3
Diagnosis
Testing for Latent Tuberculosis Infection (LTBI)
See page 11 for an explanation of the Recommendation Grading.
➤ The panel recommends performing an interferon-γ release assay
(IGRA) rather than a tuberculin skin test (TST) in individuals ≥5
years of age who meet the following criteria (S-M):
• are likely to be infected with Mtb
• have a low or intermediate risk of disease progression
• it has been decided that testing for LTBI is warranted and
• either have a history of BCG vaccination or are unlikely to return to have their
TST read.
Remarks: A TST is an acceptable alternative, especially in situations where an IGRA is
not available, too costly, or too burdensome.
➤ The panel suggests performing an IGRA rather than a TST in all
other individuals ≥5 years of age who are likely to be infected
with Mtb, who have a low or intermediate risk of disease
progression, and in whom it has been decided that testing for
LTBI is warranted (C-M).
Remarks: A TST is an acceptable alternative, especially in situations where an IGRA is
not available, too costly, or too burdensome.
There are insufficient data to recommend a preference for either a
TST or an IGRA as the first-line diagnostic test in individuals ≥5 years
of age who are likely to be infected with Mtb, who have a high risk
of progression to disease, and in whom it has been determined that
diagnostic testing for LTBI is warranted.
➤ Guidelines recommend that persons at low risk for Mtb infection
and disease progression NOT be tested for Mtb infection.
The Panel concurs with this recommendation. However, it
also recognizes that such testing may be obliged by law or
credentialing bodies. If diagnostic testing for LTBI is performed
in individuals who are unlikely to be infected with Mtb despite
guidelines to the contrary:
• The panel suggests performing an IGRA instead of a TST in individuals ≥5 years
of age (C-L).
Remarks: A TST is an acceptable alternative in settings where an IGRA is unavailable,
too costly, or too burdensome.
• The panel suggests a second diagnostic test if the initial test is positive in
individuals ≥5 years of age (C-VL).
Remarks: The confirmatory test may be either an IGRA or a TST. When such testing is
performed, the person is considered infected only if both tests are positive.
S, strong ; C, conditional; H, high; M, moderate; L, low; VL, very low quality of evidence
