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.

Barriers to CPR initiation and continuation during the emergency call relating to out-of-hospital cardiac arrest: A descriptive cohort study.

AIM: To describe the barriers to cardiopulmonary resuscitation (CPR) initiation and continuation in emergency calls for out-of-hospital cardiac arrest (OHCA). METHODS: We analysed 295 consecutive emergency calls relating to OHCA over a four-month period (1 January - 30 April 2021). Calls included were paramedic-confirmed, non-traumatic, non-EMS-witnessed OHCA, where the caller was with the patient. Calls were listened to in full and coded in terms of barriers to CPR initiation and continuation, and patient and caller characteristics. RESULTS: Overall, CPR was performed in 69% of calls and, in 85% of these, callers continued performing CPR until EMS arrival. Nearly all callers (99%) experienced barriers to CPR initiation and/or continuation during the call. The barriers identified were classified into eight categories: reluctance, appropriateness, emotion, bystander physical ability, patient access, leaving the scene, communication failure, caller actions and call-taker instructions. Of these, bystander physical ability was the most prevalent barrier to both CPR initiation and continuation, occurring in 191 (65%) calls, followed by communication failure which occurred in 160 (54%) calls. Callers stopping or interrupting CPR performance due to being fatigued was lower than expected (n = 54, 26% of callers who performed CPR). Barriers to CPR initiation that related to bystander physical ability, caller actions, communication failure, emotion, leaving the scene, patient access, procedural barriers, and reluctance were mostly overcome by the caller (i.e., CPR was performed). CONCLUSION: Barriers to CPR initiation and continuation were commonly experienced by callers, however they were frequently overcome. Future research should investigate the strategies that were successful.

Out-of-hospital cardiac arrest in residential aged care facilities is independently associated with lower survival in Perth, Australia.

Aim: To compare out-of-hospital cardiac arrest (OHCA) characteristics and outcomes between people aged ≥ 65 years who arrested in a residential aged care facility (RACF) versus a private residence in Perth, Australia. Methods: We undertook a retrospective cohort study of OHCA cases attended by emergency medical services (EMS) in Perth, January 2018-December 2021. OHCA patient and event characteristics and survival outcomes were compared via univariate analysis. Multivariable logistic regression was used to investigate the relationship between residency type and (i) return of spontaneous circulation (ROSC) at emergency department (ED) and (ii) 30-day survival. Results: A total of 435 OHCA occurred in RACFs versus 3,395 in private residences. RACF patients were significantly older (median age: 86 [IQR 79, 91] vs 78 [71, 85] years; p < 0.001), more commonly female (50.1% vs 36.8%; p < 0.001), bystander-witnessed arrests (34.9% vs 21.5%; p < 0.001), received bystander cardiopulmonary resuscitation (42.1% vs 28.6%; p < 0.001), had less shockable first monitored rhythms (4.0% vs 8.1%; p = 0.002) and more frequently had a "do not resuscitate" order identified (46.0% vs 13.6%; <0.001). Among those with EMS-attempted resuscitation or with defibrillation before EMS arrival, ROSC at ED and 30-day survival were significantly lower in the RACF group (6.2% vs 18.9%; p < 0.001 and 1.9% vs 7.7%; p < 0.001). The adjusted odds of ROSC at ED (aOR: 0.22 [95%CI: 0.10, 0.46]) and 30-day survival (aOR: 0.20 [95%CI 0.05, 0.92]) were significantly lower for RACF residents. Conclusion: RACF residency was an independent predictor of lower survival from OHCA, highlighting the importance of end-of-life planning for RACF residents.

Effect of a national awareness campaign on ambulance attendances for chest pain and out-of-hospital cardiac arrest.

AIM: Awareness of heart attack symptoms may enhance health-seeking behaviour and prevent premature deaths from out-of-hospital cardiac arrest (OHCA). We sought to investigate the impact of a national awareness campaign on emergency medical service (EMS) attendances for chest pain and OHCA. METHODS: Between January 2005 and December 2017, we included registry data for 97,860 EMS-attended OHCA cases from 3 Australian regions and dispatch data for 1,631,217 EMS attendances for chest pain across 5 Australian regions. Regions were exposed to between 11 and 28 months of television, radio, and print media activity. Multivariable negative binomial models were used to explore the effect of campaign activity on the monthly incidence of EMS attendances for chest pain and OHCA. RESULTS: Months with campaign activity were associated with an 8.8% (IRR 1.09, 95% CI: 1.07, 1.11) increase in the incidence of EMS attendances for chest pain and a 5.6% (IRR 0.94, 95% CI: 0.92, 0.97) reduction in OHCA attendances. Larger intervention effects were associated with increasing months of campaign activity, increasing monthly media spending and media exposure in 2013. In stratified analyses of OHCA cases, the largest reduction in incidence during campaign months was observed for unwitnessed arrests (IRR 0.93, 95% CI: 0.90, 0.96), initial non-shockable arrests (IRR 0.93, 95% CI: 0.90, 0.97) and arrests occurring in private residences (IRR 0.95, 95% CI: 0.91, 0.98). CONCLUSION: A national awareness campaign targeting knowledge of heart attack symptoms was associated with an increase in EMS use for chest pain and a reduction in OHCA incidence and may serve as an effective primary prevention strategy for OHCA.

Use of ketamine wafer for pain management by volunteer emergency medical technicians in rural Western Australia.

OBJECTIVE: To describe the use of sublingual ketamine wafers administered by volunteer emergency medical technicians (EMTs) for pain management to patients in rural Western Australia (WA). METHODS: This retrospective cohort study included patients older than 12 years who were attended by volunteer EMTs in Esperance, Lancelin and Kalbarri, WA and received analgesic medications from 2018 to 2021. Patients who received ketamine wafers with/without other analgesics were compared to (i) patients who received only oral paracetamol and (ii) patients who received inhalational methoxyflurane without ketamine wafers with/without paracetamol. RESULTS: The present study included 826 patients, among whom 149 patients received ketamine wafer with/without other analgesics, 82 paracetamol only and 595 methoxyflurane with/without paracetamol. Patients who received ketamine wafers were younger (median age 49 years vs 54 years for the paracetamol group vs 58 years for the methoxyflurane group), required a longer median transport interval (56 min vs 20 min vs 8 min), trauma-related (73% vs 35% vs 54%), and presented higher median initial pain score (9 vs 3 vs 8 out of 10) than those who received paracetamol and those who received methoxyflurane, respectively. Eight in the ketamine wafers group (5.4%) had a record of nausea/vomiting after the administration of ketamine wafers. CONCLUSIONS: Sublingual ketamine wafer was administered by volunteer EMTs without any evidence of major adverse events in rural WA and deemed useful as an additional pain management option when long transport to hospital was needed. No other symptoms that may be associated with the use of ketamine were recorded.

"It's not time for us to sit down yet": how group exercise programs can motivate physical activity and overcome barriers in inactive older adults.

PURPOSE: Physical activity and exercise are critical for older adults' physical and mental health. The purpose of this qualitative study was to richly capture the motivators of and barriers to engaging in physical activity in previously inactive older adults who participated in a three-arm randomized controlled trial (RCT) of eight-week group exercise interventions. METHODS: We conducted a qualitative content analysis of individual interviews with fifteen participants-five from each study arm: strength training, walking, and inactive control. Participants included nine females and six males ranging from 60 to 86 years of age. RESULTS: Key motivators of physical activity included perceived improvements in physical and mental health, positive social influences, observed health deterioration in others, and the desire to spend time with and take care of family members. Barriers to physical activity included existing health conditions, fear of getting hurt, negative social influences, perceived lack of time and motivation, inconvenient times and locations, and monetary cost. CONCLUSIONS: Our findings add to the body of literature identifying factors that motivate and stand in the way of older adults' engagement in physical activity. These factors influence older adults' self-efficacy and should be incorporated into the design of new and existing programs to encourage initiation and maintenance of physical activity.

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.

Did lockdown influence bystanders' willingness to perform cardiopulmonary resuscitation? A worldwide registry-based perspective.

AIM: Bystander cardiopulmonary resuscitation (CPR) significantly increases the survival rate after out-of-hospital cardiac arrest. Using population-based registries, we investigated the impact of lockdown due to Covid-19 on the provision of bystander CPR, taking background changes over time into consideration. METHODS: Using a registry network, we invited all registries capable of delivering data from 1. January 2017 to 31. December 2020 to participate in this study. We used negative binominal regression for the analysis of the overall results. We also calculated the rates for bystander CPR. For every participating registry, we analysed the incidence per 100000 inhabitants of bystander CPR and EMS-treated patients using Poisson regression, including time trends. RESULTS: Twenty-six established OHCA registries reported 742 923 cardiac arrest patients over a four-year period covering 1.3 billion person-years. We found large variations in the reported incidence between and within continents. There was an increase in the incidence of bystander CPR of almost 5% per year. The lockdown in March/April 2020 did not impact this trend. The increase in the rate of bystander CPR was also seen when analysing data on a continental level. We found large variations in incidence of bystander CPR before and after lockdown when analysing data on a registry level. CONCLUSION: There was a steady increase in bystander CPR from 2017 to 2020, not associated with an increase in the number of ambulance-treated cardiac arrest patients. We did not find an association between lockdown and bystanders' willingness to start CPR before ambulance arrival, but we found inconsistent patterns of changes between registries.

"If you miss that first step in the chain of survival, there is no second step"-Emergency ambulance call-takers' experiences in managing out-of-hospital cardiac arrest calls.

When a person has an out-of-hospital cardiac arrest (OHCA), calling the ambulance for help is the first link in the chain of survival. Ambulance call-takers guide the caller to perform life-saving interventions on the patient before the paramedics arrive at the scene, therefore, their actions, decisions and communication are integral to saving the patient's life. In 2021, we conducted open-ended interviews with 10 ambulance call-takers with the aim of understanding their experiences of managing these phone calls; and to explore their views on using a standardised call protocol and triage system for OHCA calls. We took a realist/essentialist methodological approach and applied an inductive, semantic and reflexive thematic analysis to the interview data to yield four main themes expressed by the call-takers: 1) time-critical nature of OHCA calls; 2) the call-taking process; 3) caller management; 4) protecting the self. The study found that call-takers demonstrated deep reflection on their roles in, not only helping the patient, but also the callers and bystanders to manage a potentially distressing event. Call-takers expressed their confidence in using a structured call-taking process and noted the importance of skills and traits such as active listening, probing, empathy and intuition, based on experience, in order to supplement the use of a standardised system in managing the emergency. This study highlights the often under-acknowledged yet critical role of the ambulance call-taker in being the first member of an emergency medical service that is contacted in the event of an OHCA.

Descriptive Study of Ambulance Attendances for Older Adults with and without Dementia in Western Australia.

OBJECTIVE: To describe and compare characteristics of ambulance attendances for older adults with and without dementia. METHODS: A retrospective cohort study was conducted using electronic patient care records from the main ambulance service in Western Australia. All attendances for people aged 65 years or older in the years 2019-21 were included. Dementia status was adjudicated from the clinical history and medication lists. Patient and case characteristics of those with and without dementia were compared and stratified by type of residence. RESULTS: There were 277,996 emergency ambulance attendances made by 124,711 older adults, of whom 23.5% had dementia. The mean number of attendances per person was 3.3 in the dementia cohort vs 2.0 in those without dementia. Falls were the leading reason for ambulance attendance. People with dementia were significantly frailer, required longer at-scene intervals, were less likely to be transported as the highest priority, and had lower 30-day survival. CONCLUSIONS: Dementia is common amongst older adults attended by paramedics and is associated with higher ambulance utilization per person. People with dementia attended by paramedics have stronger signals of vulnerability, such as increased frailty. As the number of people living with dementia increases in the future, there are implications for workforce training and service planning. There are opportunities for developing alternatives to emergency department transportation for some people with dementia.

The incidence and outcomes of out-of-hospital cardiac arrest in metropolitan versus rural locations: A systematic review and meta-analysis.

BACKGROUND/AIMS: Rurality poses a unique challenge to the management of out-of-hospital cardiac arrest (OHCA) when compared to metropolitan (metro) locations. We conducted a systematic review of published literature to understand how OHCA incidence, management and survival outcomes vary between metro and rural areas. METHODS: We included studies comparing the incidence or survival of ambulance attended OHCA in metropolitan and rural areas, from a search of five databases from inception until 9th March 2022. The primary outcomes of interest were cumulative incidence and survival (return of spontaneous circulation, survival to hospital discharge (or survival to 30 days)). Meta-analyses of OHCA survival were undertaken. RESULTS: We identified 28 studies (30 papers- total of 823,253 patients) across 13 countries of origin. The definition of rurality varied markedly. There was no clear difference in OHCA incidence between metro and rural locations. Whilst there was considerable statistical heterogeneity between studies, the likelihood of return of spontaneous circulation on arrival at hospital was lower in rural than metro locations (OR = 0.53, 95% CI 0.40, 0.70; I2 = 89%; 5 studies; 90,934 participants), as was survival to hospital discharge/survival to 30 days (OR = 0.52, 95% CI 0.38, 0.71; I2 = 95%; 15 studies; 18,837 participants). CONCLUSIONS: Overall, while incidence did not vary, the odds of OHCA survival to hospital discharge were approximately 50% lower in rural areas compared to metro areas. This suggests an opportunity for improvement in the prehospital management of OHCA within rural locations. This review also highlighted major challenges in standardising the definition of rurality in the context of cardiac arrest research.

Association between initial presenting level of consciousness and patient acuity - A potential application for secondary triage in emergency ambulance calls.

INTRODUCTION: Conscious state assessment is important for the triage of emergency patients. In this study, we measured the association between ambulance patients' conscious state and high versus lower acuity, with a view to informing telephone triage assessment of conscious state. METHODS: Data were analysed from one year of emergency ambulance incidents in Perth, Western Australia. Patient conscious state at the time of paramedic arrival was compared to acuity (based on paramedic assessment and management). We determined the proportion of high-acuity patients across six levels of consciousness (Alert, Confused, Drowsy, Voice Response, Pain Response, Unresponsive) overall, and within individual protocols of the Medical Priority Dispatch System (MPDS). RESULTS: The proportion of high acuity patients increased with each step across the consciousness scale. Applying conscious state as a binary predictor of acuity, the largest increases occurred moving the threshold from Alert to Confused (22.0-48.6% high acuity) and Drowsy to Voice Response (61.9-89.5% high acuity). The Area Under the Curve (AUC) of the Receiver Operating Characteristic was 0.65. Within individual protocols, the highest AUC was in Cardiac Arrest (0.89), Overdose/Poisoning (0.81), Unknown Problem (0.76), Diabetic Problem, (0.74) and Convulsions/Fitting (0.73); and lowest in Heart problems (0.55), Abdominal Pain (0.55), Breathing Problems (0.55), Back Pain (0.53), and Chest Pain (0.52). CONCLUSION: Based on these proportions of high acuity patients, it is reasonable to consider patients with any altered conscious state a high priority. The value of conscious state assessment for predicting acuity varies markedly between MPDS protocols. These findings could help inform secondary triage of ambulance patients during the emergency call.

Older adults who resistance train improve physical function and adopt long-term exercise habits despite COVID-19 restrictions.

Exercise interventions targeting older adults often focus on acute changes, but lasting improvements require the adoption of long-term, independent exercise habits. This study aimed to assess the influence of eight-weeks of resistance training (SSSH) on clinically relevant fall-risk indicators in older adults and to evaluate if SSSH participation altered independent exercise engagement 12 months later. Sixty adults aged 50 yrs+ were randomised into SSSH, Walk, or Control groups and completed questionnaires and muscle strength and flexibility tests pre/post 8 weeks. SSSH and Walk met 2x/wk for 60 min. Twelve months later 24 participants also completed a follow-up survey amid COVID-19 restrictions. Eight-week group changes were analysed using one-way ANOVA with Bonferroni post hoc analyses, and survey responses were compared using paired t-tests with a Bonferroni correction. SSSH demonstrated greater absolute changes over 8 weeks in sleep quality, activity engagement, 30-second-sit-to-stand and upper-body flexibility than Walk or Controls (p < 0.05). Twelve months later, SSSH participants reported significantly increasing independent resistance (+68), aerobic (+125) and flexibility (+26) training minutes per week (all p < 0.01). In conclusion, SSSH reduced fall risk in 8 weeks and sparked older adults to begin and sustain positive exercise habits 12 months later, despite COVID-19 restrictions.

Ambulance dispatch prioritisation for traffic crashes using machine learning: A natural language approach.

INTRODUCTION: Demand for emergency ambulances is increasing, therefore it is important that ambulance dispatch is prioritised appropriately. This means accurately identifying which incidents require a lights and sirens (L&S) response and those that do not. For traffic crashes, it can be difficult to identify the needs of patients based on bystander reports during the emergency phone call; as traffic crashes are complex events, often with multiple patients at the same crash with varying medical needs. This study aims to determine how well the text sent to paramedics en-route to the traffic crash scene by the emergency medical dispatcher (EMD), in combination with dispatch codes, can predict the need for a L&S ambulance response to traffic crashes. METHODS: A retrospective cohort study was conducted using data from 2014 to 2016 traffic crashes attended by emergency ambulances in Perth, Western Australia. Machine learning algorithms were used to predict the need for a L&S response or not. The features were the Medical Priority Dispatch System (MPDS) determinant codes and EMD text. EMD text was converted for computation using natural language processing (Bag of Words approach). Machine learning algorithms were used to predict the need for a L&S response, defined as where one or more patients (a) died before hospital admission, (b) received L&S transport to hospital, or (c) had one or more high-acuity indicators (based on an a priori list of medications, interventions or observations. RESULTS: There were 11,971 traffic crashes attended by ambulances during the study period, of which 22.3 % were retrospectively determined to have required a L&S response. The model with the highest accuracy was using an Ensemble machine learning algorithm with a score of 0.980 (95 % CI 0.976-0.984). This model predicted the need for an L&S response using both MPDS determinant codes and EMD text. DISCUSSION: We found that a combination of EMD text and MPDS determinate codes can predict which traffic crashes do and do not require a lights and sirens ambulance response to the scene with a high degree of accuracy. Emergency medical services could deploy machine learning algorithms to improve the accuracy of dispatch to traffic crashes, which has the potential to result in improved system efficiency.

A scoping review to determine the barriers and facilitators to initiation and performance of bystander cardiopulmonary resuscitation during emergency calls.

Background: To maximise out-of-hospital cardiac arrest (OHCA) patients' survival, bystanders should perform continuous, good quality cardiopulmonary resuscitation (CPR) until ambulance arrival. Objectives: To identify published literature describing barriers and facilitators between callers and call-takers, which affect initiation and performance (continuation and quality) of bystander CPR (B-CPR) throughout the OHCA emergency call. Eligibility criteria: Studies were included if they reported on the population (emergency callers and call-takers), concept (psychological, physical and communication barriers and facilitators impacting the initiation and performance of B-CPR) and context (studies that analysed OHCA emergency calls). Sources of evidence: Medline, CINAHL, Cochrane CENTRAL, Embase, Scopus and ProQuest were searched from inception to 9 March 2022. Charting methods: Study characteristics were extracted and presented in a narrative format accompanied by summary tables. Results: Thirty studies identified factors that impacted B-CPR initiation or performance during the emergency call. Twenty-eight studies described barriers to the provision of CPR instructions and CPR initiation, with prominent themes being caller reluctance (psychological), physical ability (physical), and callers hanging up the phone prior to CPR instructions (communication). There was little evidence examining barriers and facilitators to ongoing CPR performance (2 studies) or CPR quality (2 studies). Conclusions: This scoping review using emergency calls as the source, described barriers to the provision of B-CPR instructions and B-CPR initiation. Further research is needed to explore facilitators and barriers to B-CPR continuation and quality throughout the emergency call, and to examine the effectiveness of call-taker strategies to motivate callers to perform B-CPR.

Emotions in telephone calls to emergency medical services involving out-of-hospital cardiac arrest: A scoping review.

Aims: The purpose of this scoping review was to identify and synthesise existing research evidence on emotions in the context of emergency phone calls to emergency medical services (EMS) involving out-of-hospital cardiac arrest (OHCA). The specific objectives were to identify studies that (1) described emotions during emergency OHCA calls; (2) specified an instrument or method for measuring/assessing emotions; and (3) examined the relationship between emotions and call outcomes or patient outcomes. Methods/Data sources: Five databases were searched on 18 November 2021: Medline, Embase, PsycInfo, CINAHL, and the Cochrane Review Database. Included studies required the following three concepts to be addressed: emotions in the context of EMS calls that involved OHCA. Calls also needed to be made by a 'second-party' caller; and each study needed to address at least one of the three specific objectives, as outlined above.The review was conducted in accordance with the Joanna Briggs Institute guidelines for evidence synthesis for scoping reviews. Results: Thirteen eligible studies were included for synthesis. All studies met Objective 1; six studies met Objective 2; and seven met Objective 3. One study reported patient fatality due to heightened emotions and ensuing ineffective communications between callers and call-takers. Conclusion: The review highlights a significant gap in the evidence base of emotions in emergency OHCA-related calls, and the need for a more comprehensive and effective method in assessing and measuring emotions in this context. Relationships between emotions (their expressions and perceptions) and call outcomes (including patient outcomes) also need more rigorous investigation.

A predictive ambulance dispatch algorithm to the scene of a motor vehicle crash: the search for optimal over and under triage rates.

BACKGROUND: Calls for emergency medical assistance at the scene of a motor vehicle crash (MVC) substantially contribute to the demand on ambulance services. Triage by emergency medical dispatch systems is therefore important, to ensure the right care is provided to the right patient, in the right amount of time. A lights and sirens (L&S) response is the highest priority ambulance response, also known as a priority one or hot response. In this context, over triage is defined as dispatching an ambulance with lights and sirens (L&S) to a low acuity MVC and under triage is not dispatching an ambulance with L&S to those who require urgent medical care. We explored the potential for crash characteristics to be used during emergency ambulance calls to identify those MVCs that required a L&S response. METHODS: We conducted a retrospective cohort study using ambulance and police data from 2014 to 2016. The predictor variables were crash characteristics (e.g. road surface), and Medical Priority Dispatch System (MPDS) dispatch codes. The outcome variable was the need for a L&S ambulance response. A Chi-square Automatic Interaction Detector technique was used to develop decision trees, with over/under triage rates determined for each tree. The model with an under/over triage rate closest to that prescribed by the American College of Surgeons Committee on Trauma (ACS COT) will be deemed to be the best model (under triage rate of ≤ 5% and over triage rate of between 25-35%. RESULTS: The decision tree with a 2.7% under triage rate was closest to that specified by the ACS COT, had as predictors-MPDS codes, trapped, vulnerable road user, anyone aged 75 + , day of the week, single versus multiple vehicles, airbag deployment, atmosphere, surface, lighting and accident type. This model had an over triage rate of 84.8%. CONCLUSIONS: We were able to derive a model with a reasonable under triage rate, however this model also had a high over triage rate. Individual EMS may apply the findings here to their own jurisdictions when dispatching to the scene of a MVC.