Epidemiological transition in Australia: An analysis of immigration patterns in relation to circulatory system diseases and all-cause mortality in the mid-twentieth century

Background and Objectives: Circulatory System Diseases (CSD) patterns vary over time and between countries, related to lifestyle risk factors, associated in turn with socio-economic circumstances. Current global CSD epidemics in developing economies are similar in scale to those observed previously in the USA and Australasia. Australia exhibits an important macroeconomic phenomenon as a rapidly transitioning economy with high immigration throughout the 19th and 20th centuries. We wished to examine how that historical immigration related to CSD patterns subsequently. Methods and Setting: We provide a novel empirical analysis employing census-derived place of birth by age bracket and sex from 1891 to 1986, in order to map patterns of immigration against CSD mortality rates from 1907 onwards. Age-specific generalised additive models for both CSD mortality in the general population, and all-cause mortality for the foreign-born (FB) only, from 1910 to 1980 were also devised for both males and females. Results: The % FB fell from 32% in 1891 to 9.8% in 1947. Rates of CSD rose consistently, particularly from the 1940s onwards, peaked in the 1960s, then declined sharply in the 1980s and showed a strong period effect across age groups and genders. The main effects of age and census year and their interaction were highly statistically significant for CSD mortality for males (p < 0.001, each term) and for females (p < 0.001, each term). The main effect of age was statistically significant for all-cause mortality minus net migration rates for the FB males (p =0.005) and for FB females, both age (p < 0.001) and the interaction term (p=0.002) were significant. Conclusions: We argue our empirical calculations, supported by historical and socio-epidemiological evidence, employing immigration patterns as a proxy for epidemiological transition, affirm the lifecourse hypothesis that both early life circumstances and later life lifestyle drive CSD patterns.