An investigation of the association between Juvenile rheumatic disease and growth: a retrospective matched cohort study.

Childhood-onset rheumatic diseases including Juvenile Idiopathic Arthritis (JIA), Juvenile Systemic Lupus Erythematosus (jSLE), and Juvenile Dermatomyositis (JDM) could impact growth, but this is not well described within the UK population, particularly over the long term. This study aims to compare the growth patterns of patients with JIA, jSLE, and JDM to those of their peers. This population-based cohort study used primary care data from the Clinical Practice Research Datalink (CPRD) with follow up through to March 2023. Patients diagnosed with JIA, JDM and jSLE, were matched with up to five healthy controls by age, sex and general practice. Age and sex standardised Z-scores were calculated for height and weight. Linear mixed models were used to investigate differences in growth patterns over time. Height measurements from 3736, 182 and 111 children with JIA, jSLE and JDM and weight measurements from 5088, 251 and 144 children with JIA, jSLE and JDM respectively were extracted. JIA patients showed significant baseline differences in height compared to healthy controls (Estimate= -0.061, 95% CI 0.002, 0.121) but this initial reduction was countered by an increased rate of catch up growth over time. Similar patterns were observed in jSLE and JDM, although differences were less consistent and largely confined to specific subgroups. Overall, weight trajectories were broadly similar to those of matched controls across all three diseases. Stratified analyses suggested that growth patterns varied according to age at disease onset, with the clearest differences observed in JIA. Children with JIA, jSLE and JDM demonstrated altered longitudinal growth patterns, with the clearest evidence observed in JIA. Growth trajectories varied according to age at disease onset, particularly during the pre and peri-pubertal period, suggesting that the timing of disease onset may influence long-term growth. These findings support the importance of longitudinal growth monitoring, particularly among children diagnosed during key developmental periods.