Aligning ambulance dispatch priority to patient acuity: A methodology

Abstract

Objective: In Victoria, Australia, Emergency Medical Service (EMS) demand has increased almost 5% per annum over the past 5 years. This may adversely affect response times to time-critical patients. Additionally, >55% of cases have received Code 1 (lights/sirens) responses. Primary telephone triage occurs using the Medical Priority Dispatch System (MPDS); however, MPDS is reported to be highly sensitive, with common over-triage. The present study describes the methodology applied to better align the response allocated to MPDS determinant codes with patient acuity.

Methods: Data between October 2013 and August 2014 were extracted from the Ambulance Victoria data warehouse. The decision to allocate MPDS determinant codes to a lower response priority and/or secondary triage was based on epidemiological profiling and, in some cases, expert panel review.

Results: The review identified 105 MPDS codes receiving a Code 1 response as suitable for a Code 2 (urgent) response, and 221 Code 1 or 2 codes as suitable for secondary triage. Data analysis estimated a reduction in Code 1 responses by 28%, and an increase in the secondary triage caseload by 120%. Modelling also predicted a 2.6 percentage point improvement in the proportion of Code 1 cases attended within 15 min.

Conclusion: Analysis of a large EMS dataset supported changes to the EMS response priority for a number of MPDS determinant codes. Such changes should improve the alignment between EMS response and patient acuity, and improve response times to time-critical patients. Other EMS with electronic data could consider testing this methodology.

Keywords: emergency medical dispatch; emergency medical services; methods; patient acuity; triage.