Long-term follow-up on effectiveness and safety of etanercept in juvenile idiopathic arthritis: the Dutch national register

Objective: We undertook an observational study to obtain a complete overview of the long-term effectiveness and safety of etanercept in patients with different juvenile idiopathic arthritis (JIA) subtypes. Methods: At baseline we collected patient and disease characteristics of all Dutch patients with JIA who started treatment with etanercept. Disease activity was evaluated (at start of the study, after 3 months and then yearly) according to the JIA core set of the American College of Rheumatology paediatric definition for 30, 50 and 70% improvement (ACR Pedi 30, 50 and 70). Use of etanercept and concomitant drugs was monitored. Adverse events were recorded. Results: We included 146 patients with JIA with a median follow-up of 2.5 years per patient ( range 0.3-7.3). JIA subtypes represented: 27% systemic, 8% polyarticular rheumatoid factor positive, 38% polyarticular rheumatoid factor negative, 19% oligoarticular extended, 3% enthesitis-related and 5% psoriatica. Most patients (77%) met the criteria of the ACR Pedi 30 in the first 3 months of treatment. For the majority of patients this improvement was sustained; 53 (36%) of all patients met the remission criteria. No other second-line agents were needed in 43 patients. Although patients with systemic JIA responded initially less to etanercept therapy than patients from other subtypes, those who did respond showed equal effectiveness in the long term. Serious adverse events rate was low (0.029 per patient year). Conclusions: Etanercept is effective and safe in JIA, even for a large proportion of the patients with systemic JIA. The greatest improvement occurred in the first 3 months of treatment, and was sustained for a long time in most patients ( up to 75 months).