Estimation of the true national level of Indigenous mortality remains constrained by incomplete vital registration. While the ABS now publishes reported Indigenous death statistics for all states and territories, most detailed tabulations, and certainly those used for trend analysis, are based on information from the Northern Territory, Western Australia and South Australia only. This is based on an assessment of the completeness of recording from a comparison of registered deaths in each state and territory against an estimate of expected deaths. Overall, in 1999, a total of 1980 Indigenous deaths were registered. This was more than twice the number that would have been expected if the age-specific death rates of the total Australian population were experienced throughout the Indigenous population.

Using data for the Northern Territory, Western Australia and South Australia, age-specific death rates were higher than for other Australians at all ages, but especially among those aged between 25 and 64 years (Cunningham & Paradies 2000: 30). For example, between the ages of 35 and 44 years, the ratio of Indigenous to non-Indigenous mortality rates is 6.9 for males and 7.8 for females (ABS and AIHW 1999: 132). While it is difficult to establish detailed trends in Indigenous mortality, owing to changes over time in the coverage of Indigenous deaths in vital statistics, there appears to have been a decline in age-specific death rates since 1994 in all age groups except for 15–24 and 45–54 years (ABS 2000a: 75). Overall, it remains the case that a high proportion of registered Indigenous deaths occur among young people. In 1999, the national median age at death for Indigenous people was 53 years, some 25 years less than the median age at death of all Australians (ABS 2000a: 74).

A good deal is now known about the immediate causes of ill-health and mortality among Indigenous Australians. Across all primary categories of the International Classification of Diseases (ICD9), relative risk for both Indigenous males and females remains notably higher than for other Australians. Most disparities, however, are concentrated around diseases of the circulatory system, external causes, and malignant neoplasms, while a relatively high incidence of respiratory diseases, endocrine diseases and diseases of the digestive system is also present. Together, these causes account for more than two-thirds (69 per cent) of the excess deaths among Indigenous people.

According to the most recently available data from deaths registration, diseases of the circulatory system are the leading cause of death among the Indigenous population, accounting for 31 per cent of all cases in 1999. Primary among these is ischaemic heart disease, responsible for 56 per cent of all recorded deaths in this category, followed by cerebrovascular disease (stroke) accounting for 19 per cent of deaths.

The second leading cause of death (16% of all Indigenous deaths) is external causes (including accidents, assault and intentional self-harm). By contrast, external causes are responsible for only seven per cent of deaths among the total population. Significantly, the median age at death for external causes is much lower among Indigenous people (28 years)—more than 10 years less than among the rest of the population.

Malignant neoplasms (cancers) account for about one-seventh of Indigenous deaths (14%). The most common of these (responsible for around 50 per cent of cases) are malignant neoplasms of the trachea, bronchus and lung. Diseases of the respiratory system and endocrine, nutritional and metabolic diseases are the next main causes of death (8% and 7% respectively). Among the latter, diabetes is responsible for as much as 87 per cent of all cases. Consequently, excess mortality due to diabetes is more than eight times the expected level if age-specific rates of the total population are applied. Diseases of the digestive system represent the final leading cause of death category among Indigenous people, accounting for five per cent of all deaths. This prevalence is four times that observed among the total population. The major contributor to Indigenous mortality within this category is liver disease.