Prevalence and Predictors of Emergency Medical Service Use in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction.

AIM: We aim to describe prevalence of Emergency Medical Service (EMS) use, investigate factors predictive of EMS use, and determine if EMS use predicts treatment delay and mortality in our ST-elevation myocardial infarction (STEMI) cohort. METHOD: We prospectively collected data on 5,602 patients presenting with STEMI for primary percutaneous coronary intervention (PCI) transported to PCI-capable hospitals in Victoria, Australia, from 2013-2018 who were entered into the Victorian Cardiac Outcomes Registry (VCOR). We linked this dataset to the Ambulance Victoria and National Death Index (NDI) datasets. We excluded late presentation, thrombolysed, and in-hospital STEMI, as well as patients presenting with cardiogenic shock and out-of-hospital cardiac arrest. RESULTS: In total, 74% of patients undergoing primary PCI for STEMI used EMS. Older age, female gender, higher socioeconomic status, and a history of prior ischaemic heart disease were independent predictors of using EMS. EMS use was associated with shorter adjusted door-to-balloon (53 vs 72 minutes, p<0.001) and symptom-to-balloon (183 vs 212 minutes, p<0.001) times. Mode of transport was not predictive of 30-day or 12-month mortality. CONCLUSIONS: EMS use in Victoria is relatively high compared with internationally reported data. EMS use reduces treatment delay. Predictors of EMS use in our cohort are consistent with those prevalent in prior literature. Understanding the patients who are less likely to use EMS might inform more targeted education campaigns in the future.

Age as a predictor of clinical outcomes and determinant of therapeutic measures for emergency medical services treated cardiogenic shock.

BACKGROUND: The impact of age on outcomes in cardiogenic shock (CS) is poorly described in the pre-hospital setting. We assessed the impact of age on outcomes of patients treated by emergency medical services (EMS). METHODS: This population-based cohort study included consecutive adult patients with CS transported to hospital by EMS. Successfully linked patients were stratified into tertiles by age (18-63, 64-77, and > 77 years). Predictors of 30-day mortality were assessed through regression analyses. The primary outcome was 30-day all-cause mortality. RESULTS: A total of 3523 patients with CS were successfully linked to state health records. The average age was 68 ± 16 years and 1398 (40%) were female. Older patients were more likely to have comorbidities including pre-existing coronary artery disease, hypertension, dyslipidemia, diabetes mellitus, and cerebrovascular disease. The incidence of CS was significantly greater with increasing age (incidence rate per 100,000 person years 6.47 [95% CI: 6.1-6.8] in age 18-63 years, 34.34 [32.4-36.4] in age 64-77 years, 74.87 [70.6-79.3] in age > 77 years, P < 0.001). There was a step-wise increase in the rate of 30-day mortality with increasing age tertile. After adjustment, compared to the lowest age tertile, patients aged > 77 years had increased risk of 30-day mortality (adjusted hazard ratio = 2.26 [95% CI: 1.96-2.60]). Older patients were less likely to receive inpatient coronary angiography. CONCLUSION: Older patients with EMS-treated CS have significantly higher rates of short-term mortality. The reduced rates of invasive interventions in older patients underscore the need for further development of systems of care to improve outcomes for this patient group.

One-year quality-of-life outcomes of cardiac arrest survivors by initial defibrillation provider.

OBJECTIVE: To assess the long-term functional and health-related quality-of-life (HRQoL) outcomes for out-of-hospital cardiac arrest (OHCA) survivors stratified by initial defibrillation provider. METHODS: This retrospective study included adult non-traumatic OHCA with initial shockable rhythms between 2010 and 2019. Survivors at 12 months after arrest were invited to participate in structured telephone interviews. Outcomes were identified using the Glasgow Outcome Scale-Extended (GOS-E), EuroQol-5 Dimension (EQ-5D), 12-Item Short Form Health Survey and living and work status-related questions. RESULTS: 6050 patients had initial shockable rhythms, 3211 (53.1%) had a pulse on hospital arrival, while 1879 (31.1%) were discharged alive. Bystander defibrillation using the closest automated external defibrillator had the highest survival rate (52.8%), followed by dispatched first responders (36.7%) and paramedics (27.9%). 1802 (29.8%) patients survived to 12-month postarrest; of these 1520 (84.4%) were interviewed. 1088 (71.6%) were initially shocked by paramedics, 271 (17.8%) by first responders and 161 (10.6%) by bystanders. Bystander-shocked survivors reported higher rates of living at home without care (87.5%, 75.2%, 77.0%, p<0.001), upper good recovery (GOS-E=8) (41.7%, 30.4%, 30.6%, p=0.002) and EQ-5D visual analogue scale (VAS) ≥80 (64.9%, 55.9%, 52.9%, p=0.003) compared with first responder and paramedics, respectively. After adjustment, initial bystander defibrillation was associated with higher odds of EQ-5D VAS ≥80 (adjusted OR (AOR) 1.56, 95% CI 1.15-2.10; p=0.004), good functional recovery (GOS-E ≥7) (AOR 1.53, 95% CI 1.12-2.11; p=0.009), living at home without care (AOR 1.77, 95% CI 1.16-2.71; p=0.009) and returning to work (AOR 1.72, 95% CI 1.05-2.81; p=0.031) compared with paramedic defibrillation. CONCLUSION: Survivors receiving initial bystander defibrillation reported better functional and HRQoL outcomes at 12 months after arrest compared with those initially defibrillated by paramedics.

LidocAine Versus Opioids In MyocarDial infarction: the AVOID-2 randomized controlled trial.

AIMS: Opioid analgesia has been shown to interfere with the bioavailability of oral P2Y12 inhibitors prompting the search for safe and effective non-opioid analgesics to treat ischaemic chest pain. METHODS AND RESULTS: The lidocAine Versus Opioids In MyocarDial infarction trial was a prospective, Phase II, prehospital, open-label, non-inferiority, randomized controlled trial enrolling patients with suspected STEACS with moderate to severe pain [numerical rating scale (NRS) at least 5/10]. Intravenous lidocaine (maximum dose 300 mg) or intravenous fentanyl (up to 50 µg every 5 min) were administered as prehospital analgesia. The co-primary end points were prehospital pain reduction and adverse events requiring intervention. Secondary end points included peak cardiac troponin I, cardiac MRI (cMRI) assessed myocardial infarct size and clinical outcomes to 30 days. A total of 308 patients were enrolled. The median reduction in pain score (NRS) was 4 vs. 3 in the fentanyl and lidocaine arms, respectively, for the primary efficacy end point [estimated median difference -1 (95% confidence interval -1.58, -0.42, P = 0.5 for non-inferiority, P = 0.001 for inferiority of lidocaine)]. Adverse events requiring intervention occurred in 49% vs. 36% of the fentanyl and lidocaine arms which met non-inferiority and superiority favouring lidocaine (P = 0.016 for superiority). No significant differences in myocardial infarct size and clinical outcomes at 30 days were seen. CONCLUSION: IV Lidocaine did not meet the criteria for non-inferiority with lower prehospital pain reduction than fentanyl but was safe and better tolerated as analgesia in ST-elevation myocardial infarction (STEMI). Future trials testing non-opioid analgesics in STEMI and whether opioid avoidance improves clinical outcomes are needed. TRIAL REGISTRATION: CTRN12619001521112p.

Impact of prehospital opioid dose on angiographic and clinical outcomes in acute coronary syndromes.

BACKGROUND: An adverse interaction whereby opioids impair and delay the gastrointestinal absorption of oral P2Y12 inhibitors has been established, however the clinical significance of this in acute coronary syndrome (ACS) is uncertain. We sought to characterise the relationship between prehospital opioid dose and clinical outcomes in patients with ACS. METHODS: Patients given opioid treatment by emergency medical services (EMS) with ACS who underwent percutaneous coronary intervention (PCI) between 1 January 2014 and 31 December 2018 were included in this retrospective cohort analysis using data linkage between the Ambulance Victoria, Victorian Cardiac Outcomes Registry and Melbourne Interventional Group databases. Patients with cardiogenic shock, out-of-hospital cardiac arrest and fibrinolysis were excluded. The primary end point was the risk-adjusted odds of 30-day major adverse cardiac events (MACE) between patients who received opioids and those that did not. RESULTS: 10 531 patients were included in the primary analysis. There was no significant difference in 30-day MACE between patients receiving opioids and those who did not after adjusting for key patient and clinical factors. Among patients with ST-elevation myocardial infarction (STEMI), there were significantly more patients with thrombolysis in myocardial infarction (TIMI) 0 or 1 flow pre-PCI in a subset of patients with high opioid dose versus no opioids (56% vs 25%, p<0.001). This remained significant after adjusting for known confounders with a higher predicted probability of TIMI 0/1 flow in the high versus no opioid groups (33% vs 11%, p<0.001). CONCLUSIONS: Opioid use was not associated with 30-day MACE. There were higher rates of TIMI 0/1 flow pre-PCI in patients with STEMI prescribed opioids. Future prospective research is required to verify these findings and investigate alternative analgesia for ischaemic chest pain.

Risk-standardized mortality metric to monitor hospital performance for chest pain presentations.

AIMS: Risk-standardized mortality rates (RSMR) have been used to monitor hospital performance in procedural and disease-based registries, but limitations include the potential to promote risk-averse clinician decisions and a lack of assessment of the whole patient journey. We aimed to determine whether it is feasible to use RSMR at the symptom-level to monitor hospital performance using routinely collected, linked, clinical and administrative data of chest pain presentations. METHODS AND RESULTS: We included 192 978 consecutive adult patients (mean age 62 years; 51% female) with acute chest pain without ST-elevation brought via emergency medical services (EMS) to 53 emergency departments in Victoria, Australia (1/1/2015-30/6/2019). From 32 candidate variables, a risk-adjusted logistic regression model for 30-day mortality (C-statistic 0.899) was developed, with excellent calibration in the full cohort and with optimism-adjusted bootstrap internal validation. Annual 30-day RSMR was calculated by dividing each hospital's observed mortality by the expected mortality rate and multiplying it by the annual mean 30-day mortality rate. Hospital performance according to annual 30-day RSMR was lower for outer regional or remote locations and at hospitals without revascularisation capabilities. Hospital rates of angiography or transfer for patients diagnosed with non-ST elevation myocardial infarction (NSTEMI) correlated with annual 30-day RSMR, but no correlations were observed with other existing key performance indicators. CONCLUSION: Annual hospital 30-day RSMR can be feasibly calculated at the symptom-level using routinely collected, linked clinical, and administrative data. This outcome-based metric appears to provide additional information for monitoring hospital performance in comparison with existing process of care key performance measures.

HOSPITAL CHARACTERISTICS ARE ASSOCIATED WITH CLINICAL OUTCOMES IN PATIENTS WITH CARDIOGENIC SHOCK.

ABSTRACT: Background: Regionalized systems of care for the management of cardiogenic shock (CS) are increasingly being utilized. This study aims to assess whether receiving hospital characteristics such as the availability of 24-hour coronary angiography, on-site cardiac surgery, and annual treated CS volume influence outcomes in patients transferred by emergency medical services (EMS) to hospital with CS. Methods: This population-based cohort study included consecutive adult patients with CS who were transferred to hospital by EMS between January 1, 2015 and June 30, 2019 in Victoria, Australia. Data were obtained from individually linked ambulance, hospital, and state death index data sets. The primary outcome assessed was 30-day mortality stratified by the availability of 24-hour coronary angiography (cardiac center) at the receiving hospital. Results: A total of 3,217 patients were transferred to hospital with CS. The population had an average age of 67.9 +/- 16.1 years, and 1,289 (40.1%) were female. EMS transfer to a cardiac center was associated with significantly reduced rates of 30-day mortality (adjusted odds ratio [aOR], 0.78; 95% confidence interval [CI], 0.64-0.95), compared with noncardiac centers. Compared with the lowest annual CS volume quartile (<18 cases per year), hospitals in the highest volume quartile (>55 cases per year) had reduced risk of 30-day mortality (aOR, 0.71; 95% CI, 0.56-0.91). A stepwise reduction in the adjusted probability of 30-day mortality was observed in patients transferred by EMS to trauma level 1 centers (34.6%), compared with cardiothoracic surgical centers (39.0%), noncardiac surgical metropolitan (44.9%), and rural (51.3%) cardiac centers, all P < 0.05. Conclusion: Receiving hospital characteristics are associated with survival outcomes in patients with CS. These finding have important implications for establishing regionalized systems of care for patients with CS who are transferred to hospital by EMS.

Temperature-related chest pain presentations and future projections with climate change.

BACKGROUND: Climate change has led to increased interest in studying adverse health effects relating to ambient temperatures. It is unclear whether incident chest pain is associated with non-optimal temperatures and how chest pain presentation rates might be affected by climate change. METHODS: The study included ambulance data of chest pain presentations in Melbourne, Australia from 1/1/2015 to 30/6/2019 with linkage to hospital and emergency discharge diagnosis data. A time series quasi-Poisson regression with a distributed lag nonlinear model was fitted to assess the temperature-chest pain presentation associations overall and according to age, sex, socioeconomic status, and event location subgroups, with adjustment for season, day of the week and long-term trend. Future excess chest pain presentations associated with cold and heat were projected under six general circulation models under medium and high emission scenarios. RESULTS: In 206,789 chest pain presentations, mean (SD) age was 61.2 (18.9) years and 50.3 % were female. Significant heat- and cold-related increased risk of chest pain presentations were observed for mean air temperatures above and below 20.8 °C, respectively. Excess chest pain presentations related to heat were observed in all subgroups, but appeared to be attenuated for older patients (≥70 years), patients of higher socioeconomic status (SES), and patients developing chest pain at home. We projected increases in heat-related chest pain presentations with climate change under both medium- and high-emission scenarios, which are offset by decreases in chest pain presentations related to cold temperatures. CONCLUSIONS: Heat- and cold- exposure appear to increase the risk of chest pain presentations, especially among younger patients and patients of lower SES. This will have important implications with climate change modelling of chest pain, in particular highlighting the importance of risk mitigation strategies to minimise adverse health impacts on hotter days.

Determining the sensitivity of emergency dispatcher and paramedic diagnosis of stroke: statewide registry linkage study.

Introduction: Correctly identifying people with suspected stroke is essential for ensuring rapid treatment. Our aims were to determine the sensitivity of emergency dispatcher and paramedic identification of patients with stroke, the factors associated with correct identification, and whether there were any implications for hospital arrival times. Methods: Observational study using patient-level data from the Australian Stroke Clinical Registry (2015-2017) linked with ambulance and emergency department records for the state of Victoria. The registry diagnosis was the reference standard to compare with the provisional diagnoses made by emergency services personnel classified as "suspected" and "not suspected" stroke/transient ischemic attack (TIA). Multivariable logistic and quintile regressions were used to determine factors associated with correct identification and timely arrival to hospital. Results: Overall, 4717 (64%) were matched to ambulance transport records (median age: 73 years, 43% female). Stroke/TIA was suspected in 56% of registrants by call-takers and 69% by paramedics. Older patients (75+ years) (adjusted odds ratio [aOR]: 0.61; 95% confidence interval [CI]: 0.49-0.75), females (aOR: 0.86; 95% CI: 0.75-0.99), those with severe stroke or intracerebral hemorrhage were less often suspected as stroke. Cases identified as stroke had a shorter arrival time to hospital (unadjusted median minutes: stroke, 54 [43, 72] vs not stroke, 66 [51, 89]). Conclusions: Emergency dispatchers and paramedics identified over half of patients with stroke in the prehospital setting. Important patient characteristics, such as being female and those having a severe stroke, were found that may enable refinement of prehospital ambulance protocols and dispatcher/paramedic education. Those correctly identified as stroke, arrived earlier to hospital optimizing their chances of receiving time-critical treatments.

The influence of ambulance offload time on 30-day risks of death and re-presentation for patients with chest pain.

OBJECTIVE: To assess whether ambulance offload time influences the risks of death or ambulance re-attendance within 30 days of initial emergency department (ED) presentations by adults with non-traumatic chest pain. DESIGN, SETTING: Population-based observational cohort study of consecutive presentations by adults with non-traumatic chest pain transported by ambulance to Victorian EDs, 1 January 2015 - 30 June 2019. PARTICIPANTS: Adults (18 years or older) with non-traumatic chest pain, excluding patients with ST elevation myocardial infarction (pre-hospital electrocardiography) and those who were transferred between hospitals or not transported to hospital (eg, cardiac arrest or death prior to transport). MAIN OUTCOME MEASURES: Primary outcome: 30-day all-cause mortality (Victorian Death Index data). SECONDARY OUTCOME: Transport by ambulance with chest pain to ED within 30 days of initial ED presentation. RESULTS: We included 213 544 people with chest pain transported by ambulance to EDs (mean age, 62 [SD, 18] years; 109 027 women [51%]). The median offload time increased from 21 (IQR, 15-30) minutes in 2015 to 24 (IQR, 17-37) minutes during the first half of 2019. Three offload time tertiles were defined to include approximately equal patient numbers: tertile 1 (0-17 minutes), tertile 2 (18-28 minutes), and tertile 3 (more than 28 minutes). In multivariable models, 30-day risk of death was greater for patients in tertile 3 than those in tertile 1 (adjusted rates, 1.57% v 1.29%; adjusted risk difference, 0.28 [95% CI, 0.16-0.42] percentage points), as was that of a second ambulance attendance with chest pain (adjusted rates, 9.03% v 8.15%; adjusted risk difference, 0.87 [95% CI, 0.57-1.18] percentage points). CONCLUSIONS: Longer ambulance offload times are associated with greater 30-day risks of death and ambulance re-attendance for people presenting to EDs with chest pain. Improving the speed of ambulance-to-ED transfers is urgently required.

Gender Disparities in Cardiogenic Shock Treatment and Outcomes.

Cardiogenic shock is associated with a high risk for morbidity and mortality. The impact of gender on treatment and outcomes is poorly defined. This study aimed to evaluate whether gender influences the clinical management and outcomes of patients with prehospital cardiogenic shock. Consecutive adult patients with cardiogenic shock who were transferred to hospital by emergency medical services (EMS) between January 1, 2015 and June 30, 2019 in Victoria, Australia were included. Data were obtained from individually linked ambulance, hospital, and state death index datasets. The primary outcome assessed was 30-day mortality, stratified by patient gender. Propensity score matching was performed for risk adjustment. Over the study period a total of 3,465 patients were identified and 1,389 patients (40.1%) were women. Propensity score matching yielded 1,330 matched pairs with no differences observed in baseline characteristics, including age, initial vital signs, pre-existing co-morbidities, etiology of shock, and prehospital interventions. In the matched cohort, women had higher rates of 30-day mortality (44.7% vs 39.2%, p = 0.009), underwent less coronary angiography (18.3% vs 27.2%, p <0.001), and revascularization with percutaneous coronary intervention (8.9% vs 14.2%, p <0.001), compared with men. In conclusion, in this large population-based study, women with cardiogenic shock who were transferred by EMS to hospital had significantly worse survival outcomes and reduced rates of invasive cardiac interventions compared to men. These data underscore the urgent need for targeted public health measures to redress gender differences in outcomes and variation with clinical care for patients with cardiogenic shock.

Incidence, diagnoses and outcomes of ambulance attendances for chest pain: a population-based cohort study.

AIMS: This study aimed to determine incidences, diagnoses, and outcomes of patients with chest pain attended by paramedics using a large population-based sample. METHODS: Consecutive emergency medical services (EMS) attendances for non-traumatic chest pain in Victoria, Australia from January 2015 to June 2019 were included. Data were individually linked to emergency, hospital admission and mortality records. RESULTS: During the study period (representing 22,186,930 person-years), chest pain was the reason for contacting EMS in 257,017 of 2,736,570 attendances (9.4%). Overall incidence of chest pain attendances was 1,158 (per 100,000 person-years) with a higher incidence observed with increasing age, among females, among Aboriginal and Torres Strait Islanders, in regional settings, and in socially disadvantaged areas. The most common diagnoses were non-specific pain (46%; 30-day mortality 0.5%), non-ST elevation myocardial infarction (5.3%; mortality 1.3%), pneumonia (3.8%; mortality 3.9%), stable coronary syndromes (3.5%; mortality 0.8%), unstable angina (3.3%; mortality 1.3%), and ST-elevation myocardial infarction (2.8%; mortality 7.0%), while pulmonary embolism (0.7%; mortality 3.2%) and aortic pathologies (0.2%; mortality 22.2%) were rare. CONCLUSIONS: Chest pain accounts for one in ten ambulance calls, and underlying causes are diverse. Almost half of patients are discharged from hospital with a diagnosis of non-specific pain and low rates of mortality.

Development and validation of a comprehensive early risk prediction model for patients with undifferentiated acute chest pain.

Aims: Existing risk scores for undifferentiated chest pain focus on excluding coronary events and do not represent a comprehensive risk assessment if an alternate serious diagnosis is present. This study aimed to develop and validate an all-inclusive risk prediction model among patients with undifferentiated chest pain. Methods: We developed and validated a multivariable logistic regression model for a composite measure of early all-inclusive risk (defined as hospital admission excluding a discharge diagnosis of non-specific pain, 30-day all-cause mortality, or 30-day myocardial infarction [MI]) among adults assessed by emergency medical services (EMS) for non-traumatic chest pain using a large population-based cohort (January 2015 to June 2019). The cohort was randomly divided into development (146,507 patients [70%]) and validation (62,788 patients [30%]) cohorts. Results: The composite outcome occurred in 28.4%, comprising hospital admission in 27.7%, mortality within 30-days in 1.8%, and MI within 30-days in 0.4%. The Early Chest pain Admission, MI, and Mortality (ECAMM) risk model was developed, demonstrating good discrimination in the development (C-statistic 0.775, 95% CI 0.772-0.777) and validation cohorts (C-statistic 0.765, 95% CI 0.761-0.769) with excellent calibration. Discriminatory performance for the composite outcome and individual components was higher than existing scores commonly used in undifferentiated chest pain risk stratification. Conclusions: The ECAMM risk score model can be used as an all-inclusive risk stratification assessment of patients with non-traumatic chest pain without the limitation of a single diagnostic outcome. This model could be clinically useful to help guide decisions surrounding the need for non-coronary investigations and safety of early discharge.

Linking Data From the Australian Stroke Clinical Registry With Ambulance and Emergency Administrative Data in Victoria.

Objective: In Australia, approximately 3 in 4 people with acute stroke use an ambulance. Few examples of merging ambulance clinical records, hospital government data, and national registry data for stroke exist. We sought to understand the advantages of using linked datasets for describing the full clinical journey of people with stroke and the possibility of investigating their long-term outcomes based on pre-hospital management of stroke. Method: Patient-level data from the Australian Stroke Clinical Registry (AuSCR) (January 2013-October 2017) were linked with Ambulance Victoria (AV) records and Victorian Emergency Minimum Dataset (VEMD). Probabilistic iterative matching on personal identifiers were used and records merged with a project specific identification number. Results: Of the 7,373 episodes in the AuSCR and 6,001 in the AV dataset; 4,569 (62%) were matched. Unmatched records that were positive for "arrival by ambulance" in the AuSCR and VEMD (no corresponding record in AV) were submitted to AV. AV were able to identify 148/435 additional records related to these episodes. The final cohort included 4,717 records (median age: 73 years, female 42%, ischemic stroke 66%). Conclusion: The results of the data linkage provides greater confidence for use of these data for future research related to pre-hospital management of stroke.

Association of Socioeconomic Status With Outcomes and Care Quality in Patients Presenting With Undifferentiated Chest Pain in the Setting of Universal Health Care Coverage.

BACKGROUND This study aimed to assess whether there are disparities in incidence rates, care, and outcomes for patients with chest pain attended by emergency medical services according to socioeconomic status (SES) in a universal health coverage setting. METHODS AND RESULTS This was a population-based cohort study of individually linked ambulance, emergency, hospital admission, and mortality data in the state of Victoria, Australia, from January 2015 to June 2019 that included 183 232 consecutive emergency medical services attendances for adults with nontraumatic chest pain (mean age 62 [SD 18] years; 51% women) and excluded out-of-hospital cardiac arrest and ST-segment-elevation myocardial infarction. Age-standardized incidence of chest pain was higher for patients residing in lower SES areas (lowest SES quintile 1595 versus highest SES quintile 760 per 100 000 person-years; P<0.001). Patients of lower SES were less likely to attend metropolitan, private, or revascularization-capable hospitals and had greater comorbidities. In multivariable models adjusted for clinical characteristics and final diagnosis, lower SES quintiles were associated with increased risks of 30-day and long-term mortality, readmission for chest pain and acute coronary syndrome, lower acuity emergency department triage categorization, emergency department length of stay >4 hours, and emergency department or emergency medical services discharge without hospital admission and were inversely associated with use of prehospital ECGs and transfer to a revascularization-capable hospital for patients presenting to non-percutaneous coronary intervention centers. CONCLUSIONS In this study, lower SES was associated with a higher incidence of chest pain presentations to emergency medical services and differences in care and outcomes. These findings suggest that substantial disparities for socioeconomically disadvantaged chest pain cohorts exist, even in the setting of universal health care access.

Linking Ambulance Records with Hospital and Death Index Data to Evaluate Patient Outcomes.

OBJECTIVE: Linkage of electronic administrative datasets is becoming increasingly common, offering a powerful resource for research and analysis. However, routine linkage of prehospital data with emergency department (ED) presentation and hospital admission datasets is rare. We describe a methodology used to link ambulance data with hospital ED presentations, admissions, and death records, and examine potential biases between matched and unmatched patients. METHODS: Iterative deterministic linkage methodologies were employed to link clinical, operational, and secondary triage ambulance data to ED presentations, hospital admissions, and death records in Victoria, Australia. Descriptive analyses and standardised differences were used to examine potential biases between matched and unmatched patients. RESULTS: A total of 2,813,913 ambulance records were available for linkage. Of the patients that were transported to a public ED (n=1,753,268), 83.3% matched with an ED record. Only small differences were observed between matched and unmatched patients for sex, year, time of day and attending crew type. The data elements with the largest standardised differences were patient age (0.25) and paramedic diagnosis (0.25). Matched patients were older (mean ± standard deviation: 55.6±25.7 vs 49.0±26.0 years) and more likely to have a paramedic-suspected cardiac, respiratory, neurological, or gastrointestinal/genitourinary condition, suspected infection/sepsis, or pain. CONCLUSION: This linked dataset will facilitate a large body of research into prehospital care and patient outcomes. Although future analysis of matched patients should acknowledge the linkage error rate, our findings suggest that results are likely to be generalisable to the broader ambulance population.

Sex differences in prehospital analgesia in patients presenting with acute coronary syndromes and their association with clinical outcomes.

OBJECTIVES: This study examined if sex differences in prehospital pain scores, opioid administration, and clinical outcomes exist in acute coronary syndrome (ACS) patients. BACKGROUND: Sex differences persist in ACS presentation, management, and outcomes. The impact of sex differences on prehospital pain management of ACS with opioids is unknown. METHODS: Patients presenting with ACS via ambulance (2014-2018) that underwent percutaneous coronary intervention (PCI) were prospectively collected via the Victorian Cardiac Outcomes Registry and Melbourne Interventional Group, linked to the Ambulance Victoria database. The primary outcome was 30-day major adverse cardiac events (MACE). Secondary outcomes were descriptive analyses of prehospital pain score, intravenous morphine equivalent analgesic dosing, plus predictors of MACE and thrombolysis in myocardial infarction (TIMI) 0-1 flow pre-PCI. RESULTS: A total of 10,547 patients were included (female: 2775 [26%]). Opioids were administered to 1585 (57%) females, 5068 (65%) males (p < 0.001). Adjusted 30-day MACE was similar between opioid groups in both sexes (female: odds ratio [OR]: 1.21, confidence interval [CI] 0.82-1.79, p = 0.34; male: OR: 0.89, CI: 0.68-1.16, p = 0.40). Median pain score at presentation was 6 (interquartile range [IQR]: 4, 8) for both sexes. Median opioid dose was 2.5 mg (IQR: 0, 10) in females and 5 mg (IQR: 0, 10) in males (p < 0.001), with similar pain relief achieved. Adjusted rates of TIMI 0-1 pre-PCI were higher in patients administered opioids (female: OR 2.9, CI: 2.07-4.07, p < 0.001; male: OR: 2.67, CI: 2.19-3.25, p < 0.001). CONCLUSIONS: Female patients undergoing PCI received less opioid analgesia, but no sex differences in prehospital pain scores were seen. Opioid administration was associated with impaired antegrade flow in the culprit artery in both sexes, but not short-term MACE. Trials evaluating nonopioid analgesics in ACS are needed.

Incidence and Outcomes of Nontraumatic Shock in Adults Using Emergency Medical Services in Victoria, Australia.

Importance: Nontraumatic shock is a challenging clinical condition, presenting urgent and unique demands in the prehospital setting. There is a paucity of data assessing its incidence, etiology, and clinical outcomes. Objective: To assess the incidence, etiology, and clinical outcomes of patients treated by emergency medical services (EMS) with nontraumatic shock using a large population-based sample. Design, Setting, and Participants: This population-based cohort study included consecutive adult patients with shock not related to trauma who received care by EMS between January 1, 2015, and June 30, 2019, in Victoria, Australia. Data were obtained from individually linked ambulance, hospital, and state death index data sets. During the study period there were 2 485 311 cases attended by EMS, of which 16 827 met the study's inclusion criteria for shock. Main Outcomes and Measures: The primary outcome was 30-day mortality. Secondary outcomes included length of hospital stay, emergency department discharge disposition, rates of coronary angiography and revascularization procedures, and the use of mechanical circulatory support. Results: A total of 12 695 patients were successfully linked, with a mean (SD) age of 65.7 (19.1) years; 6411 (50.5%) were men. The overall population-wide incidence of EMS-treated prehospital shock was 76 (95% CI, 75-77) per 100 000 person-years. An increased incidence was observed in men (79 [77-81] per 100 000 person-years), older patients (eg, aged 70-79 years: 177 [171-183] per 100 000 person-years), regional locations (outer regional or remote: 100 [94-107] per 100 000 person-years), and in areas with increased socioeconomic disadvantage (lowest socioeconomic status quintile: 92 [89-95] per 100 000 person-years). Patients with hospital outcome data were stratified into shock etiologies; 3615 (28.5%) had cardiogenic shock: 3998 (31.5%), septic shock; 1457 (11.5%), hypovolemic shock; and 3625 (28.6%), other causes of shock. Nearly one-third of patients (4158 [32.8%]) were deceased at 30 days. In multivariable analyses, increased age (all etiologies: hazard ratio [HR], 1.04; 95% CI, 1.03-1.04), female sex (cardiogenic shock: HR, 1.26; 95% CI, 1.12-1.42), increased initial heart rate (all etiologies: 1.01; 95% CI, 1.00-1.01), prehospital intubation (all etiologies: HR, 3.93; 95% CI, 3.48-4.44), and preexisting comorbidities (eg, chronic kidney disease, all etiologies: HR, 1.25; 95% CI, 1.10-1.42) were independently associated with 30-day mortality, while higher socioeconomic status (all etiologies: HR, 0.96; 95% CI, 0.94-0.98) and increased initial systolic blood pressure (all etiologies: HR, 0.99; 95% CI, 0.99-0.99) were associated with lower risk. Conclusions and Relevance: This population-level cohort study found that EMS-treated nontraumatic shock was a common condition, with a high risk of morbidity and mortality regardless of etiology. It disproportionately affected men, older patients, patients in regional areas, and those with social disadvantage. Further studies are required to assess how current systems of care can be optimized to improve outcomes.

Predictors of hospital prenotification for STEMI and association of prenotification with outcomes.

BACKGROUND: Delay to reperfusion in ST-elevation myocardial infarction (STEMI) is detrimental, but can be minimised with prehospital notification by ambulance to the treating hospital. We aimed to assess whether prenotification was associated with improved first medical contact to balloon times (FMC-BT) and whether this resulted in better clinical outcomes. We also aimed to identify factors associated with use of prenotification. METHODS: This was a retrospective study of prospective Victorian Cardiac Outcomes Registry data for patients undergoing primary percutaneous coronary intervention for STEMI from 2013-2018. Postcardiac arrest were excluded. Patients were grouped by whether they arrived by ambulance with prenotification (group 1), arrived by ambulance without prenotification (group 2) or self-presented (group 3). We compared groups by FMC-BT, incidence of major adverse cardiac and cerebrovascular events (MACCE), mortality and factors associated with the use of prenotification. RESULTS: 2891 patients were in group 1 (79.3% male), 1620 in group 2 (75.7% male) and 1220 in group 3 (82.9% male). Patients who had prenotification were more likely to present in-hours (p=0.004) and self-presenters had lowest rates of cardiogenic shock (p<0.001). Prenotification had shorter FMC-BT than without prenotification (104 min vs 132 min, p<0.001) Self-presenters had superior clinical outcomes, with no difference between ambulance groups. Groups 1 and 2 had similar 30-day MACCE outcomes (7.4% group 1 vs 9.1% group 2, p=0.05) and similar mortality (4.6% group 1 vs 5.9% group 2, p=0.07). In multivariable analysis, male gender, right coronary artery culprit and in-hours presentation independently predicted use of prenotification (all p<0.05). CONCLUSION: Differences in clinical characteristics, particularly gender, time of presentation and culprit vessel may influence ambulance prenotification. Ambulance cohorts have high-risk features and worse outcomes compared with self-presenters. Improving system inequality in prehospital STEMI diagnosis is recommended for fastest STEMI treatment.

Daylight savings time transitions and risk of out-of-hospital cardiac arrest: An interrupted time series analysis.

BACKGROUND: Many studies have reported increases in the risk of acute cardiovascular events following daylight savings time (DST) transitions. We sought to investigate the effect of DST transition on the incidence of out-of-hospital cardiac arrest (OHCA). METHODS: Between January 2000 and December 2020, we performed an interrupted time series analysis of the daily number of OHCA cases of medical aetiology from the Victorian Ambulance Cardiac Arrest Registry. The effect of DST transition on OHCA incidence was estimated using negative binomial models, adjusted for temporal trends, population growth, and public holidays. RESULTS: A total of 89,409 adult OHCA of medical aetiology were included. Following the spring DST transition (i.e. shorter day), there was an immediate 13% (IRR 1.13, 95% CI: 1.02, 1.25; p = 0.02) increased risk of OHCA on the day of transition (Sunday) and the cumulative risk of OHCA remained higher over the first 2 days (IRR 1.17, 95% CI: 1.02, 1.34; p = 0.03) compared to non-transitional days. Following the autumn DST transition (i.e. longer day), there was a significant lagged effect on the Tuesday with a 12% (IRR 0.88, 95% CI: 0.77, 0.99; p = 0.04) reduced risk of OHCA. The cumulative effect following the autumn DST transition was also significant, with a 30% (IRR 0.70, 95% CI: 0.51, 0.96; p = 0.03) reduction in the incidence of OHCA by the end of the transitional week. CONCLUSION: We observed both harmful and protective effects from DST transitions on the risk of OHCA. Strategies to reduce this risk in vulnerable populations should be considered.