Social Isolation and Incident Post-Stroke Depression: A Population-Based Cohort Study

Methods

We included 7,267 UK Biobank participants with prior stroke (mean±SD age =60.5 ±6.9 years, 55.6% male) without baseline depression. Degree of social isolation was assessed with three questions: 1) “Including yourself, how many people are living together in your household? (Include those who usually live in the house such as students living away from home during term, partners in the armed forces, or professions such as pilots)” (1 point for living alone); 2) “How often do you visit friends or family or have them visit you?” (1 point for answering rarely, never, or monthly); and 3) “Which of the following [leisure/social activities] do you engage in once a week or more often? You may select more than one” (1 point for none of the above). Incident post-stroke depression was ascertained from hospital records and death registries. We used Cox cause-specific hazards models to estimate hazard ratios (HRs) adjusted for demographics, socioeconomic status, comorbidities, health behaviours and physiological covariates. We also performed a relative importance analysis to rank risk factors. We calculated the Percentage of Excess Risk Mediated (PERM) by grouping explanatory covariates into categories, such as medication, behaviors, and comorbidities.