Multiple causes of death
Deaths statistics are usually compiled using the underlying cause of death only. However, in most cases, more than one disease contributes to death.
The underlying cause of death is the disease or injury that initiated the train of events leading directly to death, or the circumstances of the accident or violence that produced the fatal injury. Deaths are referred to here as 'due to' the underlying cause of death.
Associated causes of death are all causes listed on the death certificate, other than the underlying cause of death. They include the immediate cause, any intervening causes, and conditions which contributed to the death but were not related to the disease or condition causing the death.
Multiple causes of death are defined here as all causes listed on the death certificate. This includes the underlying cause of death and all associated causes of death. This information is useful for describing the role of all diseases involved in deaths especially for chronic diseases, where there is usually more than one disease contributing to the death.
Examining multiple causes of death offers better insights into the disease processes occurring at the end of life. This in turn can be useful for developing better prevention and treatment policies and practices, refining disease surveillance activities, guiding research investment and enhancing burden of disease estimates.
Natural causes of death
Of the 190,939 deaths in Australia in 2022, 91% were due to natural causes. These are deaths that were not due to external causes such as accidents, injury and poisoning, or due to ill-defined causes.
In 2022, 81% of natural deaths had more than 1 cause recorded on the death certificate; on average, 3.4 diseases or conditions were recorded (Table S7.1).
Factors that may affect the number of causes of death recorded include the person's age, the underlying cause of death, coding changes and variations in certification practices.
Selected chronic disease causes of death
Australians who die of chronic disease often have more than 1 cause of death recorded on their death certificate (Table S7.1). For example, deaths due to coronary heart disease had 3.8 causes of death recorded on average, deaths due to asthma had 4.2 and deaths due to diabetes had 5.5 (Table S7.2).
Table 7.1 highlights some of the most common associated causes of death for selected chronic diseases as the underlying cause.
| Associated cause of death | Per cent of underlying cause of death |
|---|---|
Coronary heart disease was an associated cause of death for: |
|
Hypertensive disease was an associated cause of death for: |
|
Influenza and pneumonia were an associated cause of death for: |
|
Kidney failure was an associated cause of death for: |
|
Source: Table S7.2
Underlying versus associated cause of death
Chronic diseases that are more likely to be reported as the underlying cause of death rather than as an associated cause of death include prostate, breast, colorectal (bowel), liver and lung cancers (Figure 7.1).
Chronic diseases that are more likely to be reported as associated causes of death include chronic and unspecified kidney failure, asthma, diabetes and chronic obstructive pulmonary disease (COPD).
When deaths are reported by the underlying cause of death only, the involvement of certain diseases in overall mortality may be underestimated. This is particularly evident for chronic and unspecified kidney failure, asthma, diabetes and COPD.
Figure 7.1: Selected chronic diseases as underlying and associated causes of death in Australia, 2019–2022 (per cent)
The bar chart shows that chronic and unspecified kidney failure was an underlying cause of death in all deaths where it was specified as a cause. Liver cancer was an underlying cause in 90% of all deaths where it was specified as a cause.
| Chronic diseases | Underlying cause | Associated cause |
|---|---|---|
| Liver cancer | 89.9 | 10.1 |
| Lung cancer | 89.3 | 10.7 |
| Colorectal cancer | 81.1 | 18.9 |
| Breast cancer | 72.8 | 27.2 |
| Prostate cancer | 64.2 | 35.8 |
| Dementia including Alzheimer's disease | 53.0 | 47.0 |
| Coronary heart disease | 49.1 | 50.9 |
| Cerebrovascular disease | 48.0 | 52.0 |
| Chronic obstructive pulmonary disease (COPD) | 41.0 | 59.0 |
| Diabetes | 27.9 | 72.1 |
| Asthma | 18.8 | 81.2 |
| Chronic and unspecified kidney failure | 12.3 | 87.7 |
Note: Underlying refers to deaths with the disease recorded as the underlying cause of death, regardless of whether the disease was also recorded as an associated cause of death. Associated refers to deaths with the disease recorded only as an associated cause of death.
Source: AIHW National Mortality Database; Table S7.3.
Multiple cause of death analysis can help to answer questions about what causes and contributes to death, not only from an underlying cause of death perspective. The report What do Australians die from? uses multiple cause of death data to understand some of the complexities in answering these questions. The report uses multiple cause data to identify:
- the most common conditions which ultimately end a person’s life
- the conditions responsible for initiating the death (underlying causes of death)
- what other conditions contribute to death
- the risk factors that lead to the disease or injury causing the death.