Income inequality and deaths of despair risk in Canada, identifying possible mechanisms.

Background: Declines in life expectancy in developed countries have been attributed to increases in drug-related overdose, suicide, and liver cirrhosis, collectively referred to as deaths of despair. Income inequality is proposed to be partly responsible for increases in deaths of despair rates. This study investigated the associations between income inequality, deaths of despair risk in Canada, and potential mechanisms (stress, social cohesion, and access to health services).
Methods: We obtained data from the Canadian Community Health Survey and the Canadian Vital Statistics Database from 2007 to 2017. A total of 504,825 Canadians were included in the analyses. We used multilevel survival analyses, as measured by the Gini coefficient, to examine the relationships between income inequality and mortality attributed to drug overdose, suicide, death of despair, and all-cause. We then used multilevel path analyses to investigate whether each mediator (stress, social cohesion, and access to mental health professionals), which were investigated using separate mediation models, influenced the relationship between income inequality and drug overdose, suicide, deaths of despair, and all-cause death.
Results: Adjusted multilevel survival analyses demonstrated significant relationships between a one-SD increase in Gini coefficient was associated with an increased hazard for drug overdose (HR _adj.  = 1.28; 95 CI = 1.05, 1.55), suicide (HR _adj.  = 1.24; 95 CI = 1.06, 1.46), deaths of despair (HR _adj.  = 1.26; 95 CI = 1.12, 1.40), and all-cause death (HR _adj.  = 1.04; 95 CI = 1.02, 1.07). Adjusted path analyses indicated that stress, social cohesion, and access to mental health professionals significantly mediated the association between income inequality and mortality outcomes.
Conclusion: Income inequality is associated with deaths of despair and this relationship is mediated by stress, social cohesion, and access to mental health professionals. Findings should be applied to develop programs to address income inequality in Canada.
Competing Interests: Declaration of interest RP is a Tier 2 Canada Research Chair.
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