Citizen bystander–patient relationship and 1-month outcomes after out-of-hospital cardiac arrest of cardiac origin from the All-Japan Utstein Registry: a prospective, nationwide, population-based, observational study

OBJECTIVES: The presence of a bystander witness is a crucial predictor of patient survival after out-of-hospital cardiac arrest (OHCA). However, the differences in survival and neurological outcomes among different types of citizen bystanders are not well understood. DESIGN: We analysed data from the All-Japan Utstein Registry, a prospective, nationwide, population-based, observational study that was started in January 2005. SETTING: The registry includes all patients with OHCA who were transported to the hospital by emergency medical service (EMS) in Japan. The type of citizen bystander was classified as family member, friend, colleague, passerby or other. PARTICIPANTS: We analysed 210 642 patients in the registry who were 18 years or older and experienced OHCA of cardiac origin witnessed by a citizen bystander between 2005 and 2014. PRIMARY AND SECONDARY OUTCOME MEASURES: The main outcomes were 1 month survival and 1 month survival with minimal neurological impairment. RESULTS: Of the citizen bystander-witnessed cases, 65.1% (137 147/210 642) were witnessed by a family member. However, among patients who survived to 1 month and who had a favourable 1 month neurological outcome, much lower proportions (53.9% (10 907/20 239) and 48.9% (5722/11 696)) were witnessed by a family member. Witness by a friend, colleague or passerby was associated with good 1 month neurological function, after controlling for the patient’s age, first recorded rhythm, gender, bystander cardiopulmonary resuscitation (CPR), use of a public-access automated external defibrillator, dispatcher instructions, collapse-call time and response time compared with witness by a family member (friend: OR 1.35, 95% CI 1.24 to 1.46, colleague: OR 1.63, 95% CI 1.33 to 1.98, passerby: OR 1.60, 95% CI 1.39 to 1.84). CONCLUSIONS: One-month survival and favourable1 month neurological outcome of patients with OHCA of cardiac origin witnessed by a family member were worse than those in cases witnessed by a friend, colleague or passerby, independent of the patient characteristics and the response of EMS.