Validity of the emergency severity index in predicting patient outcomes in a major emergency department

Background and Purpose: The emergency severity index (ESI) triage system has been recommended by the Ministry of Health to classify patients at emergency departments. This study aimed to assess the validity of ESI system (version 4) in the emergency department of a teaching hospital. Outcome measures were hospitalization, emergency department (ED) length of stay, resource consumption, in-hospital mortality, and patient service costs. Methods: In this retrospective cross-sectional study, medical records of 562 ED patients were reviewed to determine the ESI level and outcome measures in April 2013. Possible correlations were assessed using Phi and Cramer's V and Spearman's Rho. Data analysis was performed in SPSS V.16, and P value of 0.05 was considered significant. Results: In this study, frequency of five ESI levels (1-5) was 24, 14, 365, 158 and 0, respectively. In addition, Phi and Cramer’s V for hospitalization and mortality were 0.350 (P<0.001) and 0.345 (P<0.001), respectively. Spearman's Rho for patient service costs, ED length of stay, and resource consumption were -0.434 (P<0.001), -0.015 (P=0.362), and -0.411 (P<0.001), respectively. According to our findings, the association between triage levels and resource consumption was more significant compared to other outcome measures. Conclusion: According to the results of this study, ESI triage ratings could successfully predict patient outcomes in terms of hospitalization, in-hospital mortality, resource consumption, and patient service costs. Therefore, use of this valid triage system is recommended for the arrangement of human and physical resources at emergency departments.