Income inequality and ′hospitalisations of despair′ in Canada: a study on longitudinal, population-based data

Background Rates of drug overdoses, alcohol-related liver disease and suicide attempts represent a major public health burden in Canada. While the existing literature does highlight some evidence of association between income inequality and mental health and deaths of despair, no existing research has investigated more intermediate events. As such, the objective of the current study is to investigate the association between income inequality and hospitalisations of despair over time. Methods Data from the 2006 Canadian Census, the 2007/2008 Canadian Community Health Survey and the 2007-2018 Discharge Abstract Database were linked. Data were analysed using Cox proportional hazards modelling accounting for robust standard errors at the area level to investigate associations between income inequality at baseline and hazards for hospitalisations of despair, hospitalisations attributable to drug overdose, alcohol-related liver disease and suicide attempts, and all-cause hospitalisations, while controlling for sociodemographics characteristics (including income) and relevant area-level variables. Results The results highlighted statistically significant associations between income inequality and hazard of hospitalisations of despair (HR 1.38, 95% CI 1.06 to 1.80), hospitalisations related to drug overdose (HR 1.51, 95% CI 1.07 to 2.13) and all-cause hospitalisations (HR 1.17, 95% CI 1.05 to 1.30). The association between income inequality and hospitalisations related to alcohol-related liver disease and suicide attempts/self-harm were not statistically significant. Conclusion Overall, the results showed evidence of associations between income inequality and hospitalisations of despair, drug overdose-related hospitalisations and all-cause hospitalisations. These findings are applicable to upstream policy discussion regarding reducing income inequality and identify potential points of intervention for prevention of drug overdose, alcohol-related liver disease and suicide attempts/self-harm.