The efficacy of PCR for tuberculosis in pleural fluid for the diagnosis of tuberculous pleuritis in patients with exudative, lymphocyte-predominant pleural effusion in a tertiary hospital

Abstract

Background: Tuberculous pleuritis is one of the current public health problems in Thailand. Its conventional diagnosis needs the granuloma in pleural pathology, positive acid-fast bacilli staining and elevated ADA or IFN-gamma in pleural fluid. Because these methods are not fully available in general hospitals, we try to simplify the diagnosis of tuberculous pleuritis, studying examination of pleural fluid, ADA and the PCR for TB in patients with pleural effusion. Patients and Methods: This retrospective study recruited medical records of patients with pleural exudate with lymphocyte predominance in medical ward, Maharat Nakhon Ratchasima Hospital between 1^st Oct 2012 and 30^th Sep 2016. The data of pleural fluid examination, ADA and real-time PCR for TB, pathological finding and chest film findings were analyzed, emphasis on the PCR. Results: Only 80 from 143 patients (55.9 %) were diagnosed as TB. And 48 from 80 (60 %) had ADA > 40 U/L. In case of probable tuberculous pleuritis, the PCR for TB was positive in 15 cases (18.8 %), negative in 65 cases (81.2 %). Whereas ADA for diagnosis of tuberculous pleuritis had sensitivity 60 %, specificity 95.2 %, PPV 94.12 % and NPV 65.2 %, the combination of ADA and PCR had sensitivity 63.8 %, specificity 95.4 %, PPV 94.4 % and NPV 68.1 %. Conclusion: The diagnosis of tuberculous pleuritis using the PCR for TB in patients with predominantly lymphocytic exudate has less advantage, low sensitivity and high cost.