Abdominal obesity and late-onset asthma: cross-sectional and longitudinal results: the 3C study.
Whereas global obesity assessed by BMI has been related to asthma risk, little is known as to the potential implication of abdominal adiposity in this relationship. In the elderly, in whom asthma remains poorly studied, abdominal adiposity tends to increase at the expense of muscle mass. The purpose of this study was to investigate the association between abdominal adiposity, assessed by waist circumference (WC), and prevalence and incidence of asthma in a large elderly cohort. Cross-sectional analysis was based on 7,643 participants aged ?65 years including 592 (7.7%) with lifetime physician-diagnosed asthma. Longitudinal analysis involved 6,267 baseline nonasthmatics followed-up for a period of 4 years, 67 of whom exhibited incident asthma. Baseline WC was categorized according to sex-specific criteria (men/women): <94/80 cm (reference), [94-102[/[80-88[ (abdominal overweight), and ?102/88 (abdominal obesity). Logistic and Cox regression models estimated asthma risk associated with WC after adjustment for age, sex, educational level, smoking status, BMI, physical ability, dyspnea, chronic bronchitis symptoms and history of cardiovascular disease. At baseline, asthma risk increased with increasing WC independently of BMI and other confounders (adjusted odds ratio (ORa), 95% confidence interval (CI): 1.30, 1.02-1.65 and ORa: 1.76, 1.31-2.36 for abdominal overweight and obesity, respectively). Asthma incidence was related to WC (hazard ratio (HRa), 95% CI: 2.69, 1.21-5.98 and HRa: 3.84, 1.55-9.49, for abdominal overweight and obesity, respectively). Estimates were similar in both sexes. In the elderly, abdominal adiposity was independently associated with increased prevalence and incidence of asthma. Studies aiming to understand the mechanisms involved in the adiposity-asthma link are needed.