Clinical chemistry score versus high-sensitivity cardiac troponin I and T tests alone to identify patients at low or high risk for myocardial infarction or death at presentation to the emergency department

CMAJ. 2018 Aug 20;190(33):E974-E984. doi: 10.1503/cmaj.180144.

Abstract

Background: Testing for high-sensitivity cardiac troponin (hs-cTn) may assist triage and clinical decision-making in patients presenting to the emergency department with symptoms of acute coronary syndrome; however, this could result in the misclassification of risk because of analytical variation or laboratory error. We sought to evaluate a new laboratory-based risk-stratification tool that incorporates tests for hs-cTn, glucose level and estimated glomerular filtration rate to identify patients at risk of myocardial infarction or death when presenting to the emergency department.

Methods: We constructed the clinical chemistry score (CCS) (range 0-5 points) and validated it as a predictor of 30-day myocardial infarction (MI) or death using data from 4 cohort studies involving patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome. We calculated diagnostic parameters for the CCS score separately using high-sensitivity cardiac troponin I (hs-cTnI) and high-sensitivity cardiac troponin T (hs-cTnT).

Results: For the combined cohorts (n = 4245), 17.1% of participants had an MI or died within 30 days. A CCS score of 0 points best identified low-risk participants: the hs-cTnI CCS had a sensitivity of 100% (95% confidence interval [CI] 99.5%-100%), with 8.9% (95% CI 8.1%-9.8%) of the population classified as being at low risk of MI or death within 30 days; the hs-cTnT CCS had a sensitivity of 99.9% (95% CI 99.2%-100%), with 10.5% (95% CI 9.6%-11.4%) of the population classified as being at low risk. The CCS had better sensitivity than hs-cTn alone (hs-cTnI < 5 ng/L: 96.6%, 95% CI 95.0%-97.8%; hs-cTnT < 6 ng/L: 98.2%, 95% CI 97.0%-99.0%). A CCS score of 5 points best identified patients at high risk (hs-cTnI CCS: specificity 96.6%, 95% CI 96.0%-97.2%; 11.2% [95% CI 10.3%-12.2%] of the population classified as being at high risk; hs-cTnT CCS: specificity 94.0%, 95% CI 93.1%-94.7%; 13.1% [95% CI 12.1%-14.1%] of the population classified as being at high risk) compared with using the overall 99th percentiles for the hs-cTn assays (specificity of hs-cTnI 93.2%, 95% CI 92.3-94.0; specificity of hs-cTnT 73.8%, 95% CI 72.3-75.2).

Interpretation: The CCS score at the chosen cut-offs was more sensitive and specific than hs-cTn alone for risk stratification of patients presenting to the emergency department with suspected acute coronary syndrome. Study registration: ClinicalTrials.gov, nos. NCT01994577; NCT02355457.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Acute Coronary Syndrome / blood
  • Acute Coronary Syndrome / diagnosis*
  • Acute Coronary Syndrome / physiopathology
  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Glucose / analysis
  • Clinical Laboratory Techniques*
  • Death
  • Emergency Service, Hospital
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Male
  • Middle Aged
  • Myocardial Infarction / epidemiology
  • Myocardium / chemistry*
  • Predictive Value of Tests
  • Prospective Studies
  • Time Factors
  • Troponin I / analysis*
  • Troponin T / analysis*

Substances

  • Blood Glucose
  • Troponin I
  • Troponin T

Associated data

  • ClinicalTrials.gov/NCT01994577
  • ClinicalTrials.gov/NCT02355457