Sensitivity and specificity of QuantiFERON-TB Gold Assay in newly diagnosed with Mycobacterium tuberculosis infection

Nyi Nyi, Naing and Wan Arfah Nadiah, Wan Abdul Jamil and Azreen, Adnan (2020) Sensitivity and specificity of QuantiFERON-TB Gold Assay in newly diagnosed with Mycobacterium tuberculosis infection. International Medical Journal, 27 (2). pp. 132-135. ISSN 13412051

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Abstract

Objective: To determine sensitivity and specificity between QuantiFERON-TB Gold assays and compared to the gold standard sputum Acid Fast Bacilli (AFB) culture for the detection of active TB as well as the association between QuantiFERON-TB Gold assay and sputum AFB culture, chest X-ray changes and clinical diagnosis in patients clinically suspected of active tuberculosis. Design: A cross sectional study. Materials and Methods: The sensitivity and specificity of QuantiFERON-TB Gold were investigated in 24 subjects who were clinically suspected of TB infection were enrolled in this study. Each patient was required to produce sputum and 5 ml of blood for IGRA test. The standard sputum AFB culture and QuantiFERON-TB Gold assay were performed. Sensitivity and specificity tests were conducted using Receiving Operating Characteristics (ROC) curve. The positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were calculated. Association and agreement between QuantiFERON-TB Gold assay and sputum AFB culture, clinical diagnosis and chest X-ray changes were measured using McNemar test and Kappa statistics using SPSS 12.0.1. Results: The QuantiFERON-TB Gold assay had 94.7% sensitivity and 80% specificity for detection of Mycobacterium tuberculosis. The positive predictive value was 0.94, a negative predictive value was 0.80, the positive likelihood ratio is 4.73 and negative likelihood ratio is 0.06. There were poor agreements and associations between QuantiFERON-TB Gold assay and other tests. Conclusion: Our study suggested that QuantiFERON-TB Gold assay was a useful diagnostic kit for the diagnosis of Mycobacterium tuberculosis infection furthermore.

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