Moderate Alcohol Intake Linked With Decreased Stroke Risk in Women CME
News Author: Fran Lowry
CME Author: Désirée Lie, MD, MSEd
CME Released: 03/30/2012; Valid for credit through 03/30/2013
According to the current study by Jimenez and colleagues, some studies have reported a reduced risk for stroke associated with light to moderate intake of alcohol, and other studies have noted a greater reduction in risk among women vs men. However, prospective cohort studies are limited, and alcohol consumption among women is lower than among men (42% of women vs 60% of men report drinking 12 or more drinks in the past year).
This prospective cohort study examines the association between the amount of alcohol consumption and the risks for ischemic and hemorrhagic stroke.
STUDY SYNOPSIS AND PERSPECTIVE
Light to moderate alcohol consumption is associated with a lower risk for both ischemic and hemorrhagic stroke in women, new research suggests.
“Alcohol consumption in moderation has been consistently associated with lower risk of heart disease, but the data for stroke, especially with regard to stroke type, has been a matter of debate,” lead author Monik Jimenez, ScD, from Brigham and Women’s Hospital, Boston, Massachusetts, told Medscape Medical News.
The study is published online March 8 in Stroke.
The investigators examined data on 83,578 women in the Nurses’ Health Study who were free of diagnosed cardiovascular disease and cancer at baseline. The participants were followed from 1980 to 2006.
Participants provided information about their use of alcohol at baseline and then every 4 years thereafter. They also provided information about lifestyle factors and stroke events every 2 years.
Strokes were classified according to the National Survey of Stroke criteria.
During the study period, there were 2171 incident strokes. Of these, 1206 were ischemic strokes, 363 were hemorrhagic strokes, and 602 were of unknown etiology.
About 30% of the women reported that they never drank alcohol, 35% reported very low levels of consumption (less than 4.9 g/day, or half a glass of wine per day), and 37% drank moderately (5 – 14.9 g/day, or ½ to 1 ½ glasses of wine, 1 mixed drink, or 1 beer daily).
Analysis of the data showed that women who consumed low to moderate amounts of alcohol had a lower risk for total stroke compared with women who never drank.
After adjusting for a number of variables, including smoking, physical activity, body mass index, family and personal history of heart disease, diabetes, hypertension, bilateral oophorectomy, postmenopausal status, hormone therapy, high cholesterol, multivitamin intake, aspirin, composite 6-nutrient diet score, highest level of education, husband’s highest level of education, and marital status, the relative risks of total stroke were 0.83 (95% confidence interval [CI], 0.75 – 0.92) for women who consumed < 5 g/day, 0.79 (95% CI, 0.70 – 0.90) for 5 to 14.9 g/day, 0.87 (95% CI, 0.72 – 1.05) for 15 to 29.9 g/day, and 1.06 (95% CI, 0.86 – 1.30) for 30 to 45 g/day.
The estimated risk for stroke in the highest category of reported alcohol intake did not reach statistical significance because there were very few heavy drinkers in the cohort, Dr. Jimenez pointed out.
“Moderate alcohol intake was associated with reduced risk of total stroke, and higher levels were not associated with reduced risk in this particular population, which really emphasizes the importance of moderation if you drink,” she said.
“There are several ways that alcohol might reduce the risk of stroke,” Dr. Jimenez speculated. “Alcohol has components which prevent blood clots and promote HDL [high-density lipoprotein] cholesterol, which is the good cholesterol. But alcohol is like a double-edge sword because higher levels can increase high blood pressure and promote atrial fibrillation, which are also risk factors for stroke.”
Dr. Jimenez stressed that women who currently do not drink should not start to drink in the belief that this will protect them from stroke.
“Our results are very much in line with the American Heart Association guidelines for up to a glass a day for women, but those recommendations are for women who are current drinkers, and we do not advocate the initiation of alcohol consumption for women who abstain from drinking,” she said.
“This paper was based on a very well-done analysis with excellent ascertainment of alcohol exposure,” R. Curtis Ellison, MD, professor of medicine at Boston University School of Medicine in Massachusetts, told Medscape Medical News.
“The findings from this study are not that new. Many studies have shown that stroke is in general 10, 15, 20% lower in moderate drinkers,” Dr. Ellison said.
“But you have to keep supporting these findings because people are always looking for flaws. Out of 200 or 300 papers, there have been about half a dozen that have not found this, so you have to reinforce your findings. This is a very large study, and it is very useful to have such confirmation.”
Dr. Jimenez and Dr. Ellison have disclosed no relevant financial relationships. Dr. Ellison reports that he is a member of the International Scientific Forum on Alcohol Research. The study was funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health and the National Cancer Institute.
Stroke. Published online March 8, 2012. Full article
- The Nurses’ Health Study enrolled 121,700 female registered nurses in 1976 from 11 US states. They completed a mailed baseline questionnaire followed by biennial questionnaires.
- A food frequency questionnaire was included every 4 years from 1981.
- Excluded were women without data on alcohol intake, those with a history of stroke or cancer, those reporting abstention and great reduction in alcohol intake in recent years, or those with a history of cardiovascular disease.
- The food frequency questionnaire included questions about alcohol intake within the past 12 months.
- Separate questions asked about consumption of beer, wine, and liquor (spirits).
- A serving of alcohol was defined as 4 ounces of wine (5 ounces after 2004), 12 ounces of beer, or 1.5 ounces of spirits.
- Total alcohol intake was calculated as the sum of all 3 beverage types and was categorized as 0 g/day, more than 0 to 4.9 g/day, 5 to 14.9 g/day, 15 to 29.9 g/day, and 30 to 45 g/day.
- Alcohol consumption reported by women was matched against 4 one-week diet diaries for validation, with correlation coefficients of 0.86 to 0.90.
- The analysis included all fatal and nonfatal strokes.
- The investigators conducted follow-up biennially by asking women or their next of kin for information.
- Medical records were examined by clinicians blinded to exposure status.
- The National Survey of Stroke criteria were used for diagnosis of stroke, requiring evidence of a neurologic deficit with sudden or rapid onset lasting for at least 24 hours.
- Stroke was classified as ischemic (thrombotic or embolic), hemorrhagic, or stroke of unknown subtype.
- Deaths were ascertained by postal information, the National Death Index, or from family members.
- Classification of fatal stroke was by hospital records or autopsy.
- 83,578 women without cardiovascular disease or cancer were observed from 1980 to 2006.
- The mean age at baseline was 46 years.
- 30% of women reported no alcohol consumption, 35% reported a very low level of consumption, and 4% reported a high intake of 2 to 3 glasses (30 – 45 g) per day.
- Only 1% of women reported drinking more than 45 g daily.
- Overall, heavier alcohol consumption was associated with a higher prevalence of smoking, a history of hypertension, increased physical activity, and a lower body mass index compared with women who abstained from drinking.
- At 26 years of follow-up, 2171 total stroke events were recorded for 1,695,324 person-years, of which 1206 were ischemic, 363 were hemorrhagic, and 602 were of unknown subtype.
- Low (> 0 to 4.9 g/day) and moderate (5 – 14.9 g/day) alcohol intake were associated with a lower risk for total stroke vs no alcohol intake.
- Compared with no alcohol intake, the relative risks for total stroke were 0.83 for less than 5 g/day of alcohol, 0.79 for 5 to 14.9 g/day, 0.87 for 15 to 29.9 g/day, and 1.06 for 30 to 45 g/day.
- Compared with women who abstained from alcohol, women who consumed 30 to 45 g/day did not have a greater risk for total stroke.
- However, intake of 30 to 45 g/day of alcohol was associated with a nonsignificant higher risk for ischemic, but not hemorrhagic, stroke vs no alcohol intake.
- There was no change in the associations when data were stratified by age, hypertension, aspirin use, hormone therapy, or smoking.
- The finding that moderate alcohol consumption was associated with a lower risk for total stroke vs abstention was only found in women without a history of atrial fibrillation. Alcohol may increase risk for atrial fibrillation; however, the study was underpowered to make this determination.
- There was no evidence of smoking as a confounding factor.
- The authors concluded that there was an inverse association between the risk for ischemic, but not hemorrhagic, stroke and low to moderate alcohol consumption among women.
- However, there was also a suggestion of a nonsignificant higher risk for ischemic stroke with heavy alcohol consumption of 30 to 45 g/day.
- Low to moderate intake of alcohol in women is associated with a lower risk for total stroke.
- Heavy intake of alcohol (30 – 45 g/day) in women is not associated with an increased risk for total or hemorrhagic stroke but is linked with a nonsignificant increased risk for ischemic stroke.