Pulmonary tuberculosis diagnostic test using fluorescence immunoassay-based interferon gamma release assay with IchromaTM IGRA-TB.

Introduction: Tuberculosis (TB) is a serious global health problem in Indonesia, which is the country with the secondhighest TB burden after India. Accuracy in TB diagnosis is the key to effective treatment and decreased transmission rate. One of the latest diagnostic methods is interferon gamma release assay (IGRA), which measures the interferon-γ release associated with Mycobacterium tuberculosis (MTB) infection. This study aims to determine the diagnostic value of IGRA-TB using IchromaTM IGRA-TB diagnostic kit (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]), compared to Ziehl-Neelsen (AFB) staining, nucleic acid amplificationbased test (Xpert-MTB) and chest-X Ray as the gold standard in TB diagnosis.

Materials And Methods: A cross-sectional observational study design was used. Patients were recruited through purposive sampling from pulmonology outpatient clinic and inpatient ward at Jemursari Islamic Hospital (RSI Jemursari), Surabaya from July 2023 to December 2023. All enrolled patients should have been previously tested positive or negative for pulmonary TB using AFB staining, Xpert MTB and chest x-ray. Blood samples of the patients were collected and processed using the IchromaTM IGRA-TB diagnostic kit. The results were then compared with gold standard methods for calculating the IGRA-TB diagnostic value.

Results: A total of 56 adult patients were enrolled in this study. The sensitivity, specificity, PPV, NPV and accuracy rate of IGRA-TB using IchromaTM IGRA-TB diagnostic kit were 80.56%, 85%, 90.62%, 70.83% and 82.14%, respectively.

Conclusion: IchromaTM IGRA-TB showed reasonably high diagnostic sensitivity and specificity, indicating that this method can be further utilised as a diagnostic and screening tool for pulmonary TB.