Rheumatoid factor value for determining the first biologic agent to use for non-systemic juvenile idiopathic arthritis

Currently, no indicators on which biologic disease-modifying anti-rheumatic drugs (bDMARDs) should be used first for juvenile idiopathic arthritis (JIA) have been established. Thus, this study aimed to determine the useful biomarkers in JIA to enable the best selection of the first bDMARDs without primary failure.This retrospective study used data of patients examined for JIA between 2015 and 2021 at Kagoshima University Hospital in Japan.Altogether, 67 cases of non-systemic JIA were analyzed, excluding cases that had been treated for <6 months. Of the 67 cases, 52 were treated with bDMARDs and all rheumatoid factor (RF)+ types (32 cases) were treated with bDMARDs. Eleven cases (31.4&) (all were RF+ types and used anti-tumor necrosis factor (TNF)α agents) switched to other bDMARDs because of primary failure, and nine cases had secondary failure (6;anti-TNF, 3;anti-Interleukin-6). A significant difference in pre-treatment RF values (177.9 vs 25.7 IU/ml, p = 0.002) and presence (Odds Ratio 1.952,p = 0.004) were observed between the primary failure group and effective group.RF+ JIA required bDMARDs with high probability. JIA with high titre of RF tends to be refractory to anti-TNFα agents. Tocilizumab or abatacept could be a first-choice bDMARD in such cases.