Evaluation of polymerase chain reaction and adenosine deaminase levels for rapid diagnosis of clinically suspected tuberculous pleural effusion

Abstract

Background: Tuberculosis (TB) often leads to pleural effusion, particularly prevalent in developing nations such as India. There has been a global rise in TB cases. Although lymphocytic predominant fluid is commonly associated with tubercular pleural effusion, it is essential to note that not all lymphocytic predominant fluids indicate TB. The diagnosis of pleural TB has benefited significantly from the use of biochemical markers. Conventional bacteriological methods are not very useful in diagnosing tubercular effusion and rarely identify Mycobacterium tuberculosis in pleural fluid. Owing to diagnostic difficulties, newer investigations, such as TB polymerase chain reaction (TB-PCR), adenosine deaminase (ADA) and culture, are amongst the most recent techniques currently used due to the challenges associated with diagnosis. Aims: This study aimed to measure the sensitivity and specificity of TB-PCR and compare them with those of ADA and TB cultures for suspected TB pleural effusion. Methods: This study included 50 patients diagnosed with pleural effusion who underwent pleural fluid analysis. Patients exhibiting exudative effusion with lymphocyte predominance also underwent a pleural biopsy. Pleural fluid ADA levels were also measured, and TB-PCR tests were conducted. Results: Eighteen patients were confirmed to have TB by biopsy. ADA was both sensitive and specific at 67% and 62.5%, respectively. However, PCR showed a sensitivity of 16.6% and a specificity of 100%. Conclusion: This study found a statistically significant association (P < 0.05) between ADA levels and distinguishing pleural effusion, which is tubercular in origin, from non-tubercular effusion. Therefore, the pleural ADA estimate appears to have the potential to be a reliable test for diagnosing TB pleural effusion. It has sufficient sensitivity and specificity while being cost-effective and easily executable compared to pleural biopsy. Our study also compared the sensitivity of PCR with pleural biopsy and discovered that PCR was more specific and less sensitive.