USPSTF, AAFP: Screen Adults at Increased Risk for Latent TB Infection

Evidence Supports Effective Screening Tests, Treatments

September 08, 2016 02:00 pm News Staff

On Sept. 6, the U.S. Preventive Services Task Force (USPSTF) published its final recommendation statement(www.uspreventiveservicestaskforce.org) and evidence summary(www.uspreventiveservicestaskforce.org) on screening for latent tuberculosis infection (LTBI) and recommended screening for adults who are at increased risk but do not have symptoms of tuberculosis (TB) -- a "B" recommendation.(www.uspreventiveservicestaskforce.org)

[X-ray of lung with tuberculosis]

The USPSTF said patients considered to be at increased risk for LTBI include those who were born in or who have lived in countries with a high prevalence of TB, including Mexico, the Philippines, Vietnam, India, China, Haiti and Guatemala. Also, people who have lived in group settings where exposure to TB is more likely, such as homeless shelters or correctional facilities, are considered to be at increased risk.

The task force's final recommendation is largely consistent with its 2016 draft and 1996 final recommendations. The USPSTF said the move from an "A" grade in 1996 to a "B" grade in 2016 reflects newer research, new screening tests for TB and changes in the group's methods for developing evidence-based recommendations during the past 20 years.

"The task force recommends that primary care clinicians screen adults at increased risk for LTBI to help prevent the progression to active TB," said USPSTF member Francisco García, M.D., M.P.H., in a news release.(www.uspreventiveservicestaskforce.org) "TB is a highly contagious, devastating disease. The best approach to prevention is identifying those populations at high risk for exposure as well as those individuals whose underlying medical disease may make them more susceptible to TB infection."

Story highlights
  • In its final recommendation statement, the U.S. Preventive Services Task Force (USPSTF) recommended screening for latent tuberculosis infection (LTBI) among adults at increased risk but without symptoms.
  • The USPSTF's final recommendation is largely consistent with its 2016 draft and 1996 final recommendations; the task force said the move from an "A" grade in 1996 to a "B" grade in 2016 reflects newer research, new screening tests for tuberculosis and changes in the group's methods for developing evidence-based recommendations during the past 20 years.
  • The AAFP released its own final recommendation that also suggested screening for LTBI in asymptomatic populations at increased risk -- a "B" recommendation.

The AAFP released its own final "B" recommendation that called for screening asymptomatic adults at increased risk for LTBI.

Screening Tests and Treatment

The USPSTF found effective screening tests that detect LTBI and also effective treatments to prevent patients from progressing from LTBI to active TB disease.

Two types of screening tests for LTBI are currently available in the United States: the Mantoux tuberculin skin test (TST) and interferon-gamma release assays (IGRAs). TST requires intradermal placement of purified protein derivative and interpretation of response 48 to 72 hours later. IGRA requires a single venous blood sample and laboratory processing within 8 to 30 hours after collection.

The CDC recommends screening with either TST or IGRA. IGRA tests may be preferred for patients who have received Bacillus Calmette-Guérin vaccine or those who may be unlikely to return for TST interpretation.

The USPSTF found no evidence regarding the optimal frequency of LTBI screening, explaining that depending on specific risk factors, it could range from one-time-only screening for patients at low risk for future exposure to annual screening for patients who are at continued risk of exposure.

As for treatment, the CDC recommends(www.cdc.gov) four different treatment regimens for LTBI. Medications include rifampin, isoniazid or isoniazid plus rifapentine. Treatment duration ranges from three to nine months. If a nondaily dosing regimen is offered, the CDC recommends directly observed therapy.

"The task force found that there are effective screening tests that can detect latent TB infection, and there are effective treatments to prevent people from progressing from latent TB infection to active TB disease," said USPSTF Chair Kirsten Bibbins-Domingo, Ph.D., M.D., in the release.

Update of 1996 Recommendation

The USPSTF last issued a recommendation on screening for tuberculosis in 1996. At that time, the task force recommended screening for TB infection with TST in asymptomatic, high-risk patients -- an "A" recommendation. It also recommended the consideration of Bacillus Calmette-Guérin vaccination for selected high-risk individuals only -- a "B" recommendation.

Family Physician's Take

Back in March, when the USPSTF's draft recommendation statement was released, family physician Kenneth Lin, M.D., M.P.H., of Washington, D.C., told AAFP News that he generally does TB testing in his office only when asked. These tests usually are for patients who work in health care settings where testing is a work requirement, or for recent immigrants from countries with high TB prevalence.

"In terms of what's changed since 1996, we now have a blood test for TB (IGRA) which is more convenient for patients since they don't have to come back in 48 to 72 hours to have it read," he said.

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American Family Physician: Update on Latent Tuberculosis Infection

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