Comparison of patient acuity, transport patterns, and outcomes according to pre-contact vs. post-contact helicopter emergency medical service requests in trauma patients: A nationwide analysis of the Japanese Society for Aeromedical Services Registry.
Chinese journal of traumatology = Zhonghua chuang shang za zhi · 2026-07-08 · Registry study
Abstract
PURPOSE: In Japan, helicopter emergency medical service (HEMS) requests may be initiated either before emergency medical services personnel make patient contact (pre-contact request) or after on-scene assessment (post-contact request). Pre-contact requests may facilitate earlier HEMS activation but may also increase overtriage because dispatch decisions are based on limited pre-arrival information. Trauma-specific nationwide evidence comparing these 2 request patterns remains limited. We therefore compared pre-contact and post-contact HEMS requests among trauma patients in the Japanese Society for Aeromedical Services Registry to examine differences in severity, urgency, transport patterns, and outcomes, to inform dispatch policy and physician-staffed HEMS utilization. METHODS: Data from the Japanese Society for Aeromedical Services Registry cases between January 1, 2020, and December 31, 2022 were retrospectively analyzed, focusing on 24,195 patients with trauma. Patients with trauma/external-cause cases were included, whereas internal medical cases, cases with missing trauma/external-cause classification, and cases with missing or unclassifiable request-timing data were excluded. Severity was assessed using the National Advisory Committee for Aeronautics score, and urgency was evaluated using the Japan Triage and Acuity Scale. Continuous variables were compared using the Wilcoxon rank-sum test and categorical variables using Pearson's Chi-squared test. RESULTS: Of the 24,195 patients with trauma, there were 7321 in the pre-contact request group and 16,874 in the post-contact request group. Patients in the pre-contact request group were younger (p = 0.008), and the percentage of males was higher (p < 0.001). The median National Advisory Committee for Aeronautics scores were similar between groups (p = 0.873), whereas the Japan Triage and Acuity Scale differed statistically between groups (p = 0.010). Transportation by helicopter and intensive care unit/high care unit-level disposition were more frequent in the post-contact group (p < 0.001). Although some time intervals were shorter in the pre-contact group, the absolute differences were small. No clinically meaningful differences were observed in hospital length of stay or survival-related outcomes. CONCLUSION: In this retrospective nationwide trauma registry analysis, pre-contact requests did not demonstrate a clinically meaningful advantage in major outcomes compared with post-contact requests. Although some process intervals were shorter in the pre-contact group, the absolute differences were small. Because several outcome-related variables had substantial missingness, these comparisons should be interpreted cautiously. Refinement of dispatch criteria may help optimize physician-staffed HEMS utilization.