The association of dementia and delirium with health outcomes in a sample of older inpatients in a New Zealand hospital setting

Abstract

Background Both dementia and delirium are seen frequently in older hospital inpatients. Dementia is present in up to one-third of older hospital inpatients, and delirium also occurs in around one-third of older inpatients, often alongside dementia. Patients’ health outcomes, such as mortality, length of stay, and discharge to a care home, may be worse in patients with dementia and/or delirium. Objective(s) To describe the association of dementia and delirium with health outcomes (length of stay, mortality, care home placement) in a sample of patients from a New Zealand hospital setting. Methods Routinely collected data from a consecutive sample of 2248 older patients assessed in a New Zealand memory service from 2013 to 2021 were extracted to examine the associations of delirium and dementia with patients’ health outcomes: length of stay, care home placement, and mortality. Results Of the 2248 patients assessed, 75% were hospitalised after diagnosis, and half of these had delirium screening in hospital. People with dementia had three times the risk of experiencing delirium (OR=3.0, 95% CI:2.0-4.6, p<0.001). In Pacific people compared to NZ Europeans, the adjusted relative risk ratios for having dementia only or delirium superimposed on dementia, compared to those with neither, were 2.3 (p<0.001) and 2.9 (p<0.001), respectively. Compared to people with neither diagnosis, people with delirium (with or without dementia) had a longer mean length of stay, were two to four times more likely to be placed in a care home, and the risk of death was 1.7-3.1 times higher. Conclusion Delirium is very common in older hospital inpatients and has a major impact on patient outcomes and health costs. Pacific peoples seem to have greater risk of both dementia and delirium, associated with worse clinical outcomes.