title: Pleural fluid cell-free DNA in parapneumonic pleural effusion.
abstract: OBJECTIVE
  To measure the accuracy of pleural fluid cell-free DNA (cfDNA) concentration for diagnosis of parapneumonic pleural effusions (PPE).
  
  
  METHODS
  We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. DNA was automatically extracted from pleural fluid using the MagNa Pure Compact instrument (Roche Diagnostics), and was measured by a real-time quantitative PCR assay for the β-globin gene using a Light-Cycler 480 Real-Time PCR instrument (Roche Diagnostics). Patients were classified into two groups according to the etiology of pleural effusion: PPE and NOT PPE. The diagnostic accuracy was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC).
  
  
  RESULTS
  We studied 78 patients with ages between 1 and 86 years old (median=64). Sixteen patients were PPE and 62 were NOT PPE (24 transudative, 30 malignant and 8 other etiology). Pleural fluid cfDNA concentration was higher in patients with PPE (median=46,240 ng/mL) than in those with NOT PPE (median=224 ng/mL). The AUC value was 0.907 (p<0.0001) and the optimal cut-off value was 6740 ng/mL exhibiting 87.5% sensitivity and 80.6% specificity. Also, there were significant differences between transudative and exudative effusions according to pleural fluid cfDNA concentration (p<0.0001). The AUC value was 0.994 and the optimal cut-off value was 162ng/mL exhibiting 100% sensitivity and 96.3% specificity.
  
  
  CONCLUSIONS
  Pleural fluid cfDNA concentration showed high accuracy for diagnosis of PPE and to discriminate between transudative and exudative effusions.
authors.affiliation: Department of Clinical Laboratory, Puerto Real University Hospital, Cadiz, Spain; Department of Biomedicine, Biotechnology and Public Health, University of Cadiz, Cadiz, Spain. Electronic address: jdsantotoribioc@gmail.com.
authors.forename: Jose D
authors.initials: JD
authors.lastname: Santotoribio
authors.affiliation: Department of Microbiology, San Cecilio University Hospital, Granada, Spain.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Cabrera-Alarcón
authors.affiliation: Department of Nephrology, Virgen del Rocío University Hospital, Seville, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Batalha-Caetano
authors.affiliation: Department of Clinical Biochemistry, Institute of Biomedicine of Seville (IBIS), Virgen del Rocío University Hospital, Seville, Spain; CSIC, University of Seville, Seville, Spain.
authors.forename: Hada C
authors.initials: HC
authors.lastname: Macher
authors.affiliation: Department of Clinical Biochemistry, Institute of Biomedicine of Seville (IBIS), Virgen del Rocío University Hospital, Seville, Spain; CSIC, University of Seville, Seville, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Guerrero
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D004247:DNA / Q000378:metabolism*; D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000737:chemistry; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D025202:Molecular Diagnostic Techniques; D010996:Pleural Effusion / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*; D016066:Pleural Effusion, Malignant / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism; D011014:Pneumonia / Q000503:physiopathology*; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D000069258:Thoracentesis; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D004247:DNA
keywords: Cell-free DNA; Parapneumonic effusion; Pleural effusion; Pleural fluid; Pneumonia