Due to the paucibacillary nature of tuberculous
pleural effusion the diagnosis of
pleural tuberculosis is challenging. This prospective study was undertaken to evaluate the diagnostic performance of ten different pleural fluid
biomarkers in the differentiation between tuberculous and non-tuberculous
pleural effusions. Two hundred and three patients with
pleural effusion (117 men and 86 women, median age 65 years) were enrolled. Routine diagnostic work-up, including thoracentesis and pleural fluid analysis, was performed to determine the cause of
pleural effusion. The following
biomarkers were measured in pleural fluid:
adenosine deaminase (ADA),
interferon gamma (IFN-γ),
interleukin 2 soluble receptor (IL-2sRα), sub-unit p40 of
interleukin 12b (IL-12p40),
interleukin 18 (IL-18),
interleukin 23 (IL-23), IFN-γ induced
protein 10 kDa (IP-10),
Fas-ligand, human
macrophage-derived chemokine (MDC) and
tumor necrosis factor alfa (TNF-α). There were 44 (21.7%) patients with tuberculous
pleural effusion, 88 (43.3%) patients with
malignant pleural effusion, 35 (17.2%) with parapneumonic
effusion/pleural empyema, 30 (14.8%) with pleural transudates, and 6 (3%) with miscellaneous underlying diseases. Pleural fluid IFN-γ was found the most accurate marker differentiating tuberculous from non-tuberculous
pleural effusion, with sensitivity, specificity, PPV, NPV, and AUC 97%, 98%, 95.5%, 99.4%, and 0.99, respectively. Two other
biomarkers (IP-10 and
Fas ligand) also showed very high diagnostic accuracy with AUC≥0.95. AUC for ADA was 0.92. We conclude that IFN-γ, IP-10, and
Fas-ligand in pleural fluid are highly accurate
biomarkers differentiating tuberculous from non-tuberculous
pleural effusion.