Alcohol and coronary heart disease: Drinking patterns and mediators of effect

An inverse association between alcohol consumption and coronary heart disease (CHD) has been shown in epidemiologic studies for more than 30 years; beneficial changes in high-density lipoprotein (HDL) cholesterol, clotting factors, insulin sensitivity, and inflammation provide biological plausibility. Recently, the importance of including drinking patterns in defining "moderate drinking" has been appreciated. A recent meta-analysis raised questions about systematic misclassification error in observational studies because of inclusion among "nondrinkers" of ex-drinkers and/or occasional drinkers. However, misclassification among a small percentage of nondrinkers cannot fully explain the inverse relation, and there is substantial evidence to refute the "sick quitter" hypothesis. Furthermore, it has been shown that moderate alcohol consumption reduces CHD and mortality in individuals with hypertension, diabetes, and existing CHD. To address the issue of residual confounding by healthy lifestyle in drinkers, in a large prospective study we restricted analysis to only "healthy" men (who did not smoke, exercised, ate a good diet, and were not obese). Within this group, men who drank moderately had a relative risk for CHD of 0.38 (95% Cl, 0.16-0.89) compared with abstainers, providing further evidence to support the hypothesis that the inverse association of alcohol to CHD is causal, and not confounded by healthy lifestyle behaviors.