Tuberculosis Infection in the United States: Prevalence Estimates from the National Health and Nutrition Examination Survey, 2011-2012

Abstract

BackgroundReexamining the prevalence of persons infected with tuberculosis (TB) is important to determine trends over time. In 2011–2012 a TB component was included in the National Health and Nutrition Examination Survey (NHANES) to estimate the reservoir of persons infected with TB.MethodsCivilian, noninstitutionalized U.S. population survey participants aged 6 years and older were interviewed regarding their TB history and eligibility for the tuberculin skin test (TST) and interferon gamma release assay (IGRA) blood test. Once eligibility was confirmed, both tests were conducted. Prevalence and numbers of TST positive (10 mm or greater), IGRA positive, and both TST and IGRA positive were calculated by adjusting for the complex survey design after applying corrections for item nonresponse and digit preference in TST induration measurements. To examine TST positivity over time, data from NHANES 1999–2000 were reanalyzed using the same statistical methods. The TST was performed using Tubersol, a commercially available purified protein derivative (PPD), rather than PPD-S, which was the antigen used in NHANES 1999–2000. Prior patient history of TB vaccination was not collected in this study nor were patients examined for the presence of a Bacillus of Calmette and Guerin (BCG) vaccine scar.ResultsFor NHANES 2011–2012, TST and IGRA results were available for 6,128 (78.4%) and 7,107 (90.9%) eligible participants, respectively. There was no significant difference between the percentage of the U.S. population that was TST positive in 2011–2012 (4.7% [95% CI 3.4–6.3]; 13,276,000 persons) compared with 1999–2000 (4.3%; 3.5–5.3). In 2011–2012 the percentage that was IGRA positive was 5.0% (4.2–5.8) and double TST and IGRA positivity was 2.1% (1.5–2.8). The point estimate of IGRA positivity prevalence in foreign-born persons (15.9%; 13.5–18.7) was lower than for TST (20.5%; 16.1–25.8) in 2011–2012. The point estimate of IGRA positivity prevalence in U.S.-born persons (2.8%; 2.0–3.8) was higher than for TST (1.5%; 0.9–2.6).ConclusionsNo statistically significant decline in the overall estimated prevalence of TST positivity was detected from 1999–2000 to 2011–2012. The prevalence of TB infection, whether measured by TST or IGRA, remains lower among persons born in the United States compared with foreign-born persons.

Latent Tuberculosis Infection Test Agreement in the National Health and Nutrition Examination Survey

“…For the foreign-born population, LTBI prevalence estimates were 20.3% if defined as TST positive, 16.3% if defined as QFT positive, and 9.1% if defined as both tests positive (Table 3). These estimates based on TST alone are similar to previous estimates for U.S. adults and a recently published study of the 2011-2012 NHANES sample (15,24,25).…”

“…Finally, our use of a 10-mm threshold for defining a positive TST would not comply with current U.S. guidelines (2) for U.S.-born individuals, which recommend use of a 15-mm cutoff in persons not known to be at increased risk for TB infection, and may have increased the false positivity rate. We chose this cutoff on the basis of prior population-based studies (12,15,21,24,25) and evaluated different TST cut-points in U.S.-and foreign-born populations. In general, LTBI testing should be targeted to individuals at high risk for LTBI and/or progression to active TB.…”

The Influence of Age at Arrival and Duration of Residence in US on Prevalence of Latent TB Infection

“…NHANES survey methodology has been previously described in detail [4,11]. In brief, NHANES is an ongoing series of cross-sectional health examination surveys conducted by the National Center for Health Statistics (NCHS) within the Centers for Disease Control and Prevention (CDC) designed to assess the health and nutritional status of U.S. residents.…”

“…In brief, NHANES is an ongoing series of cross-sectional health examination surveys conducted by the National Center for Health Statistics (NCHS) within the Centers for Disease Control and Prevention (CDC) designed to assess the health and nutritional status of U.S. residents. Every year, approximately 5,000 non-institutionalized civilian U.S. residents of all ages complete detailed health interviews in their homes, and complete a comprehensive physical health examination in a mobile examination center [4,11]. Although each survey year represents a nationally representative sample, data are released in 2-year cycles to ensure adequate sample size and protect confidentiality.…”

The Replacement Principle of Tuberculosis. Why Prevention Matters

“…This strategy identifies and treats prevalent cases but does not address the people with existing infections who are at risk for reactivation disease. Although the United States maintains a national surveillance program for tuberculosis disease, it does not have a parallel program for surveillance of latent infection, and so must rely on contact investigations and periodic surveys to measure latent infection (4).…”