Excess stroke incidence in young Aboriginal people in South Australia: Pooled results from two population-based studies

Background Retrospective data indicate increased stroke incidence in Aboriginal/Torres Strait Islander (Indigenous) Australians, possibly with poorer outcomes. We present the first prospective population-based stroke incidence study in Indigenous Australians. Methods We pooled data from ASCEND and SEARCH, two prospective ideal South Australian stroke incidence studies, ASCEND conducted in urban Northwestern Adelaide (2009-2010) and SEARCH in five South Australian rural centers (2009-2011). We calculated age-standardized incidence for Aboriginal and non-Aboriginal people. Results The study population comprised 261,403 inhabitants. Among 432 first-ever strokes, 13 were in Aboriginal people (median age 51 vs. 78 years for non-Aboriginal people, p<0.001). Age-standardized stroke incidence per 100,000 in Aboriginal patients (116, 95% CI: 95-137) was nearly two-fold that of non-Aboriginal patients (67, 95% CI: 51-84). Age-stratified excess incidence in Aboriginal people was restricted to those aged<55 years (incidence rate ratio (IRR) 3.5, 95% CI: 2-7), particularly for intracerebral hemorrhage (IRR: 16, 95% CI: 4-61). Conclusion The excess stroke incidence in Aboriginal South Australians appears substantial, especially in those aged <55 years. Further work is required to delineate and address disparities.