The long-term mortality of an Aboriginal and Torres Strait Islander Australian population after isolated coronary artery bypass graft surgery

Background: Aboriginal and Torres Strait Islander (Indigenous) Australians have an increased prevalence of coronary artery disease and present at a younger age for coronary artery bypass graft surgery (CABG) when compared to non-Indigenous Australians. Studies have reported postoperative outcomes in Indigenous people to be less favourable. Therefore, the aim of this study is to evaluate long term mortality between Indigenous and non-Indigenous people post-CABG.

Methods: We analysed data on all patients who underwent isolated CABG, with and without cardiopulmonary bypass, at our institution between January 1998 to September 2008. There were 33 395 person-years of survival for analysis with a median follow-up of 13 years (Interquartile range (IQR): 8-16 years). We analysed all-cause mortality with the Kaplan-Meier graph and log-rank test. Univariate and multivariate analysis was performed using a Cox proportional hazards model.

Results: The mean age at presentation for Indigenous people was 52 years compared to 65 yr for non-indigenous people. There were 1431 (52.1%) deaths by the study census date, with the overall mortality for Indigenous patients at 49.8% (n = 147) and 52.4% for non-Aboriginal patients (n = 1284). The age and comorbidities adjusted hazard ratio (HR) for all-cause late mortality (median years) was HR = 1.712 (95% CI: 1.288-2.277, p < 0.001).

Conclusion: Indigenous patients present for CABG at a younger age and have a higher prevalence of comorbidities. Our study demonstrates they have a higher risk of propensity adjusted all-cause long term mortality. Primary and secondary prevention strategies, tailored to Indigenous people, may improve health outcomes in the long-term post-CABG.