Background: To evaluate the long-term safety and efficacy of etanercept treatment in Polish patients with juvenile idiopathic arthritis (JIA).
Material/Methods: The study involved patients, fulfilling the JIA criteria of the International League of Associations of Rheumatology (ILAR), who were started on etanercept therapy after methotrexate and other synthetic disease-modifying antirheumatic drugs (DMARDs) had proven ineffective. Patient data were collected in an electronic registry. Disease improvement was assessed based on Giannini’s criteria.
Results: The statistical analysis involved 188 patients. Significant improvement was observed in all clinical and laboratory parameters after the first month of therapy and was maintained in the following months. ACR Pediatric 30, 50, 70, 90, and 100 improvement was observed in 81.4%, 65.9%, 27.5%, 16.2%, and 15%, respectively, of patients after 3 months and in 94.7%, 88.4%, 62.1%, 34.7%, and 26.3%, respectively, after 24 months of treatment. Throughout the 72-month safety observation period, 1162 adverse events were reported; the exposure-adjusted AE rate was 2.96 per patient per year.
Conclusions: In patients with various subtypes of JIA resistant to conventional DMARD treatment, etanercept resulted in significant and long-lasting improvements in disease activity. Combination treatment with etanercept and a DMARD was well tolerated.

Keywords: Poland - epidemiology, Incidence, Immunoglobulin G - therapeutic use, Drug Therapy, Combination, Demography, Child, Preschool, Child, Arthritis, Juvenile - epidemiology, Antirheumatic Agents - therapeutic use, Adolescent, Receptors, Tumor Necrosis Factor - therapeutic use, Registries, Tumor Necrosis Factor-alpha - metabolism