Treatment response to etanercept in methotrexate refractory juvenile idiopathic arthritis: an analysis of predictors and long-term outcomes

The aim of the study is to evaluate the long-term outcomes, predictors, and the role of inflammatory cytokines in methotrexate (MTx) refractory juvenile idiopathic arthritis (JIA) patients. This is a retrospective cohort study. MTx refractory JIA patients who received etanercept as their first biological agent in National Taiwan University Hospital (NTUH) were enrolled. Patients were classified into remission group, non-remission group, relapsing group, and non-relapsing group according to the criteria of disease remission and disease flares defined by Wallace et al. We compared the differences in the baseline data, therapeutic responses, time to etanercept tapering, and inflammatory cytokine (IL-12p70, TNF-alpha, IL-10, IL-6, and IL-1 beta) levels between these groups. Among the 58 patients, 30 (52%) reached remission. Seventeen of the 30 patients had episodes of disease flares. We found that more patients in the remission group achieved ACR pediatric 70 response at the fourth month after etanercept treatment (p < 0.002). When comparing the relapsing group and non-relapsing group, we found that patients were more likely to have disease flares if it took longer to achieve remission (p = 0.0008). Besides, etanercept was tapered earlier in the non-relapsing group (p = 0.0006). There was no significant difference in levels of inflammatory cytokine between groups. No parameter before treatment could be used as a single predictor of long-term outcomes. However, ACR pediatric 70 response at the fourth month after etanercept treatment might predict disease remission. Besides, patients who achieved remission more rapidly were less likely to have disease flares.