A LIFECOURSE PERSPECTIVE ON HISTORICAL DEMOGRAPHIC PATTERNS OF CIRCULATORY SYSTEM DISEASE AND ALL-CAUSE MORTALITY IN TWENTIETH CENTURY AUSTRALIA

Background Circulatory System Disease (CSD) patterns vary over time and between countries, related to lifestyle risk factors across the life course, associated in turn with socio-economic circumstances. Current global CSD epidemics in developing economies are similar in scale to those observed previously in the United States and Australia. We examine from a lifecourse perspective the historical context in Australia for the rise and decline of CSD based on the published scientific literature and population trends. Past epidemiological studies focused on the relative advantage of those of Southern European compared to those of British or Irish origin. Historical retrospective cohort studies in populations including world war one veterans and maternity hospital data have shown early life influences on later health outcomes. Methods We employed data from census-derived place of birth by age bracket and sex from 1891 to 1986, based on digitised paper record. CSD mortality rates were available from 1907 to 2016 and age-specific rates were computed for the general population. All-cause mortality for the foreign-born (fb) from 1910 to 1980 was not readily available, as country of origin was not recorded at death. It was constructed based on numbers of foreign-born in specific age-groups at each census employing a novel actuarial method. For example, if p is the mortality rate for the fb age 30 per year in the interval 1947–1954 then p is estimated from the data by 1- (number all fb age 35–45 in 1954/number all fb age 25–35 in 1947)1/7. p for other age-groups is calculated similarly. For all age-groups p will underestimate the mortality rate. Results The Australian population grew exponentially between 1861 and 1986, reaching 15,602,150 million; its demographic composition was 64.7% foreign born initially and of predominantly British and Irish origin. Later twentieth century immigration was from mainly Southern European and Asian countries and FB accounted for a smaller proportion (22.4%) of the population by 1986. A strong period effect across all age groups and both genders was observed for CSD mortality. Rates of CSD rose consistently, particularly from the 1940s onwards, peaked in the 1960s and then began to decline sharply in the 1980s. Both male and female foreign-born showed similar all-cause mortality patterns at age midpoints from 30 through to 60 years of age. Conclusion Our findings support both a commonly experienced period effect for CSD mortality but suggest also that early origins of foreign-born may contribute to mortality patterns.