Pleural fluid interleukin-8 and C-reactive protein for discriminating complicated non-purulent from uncomplicated parapneumonic effusions.
OBJECTIVE
This study was designed to test the hypothesis that measurement of IL-8 and CRP in pleural fluid could improve the identification of patients with non-purulent parapneumonic effusions that ultimately require chest tube drainage.


METHODS
We assessed IL-8, CRP and three classical parameters (pH, glucose and LDH) in the pleural fluid of 100 patients with parapneumonic effusions. Forty-nine of these patients had non-purulent complicated effusions (complicated parapneumonic pleural effusion, CPPE), and 51 had uncomplicated parapneumonic pleural effusions (UPPE). Receiver-operating characteristic curves were used to assess the sensitivity and specificity of pleural fluid biochemical parameters for differentiating among the two patient groups. IL-8 production was determined using a commercially available ELISA kit, and CRP was measured by immunoassay.


RESULTS
At a cutoff value of 1000 pg/mL, IL-8 differentiated CPPE from UPPE with a sensitivity of 84% and a specificity of 82%. Likewise, CRP levels were higher in CPPE than in UPPE, and showed 72% sensitivity and 71% specificity at a cutoff value of 80 mg/L. We found that all five pleural fluid tests showed similar diagnostic accuracies when evaluated by receiver-operating characteristic analysis. However, multivariate analysis indicated that the size of the effusion, as well as pleural fluid pH and IL-8 concentration, were the best discriminatory parameters, with likelihood ratios of 6.4, 4.4 and 3.9, respectively.


CONCLUSIONS
Pleural fluid IL-8 is an accurate marker for the identification of non-purulent CPPE.
Porcel
José M
JM
Pleural Diseases Unit, Department of Internal Medicine, Arnau de Vilanova University Hospital, IRBLLEIDA, Lleida, Spain. jporcelp@yahoo.es
Galindo
Carlos
C
Esquerda
Aureli
A
Trujillano
Javier
J
Ruiz-González
Agustín
A
Falguera
Miquel
M
Vives
Manuel
M
D000328:Adult; D000368:Aged; D002097:C-Reactive Protein / Q000378:metabolism*; D017714:Community-Acquired Infections / Q000150:complications / Q000175:diagnosis / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D018410:Pneumonia, Bacterial / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D011237:Predictive Value of Tests; D012372:ROC Curve; D013492:Suppuration / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism
D016209:Interleukin-8; D002097:C-Reactive Protein