Diagnostic Utility of Bronchoalveolar Lavage Xpert MTB/RIF Assay in Suspected Cases of Pulmonary Tuberculosis

ABSTRACT

Introduction: Limited data on the diagnostic accuracy of the Xpert MTB/RIF assay using bronchoalveolar lavage fluid from patients with suspected pulmonary tuberculosis have been reported in India. The aim of this study was to evaluate Xpert MTB/RIF on bronchoalveolar lavage fluid in suspected PTB patients by comparing with AFB smear microscopy and culture Material and methods: A cross sectional observational study was carried on a total of 450 bronchoalveolar lavage fluid were processed by Xpert MTB/RIF between January 2018 and December 2018. Culture results were considered as the gold standard for diagnosis of TB. Sensitivity, specificity, PPV, and negative predictive value (NPV) for the diagnosis of active PTB were calculated using the website http//vassarstats. net/clin1.html. SPSS statistics version 17.0 software (SPSS Inc., Chicago, IL, USA) was used for the statistical analysis. Results: Xpert MTB/RIF had a sensitivity of 97.05% (95% CI 88.8-99.4) while the specificity of 90.05% ( 95% CI 86.4-92.7) in culture confirmed cases and those for smear microscopy was 36.7% (95% CI 25.6-49.3) and 100% (95% CI 98.7-100) respectively. Conclusion: The Xpert MTB/RIF assay is a rapid and simple technique with significantly higher sensitivity for diagnosing pulmonary TB compared to smear microscopy.(p < 0.005