Title:
Emergency Severity Index version 4: a valid and reliable tool in pediatric emergency department triage.

Abstract:
The Emergency Severity Index version 4 (ESI v.4) is the most recently implemented 5-level triage system. The validity and reliability of this triage tool in the pediatric population have not been extensively established. The goals of this study were to assess the validity of ESI v.4 in predicting hospital admission, emergency department (ED) length of stay (LOS), and number of resources utilized, as well as its reliability in a prospective cohort of pediatric patients.
The first arm of the study was a retrospective chart review of 780 pediatric patients presenting to a pediatric ED to determine the validity of ESI v.4. Abstracted data included acuity level assigned by the triage nurse using ESI v.4 algorithm, disposition (admission vs discharge), LOS, and number of resources utilized in the ED. To analyze the validity of ESI v.4, patients were divided into 2 groups for comparison: higher-acuity patients (ESI levels 1, 2, and 3) and lower-acuity patients (ESI levels 4 and 5). Pearson χ analysis was performed for categorical variables. For continuous variables, we conducted a comparison of means based on parametric distribution of variables. The second arm was a prospective cohort study to determine the interrater reliability of ESI v.4 among and between pediatric triage (PT) nurses and pediatric emergency medicine (PEM) physicians. Three raters (2 PT nurses and 1 PEM physician) independently assigned triage scores to 100 patients; k and interclass correlation coefficient were calculated among PT nurses and between the primary PT nurses and physicians.
In the validity arm, the distribution of ESI score levels among the 780 cases are as follows: ESI 1: 2 (0.25%); ESI 2: 73 (9.4%); ESI 3: 289 (37%); ESI 4: 251 (32%); and ESI 5: 165 (21%). Hospital admission rates by ESI level were 1: 100%, 2: 42%, 3: 14.9%, 4: 1.2%, and 5: 0.6%. The admission rate of the higher-acuity group (76/364, 21%) was significantly greater than the lower-acuity group (4/415, 0.96%), P < 0.001. The mean ED LOS (in minutes) for the higher-acuity group was 257 (SD, 132) versus 143 (SD, 81) in the lower-acuity group, P < 0.001. The higher-acuity group also had significantly greater use of resources than the lower-acuity group, P < 0.001. The percentage of low-acuity patients receiving no resources was 54%, compared with only 26% in the higher-acuity group. Conversely, a greater percentage of higher-acuity patients utilized 2 or more resources than the lower-acuity cohorts, 43% vs 12%, respectively, P < 0.001. In the prospective reliability arm of the study, 15 PT nurses and 8 PEM attending physicians participated in the study; k among nurses was 0.92 and between the primary triage nurses and physicians was 0.78, P < 0.001. The intraclass correlation coefficient was 0.96 for PT nurses and 0.91 between the primary triage nurse and physicians, P < 0.001.
Emergency Severity Index v.4 is a valid predictor of hospital admission, ED LOS, and resource utilization in the pediatric ED population. It is a reliable pediatric triage instrument with high agreement among PT nurses and between PT nurses and PEM physicians.