Aims: To compare the nature and frequency of spondylarthropathy in geographically separated but genetically related populations with a high prevalence of HLA-B27.
Methods: Using a common questionnaire and disease criteria, cases were ascertained through cross-sectional community surveys in Russia and by examination and study of possible cases identified through rheumatic disease registries and the Native Health Service's computerized patient care data system in Alaska.
Results: Similar overall prevalences of spondyloarthropathy (2.0-3.4%) and a similar spectrum of disease were found, including reactive arthritis, ankylosing spondylitis and undifferentiated spondylarthropathy. Psoriatic arthritis was very rare.
Conclusion: No predisposition to one particular form of spondyloarthropathy was observed; genetic and microbial settings for a spectrum of disease were present. Among adults positive for the presence of HLA-B27 the prevalence of all types of spondylarthropathies was estimated to be 4.5%, all populations combined, and the prevalence of AS was estimated to be 1.6%.