results from a Longitudinal Cohort Study

Background/Purpose: Overweight and obesity is associated with poor outcomes in Psoriatic Arthritis (PsA), with reduced odds of achieving minimal disease activity (MDA). Whether this effect is mediated by direct inflammation or psychosocial factors such as pain perception and mood remains unclear. This study aimed to assess the influence of body mass index (BMI) on components of treatment response in patients with PsA.

Methods: Patients with available body mass index (BMI) values were selected from a large longitudinally assessed PsA cohort followed from 1978. These patients are followed every six months with comprehensive documentation of demographic data, clinical and patient-reported outcomes, and treatment details.

Generalized estimating equations (GEE) were used to assess the association of BMI with MDA and its subcomponents, adjusting for age, sex, anxiety, depression, fibromyalgia, smoking, radiographic damage (modified Steinbrocker score), and use of TNFi and PDE4i.

We also evaluated the effect of baseline BMI at drug initiation and time-varying BMI (to incorporate effects of drugs on BMI) on treatment response across six drug classes (TNFi, IL-17i, IL-23i, IL-12/23i, JAKi, PDE4i) using univariable and multivariable GEE. The multivariable model was adjusted for age, sex, anxiety, depression, fibromyalgia, smoking, radiographic damage (modified Steinbrocker score), and line of treatment. Missing data were addressed using multiple imputation (MICE).

Results: Of 1291 patients included, the mean age was 44.9 (SD 13.3) years, and 55% were males. The mean BMI was 28.8 (SD 6.34) kg/m2. 428 patients received b- and/or tsDMARDs (40 patients - infliximab, 288 - other TNFis, 113 - IL17i, 36 - IL12/23i, 43 - IL23i, 14 - JAKi, and 30 - PDE4i).

Higher BMI was significantly associated with lower odds of achieving MDA [OR 0.95; 95% CI 0.94–0.97], and worse outcomes across multiple MDA subcomponents, including enthesitis, tender joint count, PASI, patient pain, global assessments, and HAQ, but not swollen joint count (Figure 1).

This association was sustained in the multivariable GEE analyses with reduced odds for MDA with increasing BMI [OR 0.96 (0.93-0.98) with similar effects on the subcomponents (Figure 1).

In drug stratified analyses, BMI at drug initiation was significantly associated with reduced MDA [0.93 (0.89-0.97)] in the TNFi group, and TNFi group excluding infliximab [0.93 (0.89-0.97)]. BMI did not impact the response across other drug groups. This association was sustained also in the multivariable analyses (Figure 2).

Conclusion: Obesity is independently associated with poorer treatment outcomes and reduced odds of achieving MDA in PsA, largely driven by subjective and skin-related domains. The impact appears most pronounced among patients treated with TNFis. These findings highlight the need for tailored therapeutic strategies in obese PsA patients and the potential importance of addressing psychosocial factors and weight management in clinical care.