Relationship between BMI-SDS trajectories and childhood asthma: a prospective cohort study from the Japan Environment...

The association between obesity and asthma in children has been reported. However, despite its clinical and public health significance, the relationship between longitudinal body mass index standard deviation score (BMI-SDS) trajectories in early life and development of childhood asthma in Japan remains to be elucidated.

This study used fixed data on 11,433 parent-child pairs from the Japan Environment and Children's Study, an ongoing national birth cohort study. Information on bronchial asthma was collected from the caregiver-reported questionnaire. The association between body mass index standard deviation score (BMI-SDS) trajectories during the first 3 years of life and the risk of bronchial asthma was examined using multivariate logistic regression analysis.

Children with sustained above-average growth had a higher risk of bronchial asthma at 3 years of age, compared with those with a normative BMI-SDS trajectory (adjusted odds ratio [aOR] 1.31, 95% confidence interval [CI] 1.11-1.55, p = 0.001). At 3 years of age, the association between a persistently high BMI-SDS trajectory and bronchial asthma was more pronounced in boys than in girls (boys: adjusted OR [aOR] 1.39, 95%CI 1.12-1.73, p = 0.003 vs. girls: aOR 1.24, 95%CI 0.96-1.61, p = 0.100). At 4 years of age, similar associations were observed, while the association was stronger in boys, it was significant in girls as well.

The significance of this study is that it captures changes in BMI-SDS over time, rather than at a single point in time, our findings suggest that maintaining a normal BMI-SDS trajectory during childhood may be beneficial for asthma prevention.