Abstract

Light’s criteria can misclassify transudates as exudates especially in heart failure patients. We investigated classification performance of protein gradient comparatively with albumin gradient and Light’s criteria for the purpose of to increase the accuracy of separation of exudates from transudates. Eighty-five pleural effusion containing clinically 63 exudates and 22 transudates were evaluated. We calculated sensitivities of Light’s criteria, albumin gradient and protein gradient in the differentiation between exudates and transudates were 93.7%, %79.4% and 68.3% respectively, specificities were 72.7%, 86.4% and 95.5% respectively, and accuracies were 88.2%, 81.2% and 75.3 respectively. Light’s criteria misclassified 6 transudates as an exudates although they had the highest accuracy ratio. When protein gradient used additionally to Light’s criteria the specificity increased to 96.3%. There was high degree of agreement between albumin criteria and protein criteria in the differentiation of exudates and transudates (k=0.74). As the results of present study show, the protein gradient, have similar accuracy of that of albumin gradient without requiring the determination of any additional parameter to those used for calculating Light’s criteria. So we recommend the use of protein gradient with Light’s criteria for the differentiation of all pleural effusion.