32 Methotrexate in oligoarticular juvenile idiopathic arthritis: adverse effects and outcome

Abstract Background Methotrexate (MTX) is the anti-rheumatic drug of choice in juvenile idiopathic arthritis (JIA). Its adverse effects such as intolerance occur frequently, potentially hindering its efficacy Objective To describe the frequency of MTX intolerance and its various adverse effects (AE). Results A retrospective study was conducted on the AEs associated with MTX therapy in children diagnosed with oligoarticular juvenile idiopathic arthritis followed-up at the paediatric emergency and outpatient department of the children's hospital in Tunisia between January 2005 and December 2021. Among 95 cases, only 70 patients were included into the study, of whom 55 (78.5%) were girls. The median age at diagnosis was 5.9 years. Of these, 39/70 (55.7%) had required the use of MTX. The use of MTX was early (within the first 6 months after diagnosis) in 61.5% of cases. The initial median weekly dose was 11.4 mg/m². MTX intolerance was noted in 35.8% of cases. Management of intolerance included change in the dose, education and counselling. Adverse events led to MTX withdrawal in only one patient (2.5%). The adverse effects noted during the follow-up were mainly transient increased plasma transaminases (17.9%), gastrointestinal symptoms (10.2%) and cytopenia (7.6%). Impairment of kidney function and behavioural problems were not noted in any of our patients. The medium duration of the treatment was 3.8 years. The evolution was marked by the occurrence of a relapse of the disease after discontinuation of MTX in 14/33 cases (42.4%). The addition of biotherapy was necessary in 10/39 cases (25.6%). Only 7% of children have persistent joint stiffness or deformity. Conclusion In JIA, it is important to start effective treatment early to avoid long-term sequelae, such as joint damage. MTX adverse effects such as MTX intolerance occur frequently, potentially hindering its efficacy. To avoid inefficacy, the physician should be timely aware of these adverse events.