Screen for Latent TB Infection, USPSTF Says

The U.S. Preventive Services Task Force (USPSTF) said adults at increased risk for tuberculosis (TB) should still be screened for latent tuberculosis infection (LTBI).

The final recommendation statement -- a grade B recommendation -- and an updated evidence report and systematic review were published in JAMA, and build on previous guidelines from 2016, which also recommended screening for LTBI in patients at higher risk for TB.

"Screening for latent tuberculosis infection in people at increased risk is an effective way to identify the infection so that it can be treated before it progresses to active TB," said Task Force member Gbenga Ogedegbe, MD, MPH, of NYU Grossman School of Medicine in New York City, in a press release. "The Task Force continues to underscore the importance of LTBI screening in reducing rates of active TB, protecting the health of people nationwide."

Two types of screening tests for LTBI are available in the U.S. -- the tuberculin skin test (TST) and the interferon-gamma release assay (IGRA).

The systematic review showed that pooled estimates for sensitivity of the TST were 0.80 (95% CI 0.74-0.87) at the 5-mm induration threshold, 0.81 (95% CI 0.76-0.87) at the 10-mm threshold, and 0.60 (95% CI 0.46-0.74) at the 15-mm threshold.

Pooled estimates for sensitivity of IGRA tests ranged from 0.81 (95% CI 0.79-0.84) to 0.90 (95% CI 0.87-0.92). Pooled estimates for specificity of screening tests ranged from 0.95 to 0.99.

"The evidence suggests that for the populations and settings studied, currently available tests are moderately sensitive and highly specific," wrote Daniel Jonas, MD, MPH, of the Ohio State University College of Medicine in Columbus, and colleagues in the evidence report. "Previously published systematic reviews evaluating accuracy of screening tests for LTBI, including a prior review for the USPSTF, are generally consistent with these findings."

"It seems reasonable to assume applicability to primary care practice settings that serve high-risk populations ... where the use of a highly specific test among a higher-prevalence population minimizes false positives and a moderately sensitive test (conducted after it is indicated by a clinical risk assessment) can help determine the likelihood of latent infection to inform preventive treatment decisions," Jonas and co-authors added.

The approximate rate of LTBI in the U.S. is about 5% for those born in the country, and 16% for those born outside it, they noted.

The CDC defines LTBI as "an infection with M tuberculosis in which the bacteria are alive but contained by the immune system," which then has the potential to progress into active TB, the USPSTF said. People with LTBI are unable to spread TB and often present with no symptoms, but are likely to have positive results from a blood or skin TB test.

"People at increased risk for tuberculosis who would benefit from screening include people born or who have lived in countries with increased rates of TB and those who have lived in certain group settings, like prisons or homeless shelters," said Task Force chair Michael Barry, MD, of Massachusetts General Hospital in Boston, in the press release. "Importantly, anyone who screens positive needs further clinical tests to rule out active TB and confirm an LTBI diagnosis."

High-risk patients also include those who have a weakened or compromised immune system, and people who live in places with close contact with those who may have TB.

In an accompanying editorial published in JAMA, Priya Shete, MD, MPH, of San Francisco General Hospital, and co-authors highlighted the significance of the USPSTF recommendation, particularly where health inequalities exist.

"Preventive care for one of the world's leading infectious disease killers has received a much-needed push forward," they wrote. "The importance of this recommendation, particularly for immigrant communities who bear the disproportionate burden of this disease, cannot be overstated."

"In the U.S., more than half of individuals diagnosed with tuberculosis are hospitalized and almost 1 in 10 will die of the disease," they added. "The toll encompassing survival following tuberculosis treatment reveals that 1 in 5 diagnosed with tuberculosis will die within 5 years. These statistics are grim for a preventable and curable disease."

The recommendation statement points out that non-white communities are at a higher risk of TB, with the disease disproportionately affecting Asian, Black, Hispanic/Latino, Native American/Alaska Native, and Native Hawaiian/Pacific Islander populations.

"Incidence of TB varies by geography and living accommodations, suggesting an association with social determinants of health," the USPSTF wrote.

While the new data support LTBI screening for people at increased risk, Dick Menzies, MD, of the Montreal Chest Institute and the Research Institute of the McGill University Health Centre, expressed concerns over the practicality of widespread screening.

"Integration of LTBI screening into primary care has the potential to be more effective as care for LTBI is integrated with other primary care services and acceptance and adherence of TPT [TB preventive treatment] are enhanced by a stable, long-term patient-practitioner relationship," he wrote in an editorial published in JAMA Network Open. "This may also be more feasible and cost-effective because it would avoid the creation or expansion of a parallel system of public health clinics. This would also facilitate repeated attempts to screen and treat; individuals who do not complete screening and/or TPT immediately could be reminded in subsequent years."

"The available tests and treatment are appropriate for primary care; it is hoped that reimbursement mechanisms are also available in most settings," Menzies concluded. "What is still needed is evidence that this is feasible and that retention of individuals throughout the LTBI cascade of care is high, from initial identification, screening, evaluation, and initiation to completion of TPT. In this way, the full benefits of LTBI screening will be realized for individuals and the long-term goal of TB elimination in the U.S. may be achieved."

The evidence report and systematic review included 112 studies, with 69,009 participants, which were published from January 2015 to December 2021.

Jonas and colleagues noted that their review did not include people who were in close contact with active TB, pregnant women, or populations where LTBI testing is considered to be standard practice due to a higher level of risk. In addition, some studies took place over 40 years ago, limiting the applicability of their findings.