The Effect of Reference Group Classification and Change in Alcohol Consumption on the Association Between Alcohol Consumption and Cardiovascular Disease

• Published in: Alcoholism, clinical and experimental research Vol. 41; no. 2; pp. 379 - 387
• Main Authors: Park, Ji‐Eun, Ryu, Yeonhee, Cho, Sung‐Il
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-02-2017
• Subjects: Adult; Age Factors; Aged; Alcohol; Alcohol Drinking - adverse effects; Alcohol use; Asian Continental Ancestry Group; Cardiovascular; Cardiovascular disease; Cardiovascular Diseases - classification; Cardiovascular Diseases - epidemiology; Cardiovascular Diseases - etiology; Cohort Studies; Coronary Artery Disease - epidemiology; Coronary vessels; Female; Health Status; Heart attacks; Humans; Korean; Male; Middle Aged; Misclassification; Myocardial Infarction - epidemiology; Reference Standards; Republic of Korea - epidemiology; Socioeconomic Factors; Alcohol; Korean; Misclassification; Cardiovascular; Reference
• ISSN: 0145-6008; 1530-0277
• DOI: 10.1111/acer.13299

Background
Many studies suggest that mild alcohol consumption can help avert cardiovascular disease (CVD). This study investigated the association between alcohol consumption and CVD incidence, and assessed whether this differed by reference group classification. As alcohol consumption amounts may change over time, the results of simple and time‐dependent analyses were compared.
Methods
Data were from a community‐based cohort study on 40‐ to 69‐year‐old Koreans recruited in 2001 to 2002. A total of 8,330 participants were followed up for 10 years and classed as nondrinkers (0 g/d), drinker group 1 (<15 g/d), and drinker group 2 (≥15 g/d). The risk of CVD, including myocardial infarction and coronary artery disease, was compared among groups using simple and time‐dependent Cox analysis. Occasional drinkers (<2.5 g/d), nondrinkers, and lifetime abstainers were used as comparison reference groups.
Results
Simple Cox analysis indicated that drinker group 1 exhibited a significantly lower risk of myocardial infarction (hazard ratio [HR]: 0.44, 95% confidence interval [CI]: 0.21, 0.92) and coronary artery disease (HR: 0.61, 95% CI: 0.4, 0.94) than nondrinkers. Time‐dependent analysis based on alcohol consumption change showed that the beneficial effects of drinker group 1 were significant only for myocardial infarction, not for coronary artery disease. The benefits did not change significantly when either nondrinkers or lifetime abstainers were the reference group. However, when occasional drinkers were included in the reference group, the benefits of drinker group 1 were not significant for myocardial infarction (HR: 0.65, 95% CI: 0.29, 1.45) or coronary artery disease (HR: 0.71, 95% CI: 0.42, 1.19). Occasional drinkers and drinkers had more similar sociodemographic characteristics than did nondrinkers and drinkers.
Conclusions
Further studies on alcohol consumption and its effects on health must use repeated measurement to define drinking status, as simple and time‐dependent analyses can show different alcohol consumption risks. These findings do not indicate a beneficial effect of drinking <15 g/d when occasional drinkers and nondrinkers are included in the reference group.
The alcohol‐related risk of CVD did not change substantially when lifetime abstainers or non‐drinkers were used as the reference group. Although the risk associated with alcohol consumption less than 15 g/d was significantly lower than that associated with non‐drinking, it was not significant when occasional drinking was included in the reference group. The alcohol‐related risk of CVD was different when simple or time‐dependent analysis was used. The effect of alcohol consumption may differ according to reference group and type of analysis.