title: A novel troponin I rule-out value below the upper reference limit for acute myocardial infarction.
abstract: To determine cut-off values for a recently introduced high sensitive cardiac troponin assay (hs-cTnI) which provide similar sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) for acute myocardial infarction (AMI) as known cut-off values for an hs-cTnT assay.
  
  
  
  A prospective observational study was performed. Hs-cTnT (Roche) and hs-cTnI (Abbott) were measured in consecutive patients with symptoms suggestive of AMI. Representative measurements (obtained at least 3 h after chest pain has started) and serial measurements with a time delay between 2.5 h and 4.5 h were used to determine cut-off levels. Two independent clinicians adjudicated the final diagnosis.
  
  
  
  1490 patients were included in the study of whom 114 (8%) received a final diagnosis of AMI. Receiver operating characteristics analysis showed no statistically significant differences in the areas under the curve between the two assays. Cut-off values for representative hs-TnI were found to be as follows: rule-out: 10 ng/L (sensitivity: 98.2%; 95% CI 95.7% to 100.0% and NPV: 99.8%; 99.5% to 100.0%); rule-in: 70 ng/L (specificity: 90.8%; 89.3% to 92.4% and PPV: 39.7%; 36.1% to 43.3%). For serial measurements we found a Δ rule-out cut-off value of 20 ng/L (sensitivity: 94.9%; 88.0% to 100.0% and NPV: 98.7%; 96.9% to 100.0%) and Δ rule-in cut-off values of 100 ng/L (specificity: 92.7%; 87.9% to 95.8% and PPV: 57.6%; 39.4% to 74.0%) and 300% (specificity: 93.8%; 90.4% to 97.2% and PPV: 61.3%; 51.1% to 71.5%).
  
  
  
  Cut-off values for hs-cTnI measurements are determined which allow a similar diagnostic classification as compared with hs-cTnT. Importantly, for a rule-out paradigm this cut-off value is unmistakably lower than the upper reference limit.
authors.affiliation: Atalmedial Diagnostic Centres, Hoofddorp, The Netherlands.
authors.forename: Susan M I
authors.initials: SM
authors.lastname: Goorden
authors.affiliation: Department of Cardiology, Spaarne Gasthuis, Haarlem, The Netherlands.
authors.forename: Rudi A
authors.initials: RA
authors.lastname: van Engelen
authors.affiliation: Department of Cardiology, Spaarne Gasthuis, Haarlem, The Netherlands.
authors.forename: Liza S M
authors.initials: LS
authors.lastname: Wong
authors.affiliation: Research Centre Linnaeus Institute Spaarne Gasthuis, Haarlem, The Netherlands.
authors.forename: Tjeerd
authors.initials: T
authors.lastname: van der Ploeg
authors.affiliation: Department of Cardiology, Spaarne Gasthuis, Haarlem, The Netherlands.
authors.forename: Gerard J E
authors.initials: GJ
authors.lastname: Verdel
authors.affiliation: Atalmedial Diagnostic Centres, Hoofddorp, The Netherlands.
authors.forename: Madelon M
authors.initials: MM
authors.lastname: Buijs
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000209:etiology; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D019210:Troponin I / Q000097:blood*; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D019210:Troponin I