Cognitive impairment, mortality and discharge from an acute hospital

Carole Fogg is a Senior Lecturer at the University of Portsmouth/Portsmouth Hospitals Trust, (UK). She is a PhD Fellow under the Wessex Collaboration for Leadership in Applied Healthcare and Research, exploring hospital care and outcomes for patients with cognitive impairment and dementia. Her paper “The relationship between cognitive impairment, mortality and discharge characteristics in a large cohort of older adults with unscheduled admissions to an acute hospital: a retrospective observational study has recently been published in Age and Ageing. She tweets at @Carole_Fogg 

When older people with dementia are admitted to hospital, they are more likely to die or to stay in hospital longer than people without dementia. Many older people have cognitive impairment (CI) (problems with memory and thinking) which is a main feature of dementia, but have not yet been given a diagnosis, or may have CI due to other medical conditions. We investigated how common cognitive impairment is in older patients in hospital, and what the risks are for these patients of staying longer or dying in hospital.

How did we do the study?

We looked back at the anonymised electronic medical records for 19,269 hospital admissions of patients aged 75 years and over in a large hospital. Patients had been screened for existing dementia and cognitive impairment (using a series of questions on memory and the Abbreviated Mental Test Score – AMTS) as part of standard hospital practice. We categorised the admissions into three different groups, according to the information that was gathered through dementia screening: i) people with known dementia; ii) people with cognitive impairment (AMTS less than 9); iii) people with no known dementia and no cognitive impairment. We summarised the characteristics of the patients, including their age and sex, the way that they came into hospital (e.g. via the emergency department or GP), their reason for hospitalisation, the severity of illness (using National Early Warning Scores – NEWS) and their risk of malnutrition. We also described how long the admissions in each group stayed in hospital, how many were discharged to care homes following admission and how many died in hospital.

What were the results?

Approximately 20% of the admitted patients had a dementia diagnosis and 12% had cognitive impairment (CI), highlighting that CI is common in older patients. Patients with CI were more similar to those with dementia than patients with no CI, in that they were more likely to be female, older, enter the hospital through the Emergency Department and be admitted to medical wards, and had a similar spectrum of medical reasons for admission. Patients with CI or dementia were also more likely to be at ‘high risk’ from malnutrition than patients with no CI (28% and 34% vs 18%). This indicates that patients with CI may have similar care needs in hospital to those with dementia. The severity of illness was similar for all groups.

The risk of dying in hospital was high in both patients with CI (12%) and dementia (11%), as compared to patients with no CI (7%). Patients with CI stayed longer in hospital than the other two groups, with 67% of these patients staying in hospital for more than one week. Discharge to a nursing or residential home for the first time occurred after 11% of admissions of patients with CI and in 16% of admissions of patients with dementia, but only for 4% of other patients. It is possible that organising a safe discharge may have contributed to long hospital stays for both groups.

What should be done next?

In summary, this study shows that older people with cognitive impairment experience poor outcomes which are similar to older people with dementia, i.e. an increased risk of dying in hospital, long hospital stays and high likelihood of being discharged to a nursing/residential home.

We need to understand more about what is happening during hospital admission for patients with cognitive impairment, and dementia. We need to look at what happens during their stay in hospital, to see if we can identify more clearly who is likely to become more unwell, and how and when this happens. This may show us how where the focus of their care in hospital could be changed, so that we can work towards improving their outcomes.

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