Suboptimal baseline mental health associated with 4-month premature all-cause mortality: Findings from 18 years of follow-up of the Canadian National Population Health Survey

OBJECTIVE: To investigate: 1) whether baseline non-flourishing mental health is associated with a higher probability of all-cause mortality over 18-year follow-up after controlling for many risk factors for premature mortality; and 2) what other factors, independent of mental health status, are associated with all-cause mortality after adjustment for known risk factors. METHODS: Data were derived from waves 1 and 9 (1994/1995; 2010/2011) of the Canadian National Population Health Survey. An analytic sample of 12,424 participants 18 years and above was selected. Baseline information on flourishing and predictors of all-cause mortality was from wave 1 and mortality data was ascertained by the Canadian Vital Statistics-Death Database in wave 9. Mean time to all-cause mortality was estimated using Kaplan-Meir procedure. Cox proportional hazards models were used to assess the association of baseline non-flourishing mental health and potential predictors with time to all-cause mortality. RESULTS: About one in five participants was classified as non-flourishing at baseline. At the end of the study period 2317 deaths were observed. Baseline non-flourishing mental health was associated with a 19% higher probability of all-cause mortality during 18-year follow-up (HR = 1.19; 95% CI 1.08–1.32), corresponding to a 4.7-month shorter survival time. After controlling for baseline chronic health conditions, past-year depression, sociodemographics, health behaviors, social support, pain and functioning, baseline non-flourishing mental health status was associated with a 14% higher probability of death (HR = 1.14; 95% CI 1.02–1.27). CONCLUSIONS: Suboptimal mental health is associated with premature mortality even after accounting for many risk factors for early death. Future research should explore the physiological pathways through which non-flourishing influences mortality.