Association between asthma and juvenile idiopathic arthritis in children in the United States: a propensity score weighted cross-sectional study.

BACKGROUND: Asthma and juvenile idiopathic arthritis (JIA) are common pediatric inflammatory conditions that may share immunologic and environmental risk factors. Previous studies have reported inconsistent associations and often lacked rigorous control for confounding. This study investigated whether asthma is associated with increased odds of JIA in a large, population-based sample. METHODS: We analyzed data from 169,786 participants aged 0–17 years from six cycles of the National Survey of Children’s Health (2016–2021). Parent-reported and provider-diagnosed asthma and JIA were identified using survey-based measures, which may be subject to misclassification. Propensity score weighting (PSW) using generalized boosted modeling was applied to balance demographic, perinatal, socioeconomic, and environmental covariates. Logistic regression estimated odds ratios (ORs) before and after weighting, with sensitivity analyses using trimmed (1st − 9th percentile) and capped (≤ 30) weights. RESULTS: Among 14,236 children with asthma, JIA prevalence was 0.81% compared with 0.23% among 155,550 without asthma. Unweighted models showed higher odds of JIA in children with asthma (OR = 3.56; 95% CI: 2.87–4.38; p < 0.0001). After PSW adjustment, the association remained significant though attenuated (OR = 2.10; 95% CI: 1.56–2.81; p < 0.0001). Results were consistent across double-adjusted and sensitivity analyses. CONCLUSIONS: Several covariates (age, sex, and race/ethnicity) were statistically associated with JIA within the model; however, these were included for adjustment purposes and were not primary parameters of interest. After adjusting for sociodemographic and environmental confounders, asthma was independently associated with approximately twice the odds of JIA. These findings suggest shared inflammatory mechanisms between asthma and autoimmune disease and highlight the importance of early monitoring for rheumatologic symptoms in children with chronic airway inflammation. Given the survey-based outcome definition, findings should be interpreted with appropriate caution.