Borderline QuantiFERON results and the distinction between specific responses and test variability

Tuberculosis
Jonathan W UzorkaSandra M Arend

Abstract

QuantiFERON (QFT) results near the cut-off are subject to debate. We aimed to investigate which borderline QFT results were due to Mycobacterium tuberculosis (Mtb)-specific responses or to test variability. In a contact investigation, tuberculin skin test (TST), QFT and T-SPOT.TB (T-SPOT) were performed in 785 BCG-unvaccinated contacts. Contacts with a low-negative (<0.15), borderline (0.15-0.35), low-positive (0.35-0.70) or high-positive QFT (≥0.70 IU/mL) were compared with respect to exposure, TST and T-SPOT results. Development of active tuberculosis was assessed. Borderline QFT results occurred in threefold excess over test variability (p = 0.0027). In contacts with low-negative, borderline or positive QFT results, a positive TST occurred in 24.9%, 62.1% and 91.4% (p < 0.0001) and a positive T-SPOT result in 6.3%, 41.3% and 86.4%, respectively (p < 0.0001). Two-third (20/29) of contacts with a borderline and 14/16 (88%) with a low-positive QFT had a positive TST and/or T-SPOT, indicating probable Mtb-infection. During 12 years of follow-up, seven patients were diagnosed with active tuberculosis, two of whom after a low-positive QFT. In this study, most borderline and low-positive QFT results were Mtb-specific, showing the b...Continue Reading

Citations

Aug 4, 2018·The European Respiratory Journal·Jonathan W UzorkaSandra M Arend
Feb 23, 2020·European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology·Jonathan W UzorkaSandra M Arend
May 16, 2020·Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America·John WallesPer Björkman
Mar 28, 2021·Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America·Davit BaliashviliN Sarita Shah

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