Stroke and depression in very old age

Sammanfattning: Background The prevalence and incidence of stroke are known to increase with age, which, combined with demographic change, means that very old patients with stroke are a growing patient group. Risk factors for incident stroke among very old people have not been widely investigated. The impact of depression on mortality in very old people who have had a stroke also remains unclear. The aim of this thesis was to investigate the risk factors for incident stroke, the epidemiology of stroke and depression, and the consequences of having had a stroke regarding the risk of depression and mortality among very old people.Methods A randomly selected half of 85-, all 90-, and all ≥95-year-olds in certain municipalities in Västerbotten County, Sweden, and Pohjanmaa County, Finland were targeted in a population-based cohort study from 2000-2012. The 65-, 70-, 75-, and 80-year-olds in all the rural and random samples from the urban municipalities in the same counties were furthermore targeted in a survey in 2010.In the cohort study patients were assessed in their homes, by means of the 15-item Geriatric Depression Scale (GDS-15) and other assessment scales, as well as blood pressure measurements, several physical tests, and a review of medical diagnoses appearing in the medical charts. Incident stroke data were collected from medical charts guided by hospital registry records, cause of death records, and reassessments after 5 years. Depression was defined as a GDS-15 score ≥5. A clinical definition of all depressive disorders, based on assessment scale scores and review of medical charts was also used. A specialist in geriatric medicine evaluated the diagnoses. The survey included yes/no questions about stroke and depression status, and the 4-item Geriatric Depression Scale. Associations with mortality and incident stroke were tested using Cox proportional-hazard models. Results In the ≥85-year-olds examined in 2005-2007 (n=601), the stroke prevalence was 21.5%, the prevalence of all depressive disorders was 37.8% and stroke was independently associated with depressive disorders (odds ratio 1.644, p=0.038). The prevalence of depression according to GDS-15 scores was 43.2% in people with stroke compared with 25.0% in people without stroke (p=0.001). However, in ≥85-year-olds examined in Sweden from 2000-2012 (n=955), from all past data collections in the study, depression was not independently associated with incident stroke. In ≥65-year-olds who responded to a survey in 2010 (n=6098), the stroke prevalence rose with age from 4.7% among the 65- to 11.6% among the 80-year-olds (p<0.001). The prevalence of depression rose from 11.0% among the 65- to 18.1% among the 80-year-olds (p<0.001). In the group with stroke, depression was independently associated with dependence in personal activities of daily living and having a life crisis the preceding year, while in the non-stroke group, depression was independently associated with several additional demographic, social and health factors.In ≥85-year-olds examined in 2005-2007 with valid GDS-15 tests (n=452), having had a stroke was associated with increased 5-year mortality [hazard ratio (HR) 1.53, 95% confidence interval (CI) 1.15-2.03]. Having had a stroke and depression was associated with increased 5-year mortality compared with having only stroke (HR 1.90, 95% CI 1.15-3.13), having only depression (HR 1.59, 95% CI 1.03-2.45), and compared with having neither stroke nor depression (HR 2.50, 95% CI 1.69-3.69). Having only stroke without a depression did not increase mortality compared with having neither stroke nor depression.In ≥85-year-olds examined in Sweden from 2000-2012 (n=955), from all past data collections in the study, the stroke incidence was 33.8/1000 person-years during a mean follow-up period of about three years. In a comprehensive multivariate model, atrial fibrillation (HR 1.85, 95% CI 1.07–3.19) and higher systolic blood pressure (SBP; HR 1.19, 95% CI 1.08–1.30 per 10-mmHg increase) were associated with incident stroke overall. In additional multivariate models, diastolic blood pressure (DBP) ≥90 mmHg (HR 2.45, 95% CI 1.47–4.08) and SBP ≥160 mmHg (v. <140 mmHg; HR 2.80, 95% CI 1.53–5.14) were associated with incident stroke.Conclusion The prevalence of both stroke and depression increased with age, and rates were especially high among very old people. Having had a stroke was independently associated with a higher prevalence of depression among very old people, however, depression was not independently associated with a higher incidence of stroke. Having had a stroke was associated with increased all-cause mortality among very old people, but only among those who were also depressed. High SBP (≥160 mmHg), DBP (≥90 mmHg) and atrial fibrillation were the only consistent independent risk factors for incident stroke among very old people.