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 disease causes of death where there is usually more than one disease contributing to the death.

Examining multiple causes of death may offer better insights into all the disease processes occurring at the end of life, which 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 153,580 deaths in Australia in 2014, 92% 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 2014, 82% of natural deaths had more than 1 cause and, on average, 3.3 diseases or conditions were recorded on the death certificate (Table S1).

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. See more on Multiple causes of death in Australia.

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. For example, deaths due to coronary heart disease had 3.6 causes of death on average, deaths due to asthma had 3.9 and deaths due to diabetes had 4.8 (Table S2).

Figure 1: Commonly reported associated causes of death for selected chronic diseases as the underlying cause, 2012–2014

Coronary heart disease
was an associated cause of death for

48% of deaths due to diabetes
19% of deaths due to chronic obstructive pulmonary disease (COPD)
18% of deaths due to chronic and unspecified kidney failure

Hypertensive disease
was an associated cause of death for

33% of deaths due to diabetes
28% of deaths due to cerebrovascular disease (including stroke)
22% of deaths due to coronary heart disease

Influenza and pneumonia
was an associated cause of death for

28% of deaths due to asthma
27% of deaths due to COPD
25% of deaths due to dementia and Alzheimer disease

Kidney failure
was an associated cause of death for

35% of deaths due to diabetes
14% of deaths due to coronary heart disease
13% of deaths due to prostate cancer

Source: AIHW National Mortality Database (Data tables).

Underlying versus associated causes 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 2).

Chronic diseases that are more likely to be reported as associated causes of death include chronic and unspecified kidney failure, diabetes, asthma, COPD, and dementia and Alzheimer disease.

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, diabetes, asthma and COPD.

Figure 2: Selected chronic diseases as underlying and associated causes of death, 2012—2014 (per cent) 

The stacked horizontal bar chart shows the proportion of all deaths involving selected chronic diseases as the underlying cause of death or as an associated cause of death differs by chronic disease. Of all deaths involving chronic and unspecified kidney failure, chronic and unspecified kidney failure was reported as the underlying cause in 12.9%25 of deaths and as an associated cause in 87.1%25 of deaths. Of all deaths involving lung cancer, lung cancer was reported as the underlying cause in 92.3%25 of deaths and as an associated cause in 7.7%25 of deaths.

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 (Data tables).