Out-of-hospital cardiac arrest outcomes according to the time of day: a citywide multicenter retrospective observational study

¹Department of Emergency Medicine, Yeungnam University School of Medicine and College of Medicine, Daegu, Korea
²Department of Emergency Medicine, Kyungpook National University Hospital, School of Medicine, Kyungpook National University, Daegu, Korea
³Department of Public Health, Kyungpook National University Hospital, School of Medicine, Kyungpook National University, Daegu, Korea
⁴Department of Emergency Medicine, Daegu Catholic University School of Medicine, Daegu, Korea
⁵Department of Emergency Medicine, Dongsan Medical Center, Keimyung School of Medicine, Daegu, Korea

Correspondence

Jung Ho Kim ,Tel: 053-620-3191, Fax: 053-623-8030, Email: jhkimem@naver.com,

Received: May 23, 2021; Revised: July 22, 2021 Accepted: August 9, 2021. Published online: February 28, 2022.

ABSTRACT

Objective:
The characteristics and prognosis of out-of-hospital cardiac arrest (OHCA) patients can vary due to a variety of factors, including the time of the day. We tried to identify the characteristics and prognosis of OHCA in a Korean metro city based on the time of the day.
Method:
This citywide retrospective observational study was conducted from January 1, 2015, to November 31, 2020, in Daegu, Korea on patients over 18 years of age who were suspected of having a medical etiology of OHCA. We evaluated the characteristics and outcomes of OHCA, according to the time of day, divided into dawn (00:00-05:59), morning (06:00-11:59), afternoon (12:00-17:59), and night (18:00-23:59). The outcome variables were survival to hospital discharge and favorable neurological outcomes.
Results:
The median age of the total of 4,783 OHCA patients in the study was 72.0 years of which 3,096 (64.7%) were males. The number of patients who survived was 317 (7.8%) and 301 (6.3%) were discharged with favorable neurological outcomes. There were 672 (14.0%) patients admitted at dawn, 1,607 (33.6%) in the morning, 1,379 (28.8%) in the afternoon, and 1,125 (23.5%) at night. After adjusting for the possible confounding variables, compared with the morning group, the survival to hospital discharge was low in the afternoon and the night (adjusted odds ratio [aOR], 0.69; 95% confidence interval [CI], 0.48-0.98 and aOR, 0.48; 95% CI, 0.32-0.74). In addition, favorable neurological outcomes were also low in the afternoon and the night compared with the morning (aOR, 0.59; 95% CI, 0.40-0.85 and aOR, 0.62; 95% CI, 0.41-0.93).
Conclusion:
Diurnal differences in OHCA outcomes were observed. Identification of the diurnal OHCA characteristics will be necessary to devise an appropriate regional emergency medical services strategy.

Key words: Diurnal variation; Out-of-hospital cardiac arrest; Outcomes; Resuscitation; Time