A study of Light's criteria and possible modifications for distinguishing exudative from transudative pleural effusions.

STUDY OBJECTIVE To determine the usefulness of modifying Light's criteria for the separation of pleural transudates from exudates. DESIGN Retrospective review of patients who underwent a diagnostic thoracentesis during a 2-year period. SETTING Community teaching hospital in Lleida, Spain. PATIENTS AND METHODS Clinical records and pleural fluid characteristics of 230 consecutive patients with pleural effusion underwent a detailed review. Thirty-five of these patients were excluded from the analysis. As suggested recently by Romero et al, different cutoff levels for the criteria of Light et al were applied and their accuracies were calculated. RESULTS Thirty-nine (20%) pleural effusions were transudates and 156 (80%) were exudates. The accuracy of the criteria of Light et al for identifying exudates was 94.7% (confidence interval, 91.6 to 97.9) in comparison to our own modified criteria (93.1%; confidence interval, 89.5 to 96.7) and the criteria suggested by Romero et al (92.6%; confidence interval, 88.9 to 96.3). These differences were not statistically significant. CONCLUSION Changing the classic Light's criteria with different cutoff points offers no advantages for discriminating between transudative and exudative pleural effusions.