Background/Purpose: The Indigenous
populations of Canada, the United States, Australia and New Zealand have higher
disease prevalence for many inflammatory arthritis conditions and connective
tissue diseases compared to the non-Indigenous populations in those countries.
Phenotypic differences are believed to exist clinically. The objective of our
systematic review was to summarize differences in disease characteristics,
disease activity and outcomes for Indigenous populations.

Methods: A systematic search (to June 2015)
was performed in Medline, EMBASE, the Bibliography of Native North Americans,
Circumpolar Health Bibliographic Database, Metis Health Database, Native Health
Database, Native Indigenous Studies Portal, Australian Indigenous Health InfoNet, and conference abstracts from rheumatology
conferences (2012-2015) in the countries of interest and international
conferences. Search terms for Indigenous populations were combined with search
terms for inflammatory arthritis conditions (rheumatoid arthritis, spondyloarthropathies, juvenile idiopathic arthritis),
connective tissue disorders (systemic lupus erythematosus,
scleroderma, myositis, sjogren’s), crystal arthritis
and osteoarthritis. Studies were included if they reported disease activity
measures for the condition of interest, the proportion of patients with
recognized classification criteria for the condition of interest, or mortality.

Results: A total of 5,269 titles and
abstracts were reviewed, of which 523 underwent full-text review, and 87 were included
for extraction of clinical outcomes. Thirty-eight of the studies were published
before the year 2000, and only 37% made mention of Indigenous populations
collaboration on the studies. Nearly all the studies described outcomes in the
North American populations (n=38 American, n=40 Canadian), with only 5 studies
from Australia and 4 studies from New Zealand. Forty-four studies described RA characteristics
in Indigenous populations, and 14 had a comparator group defined as Caucasian,
White, Non-Aboriginal or Non-First Nations.  Indigenous populations were younger at
disease onset (age range 29-41 years vs 36-55 years).
Disease activity measures were not frequently significantly worse in Indigenous
patients, although lesser response to treatment was identified in one study.
Pain levels were higher in Indigenous patients in all studies reporting this
outcome (n=3 studies). No studies examined a mortality rate, but in one study
Indigenous patients were younger at death (53 vs 76
years). There were 22 studies identified that described lupus characteristics
and outcomes, and 13 had a comparator group. Lupus nephritis was more common in
Indigenous populations, with a higher mortality rate.

Conclusion: Our synthesis highlights
knowledge gaps that exist and assumptions  that have been made with regards
to the disease phenotype of Indigenous populations of Canada, the United States,
Australia and New Zealand. Contemporary studies performed in collaboration with
Indigenous populations are required to more fully understand the consequences
of rheumatic disease in these countries.