Explanatory factors for the increased mortality of stroke patients with depression

Abstract

Objective: To identify explanatory factors for the association between depression and increased mortality up to 5 years after stroke.

Methods: In this cohort study, data from the South London Stroke Register (1998-2013) were used. Patients (n = 3,722) were assessed at stroke onset. Baseline data included sociodemographics and stroke severity. Follow-up at 3 months included assessment for depression with the Hospital Anxiety and Depression Scale (scores ≥7 = depression). Associations between depression at 3 months and mortality within 5 years of stroke were estimated with Cox regression models adjusted for age, sex, ethnicity, and stroke severity, and subsequently adjusted for possible explanatory factors for the association. These factors, introduced into the model individually, included comorbidities at baseline, smoking and alcohol use, compliance with medication, treatment with selective serotonin reuptake inhibitors (SSRIs), social support, and activities of daily living at 3 months.

Results: A total of 1,354 survivors were assessed at 3 months: 435 (32.1%) had depression and 331 (24.4%) died within 5 years. Survivors with depression had a greater risk of mortality (hazard ratio [HR] 1.41 [95% confidence interval (CI) 1.13-1.77]; p = 0.002). The association between depression and mortality was strongest in patients younger than 65 years. Adjustment for comorbidities, smoking and alcohol use, SSRI use, social support, and compliance with medication did not change these associations. SSRIs started after stroke were associated with higher mortality, independently of depression at 3 months (HR 1.72 [95% CI 1.34-2.20]; p < 0.001).

Conclusion: Depression after stroke is associated with higher mortality, particularly among younger patients. Stroke survivors taking SSRIs have an increased mortality. The association between depression and mortality is not explained by other individual medical factors.