Background: This study examined the effects of alcohol consumption and DSM-IV alcohol dependence on the risk of mortality.
Methods: Data from the 1988 National Health Interview Survey Alcohol Supplement were matched to the National Death Index for the years 1988 to 1995 (baseline n = 37,682 U.S. adults age > or =25 linked to 3,586 deaths). All mortality analyses were based on proportional hazards models that adjusted for age, sex, race/ethnicity, marital status, education, income, labor force status, body mass index, smoking status, and poor health indicators at baseline.
Results: When dependence was not considered and all past-year abstainers were used as the reference group, both light and moderate drinkers exhibited a reduced risk of mortality, with hazards ratios of 0.76 (0.68-0.84) and 0.84 (0.74-0.96). Heavy drinkers had about the same risk of dying as did past-year abstainers, and very heavy drinkers had an increased risk that was not significant (OR = 1.17, CI = 0.93-1.47). When lifetime abstainers were used as the reference category, the protective effect of moderate drinking fell short of significance, and there were nearly significant increased risks among former drinkers and very heavy drinkers. When dependence was considered, light and moderate drinkers without dependence had a reduced mortality risk regardless of reference group, and there was no significant effect among heavy or very heavy drinkers without dependence. Among dependent drinkers, there was no protective effect of light or moderate drinking, and very heavy drinkers had a significantly increased risk (OR = 1.56 relative to past-year abstainers and 1.65 relative to lifetime abstainers).
Conclusions: Because alcohol dependence nullifies the protective effect of light and moderate drinking, it is important to understand its role as an independent risk factor for mortality. Differences between dependent and nondependent drinkers who drank comparable amounts suggest that this risk may result from longer and heavier drinking histories before baseline, more severe health problems at baseline, more heavy episodic drinking, and, possibly, differences in beverage preference.