Relationship between Changes in Body Mass Index and Pulmonary Function in Adults

ABSTRACT

BACKGROUND: Obesity is linked to a wide range of respiratory diseases. Several studies have shown that body weight at baseline and weight change were related to pulmonary function. The purpose of this study was to investigate the relationship between change in body mass index (BMI) and pulmonary function in adults. METHODS: Of those aged 40-64 years at baseline who had initially visited the health promotion center at one university-level hospital from January 2000 to December 2002, 499 (men 309, women 190) patients revisited the center over a 5-year period up to December 2009 and were enrolled in the study. Subjects were classified into 4 groups- group 1 normal-normal, group 2 normal-obese, group 3 obese-normal, and group 4 obese-obese, based on their BMI at baseline and follow-up. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC were measured by spirometry. RESULTS: Change in FEV1/FVC was significantly associated with change in BMI for men in all 4 groups. Change in FEV1/FVC was significantly different between group 1 and 3 and between group 1 and 4. Changes in FEV1, FVC and FEV1/FVC were significantly associated with change in BMI for women in all 4 groups. Change in FEV1 was significantly different between group 3 and 4, and change in FVC was significantly different between group 1 and 3. CONCLUSIONS: These results suggest that a change in BMI is negatively associated with change in pulmonary function. Obesity itself can be a risk factor for pulmonary dysfunction, and a decrease in BMI through weight reduction could reduce pulmonary dysfunction or improve pulmonary function in adults.