Mediating role of psychological distress and alcohol use in socioeconomic disparities in deaths of despair: a causal mediation analysis using record linkage data.

Background: Deaths of despair - suicide, drug overdose and chronic liver disease mortality - are major contributors to premature mortality in the USA, disproportionately affecting individuals with low socioeconomic status (SES). The mechanisms underlying these disparities, particularly the roles of psychological distress and alcohol use, remain insufficiently understood. We assessed associations of SES, alcohol use and psychological distress with deaths of despair, along with the mediating roles of alcohol use and psychological distress in the SES-deaths of despair association in men and women.

Methods: We linked US National Health Interview Survey data (1997-2018) to mortality records until 31 December 2019 by following 3 11 508 women and 2 42 463 men for 10.5 years. Using counterfactual-based inverse probability-weighted marginal structural models, we decomposed the total effect of SES (education, income) into direct and indirect effects through psychological distress (Kessler-6) and alcohol use (daily consumption). Analyses were sex-stratified and adjusted for marital status, race and ethnicity and survey year.

Results: Severe psychological distress and high alcohol use were each associated with over a threefold increased risk of death of despair. In men, psychological distress and alcohol use mediated up to 16% and 14% of the SES-deaths of despair relationship, respectively. In women, psychological distress mediated up to 20% of the association, while alcohol use did not mediate the relationship.

Conclusion: Low SES, psychological distress and alcohol use are key risk factors for deaths of despair. Intervention targeting mental health and alcohol use, especially through SES-specific and sex-specific approaches, may help reduce inequalities in these preventable causes of death.