3
Diagnosis
➤ 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.
➤ The panel suggests performing a TST rather than an IGRA in
healthy children <5 years of age for whom it has been decided
that diagnostic testing for LTBI is warranted (C-VL).
• Remarks: In situations in which an IGRA is deemed the preferred diagnostic test,
some experts are willing to use IGRAs in children >3 years of age.
The preceding recommendations are summarized in Figures 1 and 2.
While both IGRA and TST testing provide evidence for infection
with Mtb, they cannot distinguish active from latent tuberculosis.
Therefore, the diagnosis of active TB must be excluded prior
to embarking on treatment for LTBI. This is typically done by
determining whether or not symptoms suggestive of TB disease are
present, performing a chest radiograph and, if radiographic signs
of active tuberculosis (eg, airspace opacities, pleural effusions,
cavities, or changes on serial radiographs) are seen, then sampling is
performed and the patient managed accordingly.
S, strong ; C, conditional; H, high; M, moderate; L, low; VL, very low quality of evidence
