Increased risk of suicide after stroke: A population-based matched cohort study.

Background and objectives: We examined the timing of suicide after stroke, the sociodemographic factors associated with the risk of suicide, and whether major depression modified the stroke-suicide association.

Methods: We conducted a population-based retrospective cohort study of all adults in Ontario hospitalized for stroke between January 1, 2008, and December 31, 2017, who were matched 1:1 to controls from the general Ontario population on age, sex, neighborhood-level income, rurality, and comorbidities. Suicide, a composite of deliberate self-harm or death by suicide, was ascertained based on hospitalizations and emergency department visits. Cause-specific hazard models were used to evaluate the association between stroke and suicide, and major depression was treated as a time-varying covariate. Cause-specific hazard models evaluated the association between sociodemographic factors and suicide in stroke survivors. The modifying effect of major depression was assessed by adding an interaction term between stroke and major depression.

Results: We included 64,719 matched pairs of patients with stroke and general population controls (45.4% female, mean age 71.4 years). In the 627,774 person-years follow-up, 436 cases and controls had an episode of self-harm or died by suicide, with 203 (67.4%) events in stroke survivors occurring after the first year. Compared to matched controls, stroke survivors had a higher rate of suicide (11.1 vs 3.2 per 10,000 person-years, hazard ratio (HR) 2.87; 2.35-3.51). The association between stroke and suicide did not vary by the presence of major depression (P_{stroke*depression} = 0.51). Suicide rates were elevated in younger stroke survivors (HR_{18-40 vs ⩾ 80 years} 4.34; 2.48-7.61), those living in low-income neighborhoods (HR_{lowest vs highest quintile} 1.88; 1.30-2.70), and those with major depression (HR 12.3; 7.63-19.7).

Discussion: The elevated rate of suicide after stroke persists beyond one year, highlighting the need for long-term screening for suicidality, especially in younger stroke survivors and those residing in low-income neighborhoods and with major depression after stroke.