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 HLA-B27 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 HLA-B27 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 20-69 years from this nationally representative sample.

RESULTS: The age-adjusted US prevalence of B27 was 6.1% (95% confidence interval [95% CI] 4.6-8.2). By race/ethnicity, the prevalence of B27 was 7.5% (95% CI 5.3-10.4) among non-Hispanic whites and 3.5% (95% CI 2.5-4.8) among all other US races/ethnicities combined. In Mexican Americans, the prevalence was 4.6% (95% CI 3.4-6.1). 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 50-69 years of age, the prevalence of B27 was 3.6% (95% CI 2.2-5.8), 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 HLA-B27. A decline in the prevalence of HLA-B27 with age is suggested by these data but must be confirmed by additional studies.