Cognitive Predictors of Delirium on Long-Term Follow-Up after TIA and Stroke: Population-Based Cohort Study

Abstract

Introduction: TIA and stroke cause cognitive impairment with a typical "vascular"pattern, including prominent frontal/executive deficits. Cognitive impairment is associated with increased delirium risk and the few available data suggest that executive dysfunction is important. We therefore determined the predictive value of both severity and pattern of cognitive deficits for delirium on long-term follow-up after TIA/stroke. Methods: Surviving TIA/stroke participants on October 1, 2013, in the Oxford Vascular Study (OXVASC) were assessed prospectively for delirium during all hospitalizations over the subsequent 6 months. Associations between OXVASC pre-admission mini-mental state examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores, and delirium during hospitalizations on follow-up were determined using logistic regression adjusted for covariates, including demographic factors, history of depression, baseline stroke severity, and admission illness severity. Results: Among 1,565 TIA/stroke survivors, 158 patients (mean/SD age = 79.2/11.5 years) had ≥1 admission and 59 (37%) had ≥1 delirium episode. Mean/SD time between baseline TIA/stroke and admission was 4.7/3.6 years and between most recent OXVASC cognitive testing and admission was 1.7/1.8 years. MMSE and MoCA scores were associated with delirium: odds ratio (OR) = 1.16 (95% CI 1.07-1.27, p < 0.0001 per point decrease in MMSE) and OR = 1.20 (1.11-1.30, p < 0.0001 MoCA) and associations were robust to adjustment for all covariates, including stroke severity: OR = 1.11 (1.01-1.22, p = 0.03, MMSE) and OR = 1.15 (1.05-1.25, p = 0.003, MoCA). All 10 subtests on the MoCA and 4/11 on the MMSE were significantly associated with delirium with highest predictive value for frontal/executive and recall domains. Conclusions: Cognitive impairment of increasing severity after TIA/stroke predisposed to delirium particularly deficits in frontal/executive domains and recall. Long-term risk of delirium should be considered as part of the overall cerebrovascular disease burden.