Background/Purpose: High rates of rheumatoid arthritis and systemic lupus erythematosus have been described in indigenous North American (INA) populations. Few studies have investigated the prevalence or clinical patterns of juvenile idiopathic arthritis (JIA) in INA populations, but two studies have suggested high rates in specific regions of the US and Canada. The purpose of this project was to determine the prevalence of JIA overall and its subtypes in Alaska Native children statewide and to describe the clinical characteristics and treatment patterns of JIA in this population.

Methods: Potential cases of JIA were identified by a query of administrative data from the electronic health record of the Alaska Native Medical Center for codes possibly identifying JIA and from adult and pediatric rheumatology clinic databases. Cases were required to be under age 18 as of 9/30/2015 and to have a diagnosis of JIA confirmed by medical record abstraction. The denominator for prevalence was the 2015 Alaska Area Indian Health Service user population under the age of 18. Medical record abstraction was used to confirm the criteria met for JIA, subtype diagnosed, demographic features, other clinical characteristics, and medications ever used for treatment.

Results:

The unadjusted prevalence of JIA in Alaska Native children was 67.5 per 100,000 (age-adjusted 71.7 per 100,000). JIA was more common in females than males (unadjusted prevalence 91.2 vs. 45.5 per 100,000). Oligoarthritis was the most common subtype (32% of cases), but enthesitis-related arthritis was also common (26.3% of cases). The mean age at diagnosis was 9 years and the prevalence was highest in children aged 16-18. During the one year study period, cases had a mean of 2.2 visits to a rheumatologist. Of the combined cohort, 53% had a positive ANA, 26% had positive rheumatoid factor, 24% had positive anti-CCP antibody, and 26% had the presence of HLA B27. Uveitis had been diagnosed in 26% of cases. Methotrexate was the most commonly prescribed non-biologic DMARD (ever prescribed in 66% of cases) and adalimumab was the most commonly prescribed biologic (in 32%).

Conclusion: The prevalence of JIA in Alaska Native children may be slightly higher than the general US population. Enthesitis-related arthritis makes up a higher proportion of cases than in other populations described, likely because of the high prevalence of HLA B27 in this population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-juvenile-idiopathic-arthritis-in-the-alaska-native-population/