Smoking habits and incidence of cardiovascular diseases in men and women: findings of a 12 year follow up among an urban Eastern-Mediterranean population

Background Despite the strong association of smoking with cardiovascular disease (CVD) and cerebral stroke, the consequences of smoking have not been elucidated among Iranian populations. This study aimed to assess sex-specific incidence of CVDs among an urban Iranian population with different smoking habits. Methods Participants were recruited from the Tehran Lipid and Glucose Study (TLGS). Data on socio-demographic features and smoking habits from a sample of 10,400 individuals (4378 men and 6022 women), aged >= 20 years without prior CVD history were analyzed. Participants were followed up for 12 years for incidence of CVD/CHD events. Men were categorized in six groups, including never-, passive, ex-, passive and ex-, occasional and daily smokers. Women were categorized in three groups, i.e. never smokers, passive smokers and ever smokers. Using cox regression model, adjusted hazard ratios (HRs) of incident CVD/CHD were calculated for each group, given never smokers as the reference. Results In men, HR of CVD was 1.13 (95%CI: 0.80-1.59) in passive smokers, 1.23 (95%CI: 0.91-1.66) in ex-smokers, 1.46 (95%CI: 0.90-2.36) in passive and ex-smokers, 2.33 (95%CI: 1.25-4.33) in occasional smokers and 2.05 (95%CI: 1.57-2.67) in daily smokers. In smokers of >= 21 cigarettes/day, HR of CVD was 3.79 (95%CI: 2.25-6.37), with less risk observed in those who smoked lesser numbers of cigarettes/day. Quitters of >= 15 years were almost risk free. In women, none of the HRs of CVD/CHD were significant. Conclusion An increased risk of incidence of CVD/CHD was found in current male smokers. To confirm and further elaborate these findings, more data of sex-specific studies are required from culturally diverse urban and rural areas of Iran.