Initial shockable rhythm detection among patients with out-of-hospital cardiac arrest by arrest location: A population-based cohort study in Japan

Background We described the patient characteristics, bystander interventions, and outcomes after out-of-hospital cardiac arrest (OHCA) according to arrest location, focusing on initial rhythm and automated external defibrillator (AED) use. Methods We analyzed medical-origin OHCAs from a population-based registry (2016–2024) by arrest location: home, nursing home, or other locations. Patient characteristics, bystander interventions, and outcomes were summarized descriptively. Multivariable logistic regression examined the association between arrest location and initial shockable rhythm. Results Among 2,478 OHCA cases, initial shockable rhythm was identified in 36.3% (221/609) in nursing homes, 7.1% (113/1,582) at home, and 33.4% (96/287) in other locations. After adjustment, the odds of an initial shockable rhythm were higher in nursing homes than at home (adjusted OR, 12.35; 95% CI, 8.93–17.24) and than in other locations (adjusted OR, 2.35; 95% CI, 1.60–3.45). In nursing homes, 97.0% (214/221) of patients with an initial shockable rhythm received an AED shock. One-month survival with favorable neurological outcomes was the lowest in nursing homes (0.8% [5/609]). Conclusions Initial shockable rhythm was identified in more than one-third of arrests occurring in nursing homes, and 97.0% of these patients received an AED shock. This finding may partly reflect earlier AED access, potentially increasing the likelihood of detecting a shockable rhythm soon after collapse. These findings underscore the importance of early rhythm detection through prompt AED use and suggest that extending AED access to home settings warrants further investigation.