Body mass index and waist circumference are independent risk factors for low vital capacity among Japanese participants of a health checkup: a single-institution cross-sectional study.

Objective: This study aimed to examine the associations between obesity and percentage vital capacity (%VC), as well as lifestyle-related disorders, among Japanese participants of a voluntary health checkup.
Methods: Subjects were 7,892 individuals who participated in a medical health checkup from January to December 2007. Multivariate logistic regression analysis was performed to assess associations between low %VC (<80) and body mass index (BMI) and waist circumference (WC), as well as lifestyle-related disorders.
Results: Medical histories of hypertension and dyslipidemia were more frequent in the low %VC group than in the normal %VC group in both sexes. In men, BMI was significantly associated with low %VC (25.0 ≤ C2 < 27.5, odds ratio (OR) = 2.10; 27.5 ≤ C3 < 30.0, OR = 2.23; C4 ≥ 30.0, OR = 3.46) relative to the first category (C1 < 25.0). A significant association was also observed between WC and low %VC (85 ≤ C2 < 90, OR = 1.40; 90 ≤ C3 < 95, OR = 1.55; 95 ≤ C4, OR = 2.51; relative to C1 < 85.0 cm). In women, BMI was significantly associated with low %VC in C3 and C4 (C3, OR = 2.05; C4, OR = 2.84), and WC was significantly associated with low %VC in C4 (C4, OR = 2.32).
Conclusion: Our results suggest that obesity may be associated with restrictive pulmonary function and underscore the importance of maintaining ideal body weight for the prevention of restrictive pulmonary dysfunction.