Etiology of exudative pleural effusion among adults: differentiating between tuberculous and other causes, a multicenter prospective cohort study

• Tuberculosis effusion has higher lymphocyte count, protein, and adenosine deaminase. • A predictive model may be useful in the etiologic characterization of exudative pleural effusion. • Creating scoring model will be helpful to avoid the need for invasive procedures. Exudative pleural effusions have a broad etiology and usually necessitate further investigative workup, including invasive procedures. This study aimed to evaluate and compare the demographic, clinical, and biochemical characteristics of tuberculous, malignant, and chronic inflammatory pleural effusions. This is a 2-year prospective cohort study of patients referred for medical thoracoscopy with an exudative pleural effusion. A total of 159 patients were enrolled in the study, with a mean age of 42.49 ± 13.8 years and the majority being males 121 (76.1%). As expected, patients with tuberculous effusions were significantly younger than those with non-tuberculous effusions (37.7 ± 10.9 vs 49.1 ± 14.9, P <0.001). Serum analysis showed significantly lower white blood cell count (7.5 × 10 9 /L ± 2.7 vs 9.0 × 10 9 /L ± 3.3, P = 0.004), higher total protein (76.2 g/dL ± 10.1 vs 70.2 g/dL ± 8.9, P <0.001), and higher median C-reactive protein (median 77.5, interquartile range 51-116 vs median 40.5, interquartile range 8-127, P <0.001) among tuberculous compared with non-tuberculosis effusions. Our study validates previous findings showing similar results in patients with tuberculous pleural effusions. A predictive model incorporating different demographic and clinical/laboratory characteristics may be useful in the early etiologic characterization of exudative pleural effusion.