title: Inflammatory parameters predict etiologic patterns but do not allow for individual prediction of etiology in patients with CAP: results from the German competence network CAPNETZ.
abstract: BACKGROUND
  Aim of this study was to evaluate the correlation of inflammatory markers procalcitonin (PCT), C-reactive protein (CRP) and leukocyte count (WBC) with microbiological etiology of CAP.
  
  
  METHODS
  We enrolled 1337 patients (62 +/- 18 y, 45% f) with proven CAP. Extensive microbiological workup was performed. In all patients PCT, CRP, WBC and CRB-65 score were determined. Patients were classified according to microbial diagnosis and CRB-65 score.
  
  
  RESULTS
  In patients with typical bacterial CAP, levels of PCT, CRP and WBC were significantly higher compared to CAP of atypical or viral etiology. There were no significant differences in PCT, CRP and WBC in patients with atypical or viral etiology of CAP. In contrast to CRP and WBC, PCT markedly increased with severity of CAP as measured by CRB-65 score (p < 0.0001). In ROC analysis for discrimination of patients with CRB-65 scores > 1, AUC for PCT was 0.69 (95% CI 0.66 to 0.71), which was higher compared to CRP and WBC (p < 0.0001). CRB-65, PCT, CRP and WBC were higher (p < 0.0001) in hospitalised patients in comparison to outpatients.
  
  
  CONCLUSIONS
  PCT, CRP and WBC are highest in typical bacterial etiology in CAP but do not allow individual prediction of etiology. In contrast to CRP and WBC, PCT is useful in severity assessment of CAP.
authors: Medical Clinic I, University Clinic RWTH Aachen, Germany. stkrueger@ukaachen.de
authors: Stefan
authors: S
authors: Krüger
authors: Santiago
authors: S
authors: Ewig
authors: Jana
authors: J
authors: Papassotiriou
authors: Jan
authors: J
authors: Kunde
authors: Reinhard
authors: R
authors: Marre
authors: Heike
authors: H
authors: von Baum
authors: Norbert
authors: N
authors: Suttor
authors: Tobias
authors: T
authors: Welte
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood; D015740:Calcitonin Gene-Related Peptide; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology*; D005260:Female; D005858:Germany; D006801:Humans; D007249:Inflammation / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology*; D018410:Pneumonia, Bacterial / Q000209:etiology / Q000382:microbiology / Q000473:pathology; D011024:Pneumonia, Viral / Q000209:etiology / Q000473:pathology / Q000821:virology; D011498:Protein Precursors / Q000097:blood; D012372:ROC Curve; D055815:Young Adult
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide