Prescribing Patterns and Impact of Factors Associated with Time to Initial Biologic Therapy among Children with Non-systemic Juvenile Idiopathic Arthritis.

OBJECTIVE: The aim of this study was to examine patterns of initial prescriptions, investigate time to initiation of biologic disease-modifying anti-rheumatic drugs (bDMARDs), and evaluate the impact of clinical and other baseline factors associated with the time to first bDMARD in treating children with newly diagnosed non-systemic juvenile idiopathic arthritis (JIA). METHODS: Using longitudinal patient-level data extracted from electronic medical records (EMR) in a large Midwestern pediatric hospital from 2009 to 2018, the initial prescriptions and prescribing patterns of bDMARDs, conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids within 3 months of JIA diagnosis were examined. Kaplan-Meier analyses were performed to assess time to initiation of bDMARDs. Cox proportional hazard models were used to identify factors associated with time to first bDMARD. RESULTS: Of 821 children, the proportion of patients with initial csDMARDs increased from 45.3% in 2009 to 60.3% in 2018. Around 57.5% of polyarthritis rheumatoid factor-positive (Poly RF+) patients and 43.2% of polyarthritis rheumatoid factor-negative (Poly RF-) patients received a bDMARD therapy within 3 months of diagnosis, 14.4% as monotherapy and 28.3% in combination with a csDMARD. Among patients who received combination therapy, combination of methotrexate with adalimumab increased from 16.7% in 2009 to 40% in 2018. The proportion of patients treated with adalimumab gradually increased and passed etanercept in 2016. The predictors of earlier initiation of biologic therapy were JIA category enthesitis-related arthritis (ERA) [hazard ratio (HR) vs persistent oligoarthritis 4.82; p < 0.0001], psoriatic arthritis (PsA) (HR 2.46; p = 0.0002), or Poly RF- (HR 2.43; p = 0.0002); the number of joints with limited range of motion (HR 1.02; p = 0.0222), and erythrocyte sedimentation rate (ESR, HR 1.01; p = 0.0033). CONCLUSIONS: There was a substantial increase in the proportion of patients receiving the combination of methotrexate and adalimumab among patients receiving combination therapy. Adalimumab overtook etanercept as the most frequently prescribed bDMARD. Multiple factors affect the time to biologic initiation, including the number of joints with limited range of motion, ESR, and JIA category.