Excess Indigenous mortality: are Indigenous Australians more severely disadvantaged than other Indigenous populations?

Background international targets for reducing health inequalities, such as the Millennium Development Goals, are stated in terms of national targets. However, dramatic health differentials exist within countries, even developed ones. Studies indicate that the indigenous population of Australia suffers a life expectancy disadvantage greater than differentials found in Indigenous populations of other developed countries. We re-examine recent national mortality levels and trends of Indigenous Australians. Methods Analyses of Indigenous mortality are plagued by 'numerator-denominator bias', whereby reporting of indigenous status differs in deaths (numerators) and population (denominators). We apply demographic evaluation methods developed to address such problems to data from the 1991, 1996 and 2001 censuses of Australia and to the death registration data for the period. Results The propensity of Australia's population to report Indigenous status increased between each census, particularly between 1991 and 1996, while recording of deaths as Indigenous increased sharply. Adjusted for bias, the Indigenous population had a life expectancy similar to 13 years below that of the non-Indigenous population, a 2-year greater disadvantage than recently estimated for the Maori in New Zealand. Indigenous mortality fell during the 1990s, but slightly more slowly than that of non-Indigenous Australians, leaving differentials slightly increased. Conclusions Around the world Indigenous populations are estimated to suffer a mortality disadvantage compared with non-Indigenous populations. However, establishing the magnitude of and trend in the disadvantage is difficult because of bias. Using appropriate methods to adjust for bias, the Indigenous population of Australia is estimated to suffer a life expectancy shortfall of about 13 years, greater than similar gaps in other developed countries.