Abstract
BACKGROUND: To investigate the longitudinal effects of obesity on change in lung function after 1 year of follow-up in obese children and adolescents. METHODS: Obese children/adolescents aged 8-15 years with pulmonary function test (PFT) results and recorded anthropometric obesity indices from 1 year earlier for comparison were recruited. Multiple linear regression of change in each lung function parameter was applied to determine the effect of sex, change in body mass index (ΔBMI), change in chest circumference (ΔCC), change in waist circumference (ΔWC), and change in waist circumference-to-height ratio (ΔWC/Ht). RESULTS: Sixty-six children/adolescents (mean age: 12.5 ± 2.6 years) were recruited. Multiple linear regression analysis showed that ΔWC negatively affects the ratio of the forced expiratory volume in the first 1 s to the forced vital capacity of the lungs Δ(FEV(1)/FVC) (b = -0.3, p = 0.002), forced expiratory flow rate within 25-75% of vital capacity (ΔFEF(25-75%)) (b = -0.92, p = 0.006), and Δ(FEF(25-75%)/FVC) (b = -0.99, p = 0.003). When replacing ΔWC with Δ(WC/Ht) as the independent variable, Δ(WC/Ht) also negatively affects Δ(FEV(1)/FVC) (b = -33.71, p = 0.02), ΔFEF(25-75%) (b = -102.9, p = 0.03) and Δ(FEF(25-75%)/FVC) (b = -102.7, p = 0.03). CONCLUSION: After 1 year of follow-up, change in abdominal adiposity determined by WC and WC/Ht exerted significant negative effect on lung function change specific to FEV(1)/FVC, FEF(25-75%) /FVC, and FEF(25-75%). IMPACT: Longitudinal effects of change in obesity on lung function in obese children and adolescents are evidenced. Change in waist circumference or waist-to-height ratio, which indicates abdominal adiposity, was inversely correlated with a change in FEV1/FVC, FEF25-75% /FVC, and FEF25-75% in children and adolescents with obesity after 1 year of follow-up. Our results suggest using waist circumference and/or waist-to-height ratio in addition to BW and/or BMI for monitoring obesity. Fat loss programs, especially those focused on reducing abdominal adiposity should be encouraged to prevent late lung function impairment.