Background and purpose of this report
Purpose of this report
This report improves our understanding of the impacts of the COVID-19 pandemic on dementia mortality, by:
- comparing age-standardised rates of people who had dementia mentioned on their death certificate in 2020 to previous years (rates averaged over 2015–19)
- exploring differences in deaths due to COVID-19 by whether or not the person also had dementia recorded on their death certificate, and
- exploring the patterns of deaths during the pandemic among people who died with dementia recorded on the death certificate by whether or not they died due to COVID-19.
This report also provides much needed insight on deaths among all people with dementia, not just people who died due to dementia, by incorporating associated cause of death information. People who have dementia often die due to conditions other than their dementia, so including associated cause of death information provides a more comprehensive picture.
For this report, dementia status is determined solely by whether or not dementia was recorded in the death certificate. For various reasons, this is likely to be an undercount of the true number of Australians with dementia who died during the pandemic.
Dying due to dementia versus dying with dementia
Mortality data contains information about a person’s underlying cause of death – the main disease or condition causing death – as well as associated causes of death – which are conditions that contributed to the death but were not the underlying cause.
As people with dementia may die due to their dementia or from other conditions or injuries (such as influenza or a fall), dementia may be recorded as an underlying or an associated cause of death on their death certificate. In an unknown proportion of cases, dementia may not be recorded at all, either because it is incorrectly missed from the death certificate or because dementia legitimately did not contribute to their death.
In this report, people with dementia are looked at in 2 groups based on where dementia was recorded in the death certificate:
- deaths due to dementia refer to deaths where dementia was the underlying cause of death
- deaths with dementia refer to deaths where there was any record of dementia (as the underlying cause or an associated cause of death). About 3 in 5 of these deaths were deaths due to dementia.
Dementia is not always recorded consistently in death certificates as a result of various factors, such as: changes to coding rules over time; variations in certification practices; and challenges in diagnosing and reporting dementia among older individuals who have other comorbidities. In one recent study using linked data, it was shown that without linking to other datasets, mortality data only captured 31% of Australian women with dementia (Waller et al. 2017), while in another study, mortality data captured 67% of people with dementia who died in New South Wales and Victoria in 2013 (AIHW 2020b). So the number of people with dementia recorded on their death certificate as used in this report is unlikely to capture every person with dementia who died during the pandemic, even when dementia contributed to death (ABS 2015; Gao et al. 2018).
In addition, most of the information in this report relates only to deaths that were certified by a medical doctor. At the time of writing, coroner-certified deaths were only available when a person died due to COVID-19 (and these are included in this report). However, roughly 1–2% of deaths where dementia is recorded as an underlying cause of death are usually certified by a coroner (ABS 2020a). While the analyses in this report are unlikely to be significantly affected by missing coroner certified deaths, the data are considered preliminary and subject to change, and results should be interpreted with caution.
COVID-19 deaths in Australia
COVID-19 is a disease caused by a new type of coronavirus – a large group of viruses (mainly found in animals) with a small number of these viruses known to cause respiratory infections in humans. The World Health Organization (WHO) declared COVID-19 a pandemic on 11 March 2020 and issued new emergency codes to be used when coding causes of death due to COVID-19. About 99% of COVID-19 deaths in Australia were confirmed as COVID-19 by laboratory testing (ABS 2020a; Rao 2020). Due to the public health importance of COVID-19, the WHO have directed that the new coronavirus strain be recorded as the underlying cause of death, that is, the main disease or condition causing death, when it is recorded as having caused or contributed to death. In Australia, it is rare for COVID-19 to be coded as an associated cause of death (ABS 2020b). Deaths in Australia can be certified by a medical doctor or a coroner. Doctor certified deaths account for the majority of deaths, as deaths that need to be certified by a coroner are generally restricted to those where the person died: unexpectedly and by an unknown cause; in a violent or unnatural manner; as a result of anaesthesia; in custody; and where the individual’s identity is unknown (ABS 2020a; ABS 2020c). The mortality data used in this report only includes doctor certified deaths; the only exception are deaths due to COVID-19, for which information on some coroner referred deaths has been published. Coverage is substantially improved by including both doctor and coroner certified deaths due to COVID-19.