BackgroundMethotrexate (MTX) is a gold standard for treatment of juvenile idiopathic arthritis (JIA) patients. The main adverse events (AE) related to the MTX are intolerance, increased rate of infections, elevation of the liver enzymes, hematological abnormalities and stomatitis, which required to stop the MTX therapy [1]. In children without remission who tolerated MTX often the second-line treatment is the biologics, which may use alone or in the combination with MTX.ObjectivesThe aim of our study was to evaluate the main reasons of MTX discontinuation in JIA children who started first biologic.MethodsIn the study were included 173 non-systemic JIA patients, whom biologic therapy was prescribed firstly to previous MTX treatment. We evaluate the main reasons of MTX discontinuation after the starting of the biologic treatment, duration of MTX treatment (all and after biologic start), achievement the remission, according C. Wallace criteria and time to remission, flare of JIA. We compared two groups: i) patients with biologics with ongoing methotrexate and ii) patients with biologics alone, whom MTX was discontinued or not prescribed.ResultsDuring the trial MTX discontinued 40 (23.1%) patients: due to intolerance (n=11), other adverse events (AE) (n=10), except intolerance (mainly, frequent infection and transaminitis) and remission of JIA (n=19). Patients with onset age of JIA <4.4 years were in the risk of developing MTX intolerance (LogRank test, p=0.000001), but the younger patients usually developed other AE. Compare of the three subgroups of patients, who discontinued MTX we have not yet found any differences, except the onset age and frequency of remission, which was higher in patients who discontinued MTX due to other AE than due to intolerance.ConclusionThe main factor, associated with MTX discontinuation in JIA patients, who received first biologic was the disease onset age. Eldest age was related to higher risk of developing the MTX intolerance.References[1] van Dijkhuizen EH, Pouw JN, Scheuern A, Hügle B, Hardt S, Ganser G, Kümmerle-Deschner JB, Horneff G, Holzinger D, Bulatović Ćalasan M, Wulffraat NM. Methotrexate intolerance in oral and subcutaneous administration in patients with juvenile idiopathic arthritis: a cross-sectional, observational study. Clin Exp Rheumatol. 2016;34(1):148-54.Disclosure of InterestsNone declared

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