Smoking habits, waist circumference and coronary artery disease risk relationship: the PRIME study.

Introduction: Abdominal obesity is an important risk factor for coronary artery disease (CAD). The extent to which tobacco exposure influences the effect of abdominal adiposity on CAD incidence remains uncertain. Therefore, the goal of this study was to assess the effects of tobacco exposure on CAD risk associated with abdominal obesity.

Methods: A cohort of 9763 men, aged 50-59 years, without known CAD was followed 10 years for CAD events. Risk factors were recorded using a questionnaire, a clinical examination, including waist circumference (WC) and waist-to-hip ratio (WHR) and biological measurements. Cox regression was used for statistical analyses.

Results: During follow-up, there were 659 incident CAD events. BMI, WC, WHR, blood pressure, cholesterol, high-density lipid cholesterol and triglycerides, physical activity and alcohol intake varied across smoking exposure categories. The incidence of CAD increased across tertiles of waist circumference in never (5.1, 6.1 and 7.2 CAD events/1000 in first, second and third tertiles of WC distribution, respectively), former (6.6, 7.8 and 9.3 events/1000, across tertiles) and current smokers (9.4, 11 and 13.1 events/1000, across tertiles). After adjusting for age, centre, educational level, alcohol intake and physical activity, the relative risk of CAD was 1.28 (1.08-1.51) for 1 standard deviation increase of WC in never smokers, 1.23 (1.08-1.38) in former smokers and 1.14 (1.00-1.29) in current smokers. Similar results were observed for WHR. No evidence for heterogeneity among tobacco exposure strata for both WC and WHR was observed.

Conclusion: In conclusion, the relative risk of CAD associated with abdominal obesity is homogeneous in never, former and current smokers. Therefore, smokers with abdominal obesity are at high absolute risk of CAD.