How does autism spectrum disorder affect the risk and severity of childhood asthma?

Abstract Background Autism spectrum disorder (ASD) and asthma are among the most common chronic disorders in childhood. Both are associated with altered immune regulation and share several risk factors. The effects of ASD on risk for later asthma and asthma severity remain unclear. Objective To determine whether ASD in children increases the risk of incident asthma and worsens asthma severity. Methods We performed 2 distinct analytic designs (case-control and retrospective longitudinal cohort) using a multistate electronic health records database to assess the odds of new asthma and asthma severity among children with ASD. In both designs, children with ASD were matched with children without ASD according to sex, age, race, ethnicity, location, and insurance status. Pulmonary function, controller medication prescriptions, asthma exacerbations, and asthma-related hospitalizations were collected. The effects of ASD on asthma risk and severity were assessed using multivariable linear and logistic regression. Results Among children with asthma, ASD was associated with reduced exacerbations (odds ratio [OR], 0.71; 95% confidence interval [CI], 0.54–0.92), better forced expiratory volume in 1 second/forced vital capacity ratio (0.876 vs 0.841, P < .001), and lower odds of airflow obstruction (OR, 0.53; 95% CI, 0.31–0.90) but had higher odds of asthma controller prescription (OR, 2.18; 95% CI, 1.62–2.93). In a longitudinal analysis of children without asthma, ASD was found to be protective for new asthma (OR, 0.44; 95% CI, 0.26–0.74). Conclusion Among children with asthma, concomitant ASD is associated with better asthma-related outcomes but a higher controller treatment burden. In addition, our data did not support ASD as a risk factor for incident asthma.