title: Delta changes for optimizing clinical specificity and 60-day risk of adverse events in patients presenting with symptoms suggestive of acute coronary syndrome utilizing the ADVIA Centaur TnI-Ultra assay.
abstract: OBJECTIVE
  We determined diagnostic accuracy and risk stratification using delta changes for the cardiac troponin I (cTnI) Centaur Ultra assay for ruling out acute myocardial infarction (AMI) and for risk prediction of adverse events in patients with symptoms of acute coronary syndrome.
  
  
  METHODS
  cTnI was measured on admission and 6-24 h in 371 patients. Optimal deltas (percent change, absolute value of percent change, change, absolute value of change) were determined from ROC curve analysis. Risk stratification was performed for cardiac events and death within 60 days.
  
  
  RESULTS
  AMI during hospitalization occurred in 49 patients and endpoints in 11 patients. Diagnostic accuracy by ROC curve was optimal (0.96) using the absolute value of change delta. Diagnostic specificities utilizing the 99th percentile (40 ng/L) for admission and follow-up samples were 84% and 81%, compared to: [90% percent change delta] 89.7%; [66.7% absolute value of percent change delta] 85.5%, [217 ng/L change delta] 99.0% and [55 ng/L absolute value of change delta] 93.7%. All four delta values showed substantially greater risk when the initial cTn value was normal.
  
  
  CONCLUSIONS
  Utilizing delta cTnI values improves clinical specificity, diagnostic accuracy and risk assessment in patients presenting with symptoms of ACS.
authors.affiliation: Hennepin County Medical Center, University of Minnesota School of Medicine, Department of Laboratory Medicine and Pathology, Minneapolis, MN, USA. apple004@umn.edu
authors.forename: Fred S
authors.initials: FS
authors.lastname: Apple
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Smith
authors.forename: Lesly A
authors.initials: LA
authors.lastname: Pearce
authors.forename: Maryann M
authors.initials: MM
authors.lastname: Murakami
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012016:Reference Values; D018570:Risk Assessment / Q000706:statistics & numerical data; D012307:Risk Factors; D013997:Time Factors; D019210:Troponin I / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019210:Troponin I