Can tuberculous pleural effusions be diagnosed by pleural fluid analysis alone?

Abstract

Objective: To assess whether pleural fluid analysis (PFA) can confidently diagnose tuberculous pleural effusion (TPE).

Methods: PFA of 548 TPEs was performed between January 1991 and December 2011. The control group consisted of patients with malignant PE (MPE), complicated parapneumonic/empyema (infectious) PE (IPE), miscellaneous PE (MisPE) and transudative PE (TrPE).

Results: The PFA of 548 histologically or culture-positive consecutive cases of TPE was compared with that of 158 consecutive cases of MPE, 113 cases of IPE, 37 cases of MisPE and 115 cases of TrPE. Statistically significant differences were noted in pleural fluid glucose, pH, cholesterol, triglycerides, adenosine deaminase (ADA), and total percentages of lymphocytes, neutrophils and macrophages when TPEs were compared to all other groups. Of the TPEs, 99.1% were exudates. Pleural fluid protein ≥ 5.0 g/dl, lymphocytes > 80% and ADA > 45 U/l were diagnostic of TPE, with a specificity of 100%, a sensitivity of 34.9% and an area under the curve of 0.975.

Conclusion: PFA alone was diagnostic in one third of the TPE cases, with a high probability in nearly 60%.