title: C-reactive protein in outpatients with acute exacerbation of COPD: its relationship with microbial etiology and severity.
abstract: BACKGROUND
  C-reactive protein (CRP) measurement has proven valuable for detecting exacerbations, but its usefulness in predicting etiology remains controversial. Likewise, its potential value as a marker of severity, which is well established in patients with pneumonia, remains unproven in chronic obstructive pulmonary disease (COPD) exacerbations.
  
  
  METHODS
  A cohort study of 118 patients with severe COPD and acute infectious exacerbations were included and followed up over 1 year. Episodes of exacerbations meeting Anthonisen's criteria type I-II were evaluated, analyzing the etiology and inflammatory response as measured by CRP in blood.
  
  
  RESULTS
  A total of 380 episodes were recorded. Full microbiological analysis was available in 265 samples.Haemophilus influenzaewas the most commonly isolated bacteria and rhinovirus the most common virus. Median CRP levels from the 265 episodes were higher in the cases with positive cultures for bacteria (58.30 mg/L, interquartile range [IQR] 21.0-28.2) than in episodes only positive for viruses (37.3 mg/L, IQR 18.6-79.1) and cases negative for any microorganism (36.4 mg/L, IQR 10.8-93.7) (P<0.014).H. influenzaeandStreptococcus pneumoniaereached the highest CRP levels of 74.5 mg/L (IQR 23.9-167.9) and 74.1 mg/L (IQR 42.0-220.7), respectively. In the 380 exacerbations studied, 227 (~60%) were community-managed, while 153 (~40%) required hospital admission. In the multivariate analysis to assess the influence of inflammatory response on exacerbation severity, baseline hypercapnia (odds ratio [OR]: 2.70, 95% confidence interval [CI]: 1.46-4.9) and CRP levels >100 mg/L (OR: 4.23, 95% CI: 2.12-8.44) were independent predictors after adjustment for baseline characteristics.
  
  
  CONCLUSIONS
  CRP level was higher in bacterial infections, especially whenH. influenzaeandS. pneumoniaewere isolated. CRP values >100 mg/L were associated with a fourfold increased risk of hospital admission. Therefore, CRP blood levels may be a useful biomarker in the management of exacerbations appearing in patients with severe disease.
authors: Department of Respiratory Medicine, Hospital de Sabadell, Institut Universitari Parc Taulí-UAB, Sabadell; Universitat Autònoma de Barcelona, Esfera UAB, Barcelona; CIBER de Enfermedades Respiratorias, CIBERES, Bunyola.
authors: Miguel
authors: M
authors: Gallego
authors: Department of Respiratory Medicine, Hospital de Sabadell, Institut Universitari Parc Taulí-UAB, Sabadell; CIBER de Enfermedades Respiratorias, CIBERES, Bunyola.
authors: Xavier
authors: X
authors: Pomares
authors: Laboratory of Microbiology, Institut Universitari Parc Taulí-UAB, Sabadell.
authors: Silvia
authors: S
authors: Capilla
authors: Department of Clinical Microbiology, Hospital Clínic; ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic, Universitat de Barcelona, Barcelona.
authors: Maria Angeles
authors: MA
authors: Marcos
authors: Epidemiology and Assessment Unit, Fundació Parc Taulí, Universitat Autònoma de Barcelona, Sabadell.
authors: David
authors: D
authors: Suárez
authors: Department of Respiratory Medicine, Hospital de Sabadell, Institut Universitari Parc Taulí-UAB, Sabadell; Universitat Autònoma de Barcelona, Esfera UAB, Barcelona; CIBER de Enfermedades Respiratorias, CIBERES, Bunyola.
authors: Eduard
authors: E
authors: Monsó
authors: Department of Respiratory Medicine, Hospital de Sabadell, Institut Universitari Parc Taulí-UAB, Sabadell; Health Services Research on Chronic Diseases Network-REDISSEC, Galdakao, Spain.
authors: Concepción
authors: C
authors: Montón
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis*; D018450:Disease Progression; D005260:Female; D006192:Haemophilus Infections / Q000097:blood* / Q000175:diagnosis / Q000382:microbiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010045:Outpatients; D010343:Patient Admission; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000175:diagnosis / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000097:blood* / Q000175:diagnosis / Q000382:microbiology; D011024:Pneumonia, Viral / Q000097:blood* / Q000175:diagnosis / Q000821:virology; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000175:diagnosis / Q000382:microbiology / Q000821:virology; D012307:Risk Factors; D012720:Severity of Illness Index; D013183:Sputum / Q000382:microbiology / Q000821:virology; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein
keywords: C-reactive protein; COPD exacerbations; hospital admission; viruses