PT  - JOURNAL ARTICLE
AU  - Kavsak, Peter A.
AU  - Neumann, Johannes T.
AU  - Cullen, Louise
AU  - Than, Martin
AU  - Shortt, Colleen
AU  - Greenslade, Jaimi H.
AU  - Pickering, John W.
AU  - Ojeda, Francisco
AU  - Ma, Jinhui
AU  - Clayton, Natasha
AU  - Sherbino, Jonathan
AU  - Hill, Stephen A.
AU  - McQueen, Matthew
AU  - Westermann, Dirk
AU  - Sörensen, Nils A.
AU  - Parsonage, William A.
AU  - Griffith, Lauren
AU  - Mehta, Shamir R.
AU  - Devereaux, P.J.
AU  - Richards, Mark
AU  - Troughton, Richard
AU  - Pemberton, Chris
AU  - Aldous, Sally
AU  - Blankenberg, Stefan
AU  - Worster, Andrew
TI  - 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
AID  - 10.1503/cmaj.180144
DP  - 2018 Aug 20
TA  - Canadian Medical Association Journal
PG  - E974--E984
VI  - 190
IP  - 33
4099  - http://www.cmaj.ca/content/190/33/E974.short
4100  - http://www.cmaj.ca/content/190/33/E974.full
SO  - CMAJ2018 Aug 20; 190
AB  - 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