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

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.

Conflict of interest statement

Competing interests: Peter Kavsak has received research grants from the Canadian Institutes of Health Research (CIHR), Abbott Laboratories, Abbott Point of Care, Beckman Coulter, Randox Laboratories, Roche Diagnostics and Siemens Healthcare Diagnostics. He has received consultant or advisor fees, or honoraria from Abbott Laboratories, Abbott Point of Care, Abbott Diagnostics Division of Canada, Beckman Coulter, Randox Laboratories, Roche Diagnostics, Siemens Healthcare Diagnostics and Ortho Clinical Diagnostics. In addition, he has a pending patent application filed by McMaster University on a laboratory score for risk stratification in patients with possible cardiac injury. Johannes Neumann has received research grants from the German Heart Foundation/German Foundation of Heart Research and from Else Kröner Fresenius Stiftung. Louise Cullen has received grants from Abbott Diagnostics, Roche and Alere, and personal fees for education and consulting from Abbott Diagnostics, Siemens, Beckman Coulter and Alere. Martin Than has received grants and personal fees in the form of speaker fees or funding for education from Abbott, Alere, Beckman Coulter and Roche. Colleen Shortt is employed by Abbott Diagnostics. Jaimi Greenslade has received research grants that were provided to his institution from Roche and Abbott, as well as a research grant from Emergency Medicine Foundation to support data collection for this study. John Pickering has received nonfinancial support from Abbott Diagnostics and Roche Diagnostics outside the submitted work. Dirk Westermann has received speaker fees from Bayer, Boehringer Ingelheim, Berlin-Chemie, AstraZeneca, BIOTRONIK and Novartis, outside the submitted work. William Parsonage has received research grants from Abbott Laboratories and Roche during the conduct of the study, and fees for being an advisory board member and nonfinancial support from Abbott Laboratories, outside the submitted work. P.J. Devereaux reports grants from Abbott Diagnostics, Boehringer Ingelheim, Covidien, Octopharma, Philips Healthcare, Roche Diagnostics and Stryker, outside the submitted work. Richard Troughton has received research grants from the Health Research Council of New Zealand, Roche Diagnostics and Merck, as well as consulting fees from Merck. Stefan Blankenberg has received honoraria from Abbott Diagnostics, Siemens, Thermo Fisher Scientific and Roche Diagnostics, outside the submitted work. Andrew Worster has received a research grant from CIHR. In addition, he has a pending patent application filed by McMaster University on a laboratory score for risk stratification for patients with possible cardiac injury. No other competing interests were declared.

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