Psoriasis localization patterns in the Swiss Psoriasis Registry (SDNTT) over 11 years: an analysis by sex and age

Real-world data on anatomically localized psoriasis and its response to systemic therapy across different age-groups and sexes is limited. This study aimed to evaluate the severity and distribution of psoriasis over time in female and male patients receiving systemic therapies, categorized by age within the Swiss psoriasis registry (SDNTT). Patient-data was obtained over 11 years through the SDNTT. The localized Psoriasis Area and Severity Index (locPASI) of the head, trunk, upper and lower extremities was analyzed over two years following the start of systemic non-/biologic treatment. A total of 316 female and 517 male patients were analyzed. Male patients had a higher baseline locPASI for legs, trunk and arms (p < 0.001), but not for the head (p = 0.961). The locPASI for the head in younger female patients (18-40 years) had a higher score than those aged 55 + (p = 0.022) and after two years, middle aged (41-54) showed a lower score compared to younger patients (p = 0.045). Younger male patients revealed a lower score after two years of therapy in the leg- and arm-area compared to older (p = 0.018 and p = 0.048, respectively). Female patients on non-biologics had a fast initial response, converging with male patients' scores over 24 months. Over 75% locPASI reduction was observed for female head-area (81.4%), male trunk (82.7%) and legs (76.1%). Absolute locPASI ≤ 2 was achieved 3-6 months for all locations with interleukin (IL)-17, IL-12/23 and IL-23-inhibitors, except for the legs of male patients on anti-IL-17 and female patients on anti-IL-12/23 and -IL-23. After two years, male patients did not achieve a locPASI ≤ 2 for any biologic-treatment in the legs, nor for the arms on anti-TNF-α. Significant disparities in localized PASI were observed between female and male patients. The age, sex and severity of distinct localizations should be considered to optimize treatment goals.