Advanced Medical Priority Dispatch System Codes and Air Ambulance Helicopter Tasking in New Zealand: A Retrospective Observational Study

Objective: Air ambulance helicopters are a scarce and costly resource in New Zealand.Despite widespread use of the Advanced Medical Priority Dispatch System (AMPDS), no validated framework exists to determine which determinant codes are associated with helicopter tasking.This study aimed to examine whether specific AMPDS codes are associated with an increased likelihood of helicopter arrival at the scene in New Zealand.Methods: A retrospective observational study using all AMPDS-coded incidents recorded by the Emergency Ambulance Communications Centre from January 1, 2023, to December 31, 2024, was conducted.Exclusions included interhospital transfers, search and rescue events, direct air desk notifications, and nonpatient incidents.For each code, incident volume and helicopter arrivals at the scene were measured.Codes were classified as high volume ( 50 helicopter arrivals) or high yield (arrival ratio, 1:10).Results: Among 1,161,169 AMPDS-coded incidents, 34,869 (3.0%) were reviewed by an air desk clinician and 7,688 (0.66%) resulted in a helicopter arrival.Thirty-seven codes generated 50 arrivals, accounting for 59.3% of helicopter responses but representing 440,781 incidents overall.An additional 102 codes had arrival ratios of 1:10, although most had low absolute volumes.Only 3 traffic-related codes (29D06, 29D02N, 29D02K) met both criteria, accounting for 823 incidents (0.07%) and 192 arrivals (2.5%).In contrast, 791 codes never produced a helicopter arrival, including 133 with > 100 incidents.Conclusion: AMPDS codes alone have limited discriminative capacity for helicopter tasking in New Zealand.A small subset of traffic-related codes demonstrated predictive value and may support more targeted referral pathways.Integrating selected high-yield codes with geospatial thresholds and availability of local critical care resources may streamline clinician review, reduce overtriage, and optimize deployment of scarce aeromedical assets.