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Task Force Issues Draft Recommendation Statement on Screening for Latent TB Infection in Adults
The U.S. Preventive Services Task Force (USPSTF) is seeking comments on a draft recommendation statement on screening for latent tuberculosis infection (LTBI) in adults. The task force recommends screening for LTBI in adults at increased risk.
The USPSTF last issued a recommendation on screening for tuberculosis in 1996. At that time, the USPSTF recommended screening for tuberculosis infection with the Mantoux tuberculin skin test (TST) in asymptomatic, high-risk persons, and consideration of Bacillus Calmette–Guérin vaccination for selected high-risk individuals only. Given changes in the epidemiology of the disease, the development of newer screening technologies, and newer methods for developing evidence-based recommendations, the USPSTF decided to update the topic and issue a recommendation using its current methods and considering all of the available evidence, including studies published before 1996.
The new recommendation statement applies to asymptomatic adults (18 years of age and older) who are at increased risk for LTBI. It does not apply to adults with symptoms of TB or to children or adolescents. Populations that are at increased risk for LTBI include persons who were born in, or are former residents of, countries with increased TB prevalence and persons who live in, or have lived in, high-risk congregate settings (such as homeless shelters and correctional facilities).
The USPSTF found adequate evidence that accurate screening tests are available to detect LTBI. Screening tests include the Mantoux TST and interferon-gamma release assays (IGRAs); both are moderately sensitive and highly specific. TST requires intradermal placement of a purified protein derivative and the interpretation of response 48 to 72 hours later. IGRAs require a single venous blood sample and laboratory processing within eight to 30 hours after collection. Two types of IGRAs are currently approved by the FDA: T-SPOT.TB (Oxford Immunotec Global PLC) and QuantiFERON-TB Gold In-Tube (Qiagen). The Centers for Disease Control and Prevention (CDC) recommends screening with either TST or IGRAs. IGRA tests may be preferred for persons who have received a Bacillus Calmette–Guérin vaccination or for persons who may be unlikely to return for TST interpretation.
The USPSTF found that no studies have evaluated the direct benefits of screening for LTBI. The task force found adequate evidence that the treatment of LTBI with regimens recommended by the CDC reduces disease progression to active TB; the magnitude of this benefit is moderate.
The USPSTF also found no direct evidence on the harms of screening for LTBI. The task force found adequate evidence that the magnitude of harms from treating LTBI with CDC-recommended regimens is small. The primary harm of treatment is hepatotoxicity.
The USPSTF concludes with moderate certainty that the net benefit of screening for LTBI in persons who are at increased risk for TB is moderate.
In 2014, among persons of known national origin, 67% of all active TB cases in the U.S. were among foreign-born persons, and the case rate among foreign-born persons was 13 times higher than that among U.S.-born persons (15.3 versus 1.1 cases per 100,000 persons). More than half of all foreign-born persons in the U.S. with active TB come from five countries: Mexico, the Philippines, Vietnam, India, and China. In addition, the CDC has identified foreign-born persons from Haiti and Guatemala as important contributors to active TB cases in the U.S.
Source: USPSTF; March 8, 2016.