Cigarette consumption and Risk of Coronary heart disease and Stroke

Abstract

To use the relation between cigarette consumption and cardiovascular disease to quantify the risk of coronary heart disease and stroke for light smoking (one to five cigarettes/day). Medline 1946 to May 2015 design by Systematic review and meta-analysis. Prospective cohort studies with at least 50 events, reporting hazard ratios or relative risks compared with never smokers or age specific incidence in relation to risk of coronary heart disease or stroke. The meta-analysis included 55 publications containing 141 cohort studies. Among men, the pooled relative risk for coronary heart disease was 1.48 for smoking one cigarette per day and 2.04 for 20 cigarettes per day, using all studies, but 1.74 and 2.27 among studies in which the relative risk had been adjusted for multiple confounders. Among women, the pooled relative risks were 1.57 and 2.84 for one and 20 cigarettes per day. Men who smoked one cigarette per day had 46% of the excess relative risk for smoking 20 cigarettes per day, and women had 31% of the excess risk. For stroke, the pooled relative risks for men were 1.25 and 1.64 for smoking one or 20 cigarettes per day. In women, the pooled relative risks were 1.31 and 2.16 for smoking one or 20 cigarettes per day. The excess risk for stroke associated with one cigarette per day (in relation to 20 cigarettes per day) was 41% for men and 34% for women. Relative risks were generally higher among women than men. Smoking only about one cigarette per day carries a risk of developing coronary heart disease and stroke much greater than expected: around half that for people who smoke 20 per day. No safe level of smoking exists for cardiovascular disease. Smokers should aim to quit instead of cutting down to significantly reduce their risk of these two common major disorders.