Association of 6-Month Weight Change With Response to Biologic Therapy in Moderate-to-Severe Plaque Psoriasis: The PPD CorEvitas Psoriasis Registry

Introduction: Obesity is associated with greater psoriasis severity and reduced treatment response. We evaluated the association between weight change during the first 6 months after biologic initiation and treatment response among patients with moderate to severe plaque psoriasis. Methods: This retrospective longitudinal analysis used prospectively collected data from the PPDTM CorEvitasTM Psoriasis Registry through October 2025. Eligible biologic treatment initiations included TNFi, IL-17i, IL-12/23i, and IL-23i. Initiations had baseline Psoriasis Area and Severity Index (PASI) >5 and body weight and PASI recorded at baseline and at a follow-up visit 5–9 months after initiation. Weight change from baseline to follow-up was classified as ≥5% weight loss, stable weight (<5% change), or ≥5% weight gain. The unit of analysis was a biologic treatment initiation; patients could contribute more than one eligible initiation. Primary outcomes were PASI90 achievement (≥90% improvement in PASI from baseline) and change in PASI; secondary outcomes included additional clinician-assessed disease activity and patient-reported measures. Mixed-effects modified Poisson regression estimated adjusted relative risks (RRs) for binary outcomes and mixed-effects analysis of covariance estimated adjusted mean changes for continuous outcomes. Models included biologic class and baseline outcome value a priori, with additional covariates selected using prespecified criteria. Global tests evaluated differences across weight-change categories. Analyses were repeated by baseline obesity status (body mass index [BMI] ≥30 vs <30 kg/m2). Results: Among 3,598 eligible biologic treatment initiations, 379 (10.5%) involved weight loss, 2,755 (76.6%) stable weight, and 464 (12.9%) weight gain. Across PASI response thresholds, response rates were numerically highest with weight loss and lowest with weight gain: PASI75, 65.4%, 64.9%, and 62.9%; PASI90, 50.4%, 48.6%, and 47.2%; and PASI100, 35.4%, 33.8%, and 31.9%, respectively. Compared with stable weight, adjusted RRs for PASI90 were 1.07 (95% CI, 0.96–1.20) for weight loss and 0.95 (95% CI, 0.86–1.03) for weight gain (global P=0.165). Adjusted mean PASI changes were −8.35, −8.36, and −8.04, respectively (global P=0.492). Nominal global differences were observed for PASI100 (global P=0.0437), EQ Health Status (adjusted mean changes 7.43, 7.56, and 5.33; global P=0.043), and fatigue (-13.21, -11.39, and -8.84; global P=0.021), respectively. Neither adjusted PASI100 comparison with stable weight was individually statistically significant. Among initiations in patients with baseline obesity, PASI90 was achieved in 47.1%, 44.0%, and 39.1% in the weight-loss, stable-weight, and weight-gain groups, respectively (global P=0.286); no adjusted outcomes differed significantly across weight-change categories in either baseline obesity subgroup. Conclusions: Weight change during the first 6 months after biologic initiation was not significantly associated with either primary outcome. Nevertheless, PASI75, PASI90, and PASI100 response rates showed a consistent numerical gradient from weight loss to weight gain, with exploratory differences also observed for selected patient-reported outcomes. Because weight change and treatment outcomes were assessed concurrently and intentionality of weight loss was not captured, causal inferences cannot be made. These findings support prospective studies of intentional weight-management strategies in the treatment of psoriasis.