The Impact of First Responder Intervention on Survival in Out-of-Hospital Cardiac Arrest in Emilia-Romagna Region

Out-of-hospital cardiac arrest (OHCA) is a life-threatening emergency and one of the leading causes of death worldwide. Survival depends critically on how quickly help arrives and whether cardiopulmonary resuscitation (CPR) and defibrillation are started early. In recent years, many regions in Europe and Italy, including Emilia-Romagna, have introduced systems that alert nearby volunteers, called First Responders (FRs), through smartphone applications (such as DAE RespondER). These individuals can reach the patient before emergency medical services (EMS) and begin life-saving actions. The FIRSST-RER study aims to evaluate whether the intervention of First Responders improves survival in patients with out-of-hospital cardiac arrest in Emilia-Romagna. This is a multicentre observational study involving approximately 5,000 adult patients who experienced cardiac arrest between 2018 and 2025 and were treated by the regional emergency system. The study compares two groups of patients: those who received help from at least one First Responder activated via the app those who did not receive First Responder intervention The main objective is to determine whether First Responders increase survival at 30 days after cardiac arrest. Additional objectives include evaluating: survival at 6 months and 1 year neurological outcomes (brain function recovery) Data for this study are collected from existing healthcare and emergency system databases, including EMS dispatch records, national health data systems, and the DAE RespondER platform. For patients who survive, follow-up information may be collected through medical records or telephone contact. Importantly, this study does not involve any experimental treatments or changes in patient care. It is based entirely on data already collected during routine emergency care, and therefore does not pose additional risks to patients. All data are handled securely and in compliance with privacy regulations. Personal identifiers are replaced with coded information (pseudonymisation), and only authorised researchers can access the data. Patients who are alive may be contacted to provide consent and additional follow-up information; participation is voluntary, and consent can be withdrawn at any time. The results of this study will provide important evidence on the effectiveness of citizen responder systems and may help guide future improvements in emergency response organisation, public health strategies, and training programmes. Ultimately, the goal is to increase survival and improve outcomes for people experiencing cardiac arrest in the community.