Supplementary Material for: Associations of atopic dermatitis with attention deficit/hyperactivity disorder and autism spectrum disorder: a systematic review and meta-analysis

Background: Atopic dermatitis (AD) shares similarities with attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) regarding pathogenesis involving inflammation and genetics. Nevertheless, evidence on the associations of AD with ADHD and/or ASD is inconclusive. This study aimed to systematically examine the existing evidence on the associations between AD, ADHD, and ASD. Methods: The Meta-analysis of Observational Studies in Epidemiology guideline was followed. We searched MEDLINE, Embase, Cochrane Library, and Web of Science databases from their respective inceptions through February 4, 2022. Observational studies providing adjusted estimates and/or prevalences for ADHD and ASD in patients with AD were enrolled. A random-effects model meta-analysis was conducted to calculate pooled odds ratios (ORs) and confidence intervals (CIs). Subgroup analyses according to AD severity, age, geographic location, and study design were performed. Results: Overall, a total of 24 studies with 71,373,639 subjects were enrolled. Our meta-analysis demonstrated significant associations of AD with ADHD (pooled OR, 1.28; 95% CI, 1.18–1.40) and ASD (pooled OR, 1.87; 95% CI, 1.30–2.68). Subgroup analyses revealed that the associations for ADHD were most prominent in studies evaluating severe AD patients as well as in studies focusing on school-age children and adolescents. Among patients with AD, the pooled prevalence of ADHD was 6.6% and the respective prevalence of ASD was 1.6%. Conclusion: The evidence to date suggests significant associations of AD with ADHD and ASD. Psychiatric consultation and an interdisciplinary approach would benefit patients with AD presented with behavioral symptoms suggestive of ADHD or ASD.