Diagnostic Accuracy between CBNAAT, TrueNat, and Smear Microscopy for Diagnosis of Pulmonary Tuberculosis in Doda District of Jammu and Kashmir- A Comparative Study

Abstract

Introduction: The need for fast, precise diagnostic tests to identify active tuberculosis is essential, mainly in endemic nations such as India. An automated real-time Polymerase Chain Reaction (PCR) method for pulmonary tuberculosis (TB) detection known as the Cartridge Based Nucleic Acid Amplification Test (CBNAAT) or GeneXpert assay shows great promise as a complement to the TrueNat and conventional sputum microscopy techniques. Aim: To compare sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of CBNAAT with TrueNat and smear microscopy in the detection of Mycobacterium tuberculosis. Materials and Methods: A cross-sectional study on 175 patients with suspected pulmonary TB was conducted from June 2021 to November 2021 in a tertiary care hospital at Government Medical College, Doda Jammu and Kashmir. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy for the diagnosis of tuberculosis were calculated for Acid Fast Bacilli (AFB) smear microscopy, TrueNat, and the GeneXpert and compared with each other. Statistical analysis of the data was conducted with Statistical Package for the Social Science (SPSS) version 20.0. Results: Out of the total 175, 168 (96%) patients were TB positive by CBNAAT, 162 (92.6%) by TrueNat, and 148 (84.6%) as per smear microscopy. Sensitivity, specificity, PPV, NPV, and accuracy of Ziehl-Neelsen (ZN) stain in the detection of pulmonary TB in sputum samples were 86.31%, 57.14%, 97.97%, 14.81%, and 85.14%, respectively. Whereas in the case of the TrueNat technique sensitivity, specificity, PPV, NPV, and accuracy were 94.05%, 42.86%, 97.53%, 23.08%, and 92.00%. In the case of CBNAAT sensitivity, specificity, PPV, NPV, and accuracy in the detection of pulmonary TB in sputum samples were 97.02%, 28.57%, 97.02%, 28.57%, and 94.29%, respectively. Conclusion: In respiratory samples, CBNAAT is more sensitive than ZN smear microscopy and TrueNat. Positive CBNAAT, but TrueNat and AFB microscopy negative results should be read cautiously and be well correlated with the clinical and treatment history of the patient.