What is prevalence of ankylosing spondylitis (AS)?

Updated: Sep 03, 2019
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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AS is the most common of the classic spondyloarthropathies. Prevalence varies with the prevalence of the HLA-B27 gene in a given population, which increases with distance from the equator. In general, AS is more common in whites than in nonwhites. It occurs in 0.1-1% of the general population, [48, 49, 50] with the highest prevalence in northern European countries and the lowest in sub-Saharan Africa. [33, 51]

Approximately 1-2% of all people who are positive for HLA-B27 develop AS. This increases to 15-20% if they have a first-degree relative with HLA-B27 positive AS. [5, 28]

Prevalence data for undifferentiated spondyloarthropathy (USpA) are scarce, although this disorder appears to be at least as common as AS, if not more so. [48] Its actual prevalence may be as high as 1-2% of the general population.

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