title: Prognostic value of C-reactive protein in parapneumonic effusions.
abstract: OBJECTIVE
  Parapneumonic effusions (PPE) that require drainage are referred to as complicated parapneumonic effusions (CPPE). Following resolution of these effusions, residual pleural thickening (RPT) may persist. We hypothesize that the concentrations of CRP in pleural fluid (CRP(pf)) and serum (CRP(ser)) can be used to identify CPPE and to predict RPT.
  
  
  METHODS
  All patients with non-purulent PPE, who were admitted to two tertiary hospitals during a 30-month period, were enrolled in the study. Baseline CRP(pf) and CRP(ser) levels were compared between patients with complicated or uncomplicated PPE, as well as between patients with or without RPT of >10 mm, 6 months after discharge from hospital. Cut-off values for identification of CPPE and prediction of RPT were determined by receiver operating characteristic curve analysis. Logistic regression analysis was performed to assess the association between CRP levels and RPT.
  
  
  RESULTS
  Fifty-four patients were included in the study. Patients with CPPE (n = 23) had significantly higher levels of both CRP(pf) and CRP(ser) than those with uncomplicated PPE. For identification of CPPE, a CRP(pf) level >78.5 mg/L and a CRP(ser) level >83 mg/L gave 84% and 47% sensitivity, with 65% and 87% specificity, respectively. Classical criteria (pleural fluid pH <7.20, LDH >1000 IU/L, glucose <600 mg/L) were superior for this purpose. A combination of classical biomarkers with CRP levels using an 'AND' or 'OR' rule improved the positive and negative predictive values, respectively. CRP(ser) was an independent predictor for development of RPT (adjusted OR 1.18). A CRP(ser) level >150 mg/L had 91% specificity and 61% sensitivity for prediction of RPT.
  
  
  CONCLUSIONS
  This study demonstrated the value of CRP(ser) for prediction of RPT in patients with PPE. Moreover, when used in combination with classical biomarkers, CRP levels may be a useful adjunct for decision-making in relation to treatment of patients with non-purulent PPE.
authors: Pulmonary Department, 401 General Military Hospital of Athens, Athens, Greece. vskouras@otenet.gr
authors: Vasileios
authors: V
authors: Skouras
authors: Euaggelos
authors: E
authors: Boultadakis
authors: Dimitrios
authors: D
authors: Nikoulis
authors: Vlasis
authors: V
authors: Polychronopoulos
authors: Zoe
authors: Z
authors: Daniil
authors: Ioannis
authors: I
authors: Kalomenidis
authors: Konstantinos I
authors: KI
authors: Gourgoulianis
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000378:metabolism*; D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000737:chemistry*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000175:diagnosis* / Q000378:metabolism; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein