Clinical characteristics, effectiveness, safety, and predictors of PASI75/90 responses to IL-17 biologics in psoriasis involving special sites: a large real-world cohort study revealing treatment response heterogeneity

Objective Psoriasis affecting special anatomical sites (scalp, face, intertriginous areas, and genitals) poses unique treatment challenges and often shows inadequate responses. This study evaluates the real-world efficacy and safety of IL-17 inhibitors in treating psoriasis affecting special sites, and identifies clinical determinants for achieving PASI75 and PASI90 responses.Materials and methods A retrospective cohort of 1,469 patients receiving IL-17 therapy was analyzed.Generalized linear models, univariate and multivariate logistic regression analyses were used to identify clinical factors influencing the PASI75 and PASI90 response.Results At week 12, significant improvements were observed in various measures of disease severity and quality of life (BSA, IGA, PASI, DLQI), with all comparisons yielding P < 0.0001. Treatment response rates were 74.0% for PASI50, 58.6% for PASI75, and 41.5% for PASI90, while adverse events were rare (0.75%). Prediction models for PASI75 and PASI90 responses exhibited moderate discriminative ability. Independent predictors for both PASI75 and PASI90 included clinical BMI, DLQI, BSA, and IGA (all P < 0.05), while job status was an independent predictor for PASI90 only (P < 0.05).Conclusions Overall, IL-17 inhibitors show substantial efficacy and a favorable safety profile for psoriasis in special sites, with treatment response variability influenced primarily by baseline clinical characteristics such as BMI and disease severity indices.