Prevalence of dementia in ischaemic or mixed stroke populations: systematic review and meta-analysis

An understanding of the epidemiology of poststroke dementia (PSD) is necessary to inform research, practice and policy. With increasing primary studies, a contemporary review of PSD could allow for analyses of incidence and prevalence trends. Databases were searched using a prespecified search strategy. Eligible studies described an ischaemic or mixed stroke cohort with prospective clinical assessment for dementia. Pooled prevalence of dementia was calculated using random-effects models at any time after stroke (primary outcome) and at 1 year (range: 6–18 months), stratified for inclusion of prestroke dementia. Meta-regression explored the effect of year of study. Sensitivity analyses removed low-quality or outlier studies. Of 12 505 titles assessed, 44 studies were included in the quantitative analyses. At any time point after stroke, the prevalence of PSD was 16.5% (95% CI 10.4% to 25.1%) excluding prestroke dementia and 22.3% (95% CI 18.8% to 26.2%) including prestroke dementia. At 1 year, the prevalence of PSD was 18.4% (95% CI 7.4% to 38.7%) and 20.4% (95% CI 14.2% to 28.2%) with prestroke dementia included. In studies including prestroke dementia there was a negative association between dementia prevalence and year of study (slope coefficient=−0.05 (SD: 0.01), p<0.0001). Estimates were robust to sensitivity analyses. Dementia is common following stroke. At any point following stroke, more than one in five people will have dementia, although a proportion of this dementia predates the stroke. Declining prevalence of prestroke dementia may explain apparent reduction in PSD over time. Risk of dementia following stroke remains substantial and front-loaded, with high prevalence at 1 year post event.

Accuracy of the Informant Questionnaire on Cognitive Decline in the Elderly for Detecting Preexisting Dementia in Transient Ischemic Attack and Stroke

Background and Purpose: Prestroke dementia prevalence is high and impacts outcome. Although the IQCODE (Informant Questionnaire on Cognitive Decline in the Elderly) is being used to assess prestroke cognition, data on its validity for prestroke dementia are lacking. We studied the accuracy of the short-form (16-item) IQCODE for pre-event dementia in a population-based study of all transient ischemic attack (TIA)/stroke. Methods: All patients with TIA/stroke in a defined population of ≈92 720 (Oxford Vascular Study, 2002–2017) with IQCODE were included. IQCODE questionnaires were given to participants at baseline interview with instructions to pass to an informant for completion and return by post. Diagnosis of pre-event dementia was defined as prior diagnosis of dementia, or dementia by the Diagnostic and Statistical Manual of Mental Disorders-IV criteria on study interview and hand-searching of the entire medical record blinded to IQCODE. Reliability of the IQCODE for dementia was determined by the area under the receiver operating characteristic curve, sensitivity and specificity, stratified by age, event severity, and first-ever stroke. Results: Among 2059 interviewed survivors, IQCODE were returned in 1068 (mean age/SD=72.9/12.3, 47% TIA, 52.3% male, 68 [6.4%] pre-event dementia). Area under the receiver operating characteristic curve for IQCODE for pre-event dementia was 0.94 (95% CI, 0.90–0.97, P <0.001) with similar results by age: 0.92, 0.88 to 0.96, <65 years; 0.94, 0.83 to 1.00, 65 to 74 years; 0.95, 0.92 to 0.99, 75 to 84 years; 0.89, 0.82 to 0.96, ≥85 years. The optimal cutoff score overall was >3.48 (sensitivity=89.7%; specificity=84.2%) but was nonsignificantly higher for major stroke (National Institutes of Health Stroke Scale score ≥3) than minor stroke/TIA (>3.85 versus >3.47). Performance was similar in patients with first-ever stroke (area under the receiver operating characteristic curve, 0.92 [0.88–0.97]; sensitivity=85.7%; specificity=84.8% for cutoff >3.48). All 16-IQCODE questions discriminated between dementia and no dementia (all P <0.001) with the greatest differences seen for finances, using gadgets, arithmetic, and learning new things. Conclusions: IQCODE has excellent accuracy for detecting preexisting dementia in TIA and stroke with the pattern of deficits suggesting prominent executive dysfunction.