Income inequality and deaths of despair: a population-based study of 19 million Canadian adults

Purpose: To estimate the association between regional level income inequality (a relative measure of socioeconomic disparity) and deaths of despair and assess whether this association is moderated by age, gender, racialized minority status, and income. Methods: Data from the 2006 Canadian Census Health and Environment Cohort (CanCHEC) study were used. A cohort of Canadian adults (n = 19,436,790) within 288 CDs were followed from May 2006 to December 2019. Multilevel Cox-proportional hazard regression was used to estimate the association between income inequality and time to deaths attributed to suicide, drug overdose, and alcohol. Results: In models adjusted for confounders, income inequality was associated with time to death due to alcohol (HR = 1.14; 95% CI: 1.05, 1.25), drug overdose (HR = 1.19; 95% CI: 1.06, 1.33), and deaths of despair (HR = 1.05; 95% CI: 1.00, 1.11). Significant interactions were primarily observed in cases of deaths attributed to drug overdose. The association between income inequality and the hazards for drug overdose deaths was stronger for individuals aged 40–49 (HR = 1.71; 95% CI: 1.24, 2.37), males (HR = 1.69; 95% CI: 1.22, 2.35), from low-income households (HR = 1.69; 95% CI: 1.22, 2.35), self identified as White (HR = 1.69; 95% CI: 1.22, 2.35) and those living in low-income areas (HR = 1.69; 95% CI: 1.22, 2.35). Conclusion: Income inequality is associated with high risk of deaths of despair. Additionally, this association is significantly moderated by age, gender, racialized minority status and income at the household and area levels. As such, our findings suggest the need to address income inequality in interventions for reducing deaths of despair among Canadian adults.