Background/Purpose: Canada’s First Nations population reports higher rates of physician-diagnosed arthritis and rheumatism, and is known to have twice the rate of osteoarthritis. The prevalence of inflammatory arthritis conditions of Rheumatoid Arthritis (RA), Ankylosing Spondylitis (AS), Psoriatic Arthritis (PsA), Reactive Arthritis (ReA), and Crystal Arthritis has not been widely studied, although variations between FN populations based on tribal ancestry are hypothesized. The Alberta First Nations population is rich in diversity with numerous Tribal Nations represented, including Blackfoot, Chipewyan, Cree, Dene, Sarcee, Saulteaux and Sioux Nations.  Prevalence estimates from Alberta would therefore provide a good overall view of the arthritis landscape among First Nations populations in Canada. We report the prevalence of these inflammatory arthritis conditions in the population of Alberta, Canada, comparing rates in First Nations and non-First Nations.

Methods: Population-based healthcare administrative data (years 1993 to 2011), including physician billing claims and hospitalizations, was used to define cohorts of patients with RA, AS, Ps, ReA and crystal arthritis based on ICD-9-CA and ICD-10-CM codes (2 physician billing codes or 1 hospitalization). First Nations patients were identified based on premium payer status. Disease prevalence rates were calculated for fiscal year 2008/2009 as cases per 1000 persons, and the rate ratio calculated for First Nations relative to non-First Nations.

Results: RA, AS and ReA were estimated as being twice as frequent in the First Nations population (Table 1). In contrast, PsA was slightly less frequent in First Nations.  Crystal arthritis surpassed RA as the most frequent type of inflammatory arthritis in the non-First Nations population, with a rate ratio three times that of the First Nations cohort.

Conclusion: Our estimates demonstrate that RA is the most frequent inflammatory arthritis in the First Nations population of Alberta, whereas crystal arthritis is the most frequent inflammatory arthritis diagnosis in non-First Nations. RA, AS and ReA prevalence estimates in First Nations are twice that of the non-First Nations population, whereas PsA and crystal arthritis are less frequent. These results further explain the higher self-reported rates of arthritis conditions in the First Nations population beyond degenerative arthritis conditions, and validate the need for enhanced inflammatory arthritis health services to address disease burden.