Background: Biochemical analysis of pericardial effusion is a good diagnostic tool in the management of the probable etiologies of the effusion. Although few validated tests are available, investigators have successfully made correct diagnoses based on pericardial fluid analysis. The application of Light's criteria to classify transudates from exudates of pericardial effusion has been proven to be applicable. This study aimed to evaluate the applicability of Light's criteria in pericardial effusion for cost-effective clinical approach to management of cases in the local setting.
Methods: This is a validity test utilizing all the pericardial fluids submitted for biochemical study in the laboratory of Philippine Heart Center from January 2002 to June 2008. Receiver Operating Characteristics analysis was used to assess the degree of diagnostic accuracy of the tests using similar parameters used for pleural fluid.
Results: Most of the pericardial fluid samples were hemorrhagic and a total RBC count cut-off of 100 000 x 1OA6/Lwas used, gathering a sample population of 44 out of 143. All pericardial fluids were misclassified as exudates using the classic Light's criteria. Other biochemical, infectious work-up, cytology and surgical reports, together with the final diagnosis, utilized for the final classification of the fluids revealed 11 transudates and 33 exudates. ROC showed that a pericardial fluid has a higher cut-off value as compared to pleural fluid. The value for fluid LDH was >1000 U/L at 72.7% sensitivity and 78.8% specificity, pericardial fluid/serum LDH was >3.0 at 81.8% sensitivity and 54.5% specificity, and pericardial fluid/serum protein ratio was >0.8 at 45.5% sensitivity and 57.6% specificity but not discriminatory.
Conclusion: The Light's criteria may be utilized in the initial evaluation of pericardial fluids although higher cut-off values can be employed because of the behavior and characteristic of pericardial fluids as compared to pleural fluids. LDH value of >1000U/L has the best discriminatory power compared to LDH ratio. In this study, the TPAG ratio had the least utility. More study samples including a bigger normal control group are recommended for further confirmation of our current findings.