1. Enhancing the interferon-γ release assay through omission of nil and mitogen values
- Author
-
Yun Jung Jung, Ji Eun Park, Ji Won Park, Keu Sung Lee, Wou Young Chung, Joo Hun Park, Seung Soo Sheen, Seulgi You, Joo Sung Sun, Kyung Joo Park, Youn Jung Kim, and Kwang Joo Park
- Subjects
Tuberculosis ,Interferon-γ ,Immunological tests ,Latent tuberculosis ,Release assay ,Diseases of the respiratory system ,RC705-779 - Abstract
Abstract Purpose To address the limited utility of the interferon (IFN)-γ release assay (IGRA) caused by its variability and inconsistency. Methods This retrospective cohort study was based on data obtained between 2011 and 2019. QuantiFERON-TB Gold-In-Tube was used to measure IFN-γ levels in nil, tuberculosis (TB) antigen, and mitogen tubes. Results Of 9,378 cases, 431 had active TB. The non-TB group comprised 1,513 IGRA-positive, 7,202 IGRA-negative, and 232 IGRA-indeterminate cases. Nil-tube IFN-γ levels were significantly higher in the active TB group (median = 0.18 IU/mL; interquartile range: 0.09–0.45 IU/mL) than in the IGRA-positive non-TB (0.11 IU/mL; 0.06–0.23 IU/mL) and IGRA-negative non-TB (0.09 IU/mL; 0.05–0.15 IU/mL) groups (P < 0.0001). From receiver operating characteristic analysis, TB antigen tube IFN-γ levels had higher diagnostic utility for active TB than TB antigen minus nil values. In a logistic regression analysis, active TB was the main driver of higher nil values. In the active TB group, after reclassifying the results based on a TB antigen tube IFN-γ level of 0.48 IU/mL, 14/36 cases with negative results and 15/19 cases with indeterminate results became positive, while 1/376 cases with positive results became negative. Overall, the sensitivity for detecting active TB improved from 87.2 to 93.7%. Conclusion The results of our comprehensive assessment can aid in IGRA interpretation. Since nil values are governed by TB infection rather than reflecting background noise, TB antigen tube IFN-γ levels should be used without subtracting nil values. Despite indeterminate results, TB antigen tube IFN-γ levels can be informative.
- Published
- 2023
- Full Text
- View/download PDF