Depression duration and risk of incident cardiovascular disease: A population-based six-year cohort study

Background: Depression symptoms are significantly associated with an increased risk of cardiovascular disease (CVD). However, understanding of the magnitude of the association between depression duration and risk of CVD is limited. Therefore, we aimed to assess whether a longer duration of exposure to depression is associated with a higher risk of new-onset CVD. Methods: We conducted a territory-wide retrospective cohort study among patients (> 10 years old) with depression diagnosed between January and December 2014 in Hong Kong. The observation period spanned January 1, 2014, to December 31, 2019, and all participants had no CVD at baseline. Incidence of CVD was calculated. We used Cox proportional hazard regression to adjust confounders and estimate hazard ratios of CVD risk. Results: Among 11,651 participants with depression, 1306 (11.2%) individuals developed CVD. Multi-adjusted models showed individuals with depression duration of 2-5 years (Hazard Ratios [HRs]: 1.38 [95% confidence interval (CI): 1.19-1.60]) and >6 years (1.45 [1.25-1.68]) had a significantly escalated risk of developing CVD, compared to those with depression within one year. Stratified analyses indicated that the association was prominent in women and those under 65 years old. Limitations: Lack of depression severity information and the small sample size in some subgroup analyses. Conclusions: Longer exposure to depression is associated with significant increased risk of CVD. The interplay between mental and vascular health emphasizes the need for CVD prevention in patients with long-term depression.