Evaluation of the performances of InnowaveDx MTB-RIF assay in the diagnosis of pulmonary tuberculosis using bronchoalveolar lavage fluid

Abstract

Objective: To evaluate the tuberculosis diagnostic performance of the InnowaveDx MTB-RIF assay (InnowaveDx test) in bronchoalveolar lavage fluid (BALF).

Methods: A total of 213 BALF samples from suspected PTB patients were analyzed. AFB smear, culture, Xpert, Innowavedx test, CapitalBio test and simultaneous amplification and testing (SAT) were performed.

Results: Of the 213 patients included in the study, 163 were diagnosed with PTB, and 50 were TB negative. Using the final clinical diagnosis as the reference, the sensitivity of InnowaveDx assay was 70.6%, which was significantly higher than the values achieved using the other methods (P < 0.05), and the specificity was 88.0%, which was comparable with other methods (P > 0.05). Among the 83 PTB cases with negative culture results, the detection rate of InnowaveDx assay was significantly higher than those of AFB smear, Xpert, CapitalBio test and SAT (P < 0.05). Kappa analysis was used to compare the agreement of InnowaveDx and Xpert in detecting RIF sensitivity, and the result showed the Kappa value was 0.78.

Conclusions: The InnowaveDx test is a sensitive, rapid and cost-effective tool for PTB diagnosis. In addition, the sensitivity of InnowaveDx to RIF in samples with low TB load should be interpreted with caution in light of other clinical data.

Keywords: Bronchoalveolar lavage fluid; Diagnosis; InnowaveDx MTB-RIF; Pulmonary tuberculosis; Xpert MTB/RIF.