To investigate the frequency of arthritis flare and factors affecting occurrence of flare in children with juvenile idiopathic arthritis (JIA) who achieved inactive disease (ID) with methotrexate (MTX) monotherapy.
A total of 217 patients were included. The modality of treatment discontinuation, time of MTX withdrawal, and disease course were examined retrospectively. For each patient, the first episode of ID after MTX start was evaluated. Patient follow-up was censored at occurrence of flare or at last visit with persistent ID.
170 patients (78.3%) had arthritis flare after a median of 1.6 years, whereas 47 (21.7%) maintained ID until last visit, after a median of 3 years. 54.2% of patients had discontinued MTX after ID, whereas 45.8% were still receiving MTX at the time of study censoring. Among patients who had MTX withdrawn, the median interval between ID and MTX stop was 1.5 years. Occurrence of flare was more common in patients who were still receiving MTX at study censoring than in those who had discontinued MTX (p<0.001). Most patients (78.8%) had MTX tapered over time by increasing the interval between doses. Tapering modality was comparable between patients with flare and persistent ID. Only 7.7% of the patients had a biologic DMARD started at the time of flare.
Our results confirm that children with JIA who achieve ID with MTX monotherapy have a high risk of arthritis flare. The risk of flare was independent of withdrawal strategy. Most flare episodes were not treated with biologic therapy.