Adverse outcome after incident stroke hospitalization for Indigenous and non-Indigenous Australians in the Northern Territory

Abstract

Background: Survival after a stroke is lower for Indigenous than other stroke patients in Australia. It is not known whether recurrence is more common for Indigenous patients, or whether their higher prevalence of comorbidity affects their lower survival. Aims: This study aimed to investigate the stroke recurrence and role of comorbidities in adverse stroke outcomes (recurrence and death) for Indigenous compared with other Australians. Methods: A retrospective cohort study of first hospitalization for stroke (n=2105) recorded in Northern Territory hospital inpatient data between 1996 and 2011 was conducted. For the multivariable analyses of adverse outcomes, logistic regression was used for case fatality and competing risk analysis for recurrent stroke and long-term death. Comorbidities (identified from inpatient diagnosis data) were analyzed using the Charlson Comorbidity Index (modified for stroke outcomes). Results: Prevalence of comorbidities, case fatality, incidence of re-hospitalization for recurrent stroke, and long-term death rate were higher for Indigenous than non-Indigenous stroke patients. Adjustment for comorbidity in multivariable analyses considerably reduced Indigenous patients' excess risk for case fatality (odds ratio: 1·25, 0·88-1·78) and long-term death (standard hazard ratio: 1·27, 1·01-1·61) (but not recurrence), implying that their excess risk of death was in part due to higher comorbidity prevalence. Conclusion: Indigenous stroke patients have higher prevalence of comorbidities than non-Indigenous stroke patients, which explained part of the disparity in both case fatality and long-term survival but did not explain the disparity in stroke recurrence at all.