Screening for Latent Tuberculosis Infection, According to the USPSTF

The US Preventive Services Task Force (USPSTF) has stated that adults at increased risk for tuberculosis (TB) should always be screened for latent tuberculosis infection (LTBI).

THE final recommendation statement — a grade B recommendation — and a updated evidence report and systematic review were published in JAMAand rely on previous guidelines from 2016which also recommended screening for LTBI in patients at high risk for TB.

“Screening for latent TB infection in people at increased risk is an effective way to identify infection so that it can be treated before it progresses to active TB,” said Gbenga Ogedegbe, Member of Task Force, MD, MPH, from NYU Grossman School of Medicine. in New York, in a press release. “The task force continues to emphasize the importance of LTBI screening in reducing active TB rates and protecting people’s health nationwide.”

Two types of screening tests for LTBI are available in the United States: the tuberculin skin test (TST) and the interferon gamma release test (IGRA).

The systematic review showed pooled estimates of TST sensitivity to be 0.80 (95% CI 0.74-0.87) at the 5 mm induration threshold, 0.81 (95 % 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 of IGRA test sensitivity ranged from 0.81 (95% CI 0.79-0.84) to 0.90 (95% CI 0.87-0.92). Pooled estimates of screening test specificity ranged from 0.95 to 0.99.

“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 the accuracy of screening tests for LTBI, including an earlier 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 test moderately sensitive (performed 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 ITL in the United States is about 5% for those born in the country and 16% for those born outside, they noted.

THE CDC defines ITL as “an infection with Tuberculosis M in which the bacteria are alive but contained by the immune system,” which then has the potential to progress to active tuberculosis, the USPSTF said. People with ITL are unable to spread TB and often have no symptoms, but are likely to have blood or skin test results for TB.

“People at increased risk of TB who would benefit from screening include people born or who have lived in countries with increased TB rates and those who have lived in certain congregate settings, such as prisons or shelters for the -shelter,” task force chair Michael Barry, MD, of Massachusetts General Hospital in Boston, said in the press release. “It is important to note that anyone who screens positive needs further clinical testing to rule out active TB and confirm a diagnosis of ITL.”

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

In a accompanying editorial Posted in JAMAPriya Shete, MD, MPH, of San Francisco General Hospital, and co-authors highlighted the importance of the USPSTF recommendation, especially where health inequities exist.

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

“In the United States, more than half of people diagnosed with TB are hospitalized and nearly 1 in 10 will die from the disease,” they added. “The overall survival toll after TB treatment reveals that one in five diagnosed with TB will die within 5 years. These statistics are grim for a preventable and curable disease.”

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

“TB incidence varies by geography and housing, suggesting an association with social determinants of health,” the USPSTF wrote.

Although the new data support screening for LTBI in those at increased risk, Dick Menzies, MD, of the Montreal Chest Institute and the Research Institute of the McGill University Health Center, expressed concern that the practical aspect of generalized screening.

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

“The tests and treatments available 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 it is feasible and that retention of individuals throughout the LTBI care cascade is high, from initial identification, screening, assessment 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 eliminating TB in the United States can 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 screening is considered standard practice due to a high level higher risk. Additionally, some studies were conducted more than 40 years ago, limiting the applicability of their findings.