Sex differences in the relationships between BMI, WHR and incidence of cardiovascular disease: a population-based cohort study.

Objective: Body mass index (BMI) is associated with increased incidence of cardiovascular disease (CVD). However, the risk could be very different for individuals with the same body mass. The present study explored whether regional fat distribution, as measured by waist-hip ratio (WHR), could modify the impact of BMI on the risk of CVD in men and women. Design: Prospective population-based study. Subjects: A total of 10369 men and 16638 women, 45-73 years old, from general population in Malmo, Sweden. Measurements: All subjects were followed over 7 years for the incidences of first-ever cardiac event (CE) and ischemic stroke in relation to BMI category (< 25.0, 25.0-29.9, >= 30.0) and WHR. Results: The prevalence of overweight and obesity was 39.4 and 13.0%, respectively. During follow-up, 1280 subjects suffered a CVD event (750 CE, 530 ischemic stroke). The risk of CVD in women increased with increasing levels of WHR, irrespective of BMI category. In men, WHR (per 1 s.d. increase) was associated with increased incidence of CVD in those with normal weight (relative risk (RR) = 1.24; 95% CI: 1.13-1.37) after adjustments for confounding factors. However, WHR was not related to CVD in overweight men (RR = 1.06; 95% CI: 0.94-1.20) or obese men (RR = 1.04; 95% CI: 0.87-1.24). A significant interaction was observed between sex and WHR on the CVD risk. Conclusion: The effect of WHR on incidence of CVD is modified by the overall body weight and by gender. WHR adds prognostic information on the cardiovascular risk in women at all levels of BMI, and in men with normal weight.