Patient Population Under Consideration
This recommendation applies to asymptomatic adults 18 years and older
at increased risk for tuberculosis (see the “Assessment of Risk”
section for more information). It does not apply to adults with symptoms
of tuberculosis or to children and adolescents.
Assessment of Risk
Populations at increased risk for LTBI based on increased prevalence
of active disease and increased risk of exposure include persons who
were born in, or are former residents of, countries with increased
tuberculosis prevalence and persons who live in, or have lived in,
high-risk congregate settings (eg, homeless shelters and correctional
facilities). Clinicians can consult their local or state health
departments for more information about populations at risk in their
community, because local demographic patterns may vary across the United
States.
In 2015, among persons of known national origin, 66.2% of all active
tuberculosis cases in the United States were among foreign-born persons,
and the case rate of active tuberculosis among foreign-born persons was
approximately 13 times higher than among US-born persons (15.1 vs 1.2
cases per 100,000 persons).7 More
than half of all foreign-born persons in the United States with active
tuberculosis were from 5 countries: Mexico, the Philippines, Vietnam,
India, and China.7 In
addition, the CDC has identified foreign-born persons from Haiti and
Guatemala as important contributors to active tuberculosis cases in the
United States.8 The
World Health Organization (WHO) recently updated its list of countries
with a high burden of tuberculosis to include the top 20 countries with
the highest absolute numbers of cases and an additional 10 countries
with the most severe burden in terms of case rate per capita.9
Persons who live in, or have lived in, high-risk congregate settings
also have a higher prevalence rate of active tuberculosis and increased
risk for exposure. Among persons 15 years and older with active
tuberculosis, 5.6% were homeless within the past year, 2.2% were
residents of a long-term care facility, and 4.2% were in a correctional
facility at the time of diagnosis.10 Published
prevalence rates of LTBI in these settings vary widely, depending on
the type of screening test used, the TST threshold used to define the
presence of LTBI, and the population studied. Estimates of LTBI
prevalence range from 23.1% to 87.6% among prisoners and from 18.6% to
79.8% among persons who are homeless.2, 11
Other populations at increased risk for LTBI or progression to active
disease include persons who are immunosuppressed (eg, persons living
with human immunodeficiency virus [HIV], patients receiving
immunosuppressive medications such as chemotherapy or tumor necrosis
factor-alpha inhibitors, and patients who have received an organ
transplant) and patients with silicosis (a lung disease). However, given
that screening in these populations may be considered standard care as
part of disease management or indicated prior to the use of certain
medications, the USPSTF did not review evidence on screening in these
populations. Some evidence from observational studies has explored the
association between poorly controlled diabetes and progression of LTBI
to active disease. However, there is insufficient evidence on screening
for and treatment of LTBI in persons with diabetes for the USPSTF to
make a separate recommendation for this important subgroup.
Persons who are contacts of individuals with active tuberculosis,
health care workers, and workers in high-risk congregate settings may
also be at increased risk of exposure. Since screening in these
populations is conducted as part of public health12 or employee health13, 14 surveillance,
the USPSTF did not review the evidence in these populations. Clinicians
seeking further information about testing for tuberculosis in these
populations can refer to the “Useful Resources” and “Recommendations of
Others” sections.
Screening Tests
Two types of screening tests for LTBI are currently available in the
United States: the TST and IGRA. The TST requires intradermal placement
of purified protein derivative and interpretation of response 48 to 72
hours later. The skin test reaction is measured in millimeters of the
induration (a palpable, raised, hardened area or swelling).
Interferon-gamma release assays require a single venous blood sample and
laboratory processing within 8 to 30 hours after collection. Two types
of IGRAs are currently approved by the US Food and Drug Administration:
T-SPOT.TB (Oxford Immunotec Global) and QuantiFERON-TB Gold In-Tube (Qiagen).
Numerous patient and systems factors may influence the selection of a screening test.15
Generally, the CDC recommends screening with either the TST or IGRA but
not both. Testing with IGRAs may be preferable for persons who have
received a bacille Calmette–Guérin vaccination or persons who may be
unlikely to return for TST interpretation. Additional information on the
use and interpretation of the TST and IGRA is available from the CDC.16
Screening Intervals
The USPSTF found no evidence on the optimal frequency of screening
for LTBI. Depending on specific risk factors, screening frequency could
range from 1-time only screening among persons who are at low risk for
future tuberculosis exposure to annual screening among those who are at
continued risk of exposure.
Treatment
Recommendations for the treatment of LTBI are available from the CDC.17
Additional Approaches to Prevention
The public health system has an essential role in the control and
elimination of tuberculosis. Clinicians are required to report cases of
active tuberculosis to their local health department. As outlined by
local and state public health laws, local health departments investigate
and ensure treatment of active tuberculosis cases and perform contact
tracing and medical surveillance of contacts.
Occupational health services also have an important role in the
prevention and control of tuberculosis. Certain work settings (health
care settings, correctional facilities, and other high-risk congregate
housing settings) may pose a higher risk of tuberculosis exposure, and
employers often have an important role in preventing tuberculosis
exposure among employees and performing medical surveillance of
employees for exposure.
Useful Resources
Clinicians seeking guidance on tuberculosis management among persons
living with HIV can obtain additional information from the National
Institutes of Health.18 Clinicians
seeking information on medical surveillance of contacts of persons with
active tuberculosis can contact their local health department, review
their local public health law, or review guidance from the CDC.19 The CDC also provides information for public health tuberculosis programs.20
Clinicians seeking information on medical surveillance of health care
workers or employees working in high-risk settings can consult
resources from the CDC and the Occupational Safety and Health
Administration.21-23 Clinicians
seeking guidance on screening for LTBI in children can find more
information on the American Academy of Pediatrics’ Bright Futures
website.24 Clinicians seeking guidance on tuberculosis and pregnancy can obtain information from the CDC.25