Correlation Between Body Mass Index (BMI) and Severity of Bronchial Asthma in Children: A Cross-Sectional Study

Background: Nutritional status is increasingly recognised as a key modifier of asthma severity in children. Both obesity and undernutrition may influence airway inflammation and disease course through distinct mechanisms. Objective: To assess the nutritional status of children with bronchial asthma and to correlate it with the severity of asthma, with subgroup analysis by sex. Methods: A cross-sectional study with prospective data collection enrolled 42 children aged 5-18 years with physician-diagnosed bronchial asthma at a tertiary paediatric centre (June 2020 to December 2021). Asthma severity was graded using the Global Initiative for Asthma (GINA) criteria. Nutritional status was assessed by body mass index (BMI) for age plotted on the World Health Organization (WHO) gender-specific growth charts. Associations were tested with Fisher's exact test; a two-sided p-value of less than 0.05 was considered significant. Results: Of the 42 children, 25 (59.52%) had a normal BMI, 8 (19.05%) were overweight or obese, 7 (16.67%) were underweight, and 2 (4.76%) were at risk of overweight. Increasing BMI was significantly associated with greater asthma severity (p=0.007). Overweight or obese children predominantly had moderate persistent asthma (four of eight; 50.00%). The association was statistically significant in boys (p=0.012), but not in girls (p=0.30). Conclusion: Higher BMI significantly correlates with greater asthma severity in this cohort of school-age children, driven by a more pronounced effect in boys. Given the exploratory nature of this study, these findings are hypothesis-generating. While routine nutritional assessment is a reasonable component of paediatric asthma care, prospective studies are required to demonstrate whether weight optimization directly improves asthma outcomes.