Waist circumference and pulmonary function: a systematic review and meta-analysis

Background: Studies have reported an impact of central obesity on people's health. The literature is scarce on the effects of waist circumference (WC) on pulmonary function. Our objective was to review the literature on the association between WC and pulmonary function. Methods: A systematic review was carried out in the PubMed, CINAHL, Web of Science and Scopus databases. The search included published, in press and online documents up to December 2011. A meta-analysis was carried out to obtain the pooled effect, and a meta-regression was performed to evaluate sources of heterogeneity. Results: From the 547 studies identified, 10 were included. The meta-analysis revealed an inverse relationship between WC and pulmonary function parameters, indicating that the effect was greater among men (forced expiratory volume in 1 second (FEV1 beta = -15.9 (95% confidence interval = -23.2, -8.5); forced vital capacity (FVC) beta = -16.6 (95% confidence interval = -21.0, -12.2)) compared with women (FEV1 beta = -5.6 (95% confidence interval = -9.1, -2.1); FVC beta = -7.0 (95% confidence interval = -9.1, -4.8)). The meta-regression identified sex as the characteristic that most contributed to the heterogeneity (R-2 = 54.8% for FEV1 and R-2 = 85.7% for FVC). Conclusions: There seems to be an inverse relationship between WC and pulmonary function, mainly in men. More population-based studies should be performed, especially among children and adolescents, to confirm these findings.