The Yield of thoracoscopic biopsy truenat in the diagnosis of tuberculous pleural effusion

Abstract

Background and Objective: Extrapulmonary tuberculosis (EPTB) affects about 25% of patients presenting with Tuberculosis (TB). Tuberculous pleural effusion is the second-most common type of EPTB, after lymph node TB. Although the molecular TB diagnostics have lower turnaround time compared to traditional testing methods, the sensitivity in microscopy negative specimens are low. Higher cost and infrastructure requirements are other disadvantages. Truenat, developed by Mobilio diagnostics and validated by ICMR, is a rapid, polymerase chain reaction (PCR)-based diagnostic test to detect Mycobacterium Tuberculosis (MTB) and also rifampicin resistance. According to the WHO, the accuracy of Truenat is comparable to Xpert PCR. We report our experience in using Truenat for EPTB, specifically, pleural TB. Methods: We retrospectively analyzed data from thoracoscopy over the past 2 years. All data pertaining to the use of Truenat for TB in pleural fluid and thoracoscopic biopsy specimens, histopathology, and mycobacterial cultures were analyzed. Results: We had a total of 114 patients with undiagnosed pleural effusion who underwent thoracoscopy during the study. Forty-five patients (39%) had a diagnosis of TB, among the total 114 patients. The sensitivity of tissue Truenat was 51.11 (95% confidence interval [CI]: 35.77–66.30), tissue culture 37.50% (95% CI: 22.73–54.20), pleural fluid Truenat 20% (95% CI: 8.44–36.94), and fluid culture 14.29% (95% CI: 5.43–28.54). The specificities of all the confirmatory tests were 100% when compared to a reference standard which was taken as a combination of histology and culture as the reference standard with or without acid-fast bacilli in the histology samples. Tissue Truenat was significantly more sensitive than fluid Truenat (P < 0.05). Likewise, tissue culture was more sensitive than fluid culture (P < 0.05). Among all microbiology confirmatory tests performed, Truenat of pleural tissue had the highest yield (51.11). Conclusion: Thoracoscopic pleural biopsy Truenat results in improved sensitivity in cases of EPTB.