Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 6724 patients with two years follow-up

Simona Hapca; Bruce Guthrie; Feifei Bu; Alasdair Rutherford; Emma Reynish; Peter Donnan

doi:10.2147/CLEP.S174807

Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 6724 patients with two years follow-up

Simona Hapca (Lead / Corresponding author), Bruce Guthrie, Feifei Bu, Alasdair Rutherford, Emma Reynish, Peter Donnan

Population Health and Genomics

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Abstract

Purpose: Cognitive impairment is common in older people admitted to hospital, but the outcomes are generally poorly understood, and previous research has shown inconsistent associations with mortality depending on the type of cognitive impairment examined and duration of
follow-up. This study examines mortality in older people with any cognitive impairment during
acute hospital admission.

Patients and methods: Prospective cohort of 6,724 people aged ≥65 years with a structured
cognitive assessment on acute admission were included in this study. Cognitive spectrum disorder
(CSD) was defined as delirium alone, known dementia alone, delirium superimposed on known
dementia, or unspecified cognitive impairment. Mortality associated with different types of CSD
was examined using a non-proportional hazards model with 2-year follow-up.

Results: On admission, 35.4% of patients had CSD, of which 52.6% died within 2 years. After
adjustment for demographics and comorbidity, delirium alone was associated with increased
mortality in the 6 months post-admission (HR =1.45, 95% CI 1.28–1.65) and again after 1 year
(HR =1.44, 95% CI 1.17–1.77). Patients with known dementia (alone or with superimposed
delirium) had increased mortality only after 3 months from admission (HR =1.85, 95% CI
1.56–2.18 and HR =1.80, 95% CI 1.52–2.14) compared with patients with unspecified cognitive impairment after 6 months (HR =1.55, 95% CI 1.21–1.99). Similar but partially attenuated
associations were seen after adjustment for functional ability.

Conclusion: Mortality post-admission is high in older people with CSD. Immediate risk is
highest in those with delirium, while dementia or unspecified cognitive impairment is associated
with medium- to long-term risk. These findings suggest that individuals without dementia who
develop delirium are more seriously ill (have required a larger acute insult in order to precipitate
delirium) than those with pre-existing brain pathology (dementia). Further research to explain
the mortality patterns observed is required in order to translate the findings into clinical care.

Original language	English
Pages (from-to)	1743-1753
Number of pages	11
Journal	Clinical Epidemiology
Volume	10
DOIs	https://doi.org/10.2147/CLEP.S174807
Publication status	Published - 23 Nov 2018

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10.2147/CLEP.S174807Licence: CC BY

Final Published VersionFinal published version, 1.04 MBLicence: CC BY

Donnan, Peter
- Population Health and Genomics - Professor (Teaching and Research) of Epidemiology and Biostatistics
Person: Academic

Cite this

@article{8991915bef3c47a993674ca8789ce5f5,

title = "Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 6724 patients with two years follow-up",

abstract = "Purpose: Cognitive impairment is common in older people admitted to hospital, but the outcomes are generally poorly understood, and previous research has shown inconsistent associations with mortality depending on the type of cognitive impairment examined and duration offollow-up. This study examines mortality in older people with any cognitive impairment duringacute hospital admission.Patients and methods: Prospective cohort of 6,724 people aged ≥65 years with a structuredcognitive assessment on acute admission were included in this study. Cognitive spectrum disorder(CSD) was defined as delirium alone, known dementia alone, delirium superimposed on knowndementia, or unspecified cognitive impairment. Mortality associated with different types of CSDwas examined using a non-proportional hazards model with 2-year follow-up.Results: On admission, 35.4% of patients had CSD, of which 52.6% died within 2 years. Afteradjustment for demographics and comorbidity, delirium alone was associated with increasedmortality in the 6 months post-admission (HR =1.45, 95% CI 1.28–1.65) and again after 1 year(HR =1.44, 95% CI 1.17–1.77). Patients with known dementia (alone or with superimposeddelirium) had increased mortality only after 3 months from admission (HR =1.85, 95% CI1.56–2.18 and HR =1.80, 95% CI 1.52–2.14) compared with patients with unspecified cognitive impairment after 6 months (HR =1.55, 95% CI 1.21–1.99). Similar but partially attenuatedassociations were seen after adjustment for functional ability.Conclusion: Mortality post-admission is high in older people with CSD. Immediate risk ishighest in those with delirium, while dementia or unspecified cognitive impairment is associatedwith medium- to long-term risk. These findings suggest that individuals without dementia whodevelop delirium are more seriously ill (have required a larger acute insult in order to precipitatedelirium) than those with pre-existing brain pathology (dementia). Further research to explainthe mortality patterns observed is required in order to translate the findings into clinical care.",

author = "Simona Hapca and Bruce Guthrie and Feifei Bu and Alasdair Rutherford and Emma Reynish and Peter Donnan",

note = "We acknowledge the support of the HIC, University of Dundee for managing and supplying the anonymized data. The development and implementation of the OPRAA was undertaken by the Dementia Coordinating Group in NHS Fife. OPRAA assessments were carried out by the Comprehensive Geriatric Assessment (CGA) nurses in NHS Fife. The electronic clinical page for data recording was developed by the e-Health team in NHS Fife. We are also grateful for project oversight, advisory input, and constructive comments given by the project{\textquoteright}s external advisory board, namely Gordon Wilcock, Rowan Harwood, Suzanne Timmons, Jenni Harrison, Christine McGregor, Alex McConnachie, Marion Latimer, and Malcolm MacLeod. OPRAA development and data collection was funded by the Scottish Government Joint Improvement Team, initial data transfer by an NHS Fife R&D Bursary. The analysis was funded by the National Institutes for Health Research Health Services and Delivery Research Program (NIHR HS&DR 13/54/55). The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HS&DR Program, NIHR, NHS, or the Department of Health. The work presents a set of results as a part of the OPRAA project. Some very early results of the project were also presented at the Dementia & Ageing seminar organized by the Dementia Services Development Centre, at the University of Stirling on February 1, 2017. The content of the current manuscript has been significantly revised and the submitted paper has not been published elsewhere.",

year = "2018",

month = nov,

day = "23",

doi = "10.2147/CLEP.S174807",

language = "English",

volume = "10",

pages = "1743--1753",

journal = "Clinical Epidemiology",

issn = "1179-1349",

publisher = "Dove Medical Press",

}

Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 6724 patients with two years follow-up. / Hapca, Simona (Lead / Corresponding author); Guthrie, Bruce; Bu, Feifei et al.
In: Clinical Epidemiology, Vol. 10, 23.11.2018, p. 1743-1753.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital

T2 - prospective cohort study of 6724 patients with two years follow-up

AU - Hapca, Simona

AU - Guthrie, Bruce

AU - Bu, Feifei

AU - Rutherford, Alasdair

AU - Reynish, Emma

AU - Donnan, Peter

N1 - We acknowledge the support of the HIC, University of Dundee for managing and supplying the anonymized data. The development and implementation of the OPRAA was undertaken by the Dementia Coordinating Group in NHS Fife. OPRAA assessments were carried out by the Comprehensive Geriatric Assessment (CGA) nurses in NHS Fife. The electronic clinical page for data recording was developed by the e-Health team in NHS Fife. We are also grateful for project oversight, advisory input, and constructive comments given by the project’s external advisory board, namely Gordon Wilcock, Rowan Harwood, Suzanne Timmons, Jenni Harrison, Christine McGregor, Alex McConnachie, Marion Latimer, and Malcolm MacLeod. OPRAA development and data collection was funded by the Scottish Government Joint Improvement Team, initial data transfer by an NHS Fife R&D Bursary. The analysis was funded by the National Institutes for Health Research Health Services and Delivery Research Program (NIHR HS&DR 13/54/55). The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HS&DR Program, NIHR, NHS, or the Department of Health. The work presents a set of results as a part of the OPRAA project. Some very early results of the project were also presented at the Dementia & Ageing seminar organized by the Dementia Services Development Centre, at the University of Stirling on February 1, 2017. The content of the current manuscript has been significantly revised and the submitted paper has not been published elsewhere.

PY - 2018/11/23

Y1 - 2018/11/23

N2 - Purpose: Cognitive impairment is common in older people admitted to hospital, but the outcomes are generally poorly understood, and previous research has shown inconsistent associations with mortality depending on the type of cognitive impairment examined and duration offollow-up. This study examines mortality in older people with any cognitive impairment duringacute hospital admission.Patients and methods: Prospective cohort of 6,724 people aged ≥65 years with a structuredcognitive assessment on acute admission were included in this study. Cognitive spectrum disorder(CSD) was defined as delirium alone, known dementia alone, delirium superimposed on knowndementia, or unspecified cognitive impairment. Mortality associated with different types of CSDwas examined using a non-proportional hazards model with 2-year follow-up.Results: On admission, 35.4% of patients had CSD, of which 52.6% died within 2 years. Afteradjustment for demographics and comorbidity, delirium alone was associated with increasedmortality in the 6 months post-admission (HR =1.45, 95% CI 1.28–1.65) and again after 1 year(HR =1.44, 95% CI 1.17–1.77). Patients with known dementia (alone or with superimposeddelirium) had increased mortality only after 3 months from admission (HR =1.85, 95% CI1.56–2.18 and HR =1.80, 95% CI 1.52–2.14) compared with patients with unspecified cognitive impairment after 6 months (HR =1.55, 95% CI 1.21–1.99). Similar but partially attenuatedassociations were seen after adjustment for functional ability.Conclusion: Mortality post-admission is high in older people with CSD. Immediate risk ishighest in those with delirium, while dementia or unspecified cognitive impairment is associatedwith medium- to long-term risk. These findings suggest that individuals without dementia whodevelop delirium are more seriously ill (have required a larger acute insult in order to precipitatedelirium) than those with pre-existing brain pathology (dementia). Further research to explainthe mortality patterns observed is required in order to translate the findings into clinical care.

AB - Purpose: Cognitive impairment is common in older people admitted to hospital, but the outcomes are generally poorly understood, and previous research has shown inconsistent associations with mortality depending on the type of cognitive impairment examined and duration offollow-up. This study examines mortality in older people with any cognitive impairment duringacute hospital admission.Patients and methods: Prospective cohort of 6,724 people aged ≥65 years with a structuredcognitive assessment on acute admission were included in this study. Cognitive spectrum disorder(CSD) was defined as delirium alone, known dementia alone, delirium superimposed on knowndementia, or unspecified cognitive impairment. Mortality associated with different types of CSDwas examined using a non-proportional hazards model with 2-year follow-up.Results: On admission, 35.4% of patients had CSD, of which 52.6% died within 2 years. Afteradjustment for demographics and comorbidity, delirium alone was associated with increasedmortality in the 6 months post-admission (HR =1.45, 95% CI 1.28–1.65) and again after 1 year(HR =1.44, 95% CI 1.17–1.77). Patients with known dementia (alone or with superimposeddelirium) had increased mortality only after 3 months from admission (HR =1.85, 95% CI1.56–2.18 and HR =1.80, 95% CI 1.52–2.14) compared with patients with unspecified cognitive impairment after 6 months (HR =1.55, 95% CI 1.21–1.99). Similar but partially attenuatedassociations were seen after adjustment for functional ability.Conclusion: Mortality post-admission is high in older people with CSD. Immediate risk ishighest in those with delirium, while dementia or unspecified cognitive impairment is associatedwith medium- to long-term risk. These findings suggest that individuals without dementia whodevelop delirium are more seriously ill (have required a larger acute insult in order to precipitatedelirium) than those with pre-existing brain pathology (dementia). Further research to explainthe mortality patterns observed is required in order to translate the findings into clinical care.

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DO - 10.2147/CLEP.S174807

M3 - Article

C2 - 30538578

SN - 1179-1349

VL - 10

SP - 1743

EP - 1753

JO - Clinical Epidemiology

JF - Clinical Epidemiology

ER -

Mortality in people with dementia, delirium and unspecified cognitive impairment in the general hospital: prospective cohort study of 6724 patients with two years follow-up

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Donnan, Peter

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