Excess deaths from all causes, involving and with dementia as the underlying cause: Scotland 2020-2022

Background

This report examines the effect of the COVID-19 pandemic on deaths involving dementia including Alzheimer's disease from March 2020 to March 2022. It follows previous Scottish Government analysis that examined deaths involving dementia including Alzheimer's disease in Scotland from March 2020 to August 2021. 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.

National Record of Scotland (NRS) statistics showed a marked increase in deaths with dementia as the underlying cause in the early stages of the COVID-19 pandemic, and established that dementia was the most common pre-existing medical condition amongst those whose deaths involved COVID-19. In response, the Scottish Government committed to further work to understand excess deaths as part of the Dementia COVID-19: Action Plan Coronavirus (COVID-19) (2020).

Stakeholder engagement led to the Scottish Government's Dementia COVID-19: Action Plan and helped to inform its commitments. The Plan identified a need to understand the relationship between both the COVID-19 virus and the impact of restrictions on the progress of the dementia illness, health outcomes and excess deaths rates across all care settings. The Scottish Government committed to commissioning and publishing analysis in this area. 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.

In response to this evidence request, analysts from the Health and Social Care Analysis Division in the Scottish Government carried out secondary analysis of weekly statistics published by NRS. This analysis involved identifying the number of deaths involving dementia during the COVID-19 pandemic and comparing these figures to the five year average, for all settings. Routine NRS statistics only included deaths where dementia was the underlying cause. These statistics would omit the deaths of individuals who had a dementia diagnosis and had been impacted by COVID-19 infection, as COVID-19 would likely be noted as the underlying cause (with dementia as a contributory cause). Therefore, ad hoc requests were made to NRS to identify all registered deaths involving dementia i.e. where dementia was mentioned on the death certificate as either the underlying or a contributory cause.

Secondary analysis was conducted to compare the number of deaths involving dementia during the pandemic with the average number of deaths involving dementia over the previous five years. In addition, analysis of deaths from all causes during the pandemic compared with deaths over the previous five years was used to provide broader context of the impact of the pandemic on the general population.

Analysis of excess deaths involving other medical conditions were out of scope for this report. This should not be interpreted as other causes of death during the pandemic being less relevant or important than deaths involving dementia.

It is important to note that these are mortality statistics and as such are unable to provide insight on the lived experience of any individual with dementia who died during the time period analysed. While other evidence to understand the experiences and broader health outcomes of people with dementia isimportant and necessary to understand the full impact of the pandemic, these are out of scope for this report on excess deaths.

COVID-19 Public Inquiry

A Public Inquiry has been established to examine the handling of the COVID-19 pandemic in Scotland. The Inquiry works independently of government. It will provide scrutiny of and learn lessons from the handling of the COVID-19 pandemic in Scotland, to ensure that Scotland is as prepared as possible for future pandemics.

The Scottish Government remains committed to providing high quality evidence and data to understand the impact of the pandemic on excess mortality and to support resilience and recovery. We work in close partnership with Public Health Scotland and the National Records of Scotland to learn lessons and we will continue to closely monitor excess deaths.

Data handling, definitions and sources

NRS publish weekly statistics on Deaths involving coronavirus (COVID-19) in Scotland which include weekly registered deaths from all causes and by the main underlying causes of death. Death certificates of those who died with COVID-19 were examined to look at their pre-existing conditions. Pre-existing conditions are defined by NRS as a health condition mentioned on the death certificate which either came before COVID-19 or was an independent contributory factor in the death.

This report presents secondary analysis of existing data from NRS. The findings include analysis of deaths from 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.

NRS defines the underlying cause of death 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 (please see the NRS website for further background about death certificates and coding the causes of death).

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

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.

A condition must have contributed to the death for it to be mentioned on the death certificate. Since NRS data list only those conditions recorded as a contributory or underlying cause of death, this analysis cannot separate deaths where dementia was the only pre-existing health condition at the time of death from deaths where dementia was one condition amongst other comorbidities at the time 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 as a contributory cause.

Deaths with dementia as the underlying cause are therefore a subset of deaths involving dementia (which include deaths mentioned as either an underlying or contributory cause).Weekly registered deaths for 2020 were put into context by comparing to the 2015-2019 average, and the difference between the two is referred to as excess deaths.

In 2021, NRS continued to use the 2015-2019 average to measure excess deaths. It was not appropriate to compare against the 2016-2020 average in 2021, as that would have been affected by the pandemic with higher deaths in Spring 2020. However, by using the 2015-2019 average in 2021, there is a risk that we have overestimated excess deaths, by not fully accounting for the ageing population.

For 2022, the excess deaths calculation would usually incorporate the mortality data for the most recent 5 year period (2017-2021). However, given the unusual nature of the 2020 data and the decision previously taken for 2021, NRS decided to use the average of 2016, 2017, 2018, 2019 and 2021, and therefore continue to exclude 2020 from the five-year average.

Further detail on the excess deaths methodology is provided in the Limitations section, and NRS have published a paper on choosing a five year average for the measurement of 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.

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.In a period of excess deaths, which can be a result of an infection such as COVID-19 or an external factor such as a heat wave, mortality displacement can occur. Mortality displacement refers to vulnerable individuals who are near the end of their life dying earlier than expected. If a large number of deaths are hastened, a period of mortality deficit might be expected.

What is 'mortality displacement'?

Vulnerable individuals who are near the end of their life dying earlier than expected. This may be due to an infection or external factors. If a large number of deaths are hastened, a period of mortality deficit might be expected.

This analysis considers total excess deaths across all settings, as well as excess deaths in three separate settings: in care homes, in hospitals and at home or non-institutional settings, reflecting the categories of settings reported in NRS statistics. With nearly two thirds of adult care home residents having some degree of dementia (see the Public Health Scotland Care Home Census 2022), care homes are a setting that demands particular attention in relation to the analysis of excess deaths involving dementia and with dementia as the underlying cause.

While 2020 and 2021 figures from NRS are finalised, 2022 figures are provisional and subject to change. To ensure comparability, we have focussed on comparisons between 2020 and 2021, but we have considered data up to March 2022 where possible. The underlying data are available in the supplementary tables.