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Published on: July 28, 2023
VIDAS® TB-IGRA assay for diagnosing tuberculosis infection in people living with HIV: A preliminary study
Aliasgar Esmail1, Jeremi Swanepoel1, Suzette Oelofse1
1Centre for Lung Infection and Immunity, Division of Pulmonology, Department of Medicine and UCT Lung Institute & South African MRC/UCT Centre for the Study of Antimicrobial Resistance, University of Cape Town, Cape Town, South Africa.
Background:
The diagnosis of presumed latent tuberculosis (TB) infection (LTBI) is problematic in people living with HIV (PLWH) because of sub-optimal sensitivity and high indeterminate rates, especially in those with advanced immunosuppression. Better diagnostic tools for LTBI are needed in this sub-population.
Methods:
We compared the sensitivity of VIDAS TB-IGRA, a fully automated RD1-specific new interferon-ϒ-release assay (IGRA), to QFT-Plus in 77 PLWH with active pulmonary TB who had varying CD4 counts. Sputum culture positivity served as the reference standard for active TB.
Results:
The sensitivity of VIDAS TB-IGRA was similar to QFT-Plus overall [90.9% (70/77) vs 92.0% (69/75)], in those with CD4 <200 cells/mm3, [88.9% (40/45) vs 88.6% (39/44)], and in those with CD4 <100 [85.7% (18/21) vs 80.0% (16/20)]. However, VIDAS TB-IGRA had a higher sensitivity in those with CD4 <50 [92.3% (12/13) vs 75% (9/12)] and fewer indeterminate results overall [0 vs 2]. When the indeterminate results in this subgroup were regarded as negative, the comparative sensitivity was [92.3% (12/13) vs 69.2% (9/13)].
Conclusion:
VIDAS TB-IGRA had a similar sensitivity to QFT-Plus in PLWH. Whether VIDAS TB-IGRA sensitivity is significantly better at lower CD4 counts remains to be confirmed in a larger study. These data have implications for the diagnosis of LTBI in those with advanced immunosuppression.
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