[Predictive factors and biomarkers of exudative lymphocytic tuberculous pleurisy]

Tuberculosis is the leading cause of exudative lymphocytic pleural effusion.

To determine the predictive factors and assess the diagnostic performance of biomarkers for exudative lymphocytic tuberculous pleural effusion found in our practice.

Case-control study from 01 January 2015 to 30 August 2019, including patients admitted to the day-hospital facility for pleural biopsy. Histopathology of pleural biopsy fragments was the gold standard for assessing the diagnostic performance of the biomarkers studied (pleural adenosine deaminase, geneXpert and pleural fluid culture).

One hundred and nine patients were included. The average age was 35.7±18.1 years. In all, 72.5% of them were diagnosed with tuberculosis. After multivariate analysis, only patients aged under 35 years old were found to be at risk for exudative lymphocytic tuberculous pleural effusion (adjusted odds ratio: 9.18 [1.99; 42.28], P=0.004). Histopathology was suggestive of tuberculosis in 84.8% of cases (P<0.0001). The sensitivity of geneXpert was 42.1% and the specificity was 100%, with a mean concordance rate with histopathology (k=0.46). One case of rifampicin-resistant tuberculosis was detected by geneXpert (2.2%). The diagnostic performance of pleural adenosine deaminase varies according to the defined positivity threshold. For values greater than 70UI/L, its sensitivity was 25% and its specificity was 86.7%. The area under the ROC curve of the pleural adenosine deaminase was 0.70.

In patients with exudative lymphocytic pleural effusion, young age is a risk factor for pleural tuberculosis. The geneXpert, although not very sensitive, is a moderately efficient and specific test for tuberculosis. Pleural adenosine deaminase is a discriminating and useful biomarker for the diagnosis of tuberculosis.