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Dementia after stroke is a predictor of long-term survival
T K Tatemichi1, M Paik, E Bagiella
1Department of Neurology (Stroke and Aging Research Project), Columbia University, College of Physicians and Surgeons, New York, NY.
Background And Purpose:
The aim of this study was to determine whether dementia after stroke adversely influences long-term survival.
Methods:
Subjects were 251 patients > or = 60 years of age with ischemic stroke who were given neurological, neuropsychological, and functional examinations 3 months after hospitalization and were followed up prospectively. Using criteria modified from the Diagnostic and Statistical Manual of Mental Disorders-III-R, dementia was found in 66 (26.3%) patients at the 3-month baseline examination. Life-table methods were used to estimate mortality rates in the groups with and without dementia after 1 to 5 years of follow-up, Kaplan-Meier curves to estimate the cumulative proportion surviving with and without dementia, and Cox proportional-hazards analysis to compute the relative risk of mortality associated with dementia at baseline, after adjusting for other potential predictors of stroke mortality.
Results:
The mortality rate was 19.8 deaths per 100 person-years with dementia compared with 6.9 deaths per 100 person-years without dementia. The cumulative proportion surviving after a median follow-up of 58.6 months was 38.9 +/- 0.08% for those with dementia and 74.5 +/- 0.04% for those without dementia. The relative risk associated with dementia was 3.11 (95% confidence interval, 1.79 to 5.41) after adjusting for the effects of demographic factors, cardiac disease, severity of stroke (Barthel Index), stroke type (lacunar versus nonlacunar), and recurrent stroke (examined as a time-dependent variable). When the Mini-Mental State Examination score at baseline was examined instead of the diagnosis of dementia, the results of the model were similar.
Conclusion:
Our study is the first to demonstrate that dementia or cognitive impairment adversely influences long-term survival after stroke, even after adjusting for other commonly accepted predictors of stroke mortality. Impairment in intellectual function after stroke, independent of physical disability, has a significant impact on prognosis. Both cognitive and physical functions should be assessed in clinical studies of stroke outcome.