Sex specificity of asthma associated with objectively measured body mass index and waist circumference - The Humboldt study

Study objective: To investigate the possibility of sex specificity for the association of obesity and asthma using objective measures of body mass index (BMI) and waist circumference (WC). Design: Cross-sectional study of adults (n = 2,057) living in Humboldt, SK, Canada in 2003. Setting: A rural community. Measurements: Ever-asthma was defined as lifetime physician-diagnosed asthma, and recent asthma was defined as asthma diagnosed by a physician during the past 12 months. BMI and WC were objectively measured. Results: Among the participants, 5.6% of men and 10.0% of women reported having ever-asthma, and 2.7% and 6.0% had recent asthma, respectively. Higher levels of both BMI and WC were significantly associated with asthma in women but not in men. The adjusted odds ratios for women with a BMI of at least 30.0 kg/m(2) relative to women with a BMI of < 25.0 kg/m(2) were 2.06 (95% confidence interval [CI], 1.42 to 4.05) for ever-asthma and 3.47 (95% CI, 1.64 to 7.32) for recent asthma. Conclusions: Our study demonstrated that the increased risk of asthma associated with obesity was only significant in women but not in men even when BMI was objectively measured, and this association was robust to the anthropometric measures.