More Evidence of Benefit of Light/Moderate Drinking

Alcohol and CV mortality

March 26, 2010

March 26, 2010 (Boston, MA) – Light and moderate alcohol consumption was associated with lower rates of cardiovascular mortality than complete abstention, in a new study of more than 245 000 US adults [1]. Heavy drinking was not clearly associated with higher or lower risk.

The study, led by Dr Kenneth Mukamal (Beth Israel Deaconess Medical Center, Boston, MA), is published in the March 30, 2010 issue of the Journal of the American College of Cardiology.

Mukamal et al note that alcohol consumption has been consistently associated with a lower risk of cardiovascular disease in epidemiological studies, an association attributed in great part to an increase in high-density lipoprotein (HDL) cholesterol. But a number of uncertainties about the association remain, including potentially diverse effects on coronary heart disease (CHD) and stroke; inclusion of former or occasional drinkers with long-term abstainers as a referent category; generalizability to the adult US population; and the importance of drinking patterns in modifying the association. For example, measures of overall volume of alcohol consumption do not allow for knowledge of whether regular light drinking is taking place vs occasional binge drinking.

To look at these issues further, they used data on 245 207 adults participating in the US National Health Interview Survey (NHIS), an annual survey of a nationally representative sample of US adults, between 1987 and 2000. The survey includes detailed questions on alcohol consumption. Participants were assigned as abstainers (further classified as never drinkers, lifetime infrequent drinkers, or former drinkers), light drinkers (three drinks or less per week), moderate drinkers (four to seven drinks per week for women and four to 14 drinks per week for men), and heavy drinkers (more than seven/14 drinks per week, respectively).

Mortality was ascertained through linkage of the NHIS database to the National Death Index through 2002. The results were adjusted for many covariates, information on which was also recorded on the NHIS questionnaire.

During a total of 1 987 439 person-years of follow-up, there were a total of 10 670 cardiovascular deaths, including 6135 related to CHD and 1758 related to stroke.

Results showed that, in general, moderate drinking was associated with the lowest cardiovascular mortality, and light drinking was also associated with a better outcome than abstention, whereas heavy drinking was not clearly associated with higher or lower risk.

Adjusted hazard ratios* (95% CI) for cardiovascular, CHD, and stroke mortality according to alcohol consumption

Alcohol consumption, vol Nondrinkers Light Moderate Heavy
Cardiovascular deaths 1.00 0.76 (0.68–0.85) 0.67 (0.59–0.77) 0.89 (0.73–1.10)
Cardiovascular deaths (also adjusted for diet/exercise) 1.00 0.77 (0.69–0.85) 0.69 (0.61–0.80) 0.90 (0.73–1.10)
CHD mortality 1.00 0.75 (0.66–0.84) 0.67 (0.57–0.79) 0.80 (0.61–1.05)
Stroke mortality 1.00 0.80 (0.61–1.05) 0.76 (0.58–0.99) 1.25 (0.92–1.70)

Adjusted for age, sex, race, smoking, marital status, education, region, urbanization, smoking, body-mass index, and general health status

There was little difference in risk among lifelong abstainers, lifelong rare drinkers, and former drinkers in this study. And results showed no clear pattern on frequency of alcohol consumption or on binge drinking.

The authors say: "These data bolster previous epidemiological studies that have found lower rates of incident cardiovascular disease among moderate drinkers but also provide cautionary evidence that drinking above recommended limits eliminates this risk reduction."

The results also provide some of the strongest evidence to date that the observed associations of an inverse relationship between light/moderate alcohol consumption and cardiovascular mortality can be generalized to the US population and are not limited to intensively monitored cohorts of volunteers, they add.

This inverse relationship was seen in nearly all segments of the population. But there may be a different effect in different races, as the inverse association seemed stronger among non-Hispanic whites. They write: "Limited data suggest that the apparent U- or J-shaped associations of alcohol consumption with cardiovascular disease and mortality observed in other groups might not extend to African Americans, who [constitute] the largest minority population in these surveys," adding that this might reflect known ancestral variation in alcohol-metabolizing enzymes. They call for prospective studies of alcohol consumption and cardiovascular disease in minority populations to clarify this issue.

Noting that that the suggested protective effect of light/moderate drinking was not as strong for cerebrovascular mortality, Mukamal et al suggest that this may reflect the particularly strong contributions of hypertension and atrial fibrillation as risk factors for ischemic stroke, both of which are positively associated with at least heavy drinking, and also some contribution of hemorrhagic stroke, which tends to be positively associated with alcohol consumption.

No universal sensible limit

In an accompanying editorial [2], Dr Arthur Klatsky (Kaiser Permanente Medical Center, Oakland, CA) says this "characteristically elegant presentation from a leading group in the alcohol epidemiology field . . . adds to the case that the inverse relationship of light/moderate drinking to CV [cardiovascular] mortality is scientifically valid."

As a reminder, however, he notes that all observational studies will be subject to confounders, but that these might act both ways. He says he finds the case compelling, but as is often the case in medical practice, advice about lifestyle must be based on something less than certainty.

Observing that the risk of breast cancer in women is increased with even moderate drinking and that youthful drinking can often be hazardous, especially when combined with motor vehicles, he makes the point that one universal sensible limit is not possible, and the risks of moderate drinking differ by sex, age, personal history, and family history. "There is no substitute for balanced judgment by a knowledgeable, objective health professional. What is required is a synthesis of common sense and the best available scientific facts," Klatsky concludes.