Ratio of waist circumference to chest circumference is inversely associated with lung function in Chinese children and adolescents

Background and objective: In White children, waist circumference (WC) is positively correlated with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Because fat distribution differs among different races, the relationship between WC and lung function in Asian children may differ from that in White children. The present study aimed to examine the effect of WC on ventilatory function in Chinese children. Methods: A cross-sectional study was performed on 1572 healthy subjects aged 918 years. Height, weight, chest circumference (CC), WC and lung function (FVC, FEV1, peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF)) were measured. To avoid the problem of colinearity, a model that combined CC and WC as the waist-to-chest ratio (WCR) was used. The relative contributions of WCR and body mass index (BMI) to spirometric parameters were determined by linear regression analysis. Results: WCR was inversely associated with all spirometric parameters. On average, each 0.01 increase in WCR was associated with decreases of 8.14 mL for FVC, 9.36 mL for FEV1, 6.54% for FEV1/FVC, 19.81 mL/s for PEF and 17.25 mL/s for MMEF. BMI was positively associated with all spirometric parameters except FEV1/FVC. These results suggest that WC was inversely associated with lung function parameters. Conclusions: Inverse associations were identified between WCR, as well as WC, and lung function in a population of Chinese children. The underlying mechanisms need to be further explored.