title: Two-hour diagnostic algorithms for early assessment of patients with acute chest pain--Implications of lowering the cardiac troponin I cut-off to the 97.5th percentile.
abstract: OBJECTIVE
  Assessment of patients with suspected non-ST elevation myocardial infarction (NSTEMI) is based on cardiac troponin (cTn) levels with the 99th percentile as cut-off. However, cardiovascular risk starts already at lower troponin concentrations. We therefore, aimed to investigate the utility of 2-hour algorithms using the high-sensitivity cardiac troponin I (hs-cTnI) 97.5th percentile as cut-off which corresponds to the standard URL for most biomarkers.
  
  
  METHODS
  Hs-cTnI was measured at presentation and 2h in 1624 chest pain patients. Diagnostic algorithms were developed applying hs-cTnI levels dichotomized at the 99th and 97.5th percentiles combined with hs-cTnI changes and/or ECG findings.
  
  
  RESULTS
  The prevalence of NSTEMI was 13.9%. The adjusted odds ratios for 1-year mortality were 2.7 (95% CI 1.4-5.1) for the 99th percentile and 3.1 (95% CI 1.6-5.9) for the 97.5th percentile. The best-performing 99th percentile-based algorithms provided a positive predictive value (PPV) of 86.3% and a negative predictive value (NPV) of 99.3%. Using 97.5th percentile-based algorithms to define NSTEMI resulted in few reclassifications and yielded similar diagnostic estimates (PPV 85.4%, NPV 99.4%).
  
  
  CONCLUSIONS
  The hs-cTnI 97.5th percentile integrated into 2-hour algorithms provided high diagnostic estimates and could, due to better prognostic properties serve as an alternative to the 99th percentile.
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden. Electronic address: kai.eggers@ucr.uu.se.
authors.forename: Kai M
authors.initials: KM
authors.lastname: Eggers
authors.affiliation: Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Sally
authors.initials: S
authors.lastname: Aldous
authors.affiliation: Royal Brisbane and Women's Hospital, Brisbane, Australia; University of Queensland, Brisbane, Australia.
authors.forename: Jaimi H
authors.initials: JH
authors.lastname: Greenslade
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Nina
authors.initials: N
authors.lastname: Johnston
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden; Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden.
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
authors.affiliation: Royal Brisbane and Women's Hospital, Brisbane, Australia; University of Technology, Brisbane, Australia.
authors.forename: William A
authors.initials: WA
authors.lastname: Parsonage
authors.affiliation: Christchurch Hospital, Christchurch, New Zealand; University of Otago Christchurch, Christchurch, New Zealand.
authors.forename: John W
authors.initials: JW
authors.lastname: Pickering
authors.affiliation: Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Martin
authors.initials: M
authors.lastname: Than
authors.affiliation: Royal Brisbane and Women's Hospital, Brisbane, Australia; University of Technology, Brisbane, Australia.
authors.forename: Louise
authors.initials: L
authors.lastname: Cullen
mesh_terms: D000208:Acute Disease; D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D002637:Chest Pain / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016019:Survival Analysis; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I
keywords: Cardiac troponin; Chest pain; Diagnosis; Emergency department; Myocardial infarction