Treatment Patterns in Polyarticular Juvenile Idiopathic Arthritis: A Retrospective Observational Health Claims Data Study

(1) Background: Achieving inactive disease decreases long-term joint damage in patients with polyarticular juvenile idiopathic arthritis (polyJIA). The aim of our study was to describe average time to treatment and medication changes over time. (2) Methods: Incident polyJIA patients were retrospectively identified in the InGef and WIG2 longitudinal health claims databases. Drug escalation level changes were evaluated longitudinally and cross-sectionally across three years, as follows: no treatment, glucocorticoids (GCs) and/or non-steroidal anti-inflammatory drugs (NSAIDs), conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), and biological disease-modifying antirheumatic drugs (bDMARDs). (3) Results: On average, newly diagnosed polyJIA patients received their first csDMARD prescription after 128 days and their first bDMARD prescription after 327 days. More patients were treated with csDMARDs than with bDMARDs at diagnosis; however, 24% and 12% (InGef and WIG2 databases, respectively) had no JIA treatment. After three years, 45% and 31% were not taking any treatments, while 18% and 36% were prescribed bDMARDs. Among patients initiating bDMARDs, most continued treatment for three years, with some switching to csDMARDs or discontinuing treatment. Patients treated only with csDMARDs took them longer, compared to those additionally taking other DMARDs. Patients treated with bDMARDs took them about twice as long as the csDMARDs they took prior. (4) Conclusion: A substantial number of patients with polyJIA are not treated as intensively as guidelines recommend.