title: Procalcitonin levels and bacterial aetiology among COPD patients admitted to the ICU with severe pneumonia: a prospective cohort study.
abstract: BACKGROUND
  Serum procalcitonin (PCT) is considered useful in predicting the likeliness of developing bacterial infections in emergency setting. In this study, we describe PCT levels overtime and their relationship with bacterial infection in chronic obstructive pulmonary disease (COPD) critically ill patients with pneumonia.
  
  
  METHODS
  We conducted a prospective cohort study in an ICU of a University Hospital. All consecutive COPD patients admitted for pneumonia between September 2005 and September 2006 were included. Respiratory samples were tested for the presence of bacteria and viruses. Procalcitonin was sequentially assessed and patients classified according to the probability of the presence of a bacterial infection.
  
  
  RESULTS
  Thirty four patients were included. The PCT levels were assessed in 32/34 patients, median values were: 0.493 microg/L [IQR, 0.131 to 1.471] at the time of admission, 0.724 microg/L [IQR, 0.167 to 2.646] at six hours, and 0.557 microg/L [IQR, 0.123 to 3.4] at 24 hours. The highest PCT (PCTmax) levels were less than 0.1 microg/L in 3/32 (9%) patients and greater than 0.25 microg/L in 22/32 (69%) patients, suggesting low and high probability of bacterial infection, respectively. Fifteen bacteria and five viruses were detected in 15/34 (44%) patients. Bacteria were not detected in patients with PCTmax levels < 0.1 microg/L. In contrast, bacteria were detected in 4/7 (57%) patients estimated unlikely to have a bacterial infection by PCT levels (PCTmax > 0.1 and < 0.25 microg/L).
  
  
  CONCLUSIONS
  Based on these results we suggest that a PCT level cut off > 0.1 microg/L may be more appropriate than 0.25 microg/L (previously proposed for non severe lower respiratory tract infection) to predict the probability of a bacterial infection in severe COPD patients with pneumonia. Further studies testing procalcitonin-based antibiotic strategies are needed in COPD patients with severe pneumonia.
authors.affiliation: The Department of Medical Intensive Care, Caen University Hospital, 14033 Caen Cedex, France. daubin-c@chu-caen.fr
authors.forename: Cédric
authors.initials: C
authors.lastname: Daubin
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Parienti
authors.forename: Sabine
authors.initials: S
authors.lastname: Fradin
authors.forename: Astrid
authors.initials: A
authors.lastname: Vabret
authors.forename: Michel
authors.initials: M
authors.lastname: Ramakers
authors.forename: Nicolas
authors.initials: N
authors.lastname: Terzi
authors.forename: François
authors.initials: F
authors.lastname: Freymuth
authors.forename: Pierre
authors.initials: P
authors.lastname: Charbonneau
authors.forename: Damien
authors.initials: D
authors.lastname: du Cheyron
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000302:isolation & purification; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000150:complications / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000382:microbiology
chemical_list: C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide