Comparative analysis of the etanercept efficacy in children with juvenile idiopathic arthritis under the age of 4 years and children of older age groups using the propensity score matching method

Abstract

Objective: The aim of this study was to analyze the efficacy and safety of etanercept (ETA) in children with juvenile idiopathic arthritis (JIA) under the age of 4 years and to compare the data with those for older age groups.Methods: Three groups comprising 34 patients each (total of 102 patients) were selected using the propensity score matching (PSM) method. The study group (patients under the age of 4 years; the Junior group (JNR)) was compared with patients of the older age groups, adjusted for criteria such as gender, JIA category, JIA severity, and either age at disease onset (the Reference by Age of disease Onset (RAO) group) or disease duration (the Reference by Disease Duration (RDD) group).Results: All three groups showed a good response to ETA therapy. During the follow-up period, only 4 (3.9%) patients failed to reach American College of Rheumatology (ACR) Pediatric criteria improvement at ACR50 level. In the JNR group, 82.4% of patients achieved ACR90 within a median time of 3 months (IQR, 3–6 months), which was a better result compared to the other two groups: 61.8% (RAO group) and 58.8% (RDD group) of patients achieved ACR90 within 6 (Interquartile Range (IQR), 3–9) months (p = .028). Three (9%) patients in the JNR group and none of the RDD and RAO groups discontinued treatment because of clinical remission (p = .045).Conclusion: An analysis of the ETA efficacy in different age groups comparable in terms of the diagnosis and disease severity demonstrated a higher efficacy of earlier ETA therapy in children of the same age at disease onset. In children at the early stage of arthritis (≤ 2.5 years long), ETA was more efficient in those with an earlier disease onset.