Dementia as a predictor of morbidity and mortality in patients with delirium

This review examines whether functional and cognitive decline and mortality after an episode of delirium are comparable between patients with and those without dementia.

MEDLINE and EMBASE were searched systematically for 'dementia' and 'delirium'. After screening of the results, studies were rated on relevance and validity and data were extracted. Cognitive decline was defined as decline in Mini-Mental State Examination (MMSE) score. Functional decline was defined as decline in Barthel Index (BI), score on the Instrumental Activities of Daily Living (IADL) or institutionalisation.

From 5092 potentially relevant articles identified, eight studies were included in the review. The one-year mortality rate ranged from 11% to 45% in patients with dementia versus 22% to 44% in patients without dementia, and the overall absolute rate was 34% (95% CI 0.32-0.36). Pooled data did not show a significant difference between the groups. The MMSE scores and the Barthel Index had improved in both groups after six months, but scores on the Instrumental Activities of Daily Living (IADL) had declined. However, on all measurement points, patients with dementia scored significantly lower than patients without dementia. In addition, patients with dementia had a 33% risk of institutionalisation after an episode of delirium versus 20% in patients without dementia (95% CI 0.06-0.20).

No significant differences were seen in mortality after delirium between patients with and without dementia. The overall one-year mortality was high (34%). Patients with dementia had significantly lower functional and cognitive scores and their risk of institutionalisation post-delirium was higher. Patients and their caregivers should be given this information, which may also be useful in advance care planning.