The risk of dementia and death after delirium

Abstract

Background: delirium is common and is associated with many adverse short-term consequences.

Objectives: to examine the relationship between an episode of delirium and subsequent dementia and death over 3 years.

Design: prospective cohort study.

Setting: patients (n = 203) were aged 65 years or older at baseline and survivors of the index admission.

Methods: Using a standard assessment of cognitive function, we followed 38 inpatients diagnosed with delirium (22 with delirium and dementia, 16 with delirium only) and 148 patients with no delirium or dementia, for a median of 32.5 months. Follow-up was by personal interviews, supplemented by standardized clinical examinations. We calculated the incidence and odds of dementia and the incidence and hazard ratio for death, with adjustment for potential confounders.

Results: The incidence of dementia was 5.6% per year over 3 years for those without delirium and 18.1% per year for those with delirium. The unadjusted relative risk of dementia for those with delirium was 3.23 (95% confidence interval 1.86-5.63). The adjusted relative risk of death also increased (1.80; 1.11-2.92), while the median survival time was significantly shorter in those with (510 days; 433-587) than in those without delirium (1122 days; 922-1322).

Conclusion: delirium appears to be an important marker of risk for dementia and death, even in older people without prior cognitive or functional impairment.