Introduction: With an aging population, an increased number of acute stroke patients with pre-stroke dementia is expected. Although both stroke and dementia are major cause of disability, the effect of pre-stroke dementia on functional outcome after stroke has been still on debate.
Hypothesis: Pre-stroke dementia is associated with poor functional outcome after acute ischemic stroke.
Methods: Of 9198 stroke patients registered in the Fukuoka Stroke Registry in Japan from June 2007 to May 2014, 3843 patients with first-ever ischemic stroke within 24h of onset, who had been functionally independent before the onset, were enrolled in this study (cardioembolism [n=926], large artery atherosclerosis [n=583], small vessel occlusion [n=1045], others [n=1289]). Pre-stroke dementia was defined as any type of dementia that was present prior to the stroke. For propensity score (PS)-matched analysis, 320 pairs of patients with and without pre-stroke dementia were also selected. Study outcome was poor functional outcome (modified Rankin Scale 3-6) at discharge.
Results: In the total cohort, 330 (8.6%) had pre-stroke dementia. The age (80±8 vs 69±13, year, mean±SD, p<0.01), frequencies of female (46 vs 36, %, p<0.01) and cardioembolism (41 vs 23, %, p<0.01), and NIHSS score on admission (6 [3 - 12] vs 3 [1 - 6], median [interquartile], p<0.01) were higher in patients with pre-stroke dementia than those without the dementia. Poor functional outcome (62 vs 25, %, p<0.01) were more prevalent in patients with pre-stroke dementia than those without the dementia. Multivariable-adjusted analysis showed that pre-stroke dementia was significantly associated with increased risk for poor functional outcome (OR 2.3, 95% CI 1.7-3.2). There were no interactions between pre-stroke dementia and 4 variables (age, sex, stroke subtype, and initial stroke severity [NIHSS≤7 or NIHSS≥8]). In the PS-matched analysis, pre-stroke dementia was still associated with poor functional outcome (OR 4.3, 95%CI 2.1-8.8).
Conclusions: Pre-stroke dementia was significantly associated with poor functional outcome at discharge in patients with acute ischemic stroke.