Correction: Identifying areas of Australia with high out-of-hospital cardiac arrest incidence and low bystander cardiopulmonary resuscitation rates: A retrospective, observational study.

[This corrects the article DOI: 10.1371/journal.pone.0301176.].

Identifying areas of Australia with high out-of-hospital cardiac arrest incidence and low bystander cardiopulmonary resuscitation rates: A retrospective, observational study.

AIM: This study aims to explore regional variation and identify regions within Australia with high incidence of out-of-hospital cardiac arrest (OHCA) and low rates of bystander cardiopulmonary resuscitation (CPR). METHOD: Adult OHCAs of presumed medical aetiology occurring across Australia between 2017 and 2019 were mapped onto local government areas (LGA) using the location of arrest coordinates. Bayesian spatial models were applied to provide "smoothed" estimates of OHCA incidence and bystander CPR rates (for bystander-witnessed OHCAs) for each LGA. For each state and territory, high-risk LGAs were defined as those with an incidence rate greater than the state or territory's 75th percentile and a bystander CPR rate less than the state or territory's 25th percentile. RESULTS: A total of 62,579 OHCA cases attended by emergency medical services across 543 LGAs nationwide were included in the study. Nationally, the OHCA incidence rate across LGA ranged from 58.5 to 198.3 persons per 100,000, while bystander CPR rates ranged from 45% to 75%. We identified 60 high-risk LGAs, which were predominantly located in the state of New South Wales. Within each region, high-risk LGAs were typically located in regional and remote areas of the country, except for four metropolitan areas-two in Adelaide and two in Perth. CONCLUSIONS: We have identified high-risk LGAs, characterised by high incidence and low bystander CPR rates, which are predominantly in regional and remote areas of Australia. Strategies for reducing OHCA and improving bystander response may be best targeted at these regions.

A study protocol for a cluster-randomised controlled trial of smartphone-activated first responders with ultraportable defibrillators in out-of-hospital cardiac arrest: The First Responder Shock Trial (FIRST).

Objective: To describe the First Responder Shock Trial (FIRST), which aims to determine whether equipping frequently responding, smartphone-activated (GoodSAM) first responders with an ultraportable AED can increase 30-day survival rates in OHCA. Methods: The FIRST trial is an investigator-initiated, bi-national (Victoria, Australia and New Zealand), registry-nested cluster-randomised controlled trial where the unit of randomisation is the smartphone-activated (GoodSAM) first responder. High-frequency GoodSAM responders are randomised 1:1 to receive an ultraportable, single-use AED or standard alert procedures using the GoodSAM app.The primary outcome is survival to 30 days. The secondary outcome measures (shockable rhythm, return of spontaneous circulation, event survival, and time to first shock delivery) are routinely collected by OHCA registries in both regions. The trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) (Registration: ACTRN12622000448741) on 22 March 2022. Results: The trial started in November 2022 and the last patient is expected to be enrolled in November 2024. We aim to detect a 7% increase in the proportion of 30-day survivors, from 9% in patients attended by control responders to 16% in patients attended by responders randomised to the ultraportable AED intervention arm. With 80% power, an alpha of 0.05, a cluster size of 1.5 and a coefficient of variation for cluster sizes of 1, the sample size required to detect this difference is 714 (357 per arm). Conclusion: The FIRST study will increase our understanding of the potential role of portable AED use by smartphone-activated community responders and their impact on survival outcomes.

Out-of-Hospital emergency airway management practices: A nationwide observational study from Aotearoa New Zealand.

Background and Objectives: Airway management is crucial for emergency care in critically ill patients outside the hospital setting. An Airway Registry is useful in providing essential information for quality improvement purposes. Therefore, this study aimed to develop an out-of-hospital airway registry and describe airway management practices in Aotearoa New Zealand (AoNZ). Methods: Data from the Aotearoa New Zealand Paramedic Care Collection (ANZPaCC) database were used in a retrospective cohort study covering July 2020 to June 2021. All patients receiving airway interventions were included. An airway intervention was defined as one or more of the following: non-drug assisted endotracheal intubation (NDA-ETI), drug-assisted endotracheal intubation (DA-ETI; where a combination of paralytic agent and sedative were used to aid in intubation), laryngeal mask airway (LMA), oropharyngeal airway (OPA), nasopharyngeal airway (NPA), surgical airway (cricothyroidotomy), suction, jaw thrust. Descriptive statistics were analysed using Chi-Square and logistic regression modelling investigated the relationship between advanced airway success and patient characteristics. Results: The study included 4,529 patients who underwent 7,779 airway interventions. Basic airway interventions were used most frequently: OPA (45.1%), NPA (29.3%), LMA (28.9%), suction (19.9%) and jaw thrust (17.6%). Advanced airway interventions were used less frequently: NDA-ETI (19.8%), DA-ETI (8.7%), and surgical airways (0.2%). The success rate for ETI (including both NDA-ETI and DA-ETI) was 89.4%, with NDA-ETI success at 85.8% and DA-ETI success at 97.7%. ETI first-pass success rates were significantly lower for males (aOR 0.65, 95%CI 0.48-0.87, p < 0.001) and higher for non-cardiac arrest injury patients (aOR 2.94, 95%CI 1.43-6.00, p < 0.001). In this cohort receiving airway interventions the 1-day mortality rate was 41.1%, demonstrating that a high proportion of these patients were severely clinically compromised. Conclusions: Out-of-hospital airway management practices and success rates in AoNZ are comparable to those elsewhere. This research has determined the variables to be used as the AoNZ Paramedic Airway Registry ongoing and has demonstrated baseline outcomes in airway management for ongoing quality improvement using this registry.

The development of a risk-adjustment strategy to benchmark emergency medical service (EMS) performance in relation to out-of-hospital cardiac arrest in Australia and New Zealand.

INTRODUCTION: The aim of this study was to develop a risk adjustment strategy, including effect modifiers, for benchmarking emergency medical service (EMS) performance for out-of-hospital cardiac arrest (OHCA) in Australia and New Zealand. METHOD: Using 2017-2019 data from the Australasian Resuscitation Outcomes Consortium (Aus-ROC) OHCA Epistry, we included adults who received an EMS attempted resuscitation for a presumed medical OHCA. Logistic regression was applied to develop risk adjustment models for event survival (return of spontaneous circulation at hospital handover) and survival to hospital discharge/30 days. We examined potential effect modifiers, and assessed model discrimination and validity. RESULTS: Both OHCA survival outcome models included EMS agency and the Utstein variables (age, sex, location of arrest, witnessed arrest, initial rhythm, bystander cardiopulmonary resuscitation, defibrillation prior to EMS arrival, and EMS response time). The model for event survival had good discrimination according to the concordance statistic (0.77) and explained 28% of the variation in survival. The corresponding figures for survival to hospital discharge/30 days were 0.87 and 49%. The addition of effect modifiers did little to improve the performance of either model. CONCLUSION: The development of risk adjustment models with good discrimination is an important step in benchmarking EMS performance for OHCA. The Utstein variables are important in risk-adjustment, but only explain a small proportion of the variation in survival. Further research is required to understand what factors contribute to the variation in survival between EMS.

Predictive value of the New Zealand Early Warning Score for early mortality in low-acuity patients discharged at scene by paramedics: an observational study.

OBJECTIVES: The utility of New Zealand Early Warning Score (NZEWS) for prediction of adversity in low-acuity patients discharged at scene by paramedics has not been investigated. The objective of this study was to evaluate the association between the NZEWS risk-assessment tool and adverse outcomes of early mortality or ambulance reattendance within 48 hours in low-acuity, prehospital patients not transported by ambulance. DESIGN: A retrospective cohort study. SETTING: Prehospital emergency medical service provided by St John New Zealand over a 2-year period (1 July 2016 through 30 June 2018). PARTICIPANTS: 83 171 low-acuity, adult patients who were attended by an ambulance and discharged at scene. Of these, 41 406 had sufficient recorded data to calculate an NZEWS. PRIMARY AND SECONDARY OUTCOMES AND MEASURES: Binary logistic regression modelling was used to investigate the association between the NZEWS and adverse outcomes of reattendance within 48 hours, mortality within 2 days, mortality within 7 days and mortality within 30 days. RESULTS: An NZEWS greater than 0 was significantly associated with all adverse outcomes studied (p<0.01), compared with the reference group (NZEWS=0). There was a startling correlation between 2-day, 7-day and 30-day mortality and higher early warning scores; the odds of 2-day mortality in patients with an early warning score>10 was 70 times that of those scoring 0 (adjusted OR 70.64, 95% CI: 30.73 to 162.36). The best predictability for adverse outcome was observed for 2-day and 7-day mortality, with moderate area under the receiver operating characteristic curve scores of 0.78 (95% CI: 0.73 to 0.82) and 0.74 (95% CI: 0.71 to 0.77), respectively. CONCLUSIONS: Adverse outcomes in low-acuity non-transported patients show a significant association with risk prediction by the NZEWS. There was a very high association between large early warning scores and 2-day mortality in this patient group. These findings suggest that NZEWS has significant utility for decision support and improving safety when determining the appropriateness of discharging low-acuity patients at the scene.

The epidemiology of out-of-hospital cardiac arrest in Australia and New Zealand: A binational report from the Australasian Resuscitation Outcomes Consortium (Aus-ROC).

INTRODUCTION: The Australasian Resuscitation Outcomes Consortium (Aus-ROC) out-of-hospital cardiac arrest (OHCA) Epistry (Epidemiological Registry) now covers 100% of Australia and New Zealand (NZ). This study reports and compares the Utstein demographics, arrest characteristics and outcomes of OHCA patients across our region. METHODS: We included all OHCA cases throughout 2019 as submitted to the Epistry by the eight Australian and two NZ emergency medical services (EMS). We calculated crude and age-standardised incidence rates and performed a national and EMS regional comparison. RESULTS: We obtained data for 31,778 OHCA cases for 2019: 26,637 in Australia and 5,141 in NZ. Crude incidence was 107.9 per 100,000 person-years in Australia and 103.2/100,000 in NZ. Overall, the majority of OHCAs occurred in adults (96%), males (66%), private residences (76%), were unwitnessed (63%), of presumed medical aetiology (83%), and had an initial monitored rhythm of asystole (64%). In non-EMS-witnessed cases, 38% received bystander CPR and 2% received public defibrillation. Wide variation was seen between EMS regions for all OHCA demographics, arrest characteristics and outcomes. In patients who received an EMS-attempted resuscitation (13,664/31,778): 28% (range across EMS = 13.1% to 36.7%) had return of spontaneous circulation (ROSC) at hospital arrival and 13% (range across EMS = 9.9% to 20.7%) survived to hospital discharge/30-days. Survival in the Utstein comparator group (bystander-witnessed in shockable rhythm) varied across the EMS regions between 27.4% to 42.0%. CONCLUSION: OHCA across Australia and NZ has varied incidence, characteristics and survival. Understanding the variation in survival and modifiable predictors is key to informing strategies to improve outcomes.

Positive association between ambulance double-crewing and OHCA outcomes: A New Zealand observational study.

BACKGROUND AND OBJECTIVES: New Zealand emergency medical service (EMS) crewing configurations generally place one (single) or two (double) crew on each responding ambulance unit. Recent studies demonstrated that double-crewing was associated with improved survival from out-of-hospital cardiac arrest (OHCA), therefore single-crewed ambulances have been phased out. We aimed to determine the association between this crewing policy change and OHCA outcomes in New Zealand. METHODS: This is a retrospective observational study using data from the St John OHCA Registry on patients treated during two different time periods: the Pre-Period (1 October 2013-30 June 2015), when single-crewed ambulances were in use by EMS, and the Post-Period (1 July 2016-30 June 2018) when single-crewed ambulances were being phased out. Geographic areas identified as having low levels of double crewing during the Pre-Period were selected for investigation. The outcome of survival to thirty-days post-OHCA was investigated using logistic regression analysis. RESULTS: The proportion of double-crewed ambulances arriving at OHCA events increased in the Post-Period (81.8%) compared to the Pre-Period (67.5%) (p ≤ 0.001). Response times decreased by two minutes (Pre-Period: median 8 min, IQR [6-11], Post-Period: median 6 min, IQR [4-9]; p ≤ 0.001). Thirty-day survival was significantly improved in the Post-Period (OR 1.63, 95%CI (1.04-2.55), p = 0.03). CONCLUSIONS: An association between improved OHCA survival following increased responses by double-crewed ambulances was demonstrated. This study suggests that improvements in resourcing are associated with improved OHCA outcomes.

Factors Associated with Emergency Medical Service Reattendance in Low Acuity Patients Not Transported by Ambulance.

Background: The decision for emergency medical services (EMS) personnel not to transport a patient is challenging: there is a risk of subsequent deterioration but transportation of all patients to hospital would overburden emergency departments. The aim of this large-scale EMS study was to identify factors associated with an increased likelihood of ambulance reattendance within 48 hours in low acuity patients who were not transported by ambulance.Methods: We conducted a 2-year retrospective cohort study using data from the St John New Zealand EMS between 1 July 2016 and 30 June 2018 to investigate demographic and clinical associations with ambulance reattendance.Results: In total, 83,171 low acuity patients not transported by ambulance were included, of whom 4,512 (5.4%) had an EMS ambulance reattend within 48 hours. There were significant associations between EMS reattendance and patient age, sex, ethnicity, deprivation, and event location. Patients aged 60-74 years old had the highest likelihood of ambulance recall (OR 2.87, 95% CI: 2.51-3.28). Males were more likely to have an EMS ambulance reattend within 48 hours (OR 1.17, 95% CI: 1.09-1.25). Maori and Pacific Peoples had a similar likelihood of EMS recall to European/Others; however, the Asian cohort showed a reduced likelihood of reattendance (OR 0.76, 95% CI: 0.62-0.93).There were significant associations between EMS reattendance and non-transport reason, time spent on scene, event type, clinical acuity level (status), and pain score. Shorter (<30 minutes) on scene times were associated with a decreased likelihood of ambulance reattendance, whereas longer scene times (>45 minutes) were associated with an increased likelihood. Medical events were more likely to require reattendance than accident-related events (OR 1.22, 95% CI: 1.13-1.32). Non-transported patients with a severe pain score (7-10/10) were at increased likelihood of requiring reattendance (OR 1.60, 95% CI: 1.33-1.92).Discussion: The overall low rate of EMS reattendance is encouraging. Further research is needed into the clinical presentation of patients requiring ambulance reattendance within 48 hours to determine if there are early warning signs indicative of subsequent deterioration.

Ethnic disparities in the incidence and outcome from out-of-hospital cardiac arrest: A New Zealand observational study.

BACKGROUND: New Zealand (NZ) has an ethnically diverse population. International studies have demonstrated significant differences in health equity by ethnicity; however, there is limited evidence in the context of out-of-hospital cardiac arrest in NZ. We investigated whether heath disparities in incidence and outcome of out-of-hospital cardiac arrest exist between NZ ethnic groups. METHOD: A retrospective observational study was conducted using NZ cardiac arrest registry data for a 2-year period. Ethnic cohorts investigated were the indigenous Maori population, Pacific Peoples and European/Others. Incidence rates, population characteristics and outcomes (Return of Spontaneous Circulation sustained to hospital handover and thirty-day survival) were compared. RESULTS: Age-adjusted incidence rates per 100,000 person-years were higher in Maori (144.4) and Pacific Peoples (113.5) compared to European/Others (93.8). Return of spontaneous circulation sustained to hospital handover was significantly lower in Maori (adjusted OR 0.74, 95% CI 0.64-0.87, p < 0.001). Survival to thirty-days was lower for both Maori (adjusted OR 0.61, 95% CI 0.48-0.78, p < 0.001) and Pacific Peoples (adjusted OR 0.52, 95% CI 0.37-0.72, p < 0.001). A higher proportion of events occurred in all age groups below 65 years old in Maori and Pacific Peoples (p < 0.001), and a higher proportion of events occurred among women in Maori and Pacific Peoples (p < 0.001). CONCLUSIONS: There are significant differences in health equity by ethnicity. Both Maori and Pacific Peoples have higher incidence of out-of-hospital cardiac arrest and at a younger age. Maori and Pacific Peoples have lower rates of survival to thirty-days. Our results provide impetus for targeted health strategies for at-risk ethnic populations.

Direct transport to PCI-capable hospitals after out-of-hospital cardiac arrest in New Zealand: Inequities and outcomes.

BACKGROUND: It is widely accepted that survival from OHCA may be improved through direct transfer of patients to hospitals with percutaneous coronary intervention (PCI) capability. However, within the New Zealand healthcare system there is limited evidence available to support this. We aimed to compare patient characteristics and outcomes following an out-of-hospital cardiac arrest between those patients transported to hospitals with or without PCI-capability within New Zealand. METHOD: A retrospective cohort study was conducted using data from the St John New Zealand OHCA registry for adults treated for an out-of-hospital cardiac arrest of presumed cardiac aetiology between 1 October 2013 and 31 October 2018. Population characteristics were investigated using a Chi-Square analysis. Binary logistic regression modelling was used to investigate outcome differences in survival at 30 days post-event according to receiving hospital PCI-capability. RESULTS: The study included 1750 patients who were transported to hospital following an OHCA. A significantly lower proportion of patients over 65 years (49.9%) were conveyed to hospitals with PCI-capability compared to younger aged patients (15-44 years (52.1%) and 45-64 years (59.7%) (p < 0.001). When ethnic groups were compared, Maori (32.9%) had the lowest proportion transported to PCI-capable hospitals, followed by European (55.6%) then Pacific Peoples (86.2%) (p < 0.001). A lower proportion of patients located rurally (34.7%) were transported to hospitals with PCI-capability compared to patients in an urban location (59.1%) (p < 0.001). Thirty-day survival was higher in patients transported to hospitals with PCI-capability (adjusted OR 1.285, 95%CI (1.01-1.63), p = 0.04). CONCLUSIONS: Patient characteristic differences indicate that inequities in healthcare may exist in New Zealand related to age, ethnic group, and rurality. Thirty-day survival was significantly increased in patients conveyed directly to a hospital with PCI-capability.

Regional variation in the characteristics, incidence and outcomes of out-of-hospital cardiac arrest in Australia and New Zealand: Results from the Aus-ROC Epistry.

INTRODUCTION: The aim of this study was to investigate regional variation in the characteristics, incidence and outcomes of out-of-hospital cardiac arrest (OHCA) in Australia and New Zealand. METHODS: This was a population-based cohort study of OHCA using data from the Aus-ROC Australian and New Zealand OHCA Epistry over the period of 01 January 2015-31 December 2015. Seven ambulance services contributed data to the Epistry with a capture population of 19.8 million people. All OHCA attended by ambulance, regardless of aetiology or patient age, were included. RESULTS: In 2015, there were 19,722 OHCA cases recorded in the Aus-ROC Epistry with an overall crude incidence of 102.5 cases per 100,000 population (range: 51.0-107.7 per 100,000 population). Of all OHCA cases attended by EMS (excluding EMS-witnessed cases), bystander CPR was performed in 41% of cases (range: 36%-50%). Resuscitation was attempted (by EMS) in 48% of cases (range: 40%-68%). The crude incidence for attempted resuscitation cases was 47.6 per 100,000 population (range: 34.7-54.1 per 100,000 population). Of cases with attempted resuscitation, 28% survived the event (range: 21%-36%) and 12% survived to hospital discharge or 30 days (range: 9%-17%; data provided by five ambulance services). CONCLUSION: In the first results of the Aus-ROC Australian and New Zealand OHCA Epistry, significant regional variation in the incidence, characteristics and outcomes was observed. Understanding the system-level and public health drivers of this variation will assist in optimisation of the chain of survival provided to OHCA patients with the aim of improving outcomes.

Description of the ambulance services participating in the Aus-ROC Australian and New Zealand out-of-hospital cardiac arrest Epistry.

OBJECTIVE: The present study aimed to describe and examine similarities and differences in the current service provision and resuscitation protocols of the ambulance services participating in the Aus-ROC Australian and New Zealand out-of-hospital cardiac arrest (OHCA) Epistry. Understanding these similarities and differences is important in identifying ambulance service factors that might explain regional variation in survival of OHCA in the Aus-ROC Epistry. METHODS: A structured questionnaire was completed by each of the ambulance services participating in the Aus-ROC Epistry. These ambulance services were SA Ambulance Service, Ambulance Victoria, St John Ambulance Western Australia, Queensland Ambulance Service, St John Ambulance NT, St John New Zealand and Wellington Free Ambulance. The survey aimed to describe ambulance service and dispatch characteristics, resuscitation protocols and details of cardiac arrest registries. RESULTS: We observed similarities between services with respect to the treatment of OHCA and dispatch systems. Differences between services were observed in the serviced population; the proportion of paramedics with basic life support, advanced life support or intensive care training skills; the number of OHCA cases attended; guidelines related to withholding or terminating resuscitation attempts; and the variables that might be used to define 'attempted resuscitation'. All seven participating ambulance services were noted to have existing OHCA registries. CONCLUSION: There is marked variation between ambulance services currently participating in the Aus-ROC Australian and New Zealand OHCA Epistry with respect to workforce characteristics and key variable definitions. This variation between ambulance services might account for a proportion of the regional variation in survival of OHCA.

Establishing the Aus-ROC Australian and New Zealand out-of-hospital cardiac arrest Epistry.

INTRODUCTION: Out-of-hospital cardiac arrest (OHCA) is a global health problem with low survival. Regional variation in survival has heightened interest in combining cardiac arrest registries to understand and improve OHCA outcomes. While individual OHCA registries exist in Australian and New Zealand ambulance services, until recently these registries have not been combined. The aim of this protocol paper is to describe the rationale and methods of the Australian Resuscitation Outcomes Consortium (Aus-ROC) OHCA epidemiological registry (Epistry). METHODS AND ANALYSIS: The Aus-ROC Epistry is designed as a population-based cohort study. Data collection started in 2014. Six ambulance services in Australia (Ambulance Victoria, SA Ambulance Service, St John Ambulance Western Australia and Queensland Ambulance Service) and New Zealand (St John New Zealand and Wellington Free Ambulance) currently contribute data. All OHCA attended by ambulance, regardless of aetiology or patient age, are included in the Epistry. The catchment population is approximately 19.3 million persons, representing 63% of the Australian population and 100% of the New Zealand population. Data are collected using Utstein-style definitions. Information incorporated into the Epistry includes demographics, arrest features, ambulance response times, treatment and patient outcomes. The primary outcome is 'survival to hospital discharge', with 'return of spontaneous circulation' as a key secondary outcome. ETHICS AND DISSEMINATION: Ethics approval was independently sought by each of the contributing registries. Overarching ethics for the Epistry was provided by Monash University HREC (Approval No. CF12/3938-2012001888). A population-based OHCA registry capturing the majority of Australia and New Zealand will allow risk-adjusted outcomes to be determined, to enable benchmarking across ambulance providers, facilitate the identification of system-wide strategies associated with survival from OHCA, and allow monitoring of temporal trends in process and outcomes to improve patient care. Findings will be shared with participating ambulance services and the academic community.