Specialty‐Based Disparities in Biologic Use and Retention in Psoriatic Arthritis: A Nationwide Korean Claims Analysis

AIM: Biologic agents play a pivotal role in controlling both articular and cutaneous manifestations of psoriatic arthritis (PsA). Although international guidelines emphasize the appropriate use of biologics, Korea lacks standardized treatment protocols tailored for PsA across specialties. We therefore aimed to examine specialty-specific prescription patterns and treatment retention using nationwide claims data. METHODS: Health Insurance Review and Assessment (HIRA) claims data from 2011 to 2022 were analyzed, including patients with PsA who initiated treatment with their first biologic agent. Patients with concurrent autoimmune diseases were excluded. Trends in diagnosis, prescription patterns, and retention were analyzed according to medical specialty. RESULTS: Of the 2406 patients with PsA, 63.0% were diagnosed in dermatology departments and 32.8% in internal medicine departments. Most biologics were prescribed in the dermatology department (80.2%), while 17.8% were prescribed in the internal medicine department. Since 2016, dermatology has exhibited a marked increase in both PsA diagnoses and biologic prescriptions. Interleukin-23 (IL-23) inhibitors were the most frequently prescribed class (62.0%), followed by IL-17 inhibitors (21.9%) and tumor necrosis factor inhibitors (TNFi) (16.1%). Drug retention analysis revealed that dermatology was associated with a significantly higher risk of biologic discontinuation than internal medicine (hazard ratio = 1.40, 95% confidence interval 1.11-1.78). CONCLUSION: The predominance of PsA diagnosis and biologic initiation in dermatology indicates substantial specialty-specific differences in practice. This pattern warrants careful evaluation and supports the development of standardized, evidence-based guidelines across specialties to promote appropriate care.