Background: Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease that includes seven heterogeneous subgroups with different prognoses. In particular, polyarticular JIA (pJIA) has a longer period of active disease and a poorer prognosis. Tumor necrosis factor (TNF)-alpha inhibitors are effective in patients with pJIA, but the therapeutic regimen remains controversial. Here, we performed a single-center study to determine the potential correlation between TNF-alpha inhibitor (infliximab) therapy and outcomes in these patients.

Methods: Clinical data of 40 pJIA patients were collected at our center from January 1, 2010 to January 1, 2018, and patients were grouped according to the timing of infliximab therapy. The erythrocyte sedimentation rate (ESR), the number of joints with active disease, and the 27-point juvenile arthritis disease activity score (JADAS-27) were analyzed.

Results: The ESR, the active joint count, and the JADAS-27 decreased significantly in all groups after 3 months

(P = 0.041/0.415/0.008, 0.022/0.030/ < 0.001, and 0.05/0.012/ < 0.001, respectively) and 6 months (P = 0.036/0.045/0.041, 0.076/0.037/ < 0.001, and 0.096/0.006/ < 0.001, respectively) of infliximab treatment, although the rates of change of these parameters were similar. However, after 12 months, only patients treated with infliximab within 3 months of disease onset had a stable ESR, active joint count, and JADAS-27, while these parameters increased sharply when infliximab was administered 3 months and especially 1 year after disease onset.