Alcohol and ischaemic stroke

Does alcohol consumption reduce the risk of ischaemic stroke?

Alcohol has been found to prevent ischaemic heart disease (Bandolier 27 ), but the relationship between alcohol consumption and ischaemic stroke is more controversial. This study investigates this association among different ethnic groups.

Message

This case-control study found that moderate drinking, up to two drinks a day, reduced the risk of ischaemic stroke by 49% in a multiethnic, elderly population. Not surprisingly, heavier drinking, seven or more drinks a day, was associated with an increased risk of ischaemic stroke. However, it is possible that past heavier drinkers may not maintain an increased risk if they reduce their consumption to a moderate level.

Reference

R Sacco et al. The protective effect of moderate alcohol consumption on ischemic stroke. JAMA 1999 281: 53-60.

Study

Between 1993 and 1997, 677 stroke patients (from the Northern Manhattan Stroke Study) were matched by age, sex and ethnicity to 1,139 controls who had never had stroke. Controls were recruited by random digit dialing. The average age of stroke patients was 70 years (+/- 13 years), 59% were women, 20% were white, 28% black and 51% Hispanic.

Information on participants was obtained through interviews, medical records and both physical and neurological examinations. Questionnaires assessed alcohol consumption. The effects of the following were investigated: average daily alcohol consumption during the previous year; average lifetime consumption; the type of alcohol consumed; and former heavy drinking. One drink = 120 ml of wine, 360 ml of beer, 45 ml of liquor.

Results

Those consuming up to two drinks a day over the previous year reduced the risk of ischaemic stroke by 49% compared with non-drinkers, after adjusting for hypertension, diabetes, cardiac disease, smoking, education and body mass index (odds ratio 0.51, 95% confidence interval 0.39 to 0.67). This protective effect was found in men and women and in whites, blacks and Hispanics. The reduction in risk was similar for those with an average lifetime consumption of up to two drinks a day compared with lifetime abstainers (odds ratio 0.54, 95% confidence interval 0.38 to 0.78). All types of alcohol (wine, beer and liquor) had a similar protective effect.

The risk of stroke increased in those consuming seven or more drinks a day compared with non-drinkers (24 patients, 18 controls, odds ratio 2.96, 95% confidence interval 1.05 to 8.29), shown in Figure 1. Furthermore, those who had consumed at least five drinks a day during their lifetime, but were currently drinking no more than two a day did not have a significantly increased risk of stroke (24 patients, 26 controls, odds ratio 0.66, 95% confidence interval 0.31 to 1.41).

Comment

The level of alcohol found to reduce the risk of ischaemic stroke, no more than two drinks a day, corresponds with that found to minimise mortality in men (between 11 and 15 drinks per week). This study also adds further evidence to the increased health risks of heavier drinking. However, it appears that despite a lifetime of heavier drinking the increased risk of stroke may not be sustained if consumption is later reduced to a moderate level. Although notable, this result should be considered in light of the extremely small number of participants contributing to it.