The prevalence of HLA-B27 in the US: Data from the US National Health and Nutrition Examination Survey, 2009

Objective To carry out the first large-scale population study of the prevalence of HLAB27 in the US, which is needed for public health planning purposes because of recent improvements in medical therapy and diagnostic testing for ankylosing spondylitis (AS). Methods The national prevalence of HLAB27 was determined as part of the 2009 US National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey monitoring the health and nutritional status of the US civilian, noninstitutionalized population. DNA polymerase chain reaction analysis was conducted in samples from 2,320 adults ages 2069 years from this nationally representative sample. Results The age-adjusted US prevalence of B27 was 6.1% (95% confidence interval [95% CI] 4.68.2). By race/ethnicity, the prevalence of B27 was 7.5% (95% CI 5.310.4) among non-Hispanic whites and 3.5% (95% CI 2.54.8) among all other US races/ethnicities combined. In Mexican Americans, the prevalence was 4.6% (95% CI 3.46.1). The prevalence of B27 could not be reliably estimated for other US racial/ethnic groups because of the low number of B27-positive individuals in those groups. For adults 5069 years of age, the prevalence of B27 was 3.6% (95% CI 2.25.8), which suggested a decrease in B27 with age. These prevalence estimates took into account the NHANES survey design and are reviewed with respect to data from the medical literature. Conclusion Our findings provide the first US national prevalence estimates for HLAB27. A decline in the prevalence of HLAB27 with age is suggested by these data but must be confirmed by additional studies.