Validity of the Emergency Severity Index in A finnish emergency Department 

Background: The purpose of acuity assessment, triage, in the emergency department is to recognize critically ill patients and to allocate resources. The Emergency Severity Index (ESI) is used widely around the world and has been shown to be at least as good as other 5-level assessment instruments. In this study, we assess validity of the ESI triage system in a Finnish Emergency department for predicting 30-day mortality as primary outcome and hospital admissions, high dependency unit or intensive care unit admissions as secondary outcomes, and efficiency for predicting emergency department length-of-stay and utilized resources as secondary outcomes. Methods: We collected data of all adult patient visits to the emergency department during a one-month period. The data was analyzed for the primary and secondary outcomes stratified by age: younger adults (18-64 years), older adults (65-79 years) and oldest old (>80 years). Results: Of the 5909 visits, 5511 were eligible for analysis, 2725 of them men. Median age was 59 years; 30-day mortality was 150 (2.7%). In all age groups, 30-day mortality was consecutively higher with statistical significance between each step from between categories 1 to 3. There were 2274 admissions, 190 of the to HDU or ICU. Hospital admission rates were significantly higher between each step between categories 2 to 4 for all adults. HDU/ICU admissions were higher in category 2 than in category 3 in all age groups. Resource utilization was higher in category 3 than in category 4; categories 4 and 5 differed only in the younger adult group. Most patients in categories 4 and 5 required ≥2 and 0 resource, respectively. Median length of stay at the emergency department was 3h 47min. For all patients ED-LOS varied without linearity; LOS was longest in category 3 in all age groups. Conclusions: ESI seems to be a valid tool for acuity assessment in all age groups in our population: it recognized severely ill patients by predicting mortality and hospital admissions in the higher triage categories in all age groups. Having failed to predict both resource consumption and ED-LOS, ESI was not associated with efficiency in our population.