Oral or subcutaneus methotrexate: comparison of the efficacy in inducing sustained disease remission in children with oligoarticular JIA

Introduction: Methotrexate (MTX) is widely adopted as a first line treatment in moderate to severe forms of juvenile idiopathic arthritis (JIA), when NSAIDs and intra-articular corticosteroid injections are not sufficient to control joint disease. MTX is generally prescribed at 10-15 mg/m2 weekly and its administration can be either oral or parenteral (subcutaneous (SC) or intramuscular). Contrasting evidence is available in the literature about the difference in efficacy and safety of MTX, according to the route of administration. Objectives: Aim of the study is to compare the efficacy of oral versus SC MTX in inducing sustained disease remission in children with oligoarticular JIA enrolled in two prospective cohorts. Methods: Children with oligoarthritis included in 3 prospective studies were considered for inclusion: a) the TRIMECA trial (1), b) the MD-Paedigree study (2), c) the PharmaChild registry. Patient evaluated at the IRCCS Istituto Giannina Gaslini and at the Ospedale Pediatrico Bambino Gesù were included if they had received methotrexate treatment as a first line systemic medication within 6 months after disease onset and if a follow up of at least 12 month after treatment initiation was available. Patients were then grouped according to the route of MTX administration. Baseline demographic and disease features were compared between the 2 groups. Efficacy was assessed by comparing the rate of inactive disease (ID) and clinical remission on medication (CRM) at 12 months, the rate of patients changing the route of MTX administration or requiring a biologic medication due to treatment failure. Safety was assessed by comparing the frequency of treatment interruption due to side effects of MTX. Results: 79 patients were included in the study: 43 received oral MTX, 36 received SC MTX. At treatment initiation, disease duration was not different in the two groups; children receiving SC MTX were older at baseline (4.6 yrs vs. 2.5 yrs) and at disease onset (4.2 yrs vs. 2.3 yrs). Disease activity was comparable in the 2 groups, with a median of 2 active joints in both groups. Median MTX dose was 14.4 mg/m2 for oral MTX group and 15.2 mg/m2 for SC MTX (Mann-Whitney U test, p < 0.01). At 12 months, children receiving SC MTX achieved more frequently ID (84.9% vs 43.8%, Chi squared test p < 0.001) and CRM (54.5% vs 28.3%, p = 0.002). Patients in SC MTX group were more often prescribed a biologic medication (22.9% vs 6.5%, p = 0.024), but none of them were switched to the oral administration while 37% of children in oral MTX group were turned to SC MTX. One patient in both groups had MTX treatment suspended due to side effects. Conclusion: Our preliminary results support the evidence of an increased efficacy of MTX in inducing sustained disease remission when it is administered subcutaneously.