Deaths with Dementia in Indigenous and Non-Indigenous Australians: A Nationwide Study

Article type: Research Article

Authors: Waller, Michael^{a; *} | Buckley, Rachel F.^{b; c; d} | Masters, Colin L.^d | Nona, Francis R.^a | Eades, Sandra J.^e | Dobson, Annette J.^a

Affiliations: [a] University of Queensland, School of Public Health, Faculty of Medicine, Brisbane, Queensland, Australia | [b] Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA | [c] Melbourne School of Psychological Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia | [d] The Florey Institute of Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia | [e] Curtin Medical School, Curtin University, Western Australia, Australia

Correspondence: [*] Correspondence to: Dr. Michael Waller, University of Queensland, School of Public Health, Faculty of Medicine, Public Health Building, Herston Road, Herston, Queensland 4006, Australia. Tel.: +61 7 33655116; E-mail: m.waller@uq.edu.au.

Abstract: Background:The prevalence of dementia is generally reported to be higher among Indigenous peoples. Objective:The rates and coding of dementia mortality were compared between Indigenous and non-Indigenous Australians. Methods:De-identified individual records on causes of death for all people aged 40 years or more who died in Australia between 2006 and 2014 (n = 1,233,084) were used. There were 185,237 records with International Classification of Diseases, Tenth Revision, codes for dementia (Alzheimer’s Disease, vascular dementia, or unspecified dementia) as the underlying cause of death or mentioned elsewhere on the death certificate. Death rates were compared using Poisson regression. Logistic regression was used to assess whether dementia was more likely to be classified as ‘unspecified’ type in Indigenous Australians. Results:The rates of death with dementia were 57% higher in Indigenous Australians, compared to non-Indigenous, relative rate (RR) 1.57, 95% confidence interval (CI) (1.48, 1.66), p < 0.0001. This excess of deaths was highest at ages below 75 (RRs > 2, test for interaction p < 0.0001), and among men (test for interaction p < 0.0001). When the underreporting of Indigenous status on the death certificate was taken into account the relative rate increased to 2.17, 95% CI (2.07, 2.29). Indigenous Australians were also more likely to have their dementia coded as ‘unspecified’ on their death certificate (Odds Ratio 1.92, 95% CI (1.66, 2.21), p < 0.0001), compared to the non-Indigenous group. Conclusion:This epidemiological analysis based on population level mortality data demonstrates the higher dementia-related mortality rate for Indigenous Australians especially at younger ages.

Keywords: Alzheimer’s disease, dementia, Indigenous, mortality, population-level studies, rural, unspecified dementia, vascular dementia

DOI: 10.3233/JAD-201175

Journal: Journal of Alzheimer's Disease, vol. 81, no. 4, pp. 1589-1599, 2021