Asthma in patients with attention-deficit/hyperactivity disorder: a nationwide population-based study.

BACKGROUND: Asthma symptoms can interrupt daily activities, disturb sleep, and increase the risk of a child having an attention deficit or irritability, which also are symptoms of attention-deficit/hyperactivity disorder (ADHD). Previous studies have shown conflicting results regarding the association between ADHD and asthma. This study investigates the possible correlation between asthma and ADHD. METHODS: We retrieved data on 221,068 pediatric patients from Taiwan's National Health Insurance Research Database in 2005, and calculated the prevalence and risk factors of allergic diseases among ADHD patients. RESULTS: The prevalence of asthma in the ADHD group, compared with the control group, was 4.3 fold higher in the age 12 to 17 subgroup (95% CI, 1.71 to 10.6), 1.5-fold higher in males (95% CI, 1.05 to 2.03), and 1.6-fold higher for children living in urban areas (95% CI, 1.12 to 2.28). Multivariate logistic regression models showed the odds ratio of asthma for children with ADHD was 1.43 (95% CI, 1.05 to 1.95) as compared with children without ADHD. CONCLUSIONS: Pediatric ADHD was associated positively with asthma, but the underlying mechanisms require further clarification.