The Joint Effect of Education and Alcohol Use on 100% Alcohol-attributable Hospitalization or Death in Canada.

Abstract

Individuals with low socioeconomic position (SEP) experience disproportionately greater alcohol-attributable harm than individuals with high SEP despite similar or less alcohol use (i.e., the alcohol harm paradox). We examined the sex/gender- specific independent and joint effects of education and heavy drinking or volume of alcohol use on 100% alcohol-attributable hospitalization or death. We conducted a cohort study among 199,125 current and former alcohol users aged 15-64 years from population-representative Canadian Community Health Surveys (2000-2008) linked to hospitalization and mortality records through 2017. We estimated the sex/gender-specific associations between education and heavy drinking or volume of alcohol use and incident 100% alcohol-attributable hospitalization or death using multivariable Fine and Gray subdistribution hazard models with competing risk (non-100% alcohol-attributable deaths), assessing additive interactions using the Synergy Index (S). Overall, heavy drinking prevalence and volume of alcohol use were similar or lower in individuals with lower education compared with higher education. Lower education levels compared with a bachelor's degree or above were associated with increased 100% alcohol-attributable hospitalization or death [e.g., less than high school, men: hazard ratio (HR) = 2.78; 95% CI = 2.17, 3.56; women: HR = 2.98; 95% CI = 2.00, 4.44]. We found superadditive joint effects between low education and heavy drinking (men: S = 1.22; 95% CI = 1.14, 1.30; women: S = 1.34; 95% CI = 0.88, 2.04) and low education and higher volume of alcohol use (e.g., excess volume, men: S = 1.30; 95% CI = 1.05, 1.62; women: S = 1.41; 95% CI = 0.77, 2.58), with larger inequities in women than men with similar alcohol use. Our study is consistent with the hypothesis that increased vulnerability to alcohol use among individuals with lower education partially explains the alcohol harm paradox in Canada.