Sensitivity and specificity of the Manchester Triage System in risk prioritization of patients with acute myocardial infarction who present with chest pain.

Background: The purpose of the Manchester Triage System is to clinically prioritize each patient seeking care in an emergency department. Patients with suspected acute myocardial infarction who have typical symptoms including chest pain should be classified in the highest priority groups, requiring immediate medical assistance or care within 10 min. As such, the Manchester Triage System should present adequate sensitivity and specificity.

Aims: This study estimated the sensitivity and specificity of the Manchester Triage System in the triage of patients with chest pain related to the diagnosis of acute myocardial infarction, and the associations between the performance of the Manchester Triage System and selected variables.

Methods: This was an observational, analytical, cross-sectional, retrospective study. The sensitivity and specificity of the Manchester Triage System were estimated by verifying the triage classification received by these patients and their established medical diagnoses.

Results: The sample was composed of 10,087 triage episodes, in which 139 (1.38%) patients had a diagnosis of acute myocardial infarction. In 49 episodes, confirmation of medical diagnosis was not possible. The estimated sensitivity of the Manchester Triage System was 44.60% (36.18-53.27%) and the estimated specificity was 91.30% (90.73-91.85%). Of the 10,038 episodes in which the diagnosis of acute myocardial infarction was confirmed or excluded, 938 patients (9.34%) received an incorrect classification - undertriage or overtriage.

Conclusion: This study showed that the specificity of the Manchester Triage System was very good. However, the low sensitivity based on the Manchester Triage System indicated that patients in high priority categories were undertriaged, leading to longer wait times and associated increased risks of adverse events.