Mortality causes and outcomes in Indigenous populations of Canada, the United States, and Australia with rheumatic disease: A systematic review

Abstract

Background: Indigenous populations of Canada, America, Australia, and New Zealand have increased rates and severity of rheumatic disease. Our objective was to summarize mortality outcomes and explore disease and social factors related to mortality.

Methods: A systematic search was performed in medical (Medline, EMBASE, and CINAHL), Indigenous and conference abstract databases (to June 2015) combining search terms for Indigenous populations and rheumatic diseases. Studies were included if they reported measures of mortality (crude frequency, mortality rate, survival, and potential years of life lost (PYLL)) in Indigenous populations from the four countries.

Results: Of 5269 titles and abstracts identified, 504 underwent full-text review and 12 were included. No studies from New Zealand were found. In five Canadian studies of systemic lupus erythematosus (SLE) patients, First Nations ethnicity was associated with lower survival after adjusting for disease and social factors, and an increased frequency of death from lupus and its complications compared to Caucasians was found. All-cause mortality was higher in Native Americans (n = 2 studies) relative to Whites with SLE after adjusting for disease and social factors, but not in those with lupus nephritis alone. Australian Aborigines with SLE frequently developed infection and lupus complications leading to death (n = 3 studies). Mortality rates were increased in Pima Indians in the United States with rheumatoid arthritis (RA) compared to those without RA. One study in Native Americans with scleroderma found nearly all deaths were related to progressive disease.

Conclusions: Canadian and American Indigenous populations with SLE have increased mortality rates compared to Caucasian populations. Mortality in Canadian and Australian Indigenous populations with SLE, and in Native American populations with RA and scleroderma, is frequently attributed to disease progression or complications. The proportional attribution of rheumatic disease severity and social factors to mortality and complications leading to death between Indigenous and non-Indigenous populations has not been fully evaluated.

Keywords: Indigenous; Mortality; Rheumatic disease; Survival.