The United States National Health and Nutrition Examination Survey and the Epidemiology of Ankylosing Spondylitis

Currently available U.S. population– based data for ankylosing spondylitis (AS), spondyloarthritis and inflammatory back pain (IBP) from the nationally representative U.S. National Health and Nutrition Examination Survey (NHANES) include both NHANES I(1971–1975) and NHANES II (1976 –1980) surveys. The pelvic radiographs obtained in NHANES I provided U.S. prevalence estimates for radiographic sacroiliitis, an important component of the AS case definition. AS and spondyloarthritis prevalences cannot readily be calculated from NHANES I survey data; however, IBP prevalence (Rudwaleit et al Criteria 7b) can be estimated from NHANES II. The NHANES II estimate for IBP is 0.8% of the adult population ages 25 to 49 years. The prevalence of IBP in the subset of persons with a history of a back pain episode lasting 2 or more weeks was 6.7%. The 2009 –2010 NHANES U.S. Inflammatory Back Pain/Spondyloarthritis survey is currently fielded.