Assessing sensitivity and specificity of the Manchester Triage System in the evaluation of acute coronary syndrome in adult patients in emergency care: a systematic review.

BACKGROUND: Triage is the first assessment and sorting process used to prioritize patients arriving in the emergency department (ED). As a triage tool, the Manchester Triage System (MTS) must have a high sensitivity to minimize the occurrence of under-triage, but must not compromise specificity to avoid the occurrence of overtriage. Sensitivity and specificity of the MTS can be calculated using the frequency of appropriately assigned clinical priority levels for patients presenting to the ED. However, although there are well established criteria for the prioritization of patients with suspected acute coronary syndrome (ACS), several studies have reported difficulties when evaluating patients with this condition.
OBJECTIVE: The objective of this review was to synthesize the best available evidence on assessing the sensitivity and specificity of the MTS for screening high-level priority adult patients presenting to the ED with ACS.
METHOD: The current review considered studies that evaluated the use of the MTS in the risk classification of adult patients in the ED. In this review, studies that investigated the priority level, as established by the MTS to screen patients under suspicion of ACS or the sensitivity and specificity of the MTS, for screening patients before the medical diagnosis of ACS were included. This review included both experimental and epidemiological study designs.
RESULTS: The results were presented in a narrative synthesis. Six studies were appraised by the independent reviewers. All appraised studies enrolled a consecutive or random sample of patients and presented an overall moderate methodological quality, and all of them were included in this review. A total of 54,176 participants were included in the six studies. All studies were retrospective. Studies included in this review varied in content and data reporting. Only two studies reported sensitivity and specificity values or all the necessary data to calculate sensitivity and specificity. The remaining four studies presented either a sensitivity analysis or the number of true positives and false negatives. However, these four studies were conducted considering only data from patients diagnosed with ACS. Sensitivity values were relatively uniform among the studies: 0.70-0.80. A specificity of 0.59 was reported in the study including only patients with non-traumatic chest pain. On the other hand, in the study that included patients with any complaint, the specificity of MTS to screen patients with ACS was 0.97.
CONCLUSION: The current review demonstrates that the MTS has a moderate sensitivity to evaluate patients with ACS. This may compromise time to treatment in the ED, an important variable in the prognosis of ACS. Atypical presentation of ACS, or high specificity, may also explain the moderate sensitivity demonstrated in this review. However, because of minimal data, it is not possible to confirm this hypothesis. It is difficult to determine the acceptable level of sensitivity or specificity to ensure that a certain triage system is safe.