Does depressed persons with non-cardiovascular morbidity have a higher risk of CVD? A population-based cohort study in Sweden

Background Depression often co-exists with non-cardiovascular morbid conditions. Whether this comorbidity increases the risk of cardiovascular disease has so far not been studied. Thus, the aim of this study was to determine if non-cardiovascular morbidity modifies the effect of depression on future risk of CVD. Methods Data was derived from the PART study (acronym in Swedish for: Psykisk hälsa, Arbete och RelaTioner: Mental Health, Work and Relationships), a longitudinal cohort study on mental health, work and relations, including 10,443 adults (aged 20–64 years). Depression was assessed using the Major Depression Inventory (MDI) and self-reported data on non-cardiovascular morbidity was assessed in 1998–2000. Outcomes of CVD were assessed using the National Patient Register during 2001–2014. Results Both depression (HR 1.5 (95% CI, 1.1, 2.0)) and non-cardiovascular morbidity (HR 2.0 (95% CI, 1.8, 2.6)) were associated with an increased future risk of CVD. The combined effect of depression and non-cardiovascular comorbidity on future CVD was HR 2.1 (95%, CI 1.3, 3.4) after adjusting for age, gender and socioeconomic position. Rather similar associations were seen after further adjustment for hypertension, diabetes and unhealthy lifestyle factors. Conclusion Persons affected by depression in combination with non-cardiovascular morbidity had a higher risk of CVD compared to those without non-cardiovascular morbidity or depression alone.