Incidence and prevalence of dementia associated with transient ischaemic attack and stroke: analysis of the population-based Oxford Vascular Study

So if you have a severe stroke, NIHSS score >10, then your doctor needs to have a dementia prevention protocol with an incredibly high efficacy rating. NOT guidelines, A PROTOCOL! I have no clue what my NIHSS score was, but taking it myself was probably a 9 or 10. So you have described a problem. What the hell is the solution to that problem? Survivors expect solutions. Are you a doctor or just an automaton that parrots useless answers?

Incidence and prevalence of dementia associated with transient ischaemic attack and stroke: analysis of the population-based Oxford Vascular Study

Summary

Background

Risk of dementia after stroke is a major concern for patients and carers. Reliable data for risk of dementia, particularly after transient ischaemic attack or minor stroke, are scarce. We studied the risks of, and risk factors for, dementia before and after transient ischaemic attack and stroke.

Methods

The Oxford Vascular Study is a prospective incidence study of all vascular events in a population of 92 728 people residing in Oxfordshire, UK. Patients with transient ischaemic attack or stroke occurring between April 1, 2002, and March 31, 2012, were ascertained with multiple methods, including assessment in a dedicated daily emergency clinic and daily review of all hospital admissions. Pre-event and post-event (incident) dementia were diagnosed at initial assessment and during 5-years' follow-up on the basis of cognitive testing supplemented by data obtained from hand searches of all hospital and primary care records. We assessed the association between post-event dementia and stroke severity (as measured with the US National Institutes of Health Stroke Scale [NIHSS] score), location (ie, dysphasia), previous events, markers of susceptibility or reserve (age, low education, pre-morbid dependency, leucoaraiosis), baseline cognition, and vascular risk factors with Cox regression models adjusted for age, sex, and education. We compared incidence and prevalence of dementia in our population with published UK population age-matched and sex-matched rates.

Findings

Among 2305 patients (mean age 74·4 years [SD 13·0]), 688 (30%) had transient ischaemic attacks and 1617 (70%) had strokes. Pre-event dementia was diagnosed in 225 patients; prevalence was highest in severe stroke (ie, NIHSS >10) and lowest in transient ischaemic attack. Of 2080 patients without pre-event dementia, 1982 (95%) were followed up to the end of study or death. Post-event dementia occurred in 432 of 2080 patients during 5 years of follow-up. The incidence of post-event dementia at 1 year was 34·4% (95% CI 29·7–41·5) in patients with severe stroke (NIHSS score >10), 8·2% (6·2–10·2) in those with minor stroke (NIHSS score <3), and 5·2% (3·4–7·0) in those with transient ischaemic attack. Compared with the UK age-matched and sex-matched population, the 1-year standardised morbidity ratio for the incidence of dementia was 47·3 (95% CI 35·9–61·2), 5·8 (4·4–7·5), and 3·5 (2·5–4·8), respectively. Consequently, prevalence of dementia in 1-year survivors was brought forward by approximately 25 years in those who had severe strokes, 4 years in those who had minor strokes, and 2 years in those who had transient ischaemic attacks. 5-year risk of dementia was associated with age, event severity, previous stroke, dysphasia, baseline cognition, low education, pre-morbid dependency, leucoaraiosis, and diabetes (p<0·0001 for all comparisons, except for previous stroke [p=0·006]).

Interpretation

The incidence of dementia in patients who have had a transient ischaemic attack or stroke varies substantially depending on clinical characteristics including lesion burden and susceptibility factors. Incidence of dementia is nearly 50 times higher in the year after a major stroke compared with that in the general population, but excess risk is substantially lower after transient ischaemic attack and minor stroke.

Funding

Wellcome Trust, Wolfson Foundation, British Heart Foundation, National Institute for Health Research, and the National Institute for Health Research Oxford Biomedical Research Centre.

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Introduction

Reliable estimates of the incidence of dementia after transient ischaemic attack and stroke are required to counsel patients and families and to inform prevention trials. However, most available data are from cross-sectional studies and hospital-based cohorts of major stroke, which are subject to selection biases and were done before the advent of robust secondary prevention.

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Stroke has been estimated to bring forward the onset of dementia by about 10 years,

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but there are few data on the effect of event severity, particularly the risk after transient ischaemic attacks or minor stroke, which make up around 70% of all acute cerebrovascular events and often result in anxiety in patients and families about future risks.

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Anxiety could be compounded by the reportedly high rates of cognitive impairment after transient ischaemic attack,

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and by public education suggesting high incidence of dementia.

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The frequency of progression of cognitive impairment to dementia after transient ischaemic attack and minor stroke is unclear, as is the extent to which the prevalence and incidence of dementia are higher among those who have had transient ischaemic attacks or minor strokes than those expected among the age-matched general population.