Binge Drinking and Hypertension on Cardiovascular Disease Mortality in Korean Men and Women
A Kangwha Cohort Study
Background and Purpose—The purpose of this study was to examine combined effects of hypertension and binge drinking on the risk of mortality from cardiovascular disease in Koreans.
Methods—This study followed a cohort of 6100 residents in Kangwha County, aged ≥55 years as of March 1985, for cardiovascular mortality for 20.8 years up to December 31, 2005. We calculated hazard ratios (HRs) for cardiovascular mortality by blood pressure and binge drinking habits using the Cox proportional hazard model. Binge drinkers and heavy binge drinkers were defined as having ≥6 drinks on 1 occasion and ≥12 drinks on 1 occasion.
Results—After adjusting for total alcohol consumption, male heavy binge drinkers with Grade 3 hypertension had a 12-fold increased risk of cardiovascular mortality (HR, 12.7; 95% CI, 3.47 to 46.5), whereas male binge drinkers with Grade 3 hypertension had a 4-fold increased risk of cardiovascular mortality (HR, 4.41; 95% CI, 1.38 to 14.1) when compared with nondrinkers with normal blood pressure. However, in considering separate effects of heavy binge drinking and hypertension on the risk of cardiovascular mortality, HRs were rather low (HR of heavy binge drinkers, 1.88, 1.10 to 3.20; HR of hypertensives, 2.00, 1.70 to 2.35) compared with nondrinkers with normal blood pressure.
Conclusions—Binge drinkers and heavy binge drinkers with Grade 3 hypertension showed a marked increase in cardiovascular mortality risk. Even after adjusting for total alcohol consumption, the former revealed 4.41 and the latter indicated 12.7 of HR for the risk of cardiovascular mortality.
Excessive alcohol consumption causes 75 000 deaths each year in the United States, and it is the third leading preventable cause of death. Binge drinking accounts for more than half of these deaths.1 Heavy drinking is quite prevalent in Korea. According to The Third Korea National Health and Nutrition Examination Survey in 2005, in which a heavy drinker is defined as one who consumes >6 glasses or 60 g of soju for men and >4 glasses or 40 g of soju for women on 1 occasion at least once a week, 46.3% of male adults and 9.2% of female adults were heavy drinkers in Korea.2
In many studies, binge drinking has been associated with increased risks for cardiovascular mortality, including stroke.3–5 We also suggested in our recent study that frequent binge drinking is associated with increased risks of all-cause and cerebrovascular disease mortality.6 Binge drinking may also be associated with increased blood pressure and cause alcohol-related hypertension.7,8 The positive association of blood pressure level with cardiovascular disease has been well documented.9 Although hypertension and binge drinking act on cardiovascular mortality risk, combined and specified effects produced by both factors have been rarely studied.
This study examined the joint effects of hypertension and binge drinking on the risk of death from cardiovascular disease in the Korean population through over a 20-year follow-up of the Kangwha Cohort data.
The population for the Kangwha Cohort Study, recruited from the official resident registration records, included residents ≥55 years, who were born before 1930, in 10 administrative districts—eups and myeons in Korean—of Kangwha County as of February 28, 1985 (total, 9378; male, 3938; female, 5440).6 A total of 6372 persons (2724 males, 3648 females) agreed to participate in the interview and medical examination in the 1985 survey. Details of the Kangwha Cohort Study have been published elsewhere.6
Participants who were not followed up after the initial survey (n=78), had a stroke or coronary heart disease before (n=135), or had no information on blood pressure, alcohol intake at entry, education, or smoking amount (n=59) were all excluded, and thus the final study population selected for the analyses was 6100 (male, 2600; female, 3500). They were followed up for mortality over a maximum of 20.8 years until December 31, 2005. The Institutional Review Board of Human Research of Yonsei University approved the study (Approval No. 4-2007-0182).
Baseline Data Collection and Classification of Blood Pressure
Blood pressure (BP) was measured once per person; and the interobserver error was within 2 mm Hg.10 Hypertension was determined with systolic and diastolic readings of ≥140/90 mm Hg or antihypertensive medication use. Ninety-eight participants were taking antihypertensive drugs. The combined categories of systolic and diastolic BP were also categorized in line with the guidelines of the European Society of Hypertension and the European Society of Cardiology (ESH-ESC).11 With regard to chronic disease, study participants were asked to answer yes or no to the question, “Do you have any chronic disease or past accident or injury for which you feel uncomfortable in your daily lives including work?” If he or she answered yes, trained staff interviewed the participant for the kind of chronic disease and entered the data. Eight hundred one participants reported neuralgia, 304 dyspepsia, 655 hypertension, 104 arthritis, 287 dyspnea, 75 traffic accidents, 94 lumbago, and 335 other diseases. In this study, however, information on the existence of chronic disease (yes or no) only was used as a covariate for analysis.
Data for those who died from March 15, 1985, to December 31, 1991, were collected either from records of burial and death certificates of eup and myeon offices that are administrative branch offices of local government in Korea or through the family’s confirmation of cause of death at calls and visits of trained surveyors twice a year. However, from 1992, we were allowed to use all the national data on cause of death by the Korean National Statistical Office. In fact, each Korean has a unique Resident Registration Number, which is similar to the Social Security Number of the United States. Therefore, from January 1, 1992, to December 31, 2005, we followed up death records by matching data of the cause of death from the National Statistical Office using the Resident Registration Numbers of all the participants including persons who died before 1992. This follow-up, performed through record linkage at the national level, is almost complete, except for emigrants to other countries (N=1) and subjects without information on the Resident Registration Number (N=10).
The main outcome variables for this study were death due to total atherosclerotic cardiovascular disease, total stroke, and hypertensive disease as defined by the International Classification of Disease, 10th Revision (I10 to I25 and I60 to I74 for cardiovascular disease, I60 to I69 for total stroke, and I10 to I15 for hypertensive disease).
Estimation of Alcohol Consumption
Participants were asked to answer yes or no to the question, “Do you drink alcohol?” The frequency of drinking was presented as daily, almost daily, 2 to 3 times a week, 1 to 4 times a month, or 4 to 12 times a year. The question on the type of alcoholic beverage and the amount of alcohol consumption was given as: “How much (in bottle, glass) do you drink for a type of alcoholic beverage on 1 occasion?” Participants were asked to fill in up to 2 types of alcoholic beverage they usually consume on 1 occasion. A total of 83.9% of male drinkers filled in 1 type only and 16.1% 2 types. Binge drinking was defined as having ≥6 drinks of 1 or 2 types of alcoholic beverage on 1 occasion. One who has ≥12 drinks on 1 occasion was particularly classified as a heavy binge drinker. Alcoholic beverages they consumed most were soju and makkoli. Soju is a distilled alcoholic beverage native to Korea, similar to liquor or sake in Japan, and makkoli is an unfiltered alcoholic beverage, also native to Korea. In 1985, at the time of survey for the Kangwha Cohort, soju contained 25% alcohol by volume and makkoli 6% alcohol.12 To validate those questions on the alcohol consumption questionnaire and to examine the change of alcohol consumption patterns, we implemented the second interview with 3381 survivors in 1994.
With regard to binge drinking habit, they were divided into 4 groups: nondrinkers, nonbinge drinkers, moderate binge drinkers (having 6 to 11 drinks on 1 occasion), and heavy binge drinkers (having ≥12 drinks on 1 occasion). The Cox proportional hazard model was used to calculate the joint effects of hypertension and binge drinking on cardiovascular mortality with nondrinkers with the lowest levels of blood pressure as the reference group. The models according to binge drinking habit were analyzed with results for men only because the sample size of female drinkers was not large enough.
Modification of the effect of binge drinking was assessed by the inclusion of interaction terms of binge drinking category indicators with indicator variables for hypertension (2 categories) and blood pressure level (ESH-ESC categories; Figures 1 and 2⇓A). The joint effects of hypertension and total alcohol consumption on cardiovascular mortality were also analyzed (Figure 2B). The trend test was also conducted with drinking frequency as an ordinal variable. Analyses were performed with SAS Windows Version 9.1.
The baseline characteristics of normotensive and hypertensive subjects are shown in Table 1. The mean (SD) age of men and women in 1985 was 66.3 years (7.2) and 66.9 years (7.1), respectively. On average, normotensive subjects were younger than hypertensive subjects. Binge drinking was associated with the experience of hypertension in men, because hypertensive subjects were more likely to be binge drinkers. Binge drinkers accounted for 31.5% of male alcohol drinkers and 5.2% of female alcohol drinkers.
During the 20.8 years of follow-up, 759 subjects died due to cardiovascular disease. Table 2 provides hazard ratios for mortality from cardiovascular diseases by hypertension status. The hazard ratio (95% CI) for cardiovascular mortality was 2.00 (1.70 to 2.35). Hypertension also doubled the risk of dying of stroke. The hazard ratio (95% CI) for stroke mortality was 2.12 (1.75 to 2.57).
Table 3 shows that binge drinking was associated with cardiovascular mortality in men. Compared with nondrinkers, heavy binge drinkers having ≥12 drinks on 1 occasion had significantly increased risks of deaths from cardiovascular disease and hypertensive disease with a hazard ratio (95% CI) of 1.88 (1.10 to 3.20) and 3.71 (1.32 to 10.5), respectively. When we additionally adjusted for total alcohol consumption and excluded subjects who were followed up for <5 years, the association with cardiovascular disease was marginally significant with a hazard ratio (95% CI) of 1.98 (0.96 to 4.10). Although there might be a trend, drinking in these categories was not statistically significantly associated with increased stroke death risk.
The combined effects of binge drinking and hypertension on the risk of deaths from cardiovascular disease are illustrated in Figure 1. Compared with nondrinkers with normal blood pressure, heavy binge drinkers with hypertension had a hazard ratio (95% CI) of 4.33 (1.96 to 9.56) for cardiovascular mortality. However, the interaction of hypertension and heavy binge drinking was not statistically significant (P=0.128). None of the drinking categories is associated with increased cardiovascular disease death risk in normotensives.
Table 4 presents adjusted hazard ratios (HRs) for cardiovascular mortality in relation to BP categories. We observed linear trends in cardiovascular mortality with increasing BP. At the BP levels by ESH-ESC guidelines, P for trends was 0.0009. The HR (95% CI) for Grade 3 hypertension was 3.28 (2.36 to 4.57). The high normal group was also associated with an increased risk of cardiovascular disease mortality (HR, 1.54; 95% CI, 1.12 to 2.11).
Two graphs illustrated in Figure 2 represent the joint effects of BP and binge drinking habit (Figure 2A) and the joint effects of BP and total alcohol consumption (Figure 2B) in relation to ESH-ESC BP categories. Figure 2A shows an increase of cardiovascular mortality risk in the heavy binge drinking group with increasing levels of BP. The HR (95% CI) was 12.7 (3.47 to 46.5) in heavy binge drinkers with Grade 3 hypertension. However, in Figure 2B, there was a small increase in cardiovascular mortality risk among the high alcohol consumption group with increasing levels of BP. The HR (95% CI) was 3.02 (1.02 to 9.00) in the high alcohol consumption group with Grade 3 hypertension. In normotensives, any alcohol drinking group was not associated with increased cardiovascular disease mortality risk (Figure 2).
Some studies suggest that moderate alcohol intake may have a beneficial effect on cardiovascular disease, whereas other studies warn that heavy drinking is likely to increase cardiovascular risk. However, most of these studies with mixed results have not taken into account drinking patterns.13 In the present study, when study subjects were categorized by binge drinking habit, the heavy binge drinking group had a rapidly increased positive relationship with cardiovascular mortality, distinct from other groups. However, any pattern of drinking, even heavy binge drinking, did not significantly increase the risk of dying of stroke (HR, 1.65; 95% CI, 0.85 to 3.21).
In this study, binge drinking was defined as having ≥6 alcoholic drinks on 1 occasion; classified by this definition, 20.4% of male subjects were binge drinkers. When recategorized by weekly pure alcohol consumption, male binge drinkers having ≥6 drinks on 1 occasion were 354 of 558 (63.4%) in the heavy alcohol consumption group; 141 of 536 (26.4%) in the moderate alcohol consumption group; and 54 of 644 (8.4%) in the light alcohol consumption group.
Analyzing the combined effects of binge drinking habit and BP, the present study showed that the relationship of cardiovascular disease with binge drinking resulted in a greater increase in the hypertensive group than in the normative group. As for normotensive subjects, any pattern of drinking, even heavy binge drinking, did not seem to increase the risk of deaths from cardiovascular disease. A Japanese study published in 1995 also reported that the risk of cerebral hemorrhage was increasing as total alcohol consumption increased in hypertensives, whereas there was no relationship between cerebral hemorrhage and drinking in normotensives.14
Probable mechanisms for the association between binge drinking and cardiovascular disease have been presented in several studies. According to a study conducted with 20 healthy males, binge drinking increases ambulatory BP.8 Binge drinking may be associated with arterial stiffening and endothelial dysfunction.15,16 Heavy drinking also precipitates cardiac arrhythmia, thus enhancing the propagation of thrombi in patients with a history of chronic alcohol consumption and heart disease.17 Additionally, a sudden marked increase of blood flow might easily dislodge a local thrombus attached to the cerebral vessels.18,19
This study has several limitations to be discussed. First, alcohol consumption variables were collected through a questionnaire for the Kangwha Cohort of people aged ≥55 years. Some could raise an issue of validity for this. The research team implemented the second interview/test with 3381 survivors in 1994. Percent agreement between drinking status data collected in 1985 and those in 1994 is 87% and Cohen κ value is 0.697. They show substantial agreement between the 2 data. However, no research into the intake of >2 types of alcohol on 1 occasion could remain a limitation of alcohol assessment. In addition, an analysis based on the consumption of wine and beer was not made, because very few people living in rural Kangwha County in 1985 were found to drink wine or beer frequently. In the survey, just 4 participants answered they drank beer most but none for wine. Second, former drinkers were not taken into account because they had not been separately identified as nondrinkers in the survey of 1985. Third, according to a study on diabetes prevalence conducted in a Korean county in the 1970s, the prevalence of diabetes among women aged ≥30 years was 1.5% and just 5% of patients with diabetes knew they had diabetes at the time of the survey.20 In Korea, particularly Kangwha County, in 1985, diabetes was not a main concern. In the present study, participants who answered that they had ever been hospitalized with diabetes were 20. When we adjusted for diabetes, the results were not different. Additionally, when subjects who died during first 5 years of follow-up were excluded from the analysis, the result of analysis was not so different. Fourth, because smoking is 1 of the cardiovascular risk factors, the rough classification of smoking may be a confounder. To minimize any possible confounding problem, we further divided current smokers. Nevertheless, it still has a possibility of residual confounding. Fifth, the drinking habit of women is much different from that of men.21 Because of a practical reason that drinkers accounted for only 10.1% in women and female heavy drinkers were scarce, we could not examine the relationship between alcohol consumption and cardiovascular mortality in women as fully as we did in men. Sixth, some sample sizes were small with a limited number of cases. The analysis of different stage hypertension may have a limited statistical power with insufficient cases. In addition, we could not adjust for different medications for hypertension. Seventh, the physical activities of participants were not questioned at the time of the survey. Because there were a lot of people engaging in agriculture, we adjusted for occupation as a proxy indicator of physical activities instead.
In conclusion, compared with that of nondrinkers, mortality risks from total cardiovascular disease were high in heavy binge drinkers having ≥12 drinks on 1 occasion. Such a relationship markedly increased when heavy binge drinkers were hypertensive. However, because the study population included people aged ≥55 years living in an agricultural community with a small population of female drinkers, further studies need to be undertaken to truly understand the joint effects of hypertension and binge drinking in the entire population.
We thank Moon Bong Choi for his helpful comments and editorial assistance.
Sources of Funding
This work was supported by the Korea Science and Engineering Foundation grant (KOSEF: R-01-1993-000-00073-0) funded by the Ministry of Science and Technology of Korea. This study was also partly funded by the Seoul City R&BD program (10526).
- Received April 2, 2010.
- Revision received May 21, 2010.
- Accepted June 22, 2010.
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