Abstract
Background: We tested the hypothesis that multiple obesity-related risk
factors (obesity, physical activity, cardiopulmonary physical fitness,
sleep-disorder breathing (SDB), and sleep quality) are associated with
childhood asthma using a Mendelian randomization (MR) design.
Furthermore, we aim to investigate whether these risk factors were
associated with incident asthma prospectively. Methods: In total, 7069
children aged 12 from the Taiwan Children Health Study were enrolled in
the current study. Cross-sectional logistic regression, one-sample MR,
summary-level MR sensitivity analyses, and prospective survival analyses
were used to investigate each causal pathway. Results: In MR analysis,
three of the five risk factors (obesity, SDB, and sleep quality) were
associated with asthma, with the highest effect sizes per interquartile
range (IQR) increase observed for sleep quality (odds ratio [OR]
=1.42; 95% confidence interval [CI]: 1.06 to 1.92) and the lowest
for obesity (OR = 1.08; 95% CI: 1.00–1.16). In the prospective
survival analysis, obesity showed the highest risk of incident asthma
per IQR increase (hazard ratio [HR] = 1.28; 95% CI: 1.05 to 1.56),
followed by SDB (HR = 1.18; 95% CI: 1.08 to 1.29) and sleep quality (HR
= 1.10; 95% CI: 1.03 to 1.17). Conclusion: The most plausible risk
factors for asthma were obesity, SDB, and poor sleep quality. For the
prevention of childhood asthma, relevant stakeholders should prioritize
improving children’s sleep quality and preventing obesity comorbidities
such as SDB.