Treatment Patterns and Pathways of Systemic Drug Therapy in Patients With Plaque, Erythrodermic, and Generalized Pustular Psoriasis: A Retrospective Cohort Study in Japan

Systemic psoriasis treatment options have rapidly expanded in Japan, including the approval of tyrosine kinase 2 and interleukin-36 receptor inhibitors in 2022. However, contemporary real-world treatment patterns across plaque, erythrodermic, and generalized pustular psoriasis remain incompletely characterized. Using a Japanese hospital-based insurance claims database (Medical Data Vision Co. Ltd.), we conducted a retrospective cohort study for patients with these psoriasis subtypes who initiated systemic drug therapy between 2020-2023 and had a ≥ 12-month observation period. Overall, 3965 patients with plaque psoriasis, 80 with erythrodermic psoriasis, and 128 with generalized pustular psoriasis were included (median age, 62-66 years). Most patients initiated systemic therapy with a single drug. A phosphodiesterase 4 inhibitor was the most frequently prescribed index treatment for plaque psoriasis (48.8%), whereas a vitamin A derivative was most commonly prescribed for erythrodermic and generalized pustular psoriasis (42.5% and 42.2%, respectively), suggesting a distinctive Japan-specific prescription pattern. The median proportion of days covered for index treatment was nearly 100% across all subtypes. Among the index treatments, biologics generally showed longer time to discontinuation than oral medications. Elderly patients were more likely to receive a phosphodiesterase 4 inhibitor or a vitamin A derivative as index treatment than younger patients, and biologics were more commonly selected for patients with psoriatic arthritis than for those without. Early uptake of tyrosine kinase 2 inhibitor was observed in 2023. Over a median observation period of approximately 30 months, > 85% of patients received three or fewer lines of systemic drug therapy and approximately 50% remained on at least one systemic drug therapy throughout the study period. This first comprehensive Japanese claims database analysis of multiple psoriasis subtypes provides an updated real-world treatment landscape in Japan and helps address an important evidence gap arising from rapidly evolving systemic treatment options and limited contemporary real-world data.