title: Serum amyloid a is a biomarker of acute exacerbations of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Much of the total disease burden and cost of chronic obstructive pulmonary disease (COPD) is associated with acute exacerbations of COPD (AECOPD). Serum amyloid A (SAA) is a novel candidate exacerbation biomarker identified by proteomic screening.
  
  
  OBJECTIVE
  To assess SAA as a biomarker of AECOPD.
  
  
  METHODS
  Biomarkers were assessed (1) cross-sectionally (stable vs. AECOPD; 62 individuals) and (2) longitudinally with repeated measures (baseline vs. AECOPD vs. convalescence; 78 episodes in 37 individuals). Event severity was graded (I, ambulatory; II, hospitalized; III, respiratory failure) based on consensus guidelines.
  
  
  RESULTS
  Presumptively newly acquired pathogens were associated with onset of symptomatic AECOPD. In the cross-sectional study, both SAA and C-reactive protein (CRP) were elevated at AECOPD onset compared with stable disease (SAA median, 7.7 vs. 57.6 mg/L; P < 0.01; CRP median, 4.6 vs. 12.5 mg/L; P < 0.01). Receiver operator characteristics analysis was used to generate area-under-curve values for event severity. SAA discriminated level II/III events (SAA, 0.88; 95% confidence interval, 0.80-0.94 vs. CRP, 0.80; 95% confidence interval, 0.70-0.87; P = 0.05). Combining SAA or CRP with major symptoms (Anthonisen criteria, dyspnea) did not further improve the prediction model for severe episodes. IL-6 and procalcitonin were not informative.
  
  
  CONCLUSIONS
  SAA is a novel blood biomarker of AECOPD that is more sensitive than CRP alone or in combination with dyspnea. SAA may offer new insights into the pathogenesis of AECOPD.
authors.affiliation: Department of Pharmacology, Medical Building (Level 8), University of Melbourne, Parkville, 3010 Australia. bozis@unimelb.edu.au
authors.forename: Steven
authors.initials: S
authors.lastname: Bozinovski
authors.forename: Anastasia
authors.initials: A
authors.lastname: Hutchinson
authors.forename: Michelle
authors.initials: M
authors.lastname: Thompson
authors.forename: Lochlan
authors.initials: L
authors.lastname: Macgregor
authors.forename: James
authors.initials: J
authors.lastname: Black
authors.forename: Eleni
authors.initials: E
authors.lastname: Giannakis
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Karlsson
authors.forename: Roger
authors.initials: R
authors.lastname: Silvestrini
authors.forename: David
authors.initials: D
authors.lastname: Smallwood
authors.forename: Ross
authors.initials: R
authors.lastname: Vlahos
authors.forename: Louis B
authors.initials: LB
authors.lastname: Irving
authors.forename: Gary P
authors.initials: GP
authors.lastname: Anderson
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D040901:Proteomics; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D012720:Severity of Illness Index; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D015415:Biomarkers; D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein