Evaluating the diagnostic accuracy of the Xpert MTB/RIF assay on bronchoalveolar lavage fluid: A retrospective study

Abstract

Objective: Limited data on the diagnostic accuracy of the Xpert MTB/RIF assay using bronchoalveolar lavage fluid from patients with suspected pulmonary tuberculosis (PTB) have been reported in China. Therefore, a retrospective study was designed to evaluate the diagnostic accuracy of this assay.

Methods: Clinical, radiological, and microbiological characteristics of 238 patients with suspected PTB were reviewed retrospectively. The sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of active PTB were calculated for the Xpert MTB/RIF assay using TB culture or final diagnosis based on clinical and radiological evaluation as the reference standard.

Results: The sensitivity and specificity of the Xpert MTB/RIF assay were 84.5% and 98.9%, respectively, and those for smear microscopy were 36.2% and 100%, respectively, when compared to the culture method. However, compared with the sensitivity and specificity of final diagnosis based on clinical and radiological evaluation, the sensitivity and specificity of the assay were 72.9% and 98.7%, respectively, which were significantly higher than those for smear microscopy.

Conclusions: The Xpert MTB/RIF assay on bronchoalveolar lavage fluid could serve as an additional rapid diagnostic tool for PTB in a high TB-burden country and improve the time to TB treatment initiation in patients with PTB.

Keywords: Bronchoalveolar lavage fluid; Sensitivity; Specificity; Tuberculosis; Xpert MTB/RIF.