The Role of Childhood Asthma in Obesity Development: A Nationwide US Multicohort Study

Abstract

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 8,716 children between ages 6 and 18.5 years who were nonobese at study entry participating in 18 US cohorts of the Environmental influences on Child Health Outcomes program (among 7,299 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% confidence intervals [CI] = 4, 44) higher risk for subsequently developing obesity compared with 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 hazard ratios = 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.

Figure 1:

Flow diagram depicting exclusion of participants and exposure definition for asthma in the study. Obesity status at baseline could not be determined when body mass index (BMI) information was missing at baseline. Subset with complete data is a subset of the full study sample with no missing values for the covariates birth year, ethnicity/race, maternal education, maternal asthmatic history, parity, prenatal maternal smoking, and birth weight.

Figure 2.

Graph depicting a direct effect of childhood asthma on obesity risk and an indirect effect mediated through asthma medication use.

Figure 3.

Interpretations for effect estimates of being asthmatic on risk of childhood obesity from the mediation-interaction decomposition analysis using the counterfactual framework.