QuantiFERON-TB Gold Plus and QuantiFERON-TB Gold In-tube assays for detecting latent tuberculosis infection in Thai healthcare workers

Abstract

Detecting latent tuberculosis infection (LTBI) is important, especially in high-risk populations including healthcare workers (HCWs). QuantiFERON-TB Gold Plus (QFT-Plus) is a new version of the interferon-gamma release assays (IGRAs) to replace the QuantiFERON-TB Gold In-tube (QFT-GIT). However, data on the use of QFT-Plus for LTBI detection in high TB-burden countries are limited. This study was conducted in a TB-endemic setting in Thailand. HCWs were enrolled in the study and underwent both tests during the annual health screening. The testing results were compared and the concordance was determined. Of 102 HCWs, 11 (10.78%) were positive according to both tests, and 15 (14.71%) were positive according to QFT-Plus. The overall agreement between assays was 96.08%, with Cohen’s kappa coefficient ( k ) at 0.82. All four discordant results occurred with QFT-GIT negative and QFT-Plus positive. The comparison between QFT-GIT and QFT-Plus based on each antigen tube (TB1 or TB2) exhibited similar concordance with 99.02% and 95.10% agreement, respectively. The intra-comparison between TB1 and TB2 of QFT-Plus also showed good concordance at 96.08%. Among this group of HCWs, the LTBI prevalence of any positive results in both tests was low. Overall, the study showed good agreement between QFT-Plus and QFT-GIT ( k = 0.82) with a minimal difference, suggesting similar assay performance to that mainly carried out in TB-low incidence countries. The results support the use of QFT-Plus for detecting LTBI in a format similar to QFT-GIT.

Prevalence, Risk Factors, and Result Features in the Detection of Latent Tuberculosis Infection in Thai Healthcare Workers Using QuantiFERON-TB Gold Plus

“…It has been reported that TST caused more false-positive results compared to QFT testing due to the influence of BCG vaccination or other mycobacterial infections [ 7 , 22 ]. Recent studies reported the prevalence of LTBI among Thai HCWs and medical students assessed by QFT-Plus at 14.71% and 6.3%, respectively [ 23 - 24 ]. These figures were lower than the prevalence estimate of 32.73% in Thai nursing professionals working in a tertiary-care center reported recently [ 25 ] and lower than those in this study.…”

Analysis of Interferon-Gamma Release Assay Results for Latent Tuberculosis Infection Diagnosis at a Referral Clinical Laboratory in South Korea

“…The Interferon-Gamma Release Assay (IGRA) has shown moderate compassion and high specificity in detecting LTBI. A use of QuantiFERON® TB Gold Plus (QFT-Plus) is appropriate for LTBI discovery in countries burdened with TB (Matucci et al, 2023;Rudeeaneksin et al, 2023). The global estimate is that one in four individuals have LTBI.…”