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CDC Guidelines for Use of QuantiFERON ® - TB Gold Test

CDC Guidelines for Use of QuantiFERON ® - TB Gold Test. Philip LoBue, MD Centers for Disease Control and Prevention Division of Tuberculosis Elimination. Outline. Where to find guidelines Recommendations for QFT-G use Guidance for follow up of Positive test result Negative test result

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CDC Guidelines for Use of QuantiFERON ® - TB Gold Test

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  1. CDC Guidelines for Use of QuantiFERON®-TB Gold Test Philip LoBue, MD Centers for Disease Control and Prevention Division of Tuberculosis Elimination

  2. Outline • Where to find guidelines • Recommendations for QFT-G use • Guidance for follow up of • Positive test result • Negative test result • Indeterminate test result • Special situations • Contact investigation • Serial testing (e.g., occupational) • Future research needs

  3. Where Can You Find the Guidelines? • Print: Guidelines for Using the QuantiFERON®-TB Gold Test for Detecting Mycobacterium tuberculosis Infection, United States, MMWR, December 16, 2005 / Vol. 54 / No. RR-15, pp. 49-54. • Internet: http://www.cdc.gov/nchstp/tb/pubs/mmwrhtml/maj_guide.htm

  4. Recommendations for Use of QFT-G

  5. QFT-G can be used in all circumstances in which the TST is used, including • Contact investigations • Evaluation of recent immigrants who have had BCG vaccination • TB screening of health-care workers and others undergoing serial evaluation for M. tuberculosis infection

  6. QFT-G usually can be used in place of (and usually not in addition to) the TST

  7. Follow up of Positive QFT-G

  8. A positive QFT-G should prompt the same health and medical interventions as a positive TST result • No reason exists to follow a positive QFT-G with a TST • Persons with a positive QFT-G result should be evaluated for TB disease before LTBI is diagnosed • After TB has been excluded, treatment of LTBI should be considered

  9. Follow up of Negative QFT-G

  10. The majority of healthy adults who have negative QFT-G results are unlikely to have M. tuberculosis infection and do not require further evaluation

  11. Cautions and Limitations • As with a negative TST result, negative QFT-G results should not be used alone to exclude M. tuberculosis infection in persons with symptoms or signs suggestive of TB disease • The performance of QFT-G has not been determined in persons who, because of impaired immune function (e.g., HIV infection), are at increased risk for M. tuberculosis infection progressing to TB disease • As with a negative TST result, negative QFT-G results alone might not be sufficient to exclude M. tuberculosis infection in immunocompromised persons • Limited published data document the performance of QFT-G in children aged <17 years

  12. Follow up of Indeterminate QFT-G

  13. An indeterminate QFT-G result does not provide useful information regarding the likelihood of M. tuberculosis infection • Optimal follow up of persons with indeterminate QFT-G results has not been determined • Options are to repeat QFT-G with a new blood sample, administer a TST, or do neither • Decision should be based on pre-test likelihood of M. tuberculosis infection

  14. Contact Investigations

  15. For persons with recent contact to an infectious TB patient, negative QFT-G results should be confirmed with a repeat test 8-10 weeks after exposure (end of window period) as is recommended for a negative TST

  16. When “window prophylaxis” has been started for high-risk contacts exposed to an infectious TB patient, a negative QFT-G result at the end of the window period should be interpreted in light of all other clinical and epidemiologic data • A full course of LTBI treatment should be considered even with a negative result when the rate of M. tuberculosis transmission to other contacts is high or when a false-negative result is suspected because of an immunocompromising medical condition

  17. Serial Testing (e.g., Healthcare Workers)

  18. In situations with serial testing for M. tuberculosis infection (e.g., health-care workers), initial two-step testing (necessary for TST) is not necessary for QFT-G • In contrast to TST, there is no boosting with QFT-G

  19. Future Research Needs

  20. More data on performance of QFT-G in special populations (e.g., children, immunocompromised) • Longitudinal studies • Subsequent TB disease incidence after LTBI has been either diagnosed or excluded with QFT-G • Length of time after infection for QFT-G test result to become positive • Changes in QFT-G results with therapy for TB disease and LTBI • Economic evaluation and decision analysis comparing QFT-G with TST

  21. Questions?

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