Influence of prestroke dementia on early and delayed mortality in stroke patients.

Causes of early and delayed death after stroke differ. It has been suggested that delayed mortality rate was increased in patients with post-stroke dementia. Prestroke dementia is frequent: its influence on survival in stroke patients has never been evaluated. The aim of this study was to evaluate the influence of prestroke dementia on early and delayed mortality rate after stroke. In a cohort of 202 consecutive stroke patients aged >or= 40 years admitted between November 1995 and May 1996 in a primary care center, the prevalence of prestroke dementia was determined using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) with a cut-off of 104. Patients were followed-up for 3 years. Statistics were performed using life-table methods. Of 202 patients, 33 had prestroke dementia. Of 142 survivors at month-6, 44 were demented, of them 15 having prestroke and 29 new-onset post-stroke dementia. No patient was lost to follow-up. The risk of death at month-6 was higher in patients with prestroke dementia (RR 2.7; 95 % CI: 1.6-4.8). However, independent predictors of early death were age, severity of the deficit at admission, type and etiology of stroke. The risk of delayed death was higher in patients with prestroke dementia (RR 4.97; 95 % CI: 1.76-13.98) as in patients with new-onset post-stroke dementia (RR 6.24; 95 % CI: 2.67-14.57), compared with non-demented patients. The mortality rate did not differ between patients with prestroke and new-onset post-stroke dementia. Dementia at month-6 was an independent predictor of delayed death (RR 5.7; 95 % CI: 2.4-13.4), with age and stroke recurrence. Causes of death did not differ between demented and non-demented patients. Dementia adversely influences vital outcome in stroke patients, perhaps partly because the therapeutic approach differs between demented and non-demented patients.