Alcohol and Ischemic Stroke: More on the French Paradox
abstracts & commentary
Synopsis: After adjustment for heart disease, hypertension, diabetes, current smoking, body mass index, and education, moderate alcohol consumption of up to two drinks per day was significantly protective for ischemic stroke (odds ratio [OR], 0.51; 95% CI 0.39-0.67).
Sources: Truelsen T, et al. Stroke 1998;29:2467-2472; Sacco RL, et al. JAMA 1999;281:53-60.
Several studies have shown that moderate alcohol consumption has a protective effect on the risk of myocardial infarction; some investigators have suggested that certain types of alcoholic beverages, particularly wine, are more protective than others.1 A beneficial effect of wine consumption has been offered as a possible explanation for the "French Paradox," namely, a low incidence of cardiovascular disease in the French population despite an unfavorable exposure to cardiovascular risk factors. The association between alcohol and ischemic stroke is less well established. Some studies suggest that moderate alcohol consumption confers a protective effect in some populations, especially women2 and blacks,3 but not in others, such as Asians.4
Truelsen and colleagues examined the influence of alcohol intake and the different types of alcohol on the risk of first-ever stroke in a large Danish prospective cohort study. More than 13,000 men and women aged 45-84 years gave information on alcohol habits and other socioeconomic and health-related factors at baseline. During 16 years of follow-up, 833 strokes occurred: 37% were ischemic, 10% were cerebral or subarachnoid hemorrhages, and 53% were not specified.
Subjects who drank wine had a statistically significant decreased risk of stroke compared with subjects who never or hardly ever drank wine. Subjects who drank wine weekly had a lower relative risk (RR) of stroke (RR, 0.66; 95% CI 0.50-0.88) than those who drank wine daily (RR, 0.68; 95% CI 0.70-1.02) or monthly (RR, 0.84; 95% CI 0.70-1.02). In contrast, no significant effect of drinking either beer or liquor was found in either of the frequency groups.
Sacco and colleagues studied alcohol consumption among 677 patients with a first ischemic stroke and 1139 community controls matched by age, sex, and race/ethnicity. Stroke patients had a mean age of 70 years; 56% were women, 51% Hispanic, 29% black, and 20% white. After adjustment for heart disease, hypertension, diabetes, current smoking, body mass index, and education, moderate alcohol consumption of up to two drinks per day was significantly protective for ischemic stroke (odds ratio [OR], 0.51; 95% CI 0.39-0.67). A protective effect of alcohol consumption was detected both in younger and older patients, in men and women, and in all racial/ethnic groups. The results demonstrated a J-shaped relationship between alcohol consumption and stroke risk: those drinking up to two drinks daily had a reduced risk compared to those who were not current drinkers, but among those drinking seven or more drinks per day, there was a significantly increased risk of stroke (OR, 2.96; 95% CI 1.05-82.9).
Sacco et al found no differential protective effect among the types of alcoholic beverages. Among moderate drinkers in this study, 17% drank wine predominantly, 17% beer, 30% liquor, and 35% were combination drinkers. On average, those who were predominantly wine drinkers consumed less alcohol than those in the other groups.
Comment by John J. Caronna, MD
These studies, in accord with others, suggest that moderate alcohol intake has a protective effect on the risk of ischemic stroke. Truelsen et al found that this benefit was strongest among wine drinkers and not among those who drank beer and liquor alone. Sacco et al found no difference in protective effect among the types of alcoholic beverages. Therefore, it may be that the benefits of wine drinking found in the Copenhagen study were not due to components in wine other than ethanol but, rather, due to lifestyle factors or to intake of alcohol only with meals. Support for this conclusion comes from the fact that Sacco et al found that those who drank wine predominantly drank less on average than those who drank mostly beer or liquor.
The study of Sacco et al confirms that heavy drinkers are at increased risk of stroke and should be advised to decrease or discontinue alcohol intake. On the other hand, these studies do not indicate that those who do not drink should be advised to do so. Physicians should follow the National Stroke Association’s Stroke Prevention Guidelines in this matter:5 Moderate drinkers can be advised to continue consumption of alcoholic beverages, but those who do not drink should not be advised to do so. (Dr. Caronna is Vice Chairman, Department of Neurology, Cornell University Medical Center; Professor of Clinical Neurology, New York Presbyterian Hospital.)
References
1. Renaud S, Lorgeril M. Lancet 1992;339:1523-1526.
2. Stampfer MJ, et al. N Engl J Med 1988;319:267-273.
3. Klatsky AL, et al. Stroke 1989;20:741-746.
4. Kiyohara Y, et al. Stroke 1995;26:368-372.
5. Stroke Prevention Advisory Board. J Stroke Cerebrovasc Dis 1998;7:162-164.
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