Accuracy of biomarkers to diagnose acute cardiac ischemia in the emergencydepartment: A meta-analysis

Study objective: We sought to evaluate quantitatively the evidence on the d iagnostic performance of presentation and serial biochemical markers for em ergency department diagnosis of acute cardiac ischemia (ACI), including acu te myocardial infarction (AMI) and unstable angina. Methods: We conducted a systematic review and meta-analysis of the English- language literature published between 1966 and December 1998. We examined t he diagnostic performance of creatine kinase, creatine kinase-MB, myoglobin , and troponin I and T testing. Diagnostic performance was assessed by usin g estimates of test sensitivity and specificity and was summarized by summa ry receiver-operating characteristic curves. Results: Only 4 studies were found that evaluated all patients with ACI; 73 were found that focused only on a diagnosis Of AMI. To diagnose ACI, prese ntation biomarker tests had sensitivities of 16% to 19% and specificities o f 96% to 100%; serial biomarker tests had sensitivities of 31% to 45% and s pecificities of 95% to 98%. Considering only the diagnosis of AMI, presenta tion biomarker tests had summary sensitivities of 37% to 49% and summary sp ecificities of 87% to 97%; serial bio marker tests had summary sensitivitie s of 79% to 93% and summary specificities of 85% to 96%. Variation of test sensitivity was best explained by test timing, longer symptom duration or t ime between serial tests yielded higher sensitivity. Conclusion: The limited evidence available to evaluate the diagnostic accur acy of biomarkers for ACI suggests that biomarkers have very low sensitivit y to diagnose ACI. Thus, biomarkers alone will greatly underdiagnose ACI an d will be inadequate to make triage decisions. For AMI diagnosis alone, mul tiple testing of individual biomarkers overtime substantially improves sens itivity, while retaining high specificity, at the expense of additional tim e. Further high-quality studies are needed on the clinical effect of using biomarkers for patients with ACI in the ED and on optimal timing of serial testing and in combination with other tests.