TB Manual

Figure 2. Online tools that can support decision-making with respect to TST and IGRA interpretation and offering of TPT: The Online TST/IGRA Interpreter, Version 3.0 (A) and PERISKOPE TB (B).

^{Abbreviations: TST, tuberculin skin test; IGRA, interferon-gamma release assay; TPT, tuberculosis preventive treatment.}

If a health care provider decides that a TST or IGRA is truly positive, there is no clinical utility in performing a TST or IGRA in the future, so long as the test is properly performed, read and interpreted. All persons with a positive TST or IGRA should be referred for a medical evaluation to rule out TB disease prior to initiating TPT. After TB disease is ruled out, TPT should be started as soon as possible and according to guidance in Chapter 6: Tuberculosis Preventive Treatment in Adults.

Good practice statement

• There are multiple dimensions to consider when faced with a positive or negative tuberculin skin test or interferon-gamma release assay to help decide whether someone is at risk of developing TB disease and would benefit from tuberculosis preventive treatment. These include the pretest probability that the person is truly infected, the individual risk of TB disease and the ability of the test to identify persons at risk of disease. There are online tools that can help support decisions in interpreting tuberculin skin test or interferon-gamma release assay results among different populations, which consider many of these dimensions.