Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Primary Study...

To (1) determine appropriate decision thresholds and diagnostic accuracies for pleural fluid (PF) tests that discriminate between exudative and transudative pleural effusions, and (2) evaluate the quality of the primary investigations.

Formal meta-analysis of studies that report the diagnostic value of pleural fluid tests.

Data collected from international academic medical centers.

Hospitalized patients undergoing thoracentesis for pleural effusions.

Primary investigators were requested to transmit original data from patients described in their studies.

Eight primary studies described 1,448 patients with one or more of the following tests: protein (P)-PF, P-PF/serum ratio (R), bilirubin (BILI)-R, lactate dehydrogenase (LDH)-PF, LDH-R, cholesterol (C)-PF, C-R, and albumin gradient. We found that all eight tests had similar diagnostic accuracies when evaluated by receiver operating characteristic (ROC) analysis except for BILI-R, which was less diagnostically accurate. Decision thresholds determined by ROC analysis differed from previously reported values for LDH-PF (>0.45 upper limits of normal) and C-PF (>45 mg/dL). Paired and triplet test combinations tended to have higher diagnostic accuracies compared with individual tests, but examination of the odds ratios with 95% confidence intervals did not identify a clearly superior test combination. Limitations of the primary studies presented a high likelihood of bias affecting their results.

Several strategies exist for clinicians in utilizing PF tests to classify effusions as exudates or transudates but accurate interpretations of these test results will require better designed studies.