In the ED, triage helps predict the severity and determines the priority of patient treatment . The well-known triage scales are the Emergency Severity Index in the USA, the CTAS in Canada, the Australian Triage Scale in Australia, and the Manchester Triage Scale in the UK [18, 19]. In Korea, the KTAS was developed based on the CTAS and implemented in 2015. The KTAS consists of a five-level system that classifies patients using a combination of variables, including vital signs and chief complaints [14, 15]. Since the implementation of the KTAS, admission and disposition patterns have changed and reduced mortality in the ED .
Patients visit the ED with a wide variety of complaints, but the proportion of patients with infection is substantial [20, 21]. As early diagnosis of sepsis or septic shock is one of the most important factors affecting the success of treatment, many scoring systems using various markers have been used [22, 23]. However, the current triage tools are inadequate for determining the severity and prognosis of patients presenting to the ED with infection [24, 25].
The qSOFA score is an established screening tool for sepsis . However, qSOFA is not suitable as a screening tool because of its low sensitivity . The MEDS score consists of nine factors associated with a greater mortality risk, including age > 65 years, altered mental status, and terminal illness. The MEDS score has moderate accuracy in predicting mortality in ED patients with suspected infection, and the MEDS is superior to MEWS in predicting mortality in this patient population [7–9]. However, as the nine factors making up the MEDS score include platelet count and neutrophil count, it takes time to obtain the score and it is thus not suitable for use as a triage screening tool in ED.
The Early Warning Score is a simple physiological scoring system that can be easily applied at the bedside . The MEWS is used as a screening tool for septic shock patients who are at risk of clinical deterioration using values of temperature, blood pressure, pulse, respiratory rate, and level of consciousness. MEWS may be useful for screening patients with septic shock [12, 13, 16, 27]. Moreover, the MEWS does not require laboratory test results; therefore, it is immediately available at triage.
However, as the MEWS is somewhat non-specific and does not contain factors related to the chief complaint, there is a limitation in patients with infection. On the other hand, the KTAS includes the chief complaint and the vital signs, but the hemodynamic criteria are not subdivided. However, the KTAS and MEWS can be applied to ED triage because laboratories are not required. Therefore, we hypothesized that supplementing the physiological data with MEWS to KTAS could help determine prompt prognosis in infected patients.
As the KTAS includes both vital signs and chief complaints, and the MEWS includes vital signs, the KMEWS, the sum of the KTAS and the MEWS, has a weighting value for the initial vital signs. In the multivariable logistic regression analysis of this study, KTAS and KMEWS were independently associated with septic shock and showed similar odds ratios for septic shock. Therefore, the KMEWS was calculated by combining the two scores. As a result, KMEWS showed similar or higher AUC values for septic shock, ICU admission, and mortality compared to either the KTAS score or the MEWS alone. The MEDS had a slightly higher AUC value than the KMEWS, but it is unsuitable for use as a septic screening tool in the ED. Therefore, KMEWS could be a useful prognostic tool for triaging patients with suspected infection in the ED.
Nevertheless, this study had some limitations. First, it was a single-center observational study that included only patients admitted to the hospital via the ED. Patients who had transferred to another hospital or died in the ED were excluded. Therefore, the generalizability of our results may be limited. Second, it included a collection of retrospective data that could introduce potential information biases and had much missing data. Third, the sepsis diagnosis process was excluded because it was a retrospective study of patients already diagnosed with an infectious disease. Inclusion criteria in our study were based on ICD-10 codes related to infection, and no blood culture reports were available. The diagnosis of septic shock was defined as sepsis with a serum lactate level > 2 mmol/L, which did not reflect the patient's volume state. Finally, there could have been inter-clinician variability in calculating the KTAS score and the MEWS during triage.