Clinical Application of the Mycobacterium tuberculosis-RNA Assay of Pericardial Tissue Specimens in the Diagnosis of Tuberculous Pericarditis

Purpose: To assess the accuracy of the Mycobacterium tuberculosis (MTB)-RNA assay using pericardial tissue specimens for tuberculous pericarditis (TBP) diagnosis. Methods: MTB culture and MTB-RNA assay were performed for patients with suspected TBP. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of these two assays were analyzed. Results: This study included 79 patients. The sensitivity, specificity, PPV, NPV, and AUC were 28.1% (18/64), 100.0% (15/15), 100.0% (18/18), 24.6% (15/61), and 0.64 for the MTB culture and 37.5% (24/64), 100.0% (15/15), 100.0% (24/24), 27.3% (15/55), and 0.69 for the MTB-RNA assay, respectively. Patients with positive pericardial tissue culture were defined as having definite TBP; in other words, culture was the gold standard for this group of patients and had a sensitivity, specificity, PPV, and NPV of 100% and an AUC of 1.00. However, these values were found to be 72.2% (13/18), 100.0% (15/15), 100.0% (13/13), 75.0% (15/20), and 0.86 for the MTB-RNA assay, respectively. Among patients with probable TBP (culture-negative patients), the sensitivity, specificity, NPV, and AUC of MTB culture were 0.0% (0/46), 100.0% (15/15), 24.6% (15/61), and 0.50, respectively, but the PPV could not be determined. These values were found to be 23.9% (11/46), 100.0% (15/15), 100.0% (11/11), 30.0% (15/50), and 0.62 for the MTB-RNA assay, respectively. Conclusion: MTB-RNA assay using pericardial tissues had limited diagnostic efficacy for TBP. In culture-positive TBP, the diagnostic accuracy of MTB-RNA was good. In contrast, in culture-negative TBP, its diagnostic accuracy was unsatisfactory.