Changes in body mass index during childhood and risk of various asthma phenotypes: a retrospective analysis
Over the last few decades, the concomitant increases in the prevalence of asthma and obesity in children have emphasized the importance of assessing the putative relationship between these two conditions 1. Several studies have established a link between current overweight and asthma 2. In these studies, overweight was measured as high body mass index (BMI), a reliable marker of the body's density. Other studies have shown that early overweight 5 or rapid growth during the first two years of life 6 is associated with an increased risk of later wheeze or asthma. Despite these findings, the nature of the association between overweight and asthma is not completely understood, and only few studies investigated BMI status change during childhood and the risk of allergic asthma 7. In addition, it remains unclear whether childhood asthma is associated with early or current overweight and how BMI status changes during childhood may affect the risk of asthma.
The inconsistent or conflicting results from previous studies may be related to the use of different definitions of asthma, hence different asthma phenotypes, different confounding factors, different age of the study populations, and different time points at which BMI has been assessed. Thus, we chose to explore the association between changes in BMI status between birth and the age of 9–11 years and the risk of non‐allergic and allergic asthma, and the risk of other phenotypes such as exercise‐induced asthma, which has never been investigated in previous study on BMI changes. Our study population was a representative sample of primary school children in France.