Dementia in Australia

In addition to the underlying cause of death (UCOD), the National Mortality Database contains information on up to 19 associated causes of death (ACOD)—that is, other causes that were instrumental or significantly contributed to the death. This means that it is possible to examine not only people who die due to dementia (i.e. UCOD of dementia), but also people who die with dementia (i.e. UCOD or ACOD of dementia).

In 2019, 14,700 people died due to dementia (9,200 women and 5,400 men). In comparison, 26,100 people died with dementia (15,700 women and 10,400 men). This is an important difference as people who have dementia often have other health conditions, which may cause their death rather than dementia (Table S3.7).

Leading underlying causes of death

In 2019, the leading underlying causes of death for people who had dementia recorded as an associated cause of death were:

• coronary heart disease (1,800 deaths)
• cerebrovascular disease (1,600 deaths)
• accidental falls (740 deaths)
• Parkinson’s disease (720 deaths)
• diabetes (660 deaths) (Figure 3.7).

As a person may have multiple types of dementia, it is possible for a person to have dementia recorded as both the underlying and associated cause of death. For example, a person may have Alzheimer’s disease as the underlying cause and Vascular dementia as an associated cause of death. Among the 11,700 people who died with at least 1 type of dementia recorded as an associated cause, 340 (2.9%) also had dementia recorded as the underlying cause of death (Table S3.9).

The leading underlying causes of death were fairly similar for men and women where dementia was an associated cause, but varied somewhat with increasing age— Accidental falls was more common with increasing age, whereas deaths due to Diabetes decreased with increasing age.

Figure 3.7: Leading 5 underlying causes of death in 2019 when dementia was an associated cause of death, by sex and age

Trends in coding of dementia as the underlying cause of death versus an associated cause of death

Between 2010 and 2019 the rate of deaths where dementia was the underlying cause of death increased from 35 to 40 deaths per 100,000 population. In contrast, the rate of deaths where dementia was an associated cause of death decreased from 45 to 33 per 100,000 population over the same period (Figure 3.8).

While we cannot be certain why this is occurring, it may be due to various factors:

• Australians are living longer and are more likely to be dying from dementia rather than from other conditions. Notably, there have been decreases in fatal heart attacks and strokes over time. This may be resulting in dementia being increasingly attributed as the underlying cause of death, whereas in the past it was more likely to be recorded as an associated cause of death or not recorded at all
• over time, dementia awareness could have significantly improved among health professionals who record and code cause of death information, leading to an increase in dementia being recorded as the underlying cause of death
• changes to coding rules implemented from 2013 have meant that Unspecified dementia is more likely to be recorded as the underlying cause of death rather than as an associated cause of death among people who die with dementia and other specific conditions (including Pneumonitis due to food and vomit). This resulted in an increase in the number of deaths with Unspecified dementia as an underlying cause (ABS 2015).

Figure 3.8: Dementia-related deaths in Australia in 2010–2019: number and age-standardised rates, by whether dementia was recorded as the underlying cause of death (UCOD) or an associated cause of death (ACOD)