Excess deaths from all causes and dementia by setting Scotland 2020-2021

Background

With 28% of all deaths involving COVID-19 in 2020 having some category of dementia mentioned on the death certificate, it is necessary to understand the relationship between COVID-19 and dementia excess deaths across all care settings. This paper aims to examine the effect of the COVID-19 pandemic on deaths involving dementia or with dementia as the underlying cause including Alzheimer's disease.

Reference to 'dementia' throughout this document will include people with Alzheimer's disease and other types of dementia.

Deaths 'involving' a particular cause refers to all deaths that had the cause mentioned on the death certificate, as the underlying cause or as a contributory cause.

In response to the reporting by National Records of Scotland (NRS) of an increase in excess deaths attributed to dementia during the pandemic, Scotland's Data and Intelligence Network set out a number of analytical questions that required evidence to inform clinical and other professional responses to people with dementia who contract COVID-19 in the vaccination and recovery phase.

Part of the required evidence included a clearer indication of whether there had been an increase in the number of deaths of people with dementia that could be attributed to COVID-19 in comparison to the number of dementia-related deaths that occurred before the pandemic.

During April 2021, in response to this evidence request, analysts from the Health and Social Care Analysis Division carried out secondary analysis of weekly statistics published by NRS to identify the number of deaths of people with dementia during the COVID-19 pandemic to date and to compare these figures to the 2015-2019 average, for all settings. Routine NRS statistics included only deaths where dementia was the underlying cause, and it was suspected that there might be additional deaths registered in the same period with other underlying causes of death but with pre-existing dementia. Therefore, an ad hoc request was made to NRS in May 2021 to identify all registered deaths involving dementia i.e. where dementia was mentioned on the death certificate but was not necessarily the underlying cause.

Secondary analysis was conducted to compare the number of deaths of people with dementia during the pandemic with the average number of deaths of people with dementia over the previous five years. In addition, analysis of deaths of all causes during the pandemic compared with deaths over the previous five years is presented below to understand the impact of the pandemic on people with dementia compared to the wider population.

How the data was handled and where it came from

The findings presented in this paper include analysis of deaths of all causes, deaths where dementia was the underlying cause, and deaths involving dementia. Deaths involving dementia refers to deaths where dementia was an underlying or a contributory cause. The underlying cause of death is defined as "the disease or injury which initiated the chain of morbid events leading directly to the death" and a contributory cause of death is a condition which contributed to the occurrence of the death, but was not part of the main sequence leading to the death ^[1]. This paper is secondary analysis of existing data rather than Official or National Statistics.

The underlying cause of death is defined as "the disease or injury which initiated the chain of morbid events leading directly to the death"¹.

A contributory cause of death is a condition which contributed to the occurrence of the death, but was not part of the main sequence leading to the death.

Weekly registered deaths for 2020-2021 are put into context by comparing to the 2015-2019 average, and the difference between the two is referred to as excess deaths. The World Health Organisation defines excess mortality as the difference in the total number of deaths in a crisis compared to those expected under normal conditions (The true death toll of COVID-19: estimating global excess mortality (who.int)). COVID-19 excess mortality accounts for the total number of deaths directly attributed to the virus as well as the indirect impact, such as the indirect impact of restrictions and disruption to essential health services. NRS provide further information about choosing a five year average for the measurement of excess deaths.

What are 'excess deaths'?

The total number of deaths registered in a week minus the average number of deaths registered in the same week over the previous five-year period.

NRS publish weekly statistics on Deaths involving coronavirus (COVID-19) in Scotland | National Records of Scotland (nrscotland.gov.uk) which includes weekly registered deaths from all causes and by the main underlying causes of death.

Dementia deaths include deaths that are registered with either ICD code F01 (Vascular Dementia), F03 (Unspecified Dementia) or G30 (Alzheimer's Disease) as the underlying cause of death or mentioned on the death certificate.

Data sources:

https://www.nrscotland.gov.uk/files//statistics/covid19/covid-deaths-21-data-week-31.xlsx

https://www.nrscotland.gov.uk/files//statistics/covid19/covid-deaths-21-data-week-27.xlsx

https://www.nrscotland.gov.uk/files//statistics/covid19/weekly-deaths-involving-dementia-and-alzheimer-disease.xlsx

https://www.nrscotland.gov.uk/files//statistics/covid19/annual-deaths-and-excess-deaths-1855-2020.xlsx

While 2020 figures from NRS are finalised, 2021 figures are provisional and subject to change.

Only one year out of the five in 2015-2019 has a Week 53, therefore the weekly average deaths figure for Week 53 in 2015-2019 has been divided by five before comparing annual 2020 figures to the 2015-2019 average.

Potential limitations of data relating to dementia

Not every individual with dementia has a medical diagnosis. Depending on the method used to estimate prevalence, it is estimated that between 60% (EuroCoDe) and 85% (PACSIm) of people aged 65+ with dementia in Scotland receive a medical diagnosis. PACSIm is the benchmark used by NHS England, while Alzheimer Scotland prefers EuroCoDe. Further, even if a person has received a medical diagnosis of dementia, this does not mean it will be recorded on the death certificate unless determined as a contributing cause of death. NRS provide information about the recording of diseases and conditions on death certificates. This means that some people who die with dementia as a pre-existing condition will not be included in official statistics that record deaths related to dementia because: either i) dementia was not considered as a contributory factor associated with the person's death, or ii) the person did not receive a formal diagnosis.