-Original-

On-Scene Time and Outcomes in Patients with Out-of-Hospital Cardiac Arrest and Return of Spontaneous Circulation at the Scene: A Post-Hoc Analysis of a Multicenter Cohort Study

Hiroto Numata^1,2, Takashi Tagami³, Kensuke Suzuki^1,2, Ryusei Tabata^1,2, Megumi Kohri¹, Tomohito Amano¹, Suzuka Hagiwara³, Shinnosuke Kitano^1,2, Nobuya Kitamura⁴, Yosuke Homma⁵ and Satoo Ogawa¹

¹The Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
²Department of Emergency and Critical Care Medicine, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
³Department of Emergency and Critical Care Medicine, Nippon Medical School Musashi Kosugi Hospital, Kanagawa, Japan
⁴Department of Emergency and Critical Care Medicine, Kimitsu Chuo Hospital, Chiba, Japan
⁵Department of Emergency Medicine, Chiba Kaihin Municipal Hospital, Chiba, Japan

Background: The optimal on-scene time after the return of spontaneous circulation (ROSC) following out-of-hospital cardiac arrest (OHCA) has not been established. This study aimed to investigate the relationship between the on-scene time after ROSC and neurological outcomes.
Methods: We analyzed data recorded in the SOS-KANTO 2017 registry between September 2019 and March 2021. Patients with OHCA who achieved ROSC on the scene were included and categorized into three groups based on on-scene time after ROSC (0-<6 min, 6-<10 min, and ≥10 min). Comparisons were performed using multiple propensity score analysis. The primary outcome was favorable neurological status at one month, defined as cerebral performance categories 1 and 2.
Results: In total, 331 patients were included. Favorable neurological outcomes at one month were observed in 29.1% (32/123) of patients in the 0-<6 min group, 37.2% (35/104) in the 6-<10 min group, and 36.3% (29/104) in the ≥10 min group. There was no significant association between shorter on-scene times (0-<6 min) and favorable neurological outcomes at one month compared to the other groups (adjusted odds ratio [AOR], 0.97; 95% confidence interval [CI], 0.39-2.41 for 6-<10 min; AOR, 0.90; 95% CI, 0.30-2.70 for ≥10 min).
Conclusion: Differences in on-scene time after ROSC were not significantly associated with favorable neurological outcomes at one month. Future research should focus on identifying factors that may influence outcomes, and on exploring strategies to enhance care in the Japanese EMS context.

J Nippon Med Sch 2025; 92: 163-169

Keywords
cardiac arrest, post-resuscitation on-scene time, out-of-hospital

Correspondence to
Takashi Tagami, MD, MPH, PhD, Department of Emergency and Critical Care Medicine, Nippon Medical School Musashi Kosugi Hospital, 1-383 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
t-tagami@nms.ac.jp

Received, September 23, 2024
Accepted, December 20, 2024