Diagnostic accuracy of high pleural fluid Adenosine De Aminase levels in exudative pleural effusion in patients keeping pleural biopsy as gold standard

Abstract

Background: The diagnosis of tuberculous pleural effusion (TPE) is difficult even today because of low sensitivity and specificity of conventional diagnostic investigation. The diagnostic accuracy of adenosine deaminase (ADA) in TPE varies in different parts of the world. The rationale of this study is to find out the diagnostic accuracy of ADA in differentiation of TPE from non-TPE.Methodology: This cross sectional study was conducted betweenMay 2015 and February 2016 in Pulmonology Departments Khyber Teaching Hospital (KTH) Peshawar. Samples were collected using non-probability consecutive sampling technique. Patients of both gender with Exudative Pleural effusion and aged 18-60 years were included in the study. Patients with transudative pleural effusion, patients not willing for pleural biopsy and those with inconclusive biopsy report were excluded. Pleural biopsy was done through abrahm's needle for histopathology and fluid was taken for cytology, gram staining and ADA level. ADA 40U/L has been taken diagnostic for TPE. Statistical analysis was done using SPSS- 16.Results: Out of 100 patients, 61 were male and 39 female. 42 were tuberculous and 58 non-tuberculous pleural effusion. Among non-tuberculous pleural effusion group, 19 were malignant, 11 idiopathic, 23 para-pneumonic and 5 empyema. The sensitivity of pleural fluid ADA for detecting TPE was 95.2%, specificity of 79.3%, positive predictive value (PPV) 77% and negative predictive value (NPV) of 96%.Conclusion: In this study, Pleural fluid ADA level has improved sensitivity,specificity, PPV and NPV in differentiating tuberculous pleural effusions from non tuberculous pleural effusions.