Incidence and survival after acute myocardial infarction in Indigenous and non-Indigenous people in the Northern Territory, 1992–2004

Jiqiong You, John R Condon, Yuejen Zhao and Steven Guthridge
Med J Aust 2009; 190 (6): 298-302.


Objective: To estimate the incidence and survival rates of acute myocardial infarction (AMI) for Northern Territory Indigenous and non-Indigenous populations.

Design and participants: Retrospective cohort study for all new AMI cases recorded in hospital inpatient data or registered as an ischaemic heart disease (IHD) death between 1992 and 2004.

Main outcome measures: Population-based incidence and survival rates by age, sex, Indigenous status, remoteness of residence and year of diagnosis.

Results: Over the 13-year study period, the incidence of AMI increased 60% in the NT Indigenous population (incidence rate ratio [IRR], 1.04; 95% CI, 1.02–1.06), but decreased 20% in the non-Indigenous population (IRR, 0.98; 95% CI, 0.97–1.00). Over the same period, there was an improvement in all-cases survival (ie, survival with and without hospital admission) for the NT Indigenous population due to a reduction in deaths both pre-hospital and after hospital admission (death rates reduced by 56% and 50%, respectively). The non-Indigenous all-cases death rate was reduced by 29% as a consequence of improved survival after hospital admission; there was no significant change in pre-hospital survival in this population. Important factors that affected outcome in all people after AMI were sex (better survival for women), age (survival declined with increasing age), remoteness (worse outcomes for non-Indigenous residents of remote areas), year of diagnosis and Indigenous status (hazard ratio, 1.44; 95% CI, 1.21–1.70).

Conclusions: Our results show that the increasing IHD mortality in the NT Indigenous population is a consequence of a rise in AMI incidence, while at the same time there has been some improvement in Indigenous AMI survival rates. The simultaneous decrease in IHD mortality in NT non-Indigenous people was a result of reduced AMI incidence and improved survival after AMI in those admitted to hospital. Our results inform population-specific strategies for a systemwide response to AMI management.

  • Jiqiong You1
  • John R Condon2
  • Yuejen Zhao1
  • Steven Guthridge1

  • 1 Health Gains Planning, Department of Health and Community Services, Darwin, NT.
  • 2 Menzies School of Health Research, Institute of Advanced Studies, Charles Darwin University, Darwin, NT.



We acknowledge the acute care staff and data warehouse team of the NT Department of Health and Community Services for their assistance with data access; and the National Death Index team at the Australian Institute of Health and Welfare for data matching.

Competing interests:

None identified.

  • 1. d’Espaignet ET. Trends in Australian mortality: disease of the circulatory system, 1950-1991. Canberra: Australian Institute of Health and Welfare, 1993.
  • 2. Australian Institute of Health and Welfare. Australia’s health 2000: the seventh biennial health report of the Australian Institute of Health and Welfare. Canberra: AIHW, 2000.
  • 3. Australian Institute of Health and Welfare. Heart, stroke and vascular diseases — Australian facts 2004. Canberra: AIHW and National Health Foundation of Australia, 2004.
  • 4. Mathur S. Epidemic of coronary heart disease and its treatment in Australia. Canberra: Australian Institute of Health and Welfare, 2002.
  • 5. Li SQ, Guthridge SL. Mortality in the Northern Territory, 1981-2000. Darwin: Department of Health and Community Services, 2005.
  • 6. Thomas DP, Condon JR, Anderson IP, et al. Long-term trends in Indigenous deaths from chronic diseases in the Northern Territory: a foot on the brake, a foot on the accelerator. Med J Aust 2006; 185: 145-149. <MJA full text>
  • 7. Mathur S, Moon L, Leigh S. Aboriginal and Torres Strait Islander people with coronary heart disease: further perspectives on health status and treatment. Canberra: Australian Institute of Health and Welfare, 2006.
  • 8. Dobson A, Gibberd R, Leeder S. Death certification and coding for ischaemic heart disease in Australia. Am J Epidemiol 1983; 117: 397-405.
  • 9. Coutinho ES, Coeli CM. [Accuracy of the probabilistic record linkage methodology to ascertain deaths in survival studies] [Portuguese]. Cad Saude Publica 2006; 22: 2249-2252.
  • 10. Coory MD, Walsh WF. Rates of percutaneous coronary interventions and bypass surgery after acute myocardial infarction in Indigenous patients. Med J Aust 2005; 182: 507-512. <MJA full text>
  • 11. Cunningham J. Diagnostic and therapeutic procedures among Australian hospital patients identified as Indigenous. Med J Aust 2002; 176: 58-62.
  • 12. Cantor WJ, Goodman SG, Cannon CP, et al. Early cardiac catheterization is associated with lower mortality only among high-risk patients with ST- and non-ST-elevation acute coronary syndromes: observations from the OPUS-TIMI 16 trial. Am Heart J 2005; 149: 275-283.
  • 13. Ong MA, Weeramanthri TS. Delay times and management of acute myocardial infarction in Indigenous and non-Indigenous people in the Northern Territory. Med J Aust 2000; 173: 201-204.
  • 14. Rahimi AR, Spertus JA, Reid KJ, et al. Financial barriers to health care and outcomes after acute myocardial infarction. JAMA 2007; 297: 1063-1072.
  • 15. Kelman C. The Australian National Death Index: an assessment of accuracy. Aust N Z J Public Health 2000; 24: 201-203.
  • 16. Kariminia A, Butler T, Corben S, et al. Mortality among prisoners: how accurate is the Australian National Death Index? Aust N Z J Public Health 2005; 29: 572-575.
  • 17. Magliano D, Liew D, Pater H, et al. Accuracy of the Australian National Death Index: comparison with adjudicated fatal outcomes among Australian participants in the Long-term Intervention with Pravastatin in Ischaemic Disease (LIPID) study. Aust N Z J Public Health 2003; 27: 649-653.
  • 18. Powers J, Ball J, Adamson L, Dobson A. Effectiveness of the National Death Index for establishing the vital status of older women in the Australian Longitudinal Study on Women’s Health. Aust N Z J Public Health 2000; 24: 526-528.
  • 19. Madsen M, Davidsen M, Rasmussen S, et al. The validity of the diagnosis of acute myocardial infarction in routine statistics: a comparison of mortality and hospital discharge data with the Danish MONICA registry. J Clin Epidemiol 2003; 56: 124-130.
  • 20. Zingmond DS, Ye Z, Ettner SL, Liu H. Linking hospital discharge and death records — accuracy and sources of bias. J Clin Epidemiol 2004; 57: 21-29.
  • 21. Brameld KJ, Holman CD, Lawrence DM, Hobbs MS. Improved methods for estimating incidence from linked hospital morbidity data. Int J Epidemiol 2003; 32: 617-624.
  • 22. National Health Performance Committee. National report on health sector performance indicators 2003. Canberra: Australian Institute of Health and Welfare, 2004.


remove_circle_outline Delete Author
add_circle_outline Add Author

Do you have any competing interests to declare? *

I/we agree to assign copyright to the Medical Journal of Australia and agree to the Conditions of publication *
I/we agree to the Terms of use of the Medical Journal of Australia *
Email me when people comment on this article

Responses are now closed for this article.