Health Effects of Mild Alcohol Consumption in Koreans: Focus on cardiovascular disease

Abstract

Alcohol consumption has been considered a major risk factor for various diseases. However, world health organization reported that alcohol consumption showed complex relationship in cardiovascular disease (CVD), which mild alcohol consumption was beneficial. In addition, recent systematic review found beneficial effect of low alcohol consumption on all-cause mortality, CVD-related, and cancer-related mortality. Previous studies have reported that the beneficial effects of mild alcohol consumption were attributed to reference group misclassification. As one of those bias, many studies pointed out sick quitter effect which former drinkers abstaining from alcohol because of health concerns or prescription medication. Several studies have investigated whether alcohol-related risk varies according to the reference group (e.g., former drinkers, non-drinkers, or lifetime abstainers), but they reported controversial results. In addition, sick quitter effect acknowledges the possible association of health conditions with quitting alcohol consumption. Studies assessing relationship between change of health problem and quitting alcohol drinking was not so much. Besides the sick quitter effect, several studies have investigated the effect of mild alcohol consumption using a reference group comprising occasional drinkers. However, a clear conclusion was not reached. This study had three aims. First, this study aimed to investigate the association between mild alcohol consumption and mortality among Koreans, based on a systematic review and meta-analysis. Second, this study aimed to assess whether the change of health status affected quitting of alcohol drinking. Third, this study aimed to evaluate whether alcohol-related risk varies according to the reference (abstainers, non-drinker including former drinkers, and occasional drinkers) based on a Korean cohorts data. For the first aim, total 16 Korean studies regarding alcohol-related risks of all-cause mortality, cancer-related mortality, and CVD-related mortality were revealed

nine studies evaluated all-cause mortality, eight studies evaluated cancer-related mortality, and three studies evaluated CVD-related mortality. The meta-analysis did not reveal a significant effect of mild alcohol consumption on all-cause mortality (5 studies, odds ratio: 0.85, 95% confidence interval [CI]: 0.72, 1.01). Meta-analysis of studies using all-cancer mortality and cardiovascular mortality was not performed based on the limited sample size, and the results of studies were controversial. For cancer-related mortality, the results of previous studies were controversial. For cardiovascular mortality, all three studies reported a non-significant effect of occasional or mild alcohol consumption. Therefore, it appears that mild alcohol consumption is not associated with significant beneficial effects on all-cause mortality, cancer-related mortality, or CVD-related mortality in Koreans. For the second aim, the change in alcohol consumption was assessed using KoGES data (a community-based cohort study conducted by the Korean Center for Disease Control and Prevention) from 40–69 years old Korean during 2001–2002. Only 64.3% of participants in the present study maintained their baseline-assigned drinking status for the entire 10-year follow-up. Significant association of disease onset or treatment with quitting alcohol drinking was showed in only cancer, but CVD or chronic disease. Health status between abstainer and former was not significantly different based on the number of diseases or perceived health. For the third aim, the association between alcohol consumption and CVD incidence was investigated. The participants were divided into non-drinkers (0 g/day), mild drinkers (< 15 g/day), and moderate-to-heavy drinkers (≥ 15 g/day). Mild drinkers exhibited a significantly lower risk of myocardial infarction (hazard ratio [HR]: 0.44, 95% CI: 0.21, 0.92) and coronary artery disease (HR: 0.61, 95% CI: 0.4, 0.94), compared to non-drinkers. When using time-dependent analysis based on the change in alcohol consumption, the beneficial effect of mild alcohol consumption was significant only for myocardial infarction, not for coronary artery disease. The beneficial effect did not change significantly when either non-drinkers or lifetime abstainers were used as the reference group

thus, the sick quitter effect was not observed in the reference group analysis. However, when occasional drinkers who consumed < 2.5 g/day of alcohol were included in the reference group, the beneficial effect of mild alcohol consumption was not significant in myocardial infarction (HR: 0.65, 95% CI: 0.29, 1.45) or coronary artery disease (HR: 0.71, 95% CI: 0.42, 1.19). The results of this study do not support the sick quitter effect because no diseases other than cancer were associated with quitting alcohol consumption, and the risk of mild alcohol consumption was not so much different compared to non-drinkers or lifetime abstainers. The benefit of mild alcohol consumption was significant compared with non-drinkers

however, when occasional drinkers were included in the reference group, the benefit was no longer significant. Additionally, the sociodemographic characteristics between occasional drinkers and drinkers were more similar to each other than were those between non-drinkers and drinkers. Therefore, occasional drinkers might represent a more appropriate reference group with which to assess the effect of alcohol consumption. In further studies, deliberation regarding an appropriate reference group for alcohol consumption is needed through the analysis and comparison of characteristics among non-drinkers, occasional drinkers, and non-occasional drinkers.