Psychological distress as a risk factor for all-cause, chronic disease- and suicide-specific mortality: a prospective analysis using data from the National Health Interview Survey

Purpose The risk psychological distress (PD) confers on mortality due to specific chronic diseases compared to suicide is unclear. Using the National Health Interview Survey (NHIS), we investigated the association between PD levels and risk of all-cause and chronic disease-specific mortality and compared the contribution of chronic disease-related mortality to that of suicide. Methods Data from 195, 531 adults, who participated in the NHIS between 1997 and 2004, were linked to the National Death Index records through to 2006. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and their 95% confidence intervals (CIs) across four levels of PD, measured using the Kessler-6 scale. Outcomes included all-cause mortality, and mortality due to all CVDs and subtypes, all cancers and subtypes, diabetes mellitus, alcoholic liver disease and suicide. Results During a mean follow-up time of 5.9 years, 7665 deaths occurred. We found a dose-response association between levels of PD and all-cause mortality, with the adjusted HRs (95% CI) elevated for all levels of PD, when compared to asymptomatic levels: subclinical 1.10 (1.03-1.16), symptomatic 1.36 (1.26-1.46) and highly symptomatic 1.57 (1.37-1.81). A similar association was found for all CVDs and certain CVD subtypes, but not for cancers, cerebrovascular diseases diabetes mellitus. Excess mortality attributable to suicide and alcoholic liver disease was evident among those with levels of PD only. Conclusion PD symptoms, of all levels, were associated with an increased risk of all-cause and CVD-specific mortality while higher PD only was associated with suicide. These findings emphasise the need for lifestyle interventions targeted towards improving physical health disparities among those with PD.