Rates, Risks, and Routes to Reduce Vascular Dementia: A UK-Wide Multicentre Prospective Observational Cohort Study of Cognition after Stroke - Baseline Data and Statistical Analysis Plan (ISRCTN18274006).

INTRODUCTION

Stroke is often followed by vascular cognitive impairment and vascular dementia, the most feared complications of stroke. However, understanding of post-stroke cognitive impairment remains limited.

METHODS

Rates, risks, and routes to reduce vascular dementia is an observational cohort study of post-stroke cognition. Patients with haemorrhagic or ischaemic stroke, or transient ischaemic attack, were recruited within 6 weeks of stroke from hospitals across the UK. Consent was obtained from patients with capacity or from relatives/friends in those without capacity. The primary outcome is dementia rate and its severity at 2 years assessed using a 7-level ordinal cognition outcome. Final dementia rate will be compared in those with mild stroke/TIA (worst NIHSS ≤7) versus severe stroke (NIHSS >7). Secondary outcomes will include cognitive impairment, function, mood and quality of life, and predictors of cognitive impairment at 1 and 2 years. Data are shown as number (%), median (interquartile range [IQR]), or mean (standard deviation [SD]).

RESULTS

We recruited 2,441 patients from 50 hospitals. Of these, 2,432 (99.6%) had a qualifying event of stroke or TIA. The mean age was 68.2 years (SD 13.5), females 979 (40.3%), ethnic minority 170 (7.0%), NIHSS ≤7.1962 (80.7%), onset to recruitment 5 days (IQR 3-13) and diagnosis ICH 192 (7.9%), ischaemic stroke 2,097 (86.2%), TIA 143 (5.9%). The distribution of cognition at baseline (within 6 weeks of onset) was normal 1,300 (53.5%), minor neurocognitive disorder - single domain 351 (14.4%), minor neurocognitive disorder - multi-domain 263 (10.8%), major neurocognitive disorder - mild 387 (15.9%), major neurocognitive disorder - moderate 108 (4.4%), and major neurocognitive disorder - severe 23 (0.1%). Participants with more severe stroke were recruited later (8 [IQR 3-17] vs. 5 [2-11] days, p < 0.001), less likely to have capacity (86.3% vs. 96.8%, p < 0.001) and more likely to have had an intracerebral haemorrhage (12.0% vs. 6.8%, p < 0.001).

CONCLUSION

We provide baseline data with the statistical analysis plan in the supplementary material. The data highlight the substantial under-appreciated cognitive burden of stroke, even in the first few days and weeks after onset.