Cut-off value of pleural fluid C-reactive protein in etiologic diagnosis of pleural fluid

AbstractBackgroundClassification of effusion into transudates or exudates is considered as the corner stone in the etiological diagnosis of pleural effusion.ObjectivesTo determine the validity of pleural fluid (high sensitivity-CRP) concentration in etiologic diagnosis of pleural effusion and to obtain a cut-off value of pleural fluid CRP at which we can discriminate between exudative and transudative pleural effusions.Patients and methodsA study was conducted upon a hundred patients with pleural effusion. All patients were subjected to: history, clinical examination, chest radiography and thoracic ultrasound, tuberculin test and aspiration of pleural fluid. The fluid was sent for biochemical examination including: Protein, L.D.H, A.D.A and CRP levels, cytological examination and bacteriologic examination. Classification of pleural fluid into transudative or exudative is based upon Light’s criteria. Data were compared by independent sample t-test for 2 groups or by a one-way analysis of variance (ANOVA) for more than 2 groups of variables. Simple correlations between variables were examined by calculating Pearson’s product correlation coefficient, Receiver operating characteristic (ROC) curve used to calculate cut off points, area under the curve (AUC), sensitivity and specificity, and 2 tailed P