Association of body mass with pulmonary function in the Childhood Asthma Management Program (CAMP)

TLDR

BMI has been linked to asthma incidence and prevalence, but the underlying mechanisms remain unclear. The study aimed to test whether BMI independently associates with asthma severity in children with mild to moderate asthma in CAMP. The authors performed a multivariable cross‑sectional analysis of BMI against asthma severity outcomes in CAMP participants. BMI was not linked to symptoms or atopy, but higher BMI correlated with greater FEV1 and FVC while reducing the FEV1/FVC ratio, suggesting a potential impact on asthma severity.

Abstract

<b>Background:</b> While increases in body mass index (BMI) have been associated with the incidence and prevalence of asthma, the mechanisms behind this association are unclear. <b>Methods:</b> We hypothesised that BMI would be independently associated with measures of asthma severity in a population of children with mild to moderate asthma enrolled in the Childhood Asthma Management Program (CAMP). A multivariable baseline cross sectional analysis of BMI with our outcomes of interest was performed. <b>Results:</b> BMI was generally not associated with symptoms, nor was it associated with atopy. While BMI was positively associated with the methacholine concentration that causes a 20% fall in forced expiratory volume in 1 second (PC₂₀FEV₁), this association did not persist after adjustment for FEV₁. Increasing BMI was associated with increasing FEV₁ (β = 0.006 l, 95% CI (0.001 to 0.01)) and forced vital capacity (FVC) (β = 0.012 l, 95% CI (0.007 to 0.017)). However, decrements in the FEV₁/FVC ratio were noted with increasing BMI (β = −0.242, 95% CI (−0.118 to −0.366)). Thus, an increase in BMI of 5 units was associated with a decrease in FEV₁/FVC of over 1%. <b>Conclusions:</b> Although the association of FEV₁ and FVC with BMI did not support our initial hypothesis, the decrease noted in the FEV₁/FVC ratio has potential relevance in the relationship between BMI and asthma severity.