Objective: To evaluate Brazilian studies by summarizing the accuracy of adenosine deaminase in the diagnosis of the pleural tuberculosis, with the objective of lending support to the movement to make the test part of the routine in the investigation of pleural effusions. Methods: A search for Brazilian studies related to the determination of adenosine deaminase levels in the pleural liquid was carried out. These studies were evaluated and included in this study. The data were analyzed using summary receiver operating characteristic (SROC) curves, which enabled the studies to be collected and evaluated regarding the accuracy of the diagnosis. As for the global values of sensitivity and specificity, the Bayes' theorem was applied to calculate the post-test probabilities in different prevalences of the disease. Results: Twenty-five studies dating from 1987 to 2005 and including enough information to be used in the meta-analysis were identified. After evaluation, nine studies were included, totaling 1674 patients. According to the SROC curve, a sensitivity of 91.8% (95% CI: 89.8‑93.6%) and a specificity of 88.4% (95% CI: 86.0-90.5%) were found, with an area of 0.969 below the curve. The overall odds ratio was 112.0 (95% CI: 51.6-243.2). Considering a prevalence of tuberculosis of 50% (considered neutral), the post-test probability was 88.7% for a positive test and 91.5% for a negative test. Conclusion: Despite the differences found among studies, it is possible to conclude that the determination of adenosine deaminase levels has high accuracy in the diagnosis of the pleural tuberculosis and should be used as a routine test in its investigation.

Keywords: Pleural effusion; Tuberculosis; Diagnosis; Adenosine deaminase; Meta-analysis.

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 welldeveloped 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%).

Keywords: Tuberculosis, pleural/diagnosis. Adenosine deaminase/diagnosis use. Sensitivity and specificity.