[Social inequalities as a risk of ischemic heart disease--a matter of smoking habits? 17 years' follow-up in the Copenhagen Male Study]

Abstract

The Copenhagen Male Study is a prospective, cardiovascular cohort study initiated in 1970 and consisting of 5249 employed men aged from 40 to 59 years. A total of 4710 men, who had reported their tobacco habits and were initially free of ischaemic heart disease (IHD), had their mortality and morbidity recorded over a 17-year period: 585 men suffered a first incident of ischaemic heart disease, and 248 cases were fatal. There was a strong social gradient in the risk of IHD, Kendall's Tau B = 0.12, p < 0.001. After adjusting for age, blood pressure, physical activity, body mass index and alcohol consumption in a multiple logistic regression equation, men in the lowest social class had a relative risk (95% confidence interval) of IHD of: RR = 3.6 (2.5- 5.3) compared to men in the highest social class. We determined whether differences in smoking habits could explain at least some of this large increase in risk. Adjusting for the above factors as well as the form of tobacco smoked, the amount of tobacco smoked and presence or absence of inhalation had very little effect on the estimate: the relative risk was 3.5 (2.4-5.2). There was no social gradient in age at the start of smoking. When comparing social class V to social class I according to smoking habits, the relative risk was 7.7 (2.6-22.4) in cigarette smokers, 6.0 (1.1-32.1) in pipe smokers, 3.5 (1.7-7.1) in mixed smokers, 2.25 (0.4-12.9) in cheroot smokers, 3.8 (2.4-5.9) in all smokers, 1.95 (0.8-4.6) in exsmokers and 4.7 (1.01-22.2) in never smokers.(ABSTRACT TRUNCATED AT 250 WORDS)