[Reappraisal of the standard method (Light's criteria) for identifying pleural exudates].
OBJECTIVE
Light's criteria remain the best method for separating pleural exudates from transudates. We assessed their operating characteristics, as well as those resulting from omitting the pleural fluid to serum lactate dehydrogenase (LDH) ratio from the original criteria (abbreviated Light criteria), in a large series of patients. We also searched for the best combination of pleural fluid parameters, including protein, LDH and cholesterol that identify exudates.


METHODS
We conducted a retrospective study of 1,490 consecutive patients with pleural effusion who underwent a diagnostic thoracentesis. There were 1,192 exudates and 298 transudates. Sensitivity, specificity, area under ROC curve, and odds ratio for both individual and combined pleural fluid parameters were calculated.


RESULTS
Light's criteria yielded 97.5% sensitivity and 80% specificity. Both abbreviated Light criteria (sensitivity: 95.4%; specificity: 83.3%) and the combined use in an "or" rule of pleural fluid protein and LDH (sensitivity: 95.4%; specificity: 80,2%) had similar discriminative properties than standard criteria.


CONCLUSIONS
Diagnostic separation of pleural effusions into exudates or transudates can be done effectively thorough the abbreviated Light criteria when the serum LDH value is not available. On the other hand, if venipuncture wants to be avoided (an unusual circumstance) the combination of pleural fluid protein and LDH represents an alternative to Light's criteria.
Porcel
José M
JM
Servicio de Medicina Interna, Hospital Universitario Arnau de Vilanova, Lleida, Spain. jporcelp@yahoo.com
Peña
José M
JM
Vicente de Vera
Carmina
C
Esquerda
Aureli
A
D002784:Cholesterol / Q000032:analysis; D005122:Exudates and Transudates / Q000737:chemistry*; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000097:blood; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D019152:Paracentesis; D010996:Pleural Effusion / Q000737:chemistry / Q000175:diagnosis* / Q000209:etiology; D011506:Proteins / Q000032:analysis; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D011506:Proteins; D002784:Cholesterol; D007770:L-Lactate Dehydrogenase