Background/Purpose: Indigenous populations of Canada, America, Australia, and New Zealand share similar experiences of colonization impacting their rheumatic disease clinical outcomes. The objective of our systematic review was to describe mortality in Indigenous populations with rheumatic conditions.

Methods: A systematic search was performed in medical (Medline, EMBASE, CINAHL), Indigenous and conference abstract databases (to June 2015). Search terms for Indigenous populations were combined with terms for inflammatory arthritis conditions, connective tissue disorders, crystal arthritis, and osteoarthritis. Studies were selected for data extraction if they reported measures of mortality (e.g. mortality rate, survival rates, potential years of life lost). Meta-analysis was not performed due to heterogeneity in the reporting of measures in each study, and a narrative summary was prepared.

Results: A total of 5,269 titles and abstracts were reviewed, of which 504 underwent full-text review and 12 (n=5 Canadian First Nations with SLE; n=2 Native Americans with SLE; n=1 Native Americans with RA; n=1 Native Americans with scleroderma; n=3 Australian Indigenous with SLE) were included for data extraction. First Nations ethnicity was associated with higher mortality compared to Caucasians in all Canadian SLE studies, reflected by a higher crude proportion of deaths (n=3 studies), increased risk of death after adjustment for covariates (hazard ratios 2-3, relative to Caucasians, n=2 studies), higher odds of death (n=1 study) and increased potential years of life lost (n=2 studies). First Nations people with SLE were more likely to have shorter disease duration and be younger at death, and die of SLE complications (27% vs 16%). Risk of death was 43% higher In Native Americans with SLE compared to Caucasians in age and sex adjusted models, and in models with an expanded list of covariates. Risk was highest in women ages 45-65 years. Crude death rates and causes of death were reported in the three studies of Australian Indigenous people with SLE; in these cohorts created through case-finding, Aborigines had higher death rates than Caucasians, mostly related to SLE complications. The RA study in Pima Indians included a comparison of mortality rates between RA and non-RA subjects, with an age and sex-adjusted mortality rate ratio of 1.28 (95%CI 1.01 to 1.62). The one study in Native Americans with scleroderma reported a crude death rate, with nearly all deaths related to progressive disease.

Conclusion: In Canada, America and Australia, Indigenous populations with rheumatic diseases have higher mortality rates. Several studies identified the underlying rheumatic disease as contributing to the deaths. We did not identify any studies disentangling the proportional attribution of rheumatic disease severity from the underlying higher mortality rates in Indigenous populations. The future research agenda should seek to clarify this important issue while expanding the scope to include more rheumatic diseases and populations.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-in-indigenous-populations-of-canada-the-united-states-australia-and-new-zealand-with-rheumatic-disease-a-systematic-review/