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Saturday, November 12, 2011

Low liver-related mortality among heavy drinkers: results of a long-term follow-up study



Epidemiological evidence demonstrates a J-shaped relationship between alcohol consumption and mortality, implying a lower risk of all cause mortality in moderate drinkers compared to non-drinkers and heavy drinkers. Furthermore, general beliefs are that heavy
drinkers die as a result of liver disease. However, there is a lack of long term follow-up (FU) data.

The aim of this study is to investigate prospectively the relationship between mortality and alcohol consumption, over 18 years of FU in a general population of elderly.

This study was based on participants (>55 years) of the Rotterdam Study, a large population-based study in the Netherlands. Baseline examinations took place between 1989 and 1993. Data on ethanol consumption was available for 3884 participants. Mortality outcomes were registered by International Classification of Diseases codes. Alcohol intake was determined by a standardized questionnaire and divided into four categories: non drinkers (0-0.7g/day), light drinkers (≤10 g/day), moderate drinkers (>10-≤30 g/day) and heavy drinkers (>30 g/day). The association between alcohol intake and mortality was examined by Cox Regression analyses, adjusting for age, sex, hypertension, cholesterol, BMI, diabetes, smoking, and educational level.

Of 3884 participants, 1398 (36.0%) were non drinkers, 1144 (29.4%) light drinkers, 963 (24.8%) moderate drinkers and 379 (9.7%) heavy drinkers. A total of 187 heavy drinkers died during FU: 63 participants (33.9%) died of cancer-related causes, 52 participants (28%) died of cardiovascular-related causes and only 2 participants (1%) died of liver-related causes. Multiple-adjusted mortality rates showed a U-shaped relationship between alcohol intake and mortality: compared to non-drinkers hazard ratio for light drinkers was 0.85 (95%CI 0.75-0.96; p=0.03), 0.86 (95%CI 0.76-0.98; p=0.007) for moderate drinkers and 0.95 (95%CI 0.8-1.14; p=0.6) for heavy drinkers. Similar results were observed, after exclusion of deaths in the first 3 years of FU, to eliminate the effect of possible pre-existing diseases on mortality rates among non-drinkers.

We confirmed a beneficial effect of light-moderate alcohol intake on long-term survival in a large elderly population. Only a minority of heavy drinkers (1%) die of liver-related mortality during a long-term follow up, the majority die because of cancer and cardiovascular diseases.