In this study, we prospectively screened all new patients with exudative pleural effusions who had been admitted to Shanghai Pulmonary Hospital for suspected active TBP from January 2017 to December 2018. Data regarding age, sex, history of anti-TB treatment, current symptoms, course of the disease, and comorbidities were obtained from each enrolled patient using a standardized questionnaire. The exclusion criteria for enrollment were as follows: <18 years of age, seropositive for human immunodeficiency virus (HIV), and inability to provide PE for examinations. In this study the definite diagnosis of TBP is made by detecting Mycobacterium tuberculosis from the PE with BACTEC MGIT 960 culture. The patients with PE due to causes other than TB were used as controls. Enrolled patients for whom a definite diagnosis could not be made were excluded from our further analysis.
All of the patients had provided written informed consent for a protocol approved by The Ethics Committee of Shanghai Pulmonary Hospital (approval number: K19-148). Our study was performed in accordance with the Declaration of Helsinki with regard to ethical principles for research involving human subjects.
Each patient underwent physical examination, chest computed tomography (CT), blood T-SPOT.TB interferon-gamma release assay (T-SPOT.TB) and thoracentesis guided by ultrasound or CT. At least 40 mL of PE samples was collected from each patient during thoracentesis using a sterile syringe. Aliquots of each sample were simultaneously submitted for adenosine deaminase assay (ADA), lymphocyte percentage of total cells, cytology for malignant cells, bacterial culture and fungal culture, smear fluorescence microscopy (FM), BACTEC MGIT 960 culture (MGIT 960), Xpert, LAMP and SAT-TB immediately after collected from the patients. Phenotypic drug susceptibility testing (DST) to first-line drugs was performed by automatic MGIT 960. ADA was analyzed using a colorimetric assay (Diazyme Laboratories, Poway, CA, USA). T-SPOT.TB was performed as previously described (19). BACTEC MGIT 960 (Becton Dickinson Life Sciences, Franklin Lakes, NJ, USA) was performed according to the standard procedure of the manufacturer (20). SAT-TB was carried out using the method of AmpSure assay (Shanghai Rendu Biotechnology, Shanghai China) following the instructions of the manufacturer (18). LAMP reactions were conducted with Loopamp DNA amplification kit (both from Eiken Chemical, Tochigi, Japan), as previously described (11). Xpert (Cepheid, Sunnyvale, CA, USA) were performed according to the manufacturer’s instructions using a four-module GeneXpert machine and the results can be automatically generated by the machine. All tests were conducted at the TB reference laboratory in Shanghai Pulmonary Hospital by qualified technicians using routine quality control procedures. Since these tests are automatic, there is no need of blinding.
Data was analyzed using Statistics for Windows (Version 18.0, Chicago, US: SPSS Inc.). Numerical variables were reported as mean ± standard deviation, and categorical variables were shown as number and percentage of observations. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy. Continuous variables were compared with t-test, while the comparison of categorical variables were made by Fisher’s exact test or Pearson’s chi-squared analysis, as appropriate. Differences were considered statistically significant when P -value ≤ 0.05. Receiver operating characteristic (ROC) curve analysis was performed to determine the power of these tests to distinguish TBP patients from non-TBP patients.