Adults who have an increased risk for tuberculosis should be screened for latent tuberculosis infection (LTBI), according to a draft recommendation statement released by the U.S. Preventive Services Task Force (USPSTF).
The USPSTF gave a B grade to these recommendations, noting that there is high certainty of a moderate net benefit. “Approximately 30% of persons exposed to Mycobacterium tuberculosis will develop LTBI, and, if untreated, approximately 5% to 10% of these persons will progress to active tuberculosis disease,” the USPSTF stated. No studies were found that evaluated the direct benefits of screening for LTBI, but the USPSTF did find adequate evidence that treatment of LTBI with CDC-recommended treatment regimens does decrease the progression of active TB.
Individuals considered at high risk for LTBI include:
- persons who were born in, or are former residents of, countries with increased tuberculosis prevalence
- persons who live in or have lived in high-risk congregate settings, including homeless shelters and correctional facilities
- foreign-born persons from Mexico, the Philippines, Vietnam, India, and China, as well as Haiti and Guatemala
- persons who are immunosuppressed, including those with HIV, patients undergoing chemotherapy treatment or treatment with tumor necrosis factor-alpha inhibitors, and those receiving or who just received an organ transplant
- patients with silicosis
- persons who are in frequent contact with those who have active TB
- healthcare workers and those who work in high-risk congregate settings
No evidence was found to suggest an optimal frequency of LTBI screening; however, the USPSTF recommends that LTBI testing be conducted via either the Tuberculosis Skin Test (TST) or the Interferon Gamma Release Assay (IGRA), per CDC testing guidelines. In the event of positive test results, treatment may be administered via 1 of 4 CDC recommended treatment regimens.
Table. Latent TB Infection Treatment Regimens (adopted from the CDC)
|Isoniazid||9 months||Twice weekly*||76|
|Isoniazid||6 months||Twice weekly*||52|
|Isoniazid and Rifapentine||3 months||Once weekly*||12|
*Use Directly Observed Therapy (DOT)
No identified studies directly reported on potential harms of screening, although identified harms include the stigma associated with TB screening and potential false-positive results via diagnostic workup. The most consistently reported harm found across 5 good or fair quality studies was hepatoxicity at 5 years after treatment with isoniazid (300 mg for 24 weeks).
Overall, the USPSTF found adequate evidence that accurate LTBI screening tests are available and LTBI treatment provides a moderate health benefit and prevents patient progression to active disease.
“Further research that evaluates risk assessment tools to determine efficient ways of identifying candidates for LTBI testing and treatment is needed,” concluded the USPSTF. “Additional research on how often LTBI screening should be performed in different subpopulations is also needed. Additionally, more studies to help clarify if certain screening methods are preferred for certain risk groups are also needed.”
- Latent tuberculosis infection: Screening [draft recommendation statement]. Rockville, MD: U.S. Preventive Services Task Force. Published March 2016. Accessed March 10, 2016.
- Testing for Tuberculosis (TB) [fact sheet]. Atlanta, GA: Centers for Disease Control and Prevention, Division of Tuberculosis Elimination. Updated December 19, 2014. Accessed March 17, 2016.
- Treatment for Latent TB Infection. Atlanta, GA: Centers for Disease Control and Prevention, Division of Tuberculosis Elimination. Updated February 7, 2014. Accessed March 17, 2016.