BACKGROUND: In Brazil, tuberculosis is the major cause of pleural effusion. In more than 50% of cases, treatment has been initiated prior to confirmation of the diagnosis. Our objective was to identify factors that can contribute to the diagnosis. METHOD: We studied 215 consecutive patients with pleural effusion: 104 from tuberculosis (TB) and 111 from other causes (41 were from malignancies, 29 involved transudation, 28 were parapneumonic and 13 were from other etiologies). Clinical, radiological and laboratorial variables were evaluated for differences between the two groups, individually or in combination. RESULTS: Male gender and PPD > 10 mm were significantly more frequent in the tuberculosis group. Radiological features were similar in both groups. Among the continuous variables, adenosine deaminase (ADA), percentile of cells, protein and age performed better as isolated diagnostic criteria. Between the group with tuberculosis and that with pleural effusion from other causes, no significant differences were found in Lactate dehydrogenase, total leukocytes or duration of disease. The correlation of ADA with any other well-developed continuous variable showed an LR+ > 10 and an LR- < 0.1, which effectively confirmed or ruled out a diagnosis of tuberculous pleural effusion. CONCLUSIONS: In patients with ADA levels > 39 at 95% sensitivity, the specificity can be improved to more than 90% if we consider non purulent effusion or effusion with a predominance of lymphocytes (> 50%).
Tuberculosis; Tuberculosis; Adenosine deaminase; Sensitivity and specificity
