DIAGNOSTIC ACCURACY OF PLEURAL FLUID ADENOSINE DEAMINASE IN PATIENTS WITH TUBERCULOUS PLEURAL EFFUSION KEEPING CLOSED PLEURAL BIOPSY AS A GOLD STANDARD

Abstract

BACKGROUND AND OBJECTIVE: Tuberculosis (TB) and malignancy are themost common causes of exudative pleural effusion, which usually haslymphocytic and exudative characteristics. Adenosine Deaminase (ADA) is auseful biochemical marker for the diagnosis of tuberculous pleural effusion(TPE). The aim of this study was to determine the diagnostic accuracy ofpleural fluid ADA in patients with tuberculous pleural effusion while keepingpleural biopsy as a gold standard.STUDY DESIGN, PLACE AND DURATION: It was a Cross-sectional (validation)study conducted in Pulmonology Department, Post Graduate MedicalInstitute, Lady Reading Hospital (PGMI/LRH), Peshawar, from March 28, 2011to September, 27 2011.MATERIALS AND METHODS: All the patients with pleural effusion fulfillinginclusion criteria were subjected to thoracentesis and Abrams needle biopsy.Pleural fluid was sent to laboratory for measurement of ADA using commerciallyavailable ADA kit DIAZYME (Diazyme laboratories Poway, CA 92064,USA) while pleural tissue was sent for histopathological examination. All theinvestigations were performed by the laboratory to avoid any observer bias.Results: Out of 144 patients 84 (58.3%) were males and 60 (41.7%) werefemales. Mean age was 47.21+17.85 SD years. In 84 (58.3%) patients, pleuralbiopsy was suggestive of tuberculosis. In biopsy proven tuberculous pleuraleffusion (TPE) pleural fluid ADA ranged from 20-130 U/L with mean pleuralfluid ADA level of 53.93 +16.12 U/L. In non TB pleural effusion (NTPE), pleuralfluid ADA ranged from 10-75 U/L with mean pleural fluid ADA level of 33.25+14.65 U/L. Taking pleural biopsy as gold standard and taking ADA level > 40U/L as cut off value, the sensitivity, specificity, PPV and NPV of pleural fluidADA level in the diagnosis of TPE were 90.47% , 76.66%, 84.44% and 85.18%respectively.CONCLUSION: In appropriate clinical setting pleural fluid ADA level is a usefulbiochemical marker which aids in the diagnosis of Tuberculous pleuraleffusion.