title: Consideration of high-sensitivity troponin values below the 99th percentile at presentation: does it improve diagnostic accuracy?
abstract: BACKGROUND
  The introduction of high-sensitivity cardiac troponin (hs-cTn) assays allows the assessment of clinical decision values below the 99th percentile.
  
  
  METHODS
  Final diagnosis and one-year mortality were adjudicated in a multicenter, prospective cohort of 1181 patients presenting with acute chest pain to the emergency department. Hs-cTnT (Roche) and cTnI-ultra (Siemens) were measured in a blinded fashion.
  
  
  RESULTS
  At presentation hs-cTnT and cTnI-ultra were below the limit of blank (LOB) in 201 (17%) and 549 (47%) patients, below the 75th percentile in 379 (32%) and 623 (53%) patients, below the 95th percentile in 603 (51%) and 808 (68%), and below the 99th percentile in 748 (63%) and 913 (77%), respectively. Sensitivities for the diagnosis of AMI were 100.0% and 96.8% respectively for hs-cTnT and cTnI-ultra (LOB as cut-off value), 99.5% and 96.2% (75th percentile), 96.8% and 93.0% (95th percentile), and 94.1% and 88.1% (99th percentile). The proportion of patients correctly classified as having or not AMI increased from 32.9% (LOB as cut-off value) to 47.8% (75th percentile), 65.9% (95th percentile) and 77.3% (99th percentile) for hs-cTnT and from 61.2% to 67.3%, 81.9% and 89.3% respectively for cTnI-ultra. At 1 year, all-cause mortality was very low and similar for patients below all of these cut-off levels (between 0.7% and 1.5%, p=0.748 for all-groups comparison).
  
  
  CONCLUSIONS
  cTn should be considered as a continuous variable. Decision values below the 99th percentile (e.g. the 75th percentile) are associated with a very high NPV for the diagnosis of AMI, but have a lower accuracy than the 99th percentile.
authors.affiliation: Department of Cardiology, University Hospital, Basel, Switzerland; Paris XIII University, Cardiology Department, Avicenne Hospital, Bobigny, France; Paris Descartes University, Cardiology Department, Cochin Hospital, APHP, Paris, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Meune
authors.forename: Cathrin
authors.initials: C
authors.lastname: Balmelli
authors.forename: Eliane
authors.initials: E
authors.lastname: Vogler
authors.forename: Raphael
authors.initials: R
authors.lastname: Twerenbold
authors.forename: Miriam
authors.initials: M
authors.lastname: Reiter
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.forename: Philip
authors.initials: P
authors.lastname: Haaf
authors.forename: Beatrice
authors.initials: B
authors.lastname: Drexler
authors.forename: Karin
authors.initials: K
authors.lastname: Wildi
authors.forename: Rebeca
authors.initials: R
authors.lastname: Hoeller
authors.forename: Maria
authors.initials: M
authors.lastname: Rubini Gimenez
authors.forename: Berit
authors.initials: B
authors.lastname: Moehring
authors.forename: Christa
authors.initials: C
authors.lastname: Zellweger
authors.forename: Mihael
authors.initials: M
authors.lastname: Potocki
authors.forename: Christian
authors.initials: C
authors.lastname: Mueller
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016037:Single-Blind Method; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I; D020107:Troponin T
keywords: 75th percentile; 95th percentile; Acute coronary syndrome; High sensitivity Troponin