Population-based implementation of a mobile emergency medical service platform in Hiroshima, Japan

In Japan, despite high emergency medical services (EMS) demand (exceeding 7.6 million ambulance dispatches in 2023), reliance on paper-based operations and phone communication continues to delay hospital coordination. Digitizing and standardizing prehospital data collection is an important step toward improving EMS efficiency. This study describes the implementation of a mobile application to streamline EMS operations in Hiroshima Prefecture, Japan, and characterizes the population-based prehospital data it captures. This population-based, descriptive study analyzed EMS transport cases, including interhospital transfers, in Hiroshima Prefecture from October 2023 to December 2024. Our mobile app was used by EMS personnel to collect structured data, including demographics, chief complaints, past medical histories, medications, vital signs, and prehospital interventions. The app featured a dedicated data entry mode for cardiac arrest cases; these data were aggregated and analyzed separately. Data entry was facilitated by features such as optical character recognition (OCR), voice input, and automatic coding standardization (e.g., ICD-10). During the 15-month study period, 147,213 EMS transport cases were eligible for analysis. 131,843 (90%) were emergency transports, including 129,855 standard emergency transport cases and 1,988 cardiac arrest mode cases, and 15,370 (10%) were interhospital transfers. Of the standard emergency transport patients, the median age was 75 years (< 18 years, 7%, 65–84, 39%, > 84, 26%), and 50% were male. Common chief complaints were fatigue/weakness (8%), abdominal pain (8%), and shortness of breath (7%). Hypertension (24%) and diabetes (14%) were the most prevalent comorbidities. The median on-scene time was 19 min, and the median transport time was 11 min. Hospital acceptance was achieved on the first request in 66% of cases, with a median negotiation time of 5.2 min. The OCR feature was used in 74% of cases, and voice input in 5%. A total of 1,988 cases of cardiac arrest or suspected cardiac arrest were recorded, providing detailed data on prehospital settings. Our mobile app was used to achieve standardized and real-time data collection for 147,213 cases in Hiroshima Prefecture. Future research may explore the potential impact of the app on clinical outcomes and examine possibilities for integration with hospital electronic records.