title: Value of procalcitonin, C-reactive protein, and neopterin in exacerbations of chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  The identification of biological markers in order to assess different aspects of COPD is an area of growing interest. The objective of this study was to investigate whether levels of procalcitonin (PCT), C-reactive protein (CRP), and neopterin in COPD patients could be useful in identifying the etiological origin of the exacerbation and assessing its prognosis.
  
  
  METHODS
  We included 318 consecutive COPD patients: 46 in a stable phase, 217 undergoing an exacerbation, and 55 with pneumonia. A serum sample was collected from each patient at the time of being included in the study. A second sample was also collected 1 month later from 23 patients in the exacerbation group. We compared the characteristics, biomarker levels, microbiological findings, and prognosis in each patient group. PCT and CRP were measured using an immunofluorescence assay. Neopterin levels were measured using a competitive immunoassay.
  
  
  RESULTS
  PCT and CRP showed significant differences among the three patient groups, being higher in patients with pneumonia, followed by patients with exacerbation (P < 0.0001). For the 23 patients with paired samples, PCT and CRP levels decreased 1 month after the exacerbation episode, while neopterin increased. Neopterin showed significantly lower levels in exacerbations with isolation of pathogenic bacteria, but no differences were found for PCT and CRP. No significant differences were found when comparing biomarker levels according to the Gram result: PCT (P = 0.191), CRP (P = 0.080), and neopterin (P = 0.109). However, median values of PCT and CRP were high for Streptococcus pneumoniae, Staphylococcus aureus, and enterobacteria. All biomarkers were higher in patients who died within 1 month after the sample collection than in patients who died later on.
  
  
  CONCLUSIONS
  According to our results, biomarker levels vary depending on the clinical status. However, the identification of the etiology of infectious exacerbation by means of circulating biomarkers is encouraging, but its main disadvantage is the absence of a microbiological gold standard, to definitively demonstrate their value. High biomarker levels during an exacerbation episode correlate with the short-term prognosis, and therefore their measurement can be useful for COPD management.
authors.affiliation: Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Fundació Institut d'Investigació en Ciències de Salut Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Lacoma
authors.forename: Cristina
authors.initials: C
authors.lastname: Prat
authors.forename: Felipe
authors.initials: F
authors.lastname: Andreo
authors.forename: Luis
authors.initials: L
authors.lastname: Lores
authors.forename: Juan
authors.initials: J
authors.lastname: Ruiz-Manzano
authors.forename: Vicente
authors.initials: V
authors.lastname: Ausina
authors.forename: Jose
authors.initials: J
authors.lastname: Domínguez
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; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D005455:Fluorescent Antibody Technique; D005541:Forced Expiratory Volume; D006801:Humans; D007118:Immunoassay; D018836:Inflammation Mediators / Q000097:blood*; D053208:Kaplan-Meier Estimate; D008168:Lung / Q000382:microbiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D019798:Neopterin / Q000097:blood*; D018410:Pneumonia, Bacterial / Q000276:immunology / Q000382:microbiology / Q000401:mortality; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011498:Protein Precursors / Q000097:blood*; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology / Q000401:mortality / Q000503:physiopathology; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013030:Spain; D013183:Sputum / Q000382:microbiology; D013997:Time Factors
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D018836:Inflammation Mediators; D011498:Protein Precursors; D019798:Neopterin; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide