title: Utility of procalcitonin, C-reactive protein and white blood cells alone and in combination for the prediction of clinical outcomes in community-acquired pneumonia.
abstract: BACKGROUND
  The added value of biomarkers, such as procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBC), as adjuncts to clinical risk scores for predicting the outcome of patients with community-acquired pneumonia (CAP) is in question. We investigated the prognostic accuracy of initial and follow-up levels of inflammatory biomarkers in predicting death and adverse clinical outcomes in a large and well-defined cohort of CAP patients.
  
  
  METHODS
  We measured PCT, CRP and WBC on days 1, 3, 5, and 7 and followed the patients over 30 days. We applied multivariate regression models and area under the curve (AUC) to investigate associations between these biomarkers, the clinical risk score CURB-65, and clinical outcomes [i.e., death and intensive care unit (ICU) admission].
  
  
  RESULTS
  Of 925 patients with CAP, 50 patients died and 118 patients had an adverse clinical outcome. None of the initial biomarker levels significantly improved the CURB-65 score for mortality prediction. Follow-up biomarker levels showed significant independent association with mortality at days 3, 5, and 7 and with improvements in AUC. Initial PCT and CRP levels were independent prognostic predictors of adverse clinical outcome, and levels of all biomarkers during the course of disease provided additional prognostic information.
  
  
  CONCLUSIONS
  This study provides robust insights into the added prognostic value of inflammatory markers in CAP. Procalcitonin, CRP, and to a lesser degree WBC provided some prognostic information on CAP outcomes, particularly when considering their kinetics at days 5 and 7 and when looking at adverse clinical outcomes instead of mortality alone.
authors.forename: Andriy
authors.initials: A
authors.lastname: Zhydkov
authors.forename: Mirjam
authors.initials: M
authors.lastname: Christ-Crain
authors.forename: Robert
authors.initials: R
authors.lastname: Thomann
authors.forename: Claus
authors.initials: C
authors.lastname: Hoess
authors.forename: Christoph
authors.initials: C
authors.lastname: Henzen
authors.forename: Zimmerli
authors.initials: Z
authors.lastname: Werner
authors.forename: Beat
authors.initials: B
authors.lastname: Mueller
authors.forename: Philipp
authors.initials: P
authors.lastname: Schuetz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000097:blood* / Q000175:diagnosis* / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000175:diagnosis* / Q000628:therapy; D011379:Prognosis; D011498:Protein Precursors / Q000097:blood*
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide