The Role of Childhood Asthma in Obesity Development: A Nationwide U.S. Multi-cohort Study.

Rationale Asthma and obesity often co-occur. It has been hypothesized that asthma may contribute to childhood obesity onset. Objectives To determine if childhood asthma is associated with incident obesity and examine the role of asthma medication in this association. Methods We studied 8716 children between ages 6-18.5 years who were non-obese at study entry participating in 18 U.S. cohorts of the Environmental influences on Child Health Outcomes program (among 7299 children with complete covariate data mean [SD] study entry age=7.2 [1.6] years and follow-up=5.3 [3.1] years). Measurements and main results We defined asthma based on caregiver report of provider diagnosis. Incident obesity was defined as the first documented body mass index ≥95th percentile for age and sex following asthma status ascertainment. Over the study period, 26% of children had an asthma diagnosis and 11% developed obesity. Cox proportional hazards models with sex-specific baseline hazards were fitted to assess the association of asthma diagnosis with obesity incidence. Children with asthma had a 23% (95%CI: 4%, 44%) higher risk for subsequently developing obesity compared to those without asthma. A novel mediation analysis was also conducted to decompose the total asthma effect on obesity into pathways mediated and not mediated by asthma medication use. Use of asthma medication attenuated the total estimated effect of asthma on obesity by 64% (excess HR:-0.64 [95%CI:-1.05,-0.23]). Conclusions This nationwide study supports the hypothesis that childhood asthma is associated with later risk of obesity. Asthma medication may reduce this association and merits further investigation as a potential strategy for obesity prevention among children with asthma.