Temporal trends in bystander cardiopulmonary resuscitation and favourable neurological outcome among older patients with out-of-hospital cardiac arrest stratified by bystander–patient relationship and age: A JCS-ReSS Study

Aim To describe temporal trends in bystander cardiopulmonary resuscitation (CPR) and favourable neurological outcomes among older patients with bystander-witnessed out-of-hospital cardiac arrest (OHCA) according to bystander–patient relationship and age. Methods A total of 322,943 patients aged ≥65 years with bystander-witnessed OHCA of cardiac origin were enrolled from the All-Japan Utstein Registry (2005–2022). Patients were stratified by age (65–74, 75–89, and ≥90 years) and bystander type (family member, friend/colleague/passerby, or other). Temporal trends in the proportions of bystander CPR and favourable neurological outcome at 1-month, defined as Cerebral Performance Category (CPC) 1–2, were assessed using the Cochran–Armitage test. Results During the study period, the annual proportions of bystander CPR and CPC 1–2 in family member-witnessed OHCAs significantly increased across all age groups (all p for trend < 0.001). However, bystander CPR remained at approximately 50% in all age groups. In other-witnessed OHCAs, bystander CPR also significantly increased across all age groups (all p for trend < 0.001). However, CPC 1–2 significantly increased only in those aged 65–74 years (p for trend < 0.05), with no significant temporal trend in older groups. Among those aged ≥90 years, bystander CPR increased to approximately 80%, whereas CPC 1–2 remained at approximately 1%, with no significant temporal trend. Conclusions Temporal trends in bystander CPR and CPC 1–2 varied according to bystander–patient relationship and age. Further investigation is warranted to identify the factors underlying the observed differences in bystander CPR and favourable neurological outcomes.