Characteristics of patients who received helicopter emergency medical services in Japan from 2012 to 2019: a retrospective analysis of data from Tochigi Prefecture

Background Helicopter Emergency Medical Services (HEMS) has been in operation in Japan since 2001, allowing patients almost anywhere in the nation to receive on-scene emergency treatment from physicians. However, there is insufficient literature on the characteristics of the patients who use Japanese HEMS. Thus, this study aimed to investigate the overall characteristics of patients receiving HEMS care within a single prefecture in Japan. Methods We retrospectively analyzed the data of 5163 patients-in Tochigi Prefecture-who received HEMS care from 2012 to 2019. Descriptive statistics were used to analyze the following aspects of care: diagnosis, severity, background characteristics, geographical and environmental variables, immediate pre-hospital intervention, transportation type, and short-term clinical outcomes. Results Among 7370 HEMS requests received during the study period, treatment was provided to 5163 patients (1.8 cases per day; 3489 men [67.6%]). Nearly 55% (n = 2856) of patients were aged above 60 years. Age peaks were observed at 0-9 years and 60-69 years. The median distance from the base hospital to the site was 26.7 km. The age-standardized rate of HEMS treatment was 30.3 patients per 100,000 people. Cases of trauma and cardiovascular diseases were the most common (65.3%). Most individuals aged 0-9 years and 60-69 years had neurological disease (seizures accounted for 80.5% of this group) and cardiovascular disease, respectively. The number of patients was similar across all four seasons. After immediate pre-hospital intervention, 81.6% of patients receiving HEMS care were transferred by the helicopter ambulance (53.4% and 28.2% to the base hospital and to other hospitals, respectively). Overall, 56.6% of patients receiving HEMS care were transferred to the base hospital, and the short-term recovery rate was above 75%. Intravenous drip and oxygen administration were the most common pre-hospital interventions (93.1% and 72.7%, respectively). Conclusions This study is the first to describe the overall characteristics of HEMS patients using comprehensive data of all HEMS patients in one prefecture in Japan. Further research using both local- and national-level data is needed to accelerate the understanding of the benefits of HEMS.