Differential mortality in Australia : with special reference to the period 1970-1972

Abstract

The overall mortality in the developed countries is now at the lowest level ever recorded. It is believed that any significant gain in longevity in these countries can be achieved only through a better understanding of the fundamental processes of ageing. However, despite low mortality, various socio-economic groups of the population in these countries still exhibit considerable mortality differentials. There is some evidence to suggest that such differentials have even increased recently. Thus, there is also scope for a further reduction in the overall mortality if the existing differentials are minimized. The purpose of this thesis is to study differential mortality in the adult and infant population of Australia. The male population of working ages classified by occupational groups exhibited considerable differentials in mortality, both at the beginning of the century and at the present time (1970-1972). It has been argued that such differentials reflect not only occupational health hazards, but to a large extent, socio-economic differentials in mortality caused by differences in life-style and use of medical and health care facilities. Variations in infant mortality of the statistical divisions of Australia in 1970-1972 were significantly correlated with variations in socio-demographic and environmental characteristics of these divisions. Chief among these were the proportion of Aboriginal population, the percent ex-nuptial births and the index of heat discomfort. When statistical divisions containing large proportions of Aboriginal population were included in the analysis, the influence of socio-demographic and climatic variables on infant mortality was mainly through postneonatal mortality. But when such statistical divisions were excluded, the effect of these variables on infant mortality was mainly through neonatal mortality. Ethnic groups in Australia (defined by country of birth) had significantly lower mortality than the Australian-born population in 1970-1972. This has been attributed to medical screening of prospective immigrants before being admitted to Australia, resulting in the selection of healthier individuals for immigration. However, the mortality advantage of an ethnic group tended to become smaller as its duration of residence in Australia increased. It has been argued that this tendency was due to the immigrant groups' adoption of the life-styles of the Australian-born population, in addition to the stresses and strains of adverse living and working conditions commonly encountered during the initial stages of settlement in Australia. This thesis has identified some of the high mortality risk groups in Australia. Paucity of required information has hindered a comprehensive explanation of the observed mortality differentials. A strong need for research into aspects of life-style, working and living conditions and use of medical and health care facilities among different sections of the population has been pointed out. Alternative ways of using available data, such as record-linkage, have also been suggested.