title: Clinical performance of two highly sensitive cardiac troponin I assays.
abstract: BACKGROUND
  The aim of this study was to compare the clinical performance of 2 sensitive cTnI assays with 10% CV imprecision below the 99th percentile upper reference limit.
  
  
  METHODS
  We measured cardiac troponin and N-terminal pro-brain natriuretic peptide (NT-proBNP) concentrations in a random sample of the Global Use of Strategies To Open Occluded Coronary Arteries (GUSTO) IV cohort (n = 1251). Outcome data of 1-year mortality and the composite endpoint DMI [death and/or myocardial infarction (MI) within 30 days] were available in all patients. The 99th percentile of a healthy population was estimated from the Sweden Women and Men and Ischemic Heart Disease (SWISCH) cohort (n = 442). We measured cardiac troponin I (cTnI) using the Access AccuTnI (Beckman Coulter) and Centaur TnI Ultra (Siemens Healthcare Diagnostics) and NT-proBNP using the Elecsys 2010 (Roche Diagnostics).
  
  
  RESULTS
  Applying the 10% CV cutoff, the sensitivity of the Access AccuTnI assay in identifying DMI and death was higher than that of the Centaur TnI Ultra (P = 0.02 and P < 0.001), and the AccuTnI assay also identified more patients at risk (P < 0.001) and with poor outcome. Applying the 99th percentile cutoffs, AccuTnI identified more patients at risk than the Centaur TnI (P < 0.001) and with significant differences in outcome. Significantly more patients with cardiac troponins below the cutoffs as measured by Centaur TnI had increased NT-proBNP concentrations (P < 0.001) compared with AccuTnI.
  
  
  CONCLUSIONS
  The AccuTnI assay identified more patients at risk than the Centaur cTnI Ultra assay. Our results demonstrate the clinical potential of high-sensitivity cardiac troponin assays for the identification of patients at risk of dying from cardiovascular disease.
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University of Uppsala. per.venge@akademiska.se
authors.forename: Per
authors.initials: P
authors.lastname: Venge
authors.forename: Stefan
authors.initials: S
authors.lastname: James
authors.forename: Leif
authors.initials: L
authors.lastname: Jansson
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000097:blood* / Q000188:drug therapy; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016019:Survival Analysis; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; D019210:Troponin I; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain