The Western Japan Atopic Dermatitis Registry (WJADR): A Multicenter Real-World Registry of Systemic Therapies for Atopic Dermatitis.

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease with substantial impact on quality of life. The introduction of biologics and Janus kinase (JAK) inhibitors has markedly transformed systemic treatment strategies. However, long-term prospective real-world registries evaluating drug survival, safety, phenotype-specific treatment response, and post-discontinuation outcomes remain limited, particularly in Asian populations. Methods: The Western Japan Atopic Dermatitis Registry (WJADR) is a multicenter, prospective, observational registry coordinated by Kyushu University and collaborating institutions across western Japan. Patients initiating or currently receiving systemic therapy for AD are enrolled. Longitudinal data collection includes clinical phenotype classification, disease course classification, treatment exposure, physician-assessed severity scores, patient-reported outcomes, biomarkers, and safety information. The primary outcome is drug survival, while secondary outcomes include clinical improvement, adverse events, phenotype-treatment interactions, biomarker-treatment correlations, and treatment-switch patterns. Results: WJADR was designed as a phenotype-integrated real-world registry to evaluate comprehensive systemic treatment strategies and post-discontinuation outcomes in AD prior to the completion of patient enrollment and outcome analyses. Unlike existing registries primarily focused on biologic initiator cohorts or treatment burden, WJADR integrates clinical phenotypes, biomarkers, and longitudinal outcomes to support precision medicine approaches. Conclusions: WJADR represents the first large-scale multicenter prospective AD registry in western Japan and may provide ethnicity-specific real-world evidence to support long-term safety evaluation, treatment optimization, and phenotype-guided therapeutic strategies in AD.