Relation of cigarette smoking to 25-year mortality in middle-aged men with low baseline serum cholesterol: the Chicago Heart Association Detection Project in Industry.

It has been suggested that smoking does not influence risk of cardiovascular diseases in populations with low serum cholesterol levels. To determine whether cigarette smoking is an independent risk factor among men with low levels of serum cholesterol, data on 25-year coronary, cardiovascular, and all-cause mortality for 8,816 middle-aged men screened between 1967 and 1973 by the Chicago Heart Association Detection Project in Industry were examined. With Cox multivariate proportional hazards regression, relative risks of coronary heart disease and cardiovascular disease mortality associated with smoking for the two subcohorts with favorable levels of serum total cholesterol, that is, less than 180 and 180-199 mg/dl, were of the same magnitude as those for men with elevated serum cholesterol, that is, 200-239 and 240 mg/dl. In the two lower strata of cholesterol, the absolute risk and absolute excess risk of mortality for current smokers at baseline were substantially higher compared with men who never smoked, with all-cause death rates of 423.0 and 428.0 per 1,000 and absolute excess rates of 209.8 and 225.7 per 1,000. These translate to estimated shorter life expectancies of 5.3 and 5.7 years, respectively. Adverse effects of smoking on risk of coronary, cardiovascular, and all-cause mortality prevail for men with lower as well as higher serum cholesterol levels.