Prevalence of spondyloarthropathies in Alaskan Eskimos

To estimate the prevalence of spondyloarthropathies (SpA) in 2 Alaskan Eskimo populations, using improved methodology for case ascertainment and new, more inclusive classification criteria.

Through existing rheumatic disease registries, health care providers and the Alaska Area Native Health Service (AANHS) computerized patient information system, we identified all native residents of the 2 study regions with a diagnosis of any inflammatory arthritis or problems characteristic of SpA, such as iritis or persistent back pain. Individuals with such diagnoses or problems were evaluated in clinic, according to a standardized protocol (interview, examination), and by medical record review, pelvic radiography and laboratory tests. Each case was evaluated according to standard diagnostic criteria for the individual disease entities and by the Amor and European Spondylarthropathy Study Group (ESSG) preliminary classification criteria for SpA.

We identified 104 cases of SpA in the combined Eskimo populations, an overall prevalence of 2.5% in adults aged 20 and over. Both undifferentiated (USpA) and reactive SpA were more common than ankylosing spondylitis (AS).

Using the new criteria and a more effective approach to case ascertainment we found the prevalence of SpA to be about twice that found in our earlier studies of adult Eskimo populations. The prevalence of SpA was very similar in men and women. Despite the known high prevalence (25-40%) of HLA-B27 in the study populations we did not find the prevalence of any form of SpA to be as strikingly high as that of AS (6-10%) for the Canadian Haida.