Association between obesity and lung function in South African adolescents of African Ancestry

BACKGROUND: There is a growing body of literature on the increasing prevalence of obesity in adolescents of Sub-Saharan African ancestry. However, limited data is available on the impact of obesity on pulmonary function. This study assessed the relationship between obesity and lung function in South African adolescents of African ancestry. METHODS: This was a cross-sectional study involving 10–14 year old adolescents recruited from middle schools of the Eastern Cape Province of South Africa. Anthropometric measurements were performed. Body mass index (BMI) was converted to percentiles for age and sex and used to classified obesity. Spirometry was performed to assess lung function. Chi-square test of association and binary regression analysis were used to assess the relationship between obesity and airway obstruction. Adjusted linear regression was used to determine the relationship between obesity and lung function parameters. RESULTS: A total of 540 adolescents were recruited for the study among which 77 (14.3%) were obese. Lung function parameters: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)) were higher (p < 0.001) in obese than in non-obese adolescents while peak expiratory flow (PEF) % and FEV(1)/FVC ratio were lower (p < 0.05) in obese than non-obese adolescents. Obesity was associated (χ2 = 9.614; p < 0.01) with airway obstruction and obese adolescents were over 1.5 times more likely to have pulmonary obstruction (OR: 1.57; p < 0.05) than their non-obese counterparts. Anthropometric measures were positively associated (p < 0.05) with FVC, FEV1, PEF and/or FEV(25-75) but negatively associated with FEV(1)/FVC ratio. CONCLUSIONS: Obesity was associated with airway obstruction in South Africa adolescents of African ancestry.