Long-term safety of etanercept and adalimumab compared to methotrexate in patients with juvenile idiopathic arthritis (JIA).

Importance: Published evidence on the long-term safety of etanercept (ETA) and adalimumab (ADA) in patients with polyarticular juvenile idiopathic arthritis (pJIA) is still limited.
Objectives: To investigate the rates of serious adverse events (SAE) and of events of special interest (ESI) under ETA and ADA treatment.
Design, Setting and Participants: Patients with pJIA were prospectively observed in the national JIA biological register, Biologika in der Kinderrheumatologie, and its follow-up register, Juvenile arthritis Methotrexate/Biologics long-term Observation.
Main Outcomes and Measures: We calculated the relative risks of SAE and ESI for ETA and ADA compared with methotrexate (MTX).
Results: Among the 1414 patients treated with ETA (n=1414; 4461 exposure years (EY)) and ADA (n=320; 493 EY), significantly more SAE, infections and medically important infections were observed (ETA: 4.5, 5.7, 0.9; ADA: 4.7, 11.4, 0.4 per 100 EY) compared with those treated with MTX alone (n=1455; 2.907 EY; 2.6, 5.5, 0.5 per 100 EY). The risk for malignancies was not significantly increased for ETA and ADA compared with MTX (0.09, 0.27 and 0.07/100 person-years). Patients under ETA monotherapy developed more frequently incident inflammatory bowel disease (IBD) and incident uveitis (0.5 and 0.8/100 EY) than patients treated by ETA in combination with MTX (0.1 and 0.2/100 EY) or MTX alone (0.03 and 0.1/100 EY).
Conclusions and Relevance: Our data confirm the acceptable long-term tolerability of ETA and ADA in pJIA. However, whether the onset of IBD and uveitis during ETA monotherapy is a paradoxical effect or an inadequate response to therapy remains unclear and requires further investigation in this growing cohort.
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