Methods

Study design

This study was a registry-based retrospective cohort study using data collected using myOHCA2.0 from 1st April 2023 to 31st March 2024 in Penang, Malaysia. The study was conducted in compliance with the Declaration of Helsinki, and ethics approval was obtained from the Medical Research Ethics Committee of the Ministry of Health, Malaysia (protocol #: KKM/NIHSEC/22-02543).

Study setting

The state of Penang in Malaysia has a population of 1.74 million and a land area of 1039 km2. Penang EMS is a single-tier, hospital-based public service that dispatches ambulances from six government hospitals via the state Medical Emergency Coordination Centre (MECC), supplemented by non-government organisations and private hospitals. The service responds to all OHCAs occurring within the state using an electronic dispatch system (myPHC2.0) for real-time coordination between call dispatchers, paramedics (Assistant Medical Officers), and personnel from receiving hospitals (Fig. 1). Government paramedics are trained in advanced life support (ALS) and are permitted to provide manual defibrillation, administer adrenaline and amiodarone, and establish an advanced airway (via endotracheal tube or supraglottic airway). EMS personnel adhere to the Minimum Standards Required for the Management of Adult OHCA in Prehospital Care Services, published by the College of Emergency Physicians, Academy of Medicine Malaysia in 2016.2 Resuscitation is initiated for unconscious, apnoeic, or abnormal-breathing patients suspected of OHCA and continued if paramedics witnessed bystander CPR. Paramedics may terminate resuscitation under certain criteria (Fig. 2), then confirm absence of signs of life, notify family members, and inform authorities for death certification.

Fig. 1: EMS system coordination for OHCA response in Penang.Abbreviations: out-of-hospital cardiac arrest (OHCA); Medical Emergency Coordination Centre (MECC); dispatcher-assisted cardiopulmonary resuscitation (DACPR).

Fig. 2: Utstein-style patient flow diagram for OHCAs in Penang.Abbreviations: do not attempt resuscitation (DNAR); cardiopulmonary resuscitation (CPR); return of spontaneous circulation (ROSC).

Participants

The Penang OHCA registry includes all OHCA cases occurring in adult, paediatric, and neonatal patients who experienced cessation of cardiac function regardless of aetiology, and who are attended by Penang EMS at any stage during the event.

Variables

Patient and event characteristics were recorded following the Utstein guidelines.3 Additional characteristics relevant to the Malaysian context (e.g., patient ethnicity) were also collected. The primary outcome was any EMS-documented return of spontaneous circulation (ROSC) before Emergency Department arrival. The secondary outcome was 30-day survival.

Data collection

When OHCA is recognised by a dispatcher and confirmed by an on-scene paramedic, an incident record is created on myOHCA2.0. Data collected following the Utstein guidelines3 is populated from three sources: 9-9-9 call details auto-synced via myPHC2.0; paramedic-entered on-scene treatment or transport data; and in-hospital treatment and patient outcome entered by trained research assistants. The myOHCA2.0 platform utilises standardised data-entry fields and automated numeric validation to ensure accuracy and data completeness. Research assistants review each record before finalising it in the registry.

Data analysis

Descriptive statistics were computed for patient, event, response, and outcome characteristics. OHCAs were stratified by whether or not EMS personnel attempted resuscitation, and groups were compared using Mann-Whitney U tests for continuous variables and chi-squared tests for categorical variables. All statistical tests were two-sided, with a p-value less than 0.05 deemed statistically significant. All missing data were acknowledged and excluded from analysis. Data analysis was conducted using SPSS Version 29 (IBM Inc., Armonk, NY, USA).