Lung function impairment and metabolic syndrome: the critical role of abdominal obesity.

RATIONALE: Increased risk for cardiovascular morbidity and mortality has been related to both lung function impairment and metabolic syndrome. Data on the relationship between lung function and metabolic syndrome are sparse. OBJECTIVES: To investigate risk for lung function impairment according to metabolic syndrome traits. METHODS: This cross-sectional population-based study included 121,965 men and women examined at the Paris Investigations Préventives et Cliniques Center between 1999 and 2006. The lower limit of normal was used to define lung function impairment (FEV(1) or FVC < lower limit of normal). Metabolic syndrome was assessed according to the American Heart Association/National Heart, Lung, and Blood Institute statement. MEASUREMENTS AND MAIN RESULTS: We used a logistic regression model and principal component analysis to investigate the differential associations between lung function impairment and specific components of metabolic syndrome. Lung function impairment was associated with metabolic syndrome (prevalence = 15.0%) independently of age, sex, smoking status, alcohol consumption, educational level, body mass index, leisure-time physical activity, and cardiovascular disease history (odds ratio [OR] [95% confidence interval], 1.28 [1.20-1.37] and OR, 1.41 [1.31-1.51] for FEV(1) and FVC, respectively). Three factors were identified from factor analysis: "lipids" (low high-density lipoprotein cholesterol, high triglycerides), "glucose-blood pressure" (high fasting glycemia, high blood pressure), and "abdominal obesity" (large waist circumference). All factors were inversely related to lung function, but abdominal obesity was the strongest predictor of lung function impairment (OR, 1.94 [1.80-2.09] and OR, 2.11 [1.95-2.29], for FEV(1) and FVC, respectively). Similar results were obtained for women and men. CONCLUSIONS: We found a positive independent relationship between lung function impairment and metabolic syndrome in both sexes, predominantly due to abdominal obesity. Further studies are required to clarify the underlying mechanisms.