To evaluate the conversion of QuantiFERON-TB Gold plus (QFT-Plus)following Isoniazid prophylaxis among latent tuberculosis (LTB) patient.
We conducted a case series starting in December 2016up to the present March 2019. Twenty asymptomatic cases were identified to have hadexposure to active tuberculosis (TB) infection, undergone chest x-ray and QFT-Plustest. Those with positive test QFT-Plus results with negative chest x-ray reports wereprescribed with Isoniazid 300mg tablet once daily for nine months. Post prophylaxis,chest x-ray and QFT-Plus were repeated to determine the conversion results.
All 20 participants were QFT-Plus test positive and chest x-ray negative. Theaverage age was 47 ± 5.7 years and there were eighteen females and two males. Two hadunderlying conditions: valvular heart disease and peripheral neuropathy. All took thenine-month Isoniazid prophylaxis and repeated the QFT-Plus test and chest x-ray. Chestx-ray results again were all negative. Eighteen cases revealed persistence of positiveQFT-Plus and two cases were negative. The initial conversion rate of QFT-Plus post treatment(2017) was ten percent. In the succeeding years (2018 and 2019), another ten percentconversion was reported and sixteen cases maintained their positive baseline score.
To our knowledge this clinical series is the first to report 20% conversionrate of QFT-Plus among LTB participants prescribed with a nine-month Isoniazidprophylaxis. This study only evaluated the conversion of QFT-Plus with LTB participantsbeing treated with 9-month Isoniazid. As there is no gold standard on the definition anddistinction of conversion and reversion, further studies are warranted to optimize thecorrelation between the efficacy of varied latent tuberculosis infection (LTBI) and TBtreatment regimen and conversion of QFT-Plus results.
quantiferon-tuberculosis gold plus, QFT-Plus
Received: April 26, 2019
Revision received: June 02, 2019
Accepted after revision: July 10, 2019
BKK Med J 2019;15(2): 145-148.