Mortality in Individuals with Depression and Problematic Substance Use: A Canadian population-based study
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2020-11-10
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Abstract
The simultaneous presence of depression and problematic substance use is a complex healthcare and public health issue that results in poor mental health outcomes. Individuals with these conditions may be vulnerable to an increased risk of mortality. The purpose of this study is to describe the occurrence and causes of mortality in patients with co-occurrence of major depressive episode (MDE) and problematic substance use in the Canadian household population. The study was performed through the linkage between CCHS Cycle 1.2 to the Canadian Vital Statistics Death Database. Cox proportional hazard model was used to estimate hazard ratios as the measure of association for all-cause mortality. Competing risk regression was used to estimate sub-hazard ratios for injury-related and other causes-related deaths. Interaction analysis between MDE and problematic substance use on the multiplicative (product term) and additive scales (Relative Excess Risk Due to Interaction) was used to determine if the magnitude of effect of problematic substance use or MDE on mortality is modified by the presence of the other disorder. Compared to the general population, the hazard of all-cause mortality was elevated in individuals with MDE (HR: 1.47 (95% CI 1.18–1.82)), problematic substance use (HR: 1.35 (95% CI1.18–1.53)) or with problematic substance use and MDE (HR: 2.13 (95% CI 1.24–3.67)). Individuals with MDE (HR: 3.13 (95% CI 1.82–5.36)), problematic substance use (HR: 1.82 (95% CI 1.22–2.71) or with problematic substance use and MDE (HR: 4.91 (95% CI 1.93–12.51) were also at an increased hazard of injury-related deaths. There was no interaction on the multiplicative or additive scales between the exposures for the outcome of all-cause mortality, injury-related mortality or other causes-related mortality. Individuals with MDE and problematic substance use are at increased hazard of mortality, regardless of the presence of the other exposure. As no interaction was found between MDE and problematic substance use on the multiplicative or additive scale, the simultaneous presence of MDE and substance use doe not increase the strength of association with mortality beyond what is expected given the joint effects of each exposure.
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Shafiq, S. (2020). Mortality in Individuals with Depression and Problematic Substance Use: A Canadian population-based study (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.