Cautions in Interpreting the Cardiovascular Effects of Moderate Drinking
Moderate drinking has been linked to lower risks of cardiovascular disease (CVD) and death. These potential benefits, however, may be explained by more CVD risk factors in nondrinkers (i.e., confounders). To explore this possibility, investigators at the Centers for Disease Control studied 235,730 adult nondrinkers* and moderate drinkers** who had participated in a nationally representative telephone survey (54% response rate).
(27 of 30) characteristics associated with CVD were
significantly more common in nondrinkers than in moderate
- Nondrinkers were older; less likely to be white, married, educated, and physically active; and less likely to have a high income, health insurance, a personal doctor, a flu shot, and cholesterol or colorectal cancer screenings.
- They were also more likely to have diabetes, hypertension, obesity, high cholesterol, asthma, poor dental health, arthritis, and poor health status.
- Smoking and male sex were the only CVD risk factors more common in moderate drinkers.
Many epidemiological studies of moderate drinking have adjusted for certain confounders but have either ignored others (e.g., psychosocial risks) or not accounted for the interactions between confounders (e.g., diabetes and lack of health insurance). Although this study examined the prevalence of possible confounders and found that most CVD risk factors were more common in nondrinkers, it did not directly test whether these confounders explained the relationship between alcohol and CVD. A prominent alcohol epidemiologist recently wrote that confounders may largely—or entirely—explain the observed cardiovascular benefits of moderate drinking. Only a large-scale, randomized trial can determine whether alcohol decreases CVD. In the meantime, I agree with the American Heart Association's statement that "there is little current justification to recommend alcohol as a cardioprotective strategy."Richard Saitz, MD, MPH
**<=2 standard drinks per day for men, <=1 for women
Naimi TS, Brown DW, Brewer RD. Cardiovascular risk factors and confounders among nondrinking and moderate drinking U.S. adults. Am J Prev Med. 2005;28(4):369-373.
Wannamethee SG. Alcohol and mortality: diminishing returns for benefits of alcohol. Int J Epidemiol. 2005;34(1):205-206.
Goldberg IJ, Mosca L, Piano MR. Wine and your heart: a science advisory for healthcare professionals from the Nutrition Committee, Council on Epidemiology and Prevention, and Council on Cardiovascular Nursing of the American Heart Association. Circulation. 2001;103(3):472-475.