Changes in alcohol intake and risk of coronary heart disease and all-cause mortality in the MONICA/KORA-Augsburg cohort 1987-97

Background: Most studies on the effect of alcohol consumption on coronary heart disease or all-cause mortality assess alcohol intake at one point in time and therefore do not take into consideration changes in drinking habits over time. We investigate whether a second assessment of alcohol intake substantially improves estimation of the effects of alcohol intake on these outcomes. Design: A prospective cohort study of 2710 men and women, age 35-64 years at baseline in 1984/85 in the Augsburg region in southern Germany. We recorded incident fatal and non-fatal coronary events and all-cause mortality until 1997. Alcohol intake and other explanatory variables were assessed in 1984/85 and 1987/88. Methods: Based on these assessments, participants were classified as non-drinkers, quitters, starters and constant drinkers. We calculated hazard rate ratios for coronary events and all-cause mortality in these groups and adjusted for several potential confounders using Cox's proportional hazards model. These estimates were compared with hazard rate ratios based on a single assessment of alcohol intake in 1987/88. Results: Among male constant drinkers the adjusted hazard rate ratio (HRR) for coronary events was lowest among those consuming 0.1-19.9 g alcohol per day, compared with non-drinkers [HRR 0.29; 95% confidence interval (Cl) 0.12-0.70]. The lowest all-cause mortality risk was observed among men drinking 20.0-39.9g per day (HRR 0.48; 95% Cl 0.26-0.88). In female constant drinkers the HRR for all-cause mortality was 0.71 (95% Cl 0.40-1.26) for those reporting 0.1-19.9 g daily alcohol consumption. Hazard rate ratios for alcohol intake classified by two assessments consistently revealed a more pronounced beneficial effect of alcohol consumption than those for alcohol intake groups based on a single measurement. Conclusions: Assessment of alcohol intake at two points in time seems slightly to improve the risk estimation for coronary heart disease (CHD) and for all-cause mortality, compared with a single measurement. Thus, our findings strengthen the evidence of a beneficial effect of light to moderate alcohol consumption on coronary heart disease and all-cause mortality.