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

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.

Covid-19 and excess mortality rates not comparable across countries (preprint)

Abstract: Evidence that more people in some countries and fewer in others are dying because of the pandemic, than is reflected by reported Covid-19 mortality rates, is derived from mortality data. Worldwide, mortality data is used to estimate the full extent of the effects of the Covid-19 pandemic, both direct and indirect; the possible short fall in the number of cases reported to the WHO; and to suggest explanations for differences between countries. Excess mortality data is largely varying across countries and is not directly proportional to Covid-19 mortality. Using publicly available databases, deaths attributed to Covid-19 in 2020 and all deaths for the years 2015-2020 were tabulated for 36 countries together with economic, health, demographic, and government response stringency index variables. Residual death rates in 2020 were calculated as excess deaths minus death rates due to Covid-19 where excess deaths were observed deaths in 2020 minus the average for 2015-2019. For about half the countries, residual deaths were negative and for half, positive. The absolute rates in some countries were double those in others. In a regression analysis, the stringency index (p=0.026) was positively associated with residual mortality. There was no evidence of spatial clustering of residual mortality. The results show that published data on mortality from Covid-19 cannot be directly comparable across countries, likely due to differences in Covid-19 death reporting. In addition, the unprecedented public health measures implemented to control the pandemic may have produced either increased or reduced excess deaths due to other diseases. Further data on cause-specific mortality is required to determine the extent to which residual mortality represents non-Covid-19 deaths and to explain differences between countries.