THU0556 Impact of methotrexate on growth in children with juvenile idiopathic arthritis
Authors: A. Fazaa, M. Sellami, K. Ouenniche, S. Miladi, S. Kassab, S. Chekili, K. Ben Abdelghani, A. Laatar
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Juvenile idiopathic arthritis (JIA) is a heterogeneous group of chronic inflammatory disease which could be responsible for functional impairment and severe growth disturbance. Conventional disease-modifying antirheumatic drugs, such as methotrexate (MTX), may improve growth velocity especially by regulating systemic inflammation. <h3>Objectives</h3> The objective of this study was to evaluate the effect of MTX on growth parameters in pre-pubertal children with JIA and to determine the factors affecting the growth velocity. <h3>Methods</h3> We assessed height and changes in the height standard deviation score (SDS) at disease onset, at the onset of MTX and at the last follow-up visit in a cross-sectional study of JIA children. All patients were pre-pubertal when MTX began and were followed for at least 6 months afterward. We compared growth parameters (height, growth rate, weight and body mass index (BMI)) in responders and non-responders to MTX. The growth rate was defined as the number of millimetres of height acquired during 1 year. Associations between changes in the height SDS and discrete variables were evaluated using chi-square or Fisher's exact tests. The significance level was set at 0.05. <h3>Results</h3> We enrolled 36 pre-pubertal children with JIA (24 boys and 12 girls) who had been treated with MTX orally. Median patient age was 6.2 years<sup>4–13</sup> at the onset of MTX and 8.4 years [6.1–14.9] at the latest follow-up. The median disease duration was 2.7 years [2.5–5.3]. Twenty-one patients (58.3%) had oligoarticular JIA, 2 patients (5.5%) had systemic JIA, 10 (27.7%) had polyarticular JIA and 3 (8.3%) had enthesitis-related arthritis. Nineteen children (52.7%) had received corticosteroids during an average period of 1.7 years [0.6–3] with a mean of 10 mg/day of prednisone or equivalent. The median duration of MTX at the latest follow-up was 3.1 years [0.62–5.5] with a mean MTX dose of 10 mg/m2/week.<sup>10–15</sup> Twenty-eight patients responded to MTX treatment and 8 did not. There were no significant differences between the responders and non-responders for age at treatment initiation, disease duration and mean MTX dose. At MTX onset, no significant differences between the two groups in terms of height (p=0.52), growth rate (p=0.08), weight (p=0.74) and BMI (p=0.9) were found. One year after MTX therapy, mean height (0.2 versus −1.1; p=0.03), mean growth rate (0.5 versus –2.9 SDS; p=0.01), mean weight (0.4 versus −2.3 SDS; p=0.01) and mean BMI (0.6 versus −1.9; p=0.04) were significantly higher in the responder group than in non responders, respectively. At the latest follow-up, this increase was significantly maintained for growth rate (p=0.001) and height (p=0.002) in the responder group. In the multivariate analysis, patients who required more than 10mg/m<sup>2</sup>/week of MTX, systemic JIA and patients with reliance on steroids had a significantly lower growth velocity after the onset of MTX (p&lt;001, p=0.02, p=0.02 respectively). <h3>Conclusions</h3> In our study, the increase in growth parameters in pre-pubertal children with JIA was associated with a better control of the disease activity under MTX therapy. <h3>Disclosure of Interest</h3> None declared