Tuberculosis Diagnostic Guidelines

Priority At-Risk Populations Requiring Systematic Testing

The World Health Organization strongly recommends systematic testing and treatment for people living with HIV, with a risk of progression of 35-162 cases per 1000 person-years, and a TST positive result if ≥5mm induration 2, 1, 3, 4, 5
The World Health Organization strongly recommends systematic testing and treatment for adult and child contacts of pulmonary TB cases, especially children <4 years, with a TST positive result if ≥5mm 2, 5, 4
The World Health Organization strongly recommends systematic testing and treatment for patients initiating anti-TNF therapy, requiring pre-treatment screening algorithm 2, 4
The World Health Organization strongly recommends systematic testing and treatment for patients receiving dialysis 2, 3
The World Health Organization strongly recommends systematic testing and treatment for patients preparing for organ or hematological transplantation 2, 3
The World Health Organization strongly recommends systematic testing and treatment for patients with silicosis 2, 3
The World Health Organization strongly recommends systematic testing and treatment for immunosuppressed patients, including those on ≥15mg/day prednisone for ≥1 month, with a TST positive result if ≥5mm 5
The World Health Organization strongly recommends systematic testing and treatment for persons with fibrotic changes on chest radiograph consistent with prior TB, with a TST positive result if ≥5mm 5

The World Health Organization conditionally recommends systematic testing for prisoners and residents of congregate settings, with a TST positive result if ≥10mm 2, 5, 4
The World Health Organization conditionally recommends systematic testing for healthcare workers, with a TST positive result if ≥10mm 2, 5, 4
The World Health Organization conditionally recommends systematic testing for immigrants from high TB burden countries within the last 5 years, with a TST positive result if ≥10mm 2, 5, 4
The World Health Organization conditionally recommends systematic testing for homeless persons 2, 4
The World Health Organization conditionally recommends systematic testing for illicit drug users, with a TST positive result if ≥10mm 2, 5, 4

Testing should be considered for individuals with diabetes mellitus, with a 2-4 times increased risk, and a TST positive result if ≥10mm 4, 5
Testing should be considered for individuals with chronic renal failure and glomerular diseases, with the highest risk with SIR 23.36, and a TST positive result if ≥10mm 4, 5
Testing should be considered for individuals with hematologic disorders, such as leukemias and lymphomas 5
Testing should be considered for individuals with head/neck and lung carcinomas 5
Testing should be considered for individuals with gastrectomy or jejunoileal bypass 5
Testing should be considered for individuals with weight loss >10% of ideal body weight, and a TST positive result if ≥10mm 5
Testing should be considered for individuals with untreated hepatitis C, with an adjusted HR 2.9 for active TB, and a TST positive result if ≥10mm 4
Testing should be considered for individuals with rheumatoid arthritis, with a SIR 10.9 vs general population, and a TST positive result if ≥10mm 4

Before any LTBI testing, all individuals must be screened for TB symptoms, including cough, hemoptysis, fever, night sweats, weight loss, chest pain, shortness of breath, and fatigue, and the presence of any one of these symptoms warrants further evaluation 2, 1
Chest radiography must be performed before LTBI treatment to rule out active TB disease, and is a strong recommendation even in asymptomatic individuals being evaluated for LTBI 2, 6
The combination of symptom screening plus chest radiography offers the highest sensitivity and negative predictive value to rule out active TB 1, 3

Either TST or IGRA can be used in high-income countries with TB incidence <100 per 100,000, but IGRA is preferred over TST in BCG-vaccinated individuals to avoid false-positive results 2, 1, 4
TST should not be replaced by IGRA in low-income countries 2
Two-step TST is required at baseline if no testing was performed in the preceding year 7
The three cutoff levels for TST positivity are ≥5mm induration for highest risk groups, ≥10mm induration for moderate risk, and ≥15mm induration for persons with no risk factors for TB 5, 8

Do not perform routine testing in low-risk populations without risk factors, as this diverts resources and increases false-positive results 2, 4, 8
Do not test unless prepared to treat, as testing should only be conducted when a plan exists to complete treatment in LTBI-positive persons 8
BCG vaccination does not contraindicate TST, but may affect interpretation, and IGRA should be used when available 4
Do not perform routine anergy testing in HIV-positive or immunosuppressed persons 4
In pregnant women with positive TST or recent TB contact, perform chest radiography with appropriate shielding as soon as possible, even in first trimester 4