title: Usefulness of procalcitonin levels in community-acquired pneumonia according to the patients outcome research team pneumonia severity index.
abstract: OBJECTIVE
  To evaluate the usefulness of procalcitonin serum levels as a predictor of etiology and prognosis in adult patients with community-acquired pneumonia (CAP) when they are stratified according to severity.
  
  
  METHODS
  One-year, population-based, prospective study.
  
  
  METHODS
  University teaching hospital.
  
  
  METHODS
  All adult patients who received a diagnosis of CAP throughout the study period.
  
  
  METHODS
  An extensive noninvasive microbiological workup was performed. In patients who gave informed consent, a blood sample was collected at the time the diagnosis of CAP was established to measure biological markers. Procalcitonin levels were measured by a commercially available monoclonal immunoluminometric assay (limit of detection, 0.1 microg/L). Patients were classified according to microbial diagnosis, Patients Outcome Research Team pneumonia severity index (PSI), and outcome measures, and procalcitonin levels were compared among groups.
  
  
  RESULTS
  Of 240 patients who received a diagnosis of CAP during the study period, procalcitonin concentrations were measured in 185 patients (77.1%). Levels were higher in patients with high-severity risk classes (PSI classes III-V) [p = 0.01] and in those with complications (p = 0.03) or death (p < 0.0001). Among patients classified into PSI low-severity risk classes (classes I-II), levels tended to be higher in those with bacterial etiology (p = 0.08); in this group, a serum procalcitonin level > or = 0.15 microg/L was more frequently found in patients with bacterial pneumonia than in those with nonbacterial pneumonia (p = 0.03). In patients with higher-severity risk classes, no significant differences were observed in procalcitonin levels among etiologic groups, but higher concentrations were associated with development of complications (p = 0.01) and death (p < 0.0001).
  
  
  CONCLUSIONS
  Procalcitonin contribution to the evaluation of CAP varies according to severity. While procalcitonin may have a role to predict the microbial etiology in patients with a low PSI score, in patients classified within high PSI risk classes, it is a prognostic marker rather than a predictor of etiology.
authors.affiliation: Infectious Diseases Unit, Internal Medicine Department, Hospital General Universitario de Elche, Camí de la Almazara S/N; 03203 ELCHE, Alicante, Spain. marmasia@ya.com
authors.forename: Mar
authors.initials: M
authors.lastname: Masiá
authors.forename: Félix
authors.initials: F
authors.lastname: Gutiérrez
authors.forename: Conrado
authors.initials: C
authors.lastname: Shum
authors.forename: Sergio
authors.initials: S
authors.lastname: Padilla
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Navarro
authors.forename: Emilio
authors.initials: E
authors.lastname: Flores
authors.forename: Ildefonso
authors.initials: I
authors.lastname: Hernández
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D017714:Community-Acquired Infections / Q000097:blood*; D006784:Hospitals, Teaching; D006801:Humans; D007118:Immunoassay; D008875:Middle Aged; D011014:Pneumonia / Q000097:blood*; D018410:Pneumonia, Bacterial / Q000097:blood; D011024:Pneumonia, Viral / Q000097:blood; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012720:Severity of Illness Index; D013030:Spain; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide