Latent TB detection: QuantiFERON-TB Gold Plus vs QuantiFERON-TB Gold In-Tube

A cohort study of patients with renal failure, who were undergoing dialysis or had undergone kidney transplantation were screened and evaluated. The study results were presented at the American Thoracic Society International Conference held May 17-22, in Dallas, Texas.

To successfully control TB infection, screening for and treating LTBI is an important approach. Besides close contacts of patients with TB, patients who experience renal failure are at a higher risk for TB. Although use of the interferon-gamma release assay (IGRA) is considered the gold standard for diagnosis of LTBI, this test is challenged by the high negative conversion rates from positive results, which are between 33% and 44% at 6 months. Researchers sought to compare the consistency of QFT-G plus with QFT-GIT in participants undergoing dialysis or who had received a kidney transplant.

A total of 610 patients were screened; the QFT-GIT test was performed in 463 patients on dialysis or postkidney transplantation. Overall, 14% (64 of 463) of the participants had a positive QFT-GIT test. The researchers followed the LTBI status of 50 patients by QFT-GIT1 and QFT-G plus1 together. The average patient age was 51.4 years; 68% of whom were men.

Persistent positive results were reported in 30 patients and 29 patients with the use of QFT-GIT1 testing and QFT-G plus1 testing, respectively. Five patients had a discrepancy between QFT-GIT (positive) and QFT-G plus (negative), whereas 4 patients were QFT-GIT negative but QFT-G plus positive. There was a significant correlation between QFT-GIT1 and QFT-G plus1 (P <.001). The difference in the initial QFT-GIT response between those with QFT-G plus 1 (positive) and those with QFT-G plus 1 (negative) was greater than the difference between QFT-GIT1 (positive) and QFT-GIT (negative).

Overall, there were 32 cases with a follow-up of a second IGRA. The consistent positivity that was demonstrated was 82.4% by QFT-G plus vs 65% by QFT-GIT testing. Regarding the correlation between QFT1 and QFT2, the QFT-G plus (positive) was significantly associated with the response of QFT-GIT1 (P <.001 for both). Moreover, the correlation between QFT-GIT2 and QFT-GIT1 was also significant (P <.001).

The difference between persistent positive QFT and negative converter was greater with QFT-G plus than with QFT-GIT. These findings suggest that in patients with renal failure or those undergoing kidney transplantation, QFT-G plus testing may be able to identify those with persistent positivity with the initial test.

Reference

Shu C. The positive status of latent tuberculosis infection is more consistent by QuantiFERON-TB Gold Plus than that by QuantiFERON-TB Gold In-Tube. Presented at: American Thoracic Society International Conference; May 21, 2019; Dallas, TX. Abstract A5175/P72.

Source: Pulmonology Advisor