Risk of stroke accompanying alcohol consumption with or without single-occasion drinking.

Background: Previous research on the relationship between alcohol and stroke has highlighted several issues. Notably, the conventional categorization based on average consumption, which categorizes both those who consume 20 g/day of alcohol daily and those who engage in risky single-occasion drinking (RSOD) only on weekends into low drinkers, makes it difficult to account for individuals who fall into distinct characteristics. This study examined the association between alcohol and stroke, accounting for both average drinking levels and RSOD occurrences.

Methods: In a community-based prospective cohort study in Japan, 8026 men and 12,461 women were followed from 1989 to 2018. The outcome was the first-ever stroke event during the follow-up period. Alcohol consumption was divided into seven categories: never drinkers; former drinkers; low drinkers (<20 g/day on average for men and <10 g/day for women) without RSOD; moderate drinkers (20-59 g/day on average for men and 10-39 g/day for women) without RSOD; low drinkers with RSOD; moderate drinkers with RSOD; and heavy drinkers (≥60 g/day on average for men and ≥40 g/day for women). RSOD was defined as consuming ≥60 g for men and ≥40 g for women on a single occasion. We calculated sex-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for stroke across these drinking categories compared with never drinkers.

Results: Low-to-moderate drinkers with RSOD experienced a significantly higher hazard of stroke; the multivariable HR (95% CI) of 1.47 (1.01-2.13) among men and 3.41 (1.50-7.79) among women. Overall, although some were not significant, low-to-moderate drinkers with and without RSOD tended to be associated with a higher hazard of stroke, except for low drinkers with RSOD in women.

Conclusions: RSOD potentially increases the risk of stroke among men and women, even if their usual amount of alcohol consumption is low to moderate.