Comparison between the diagnostic yield of tissue Xpert MTB/Rif assay and culture in pleural tuberculosis patients

Abstract

Introduction: Early diagnosis of pleural tuberculosis is difficult as it is a pauci-bacillary disease and a combination of tests is required to diagnose it, which have varied diagnostic accuracy and increase the cost. Objective: To evaluate the diagnostic performance of Xpert MTB/Rif assay on thoracoscopic pleural biopsy specimen. Methods: A total of 201 patients with exudative pleural effusion and normal lung parenchyma were included in the study. All patients underwent thoracoscopic pleural biopsy. Biopsy samples were sent for Xpert MTB/Rif assay and culture, along with histopathology. Chronic granulomatous inflammation on histopathology and response to anti-tuberculous treatment was taken as reference standard for diagnosis of tuberculous pleurisy. Result: Of the 198 patients included in final analysis, 134 had pleural tuberculosis. The sensitivity of the Xpert assay was 52.2% and specificity was 100%; and that of pleural biopsy culture were 41% and 100% respectively. Conclusion: Usually multiple tests are required to diagnose pleural tuberculosis. This increases the cost per patient and often there is a delay in diagnosis. Sensitivity and specificity of Xpert MTB/Rif assay scores high, hence escalating speed of diagnosis and imparts significant impact on patients’ outcome as it also gives status of drug resistance early. Xpert MTB/Rif assay is a potential game changer in diagnosing pleural tuberculosis.