Role of ADA and CBNAAT(Cartridge Based Nucleic Acid Amplification Test) in diagnosis of Tuberculosis in straw coloured exudative pleural effusion in patients attending Government General Hospital, KAKINADA

Abstract

India is presently one of the high burden countries for tuberculosis and accounts for 23% of global TB burden with 2.2 million patients. Of these reported cases in India around 20% are of Extra Pulmonary Tuberculosis (EPTB).Pleural effusion due to TB is currently the second common location for EPTB next to TB lymphadenitis . The bacteriological confirmation to diagnose EPTB is more difficult due to its paucibacillary nature. The present study was done to determine the role of ADA and CBNAAT both being rapid and non-invasive diagnostic methods for early detection of tuberculous pleuritis, which is essential for treatment initiation, improved patient outcome and for more effective public health intervention. Materials and Methods: An observational study was done on 100 patients presenting with clinicoradiological picture suggestive of pleural effusion, either admitted or attending OPD of Department of Pulmonary Medicine from Nov 2017 to Nov 2019 at GGH, Kakinada. Results: Out of 100 exudative pleural effusions in study, male predominance with 80% of males and 20% females. Lymphocyte predominance is 74%, sputum AFB was positive in 6 cases. With ADA cut off as 40IU/L, 70 cases had an ADA > 40IU/L out of which 64 were tubercular, and 6 were malignant effusions .ADA has a sensitivity of 94% and specificity of 60%.Pleural fluid CBNAAT was positive in 30 cases, out of which 2 cases had an ADA < 40 IU/L .All are rifampicin sensitive. The sensitivity of CBNAAT is 40% and specificity 82%.There is a positive correlation between the lymphocyte predominance with ADA and CBNAAT with P<0.05%. Conclusion: Estimation of ADA in pleural fluid is a simple, rapid, and less expensive laboratory investigation where the diagnosis is uncertain. The sensitivity of ADA, when combined with lymphocytepredominant exudates, helps to diagnose tubercular effusions. The role of CBNAAT in diagnosing pleural TB is limited due to its poor sensitivity.