Abstract:
Background
Rheumatic Heart Disease (RHD) is a major cause of premature mortality, especially among Indigenous Australians. Recently, End RHD in Australia: Study of Epidemiology (ERASE) reported that RHD was coded as underlying cause of death (COD) in only 15% of RHD-affected people age <65 years, and COD was often missing in Indigenous Australians. We aimed to estimate RHD-related mortality independently of RHD-COD records from the Australian Bureau of Statistics (ABS) using an excess mortality approach.
Methods
RHD-related mortality was estimated in two steps (1) All-cause mortality rates by age/Indigenous status were determined in people with RHD aged <65 years (55% Indigenous) within the ERASE cohort 2013-2017. Subtracting the background population all-cause mortality rates (from ABS, stratified by age/Indigenous status), yielded excess RHD-related mortality; (2) Excess RHD-related mortality rates were used to generate theoretical RHD-related death frequencies, which were compared to ABS RHD-COD frequencies.
Results
Indigenous people with RHD experienced much higher RHD-related excess mortality rates than non-Indigenous people within the ERASE cohort; 1166/100,000 versus 771/100,000 person-years, respectively. For non-Indigenous people, the theoretical excess RHD-related death frequency estimated using the excess mortality approach was similar to ABS RHD-COD frequency (272 theoretical, 300 ABS), but was much higher for Indigenous people with RHD (319 theoretical, 145 ABS).
Conclusion
Our study, using an excess mortality approach, suggests that RHD-related deaths are potentially undercounted for the Indigenous population when based on actual RHD-COD frequencies from the ABS. This may be partially explained by missing COD records, but other contributing factors need to be explored.