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

The diagnostic utility of prehospital hyperglycaemia in major trauma patients: An observational study

OBJECTIVES

Stress-induced hyperglycaemia (SIH) is an elevated blood glucose level (≥11.1 mmol/L) in patients experiencing physiological stress, in the absence of diabetes mellitus. Although early in-hospital SIH has been associated with worse outcomes following major trauma, the predictive value of SIH in the prehospital setting has not been established. To investigate the role of prehospital SIH as a predictor of in-hospital mortality following major trauma.

METHODS

A retrospective cohort study of non-diabetic, adult major trauma patients was undertaken to determine the association between prehospital SIH and in-hospital mortality. Secondary outcomes included ED disposition and ED length of stay.

RESULTS

Of 1179 trauma patients included, 89 (8%) had SIH. Prehospital SIH was associated with higher Injury Severity Scores (median (interquartile range): 25 (17-33) vs 17 (14-25)), lower GCS (GCS 3-7: 48.3% vs 10.9%, P < 0.001), lower systolic BP (mean (SD): 122 (44.0) vs 133 (30.3)), lower oxygen saturations (mean (SD): 88% (16) vs 96% (7)) and abnormal heart and respiratory rate. The in-hospital mortality rate was 9.9% in non-SIH patients and 42.7% among patients with SIH (odds ratio (OR): 6.8; 95% confidence interval (CI): 4.3-10.8, P < 0.001). The area under the receiver operating curve for blood glucose alone in predicting mortality was 0.65 (95% CI: 0.60-0.70). Prehospital blood glucose was an independent predictor of mortality after adjustment for age, sex, GCS and vital signs (adjusted OR = 2.9; 95% CI: 1.5-5.5, P = 0.001).

CONCLUSION

The present study demonstrated an association between prehospital SIH and in-hospital mortality following major trauma. Further prospective research is warranted to examine the utility and integration of prehospital SIH into predicting models of trauma care.

The burden of atrial fibrillation on emergency medical services: A population-based cohort study

BACKGROUND

Atrial fibrillation (AF) is a growing burden on healthcare resources, despite improvements in prevention and management. AF is a common cause of hospitalisation, and Emergency Medical Services (EMS) use. However, there is a paucity of data describing the burden of AF on EMS. We aimed to determine the prevalence, characteristics, and outcomes of patients presenting with AF to EMS using a large population-based sample.

METHODS

Consecutive attendances for AF in Victoria, Australia (January 2015-June 2019) were included if patients had a diagnosis of "AF" or "arrhythmia" with AF on electrocardiogram. Data were individually linked to emergency, hospital, and mortality records.

RESULTS

Of 2,613,056 EMS attendances, 16,525 were a first attendance for AF and linked to hospital records. Median (IQR) age was 76 (67,84) years (43% female). Seventy-eight percent had high thromboembolic risk (CHA2DS2-VASc score ≥ 2), and 72% had a heart rate ≥ 100 bpm. Forty-two percent of patients received no treatment by paramedics and 99.4% were transported to hospital. Fifty-three percent were discharged from ED. Median length of hospital stay was 2 days. Of 2542 cases reattended for AF, 19% occurred within 30 days, with increased odds for females and those of low socioeconomic status. Overall, 24% died during the study period, 12% within 30 days. Increasing age, heart failure, stroke, COPD, and low socioeconomic status increased the odds of 30-day mortality.

CONCLUSIONS

EMS utilisation for AF is common and associated with frequent reattendance. Further studies are required to investigate novel pathways of care to reduce AF burden on healthcare systems.

Refining ambulance clinical response models: The impact on ambulance response and emergency department presentations

OBJECTIVE

The ambulance service in Victoria, Australia implemented a revised clinical response model (CRM) in 2016 which was designed to increase the diversion of low-acuity Triple Zero (000) calls to secondary telephone triage and reduce emergency ambulance dispatches. The present study evaluates the influence of the revised CRM on emergency ambulance response times and ED presentations.

METHODS

A retrospective study of emergency calls for ambulance between 1 January 2015 and 31 December 2018. Ambulance data were linked with ED presentations occurring up to 48 h after contact. Interrupted time series analyses were used to evaluate the impact of the revised CRM.

RESULTS

A total of 2 365 529 calls were included. The proportion allocated a Code 1 (time-critical, lights/sirens) dispatch decreased from 56.6 to 41.0% after implementation of the revised CRM. The proportion of calls not receiving an emergency ambulance increased from 10.4 to 19.6%. Interrupted time series analyses demonstrated an improvement in Code 1 cases attended within 15 min (Key Performance Indicator). However, for patients with out-of-hospital cardiac arrest or requiring lights and sirens transport to hospital, there was no improvement in response time performance. By the end of the study period, there was also no difference in the proportion of callers presenting to ED when compared with the estimated proportion assuming the revised CRM had not been implemented.

CONCLUSION

The revised CRM was associated with improved Code 1 response time performance. However, there was no improvement in response times for high acuity patients, and no change in the proportion of callers presenting to ED.

Utilization of Emergency Medical Services by Culturally and Linguistically Diverse Patients: A Population-Based Retrospective Study

OBJECTIVES

To compare emergency medical services (EMS) utilization between culturally and linguistically diverse (CALD) and non-CALD patients in Victoria, Australia.

METHODS

A retrospective study of EMS attendances and transports in Victoria from January 2015 to June 2019, utilizing linked EMS, hospital emergency and admissions data. The CALD and non-CALD patients who received EMS care and transport to a Victorian public emergency department were included. The incidence of EMS use for CALD and non-CALD patients based on the 2016 Census population and expressed per 100,000 person-years.

RESULTS

In 1,261,167 included patients, there were 272,100 (21.6%) CALD and 989,067 (78.4%) non-CALD patients. Before adjustment for age and sex, EMS utilization for CALD patients was 13% lower than non-CALD patients (incidence rate ratio [IRR] 0.87, 95% CI: 0.87-0.87). When stratified by age groups, CALD patients aged under 70 years had significantly lower rates of EMS utilization than non-CALD patients, while CALD patients aged 75 years or older were more likely than non-CALD patients to use EMS (IRR 1.08, 95% CI: 1.07-1.09). The CALD patients were less likely to utilize EMS for trauma/external injury (IRR = 0.67, 95% CI: 0.66-0.68) and mental health/alcohol/drug problems (IRR = 0.39, 95% CI: 0.38-0.40). After adjustment for differences in the age and sex distribution of CALD and non-CALD populations, CALD patients were 51% less likely to utilize EMS than non-CALD patients (IRR 0.49, 95% CI: 0.42-0.56).

CONCLUSIONS

The CALD patients used EMS less frequently than non-CALD patients with significant variation observed across age groups, countries of birth, and clinical presentation. Further research is needed to understand the factors that may be contributing to these disparities.

The burden and prognostic significance of suspected sepsis in the prehospital setting: A state-wide population-based cohort study

OBJECTIVE

Despite high in-hospital mortality, the epidemiology of prehospital suspected sepsis presentations is not well described. This retrospective cohort study aimed to quantify the burden of such presentations, and to determine whether such a diagnosis was independently associated with longer-term mortality.

METHODS

Retrospective, observational population-based cohort study examining all adult prehospital presentations in Victoria, between January 2015 and June 2019, who required subsequent in-hospital assessment. Linked data were extracted from clinical and administrative datasets. Demographics, illness severity, prehospital treatment and mortality were compared between prehospital suspected sepsis and non-sepsis patients. Multivariable logistic regression was used to determine the adjusted association between prehospital assessment (suspected sepsis vs non-sepsis) and 6-month mortality.

RESULTS

A total of 1 218 047 patients were included. The age-adjusted incidence rate of prehospital suspected sepsis was 65 cases per 100 000 person-years. Those with prehospital suspected sepsis were older (74 vs 62 years), more frequently male (55% vs 47%), with greater physiological derangement. Intravenous cannulas were more often inserted prehospital (60% vs 29%). Crude in-hospital mortality was 6.5-fold higher in the prehospital suspected sepsis group (11.8% vs 1.8%), and by 6 months, 22.6% had died. After adjustment for demographics, illness severity, comorbidity, treatment and hospital location, a diagnosis of prehospital suspected sepsis was associated with a 35% higher likelihood of 6-month mortality (OR 1.35, 95% CI 1.29-1.41).

CONCLUSIONS

The burden of prehospital suspected sepsis in the Australian setting is significant, with paramedics identifying patients at high-risk of poor longer-term outcomes. This implies the need to consider improved care pathways for this highly vulnerable group.

Exploring factors influencing time from dispatch to unit availability according to the transport decision in the pre-hospital setting: an exploratory study

BACKGROUND

Efficient resource distribution is important. Despite extensive research on response timings within ambulance services, nuances of time from unit dispatch to becoming available still need to be explored. This study aimed to identify the determinants of the duration between ambulance dispatch and readiness to respond to the next case according to the patients' transport decisions.

METHODS

Time from ambulance dispatch to availability (TDA) analysis according to the patients' transport decision (Transport versus Non-Transport) was conducted using R-Studio™ for a data set of 93,712 emergency calls managed by a Middle Eastern ambulance service from January to May 2023. Log-transformed Hazard Ratios (HR) were examined across diverse parameters. A Cox regression model was utilised to determine the influence of variables on TDA. Kaplan-Meier curves discerned potential variances in the time elapsed for both cohorts based on demographics and clinical indicators. A competing risk analysis assessed the probabilities of distinct outcomes occurring.

RESULTS

The median duration of elapsed TDA was 173 min for the transported patients and 73 min for those not transported. The HR unveiled Significant associations in various demographic variables. The Kaplan-Meier curves revealed variances in TDA across different nationalities and age categories. In the competing risk analysis, the 'Not Transported' group demonstrated a higher incidence of prolonged TDA than the 'Transported' group at specified time points.

CONCLUSIONS

Exploring TDA offers a novel perspective on ambulance services' efficiency. Though promising, the findings necessitate further exploration across diverse settings, ensuring broader applicability. Future research should consider a comprehensive range of variables to fully harness the utility of this period as a metric for healthcare excellence.

Healthcare and economic cost burden of emergency medical services treated non-traumatic shock using a population-based cohort in Victoria, Australia

OBJECTIVES

We aimed to assess the healthcare costs and impact on the economy at large arising from emergency medical services (EMS) treated non-traumatic shock.

DESIGN

We conducted a population-based cohort study, where EMS-treated patients were individually linked to hospital-wide and state-wide administrative datasets. Direct healthcare costs (Australian dollars, AUD) were estimated for each element of care using a casemix funding method. The impact on productivity was assessed using a Markov state-transition model with a 3-year horizon.

SETTING

Patients older than 18 years of age with shock not related to trauma who received care by EMS (1 January 2015-30 June 2019) in Victoria, Australia were included in the analysis.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome assessed was the total healthcare expenditure. Secondary outcomes included healthcare expenditure stratified by shock aetiology, years of life lived (YLL), productivity-adjusted life-years (PALYs) and productivity losses.

RESULTS

A total of 21 334 patients (mean age 65.9 (±19.1) years, and 9641 (45.2%) females were treated by EMS with non-traumatic shock with an average healthcare-related cost of $A11 031 per episode of care and total cost of $A280 million. Annual costs remained stable throughout the study period, but average costs per episode of care increased (Ptrend=0.05). Among patients who survived to hospital, the average cost per episode of care was stratified by aetiology with cardiogenic shock costing $A24 382, $A21 254 for septic shock, $A19 915 for hypovolaemic shock and $A28 057 for obstructive shock. Modelling demonstrated that over a 3-year horizon the cohort lost 24 355 YLLs and 5059 PALYs. Lost human capital due to premature mortality led to productivity-related losses of $A374 million. When extrapolated to the entire Australian population, productivity losses approached $A1.5 billion ($A326 million annually).

CONCLUSION

The direct healthcare costs and indirect loss of productivity among patients with non-traumatic shock are high. Targeted public health measures that seek to reduce the incidence of shock and improve systems of care are needed to reduce the financial burden of this syndrome.

Mortality rates in Norwegian HEMS-a retrospective analysis from Central Norway

BACKGROUND

Helicopter Emergency Medical Services (HEMS) provide rapid and specialized care to critically ill or injured patients. Norwegian HEMS in Central Norway serves an important role in pre-hospital emergency medical care. To grade the severity of patients, HEMS uses the National Advisory Committee for Aeronautics' (NACA) severity score. The objective of this study was to describe the short- and long term mortality overall and in each NACA-group for patients transported by HEMS Trondheim using linkage of HEMS and hospital data.

METHODS

The study used a retrospective cohort design, aligning with the STROBE recommendations. Patient data from Trondheim HEMS between 01.01.2017 and 31.12.2019 was linked to mortality data from a hospital database and analyzed. Kaplan Meier plots and cumulative mortality rates were calculated for each NACA group at day one, day 30, and one year and three years after the incident.

RESULTS

Trondheim HEMS responded to 2224 alarms in the included time period, with 1431 patients meeting inclusion criteria for the study. Overall mortality rates at respective time points were 10.1% at day one, 13.4% at 30 days, 18.5% at one year, and 22.3% at three years. The one-year cumulative mortality rates for each NACA group were as follows: 0% for NACA 1 and 2, 2.9% for NACA 3, 10.1% for NACA 4, 24.7% for NACA 5 and 49.5% for NACA 6. Statistical analysis with a global log-rank test indicated a significant difference in survival outcomes among the groups (p < 2⋅10- 16).

CONCLUSION

Among patients transported by Trondheim HEMS, we observed an incremental rise in mortality rates with increasing NACA scores. The study further suggests that a one-year follow-up may be sufficient for future investigations into HEMS outcomes.

Characteristics and Outcomes of Patients Referred to a General Practitioner by Victorian Paramedics

OBJECTIVE

Many patients who are attended by paramedics do not require conveyance to an emergency department (ED). Our study focuses on comparing the characteristics and outcomes of patients who were advised to follow up with a general practitioner (GP) by an attending paramedic with those of patients who were discharged at scene or transported to hospital.

METHODS

This was a retrospective data linkage cohort study of ambulance, ED, hospital admission, and death records for all adults attended by paramedics in Victoria, Australia between the 1st of January 2015 and 30th of June 2019. Patients were excluded if they presented in cardiac arrest, resided in a residential aged care facility, or were receiving palliative care services. Outcomes of interest included reattendance by ambulance, ED presentation; and, a high acuity outcome which we defined as a patient who (1) presented to ED and received an Australasian Triage Scale of category 1 (Resuscitation) or 2 (Emergency) AND was admitted to a ward OR (2) was admitted to an Intensive Care Unit, Coronary Care Unit or Catheter laboratory (regardless of triage category) OR (3) died. Outcomes of interest were considered within 48-h of initial EMS attendance.

RESULTS

A total of 1,777,950 cases were included in the study of which 3.1% were referred to a GP, 9.0% were discharged at scene without a follow-up recommendation, and 87.9% were transported to hospital. Patients referred to a GP were more likely than those discharged at scene to subsequently present to an ED within 48 h of their attendance (5.3% vs 3.8%). However, GP referral was not associated with any change to high acuity outcome (0.3% vs 0.2%) or ambulance reattendance (6.0% vs 6.0%) compared to discharge at scene. The only factors that were associated with ambulance reattendance, ED presentation, and a high acuity outcome were male gender and elevated temperature.

CONCLUSIONS

Despite increasing low and medium-acuity casework in this EMS system, paramedic referral to a GP is not common practice. Referring a patient to a GP did not reduce the likelihood of patients experiencing a high acuity outcome or recalling an ambulance within 48 h, suggesting opportunity exists to refine paramedic to GP referral practices.

Impact of socioeconomic status on presentation, care quality and outcomes of patients attended by emergency medical services for dyspnoea: a population-based cohort study

BACKGROUND

Low socioeconomic status (SES) has been linked to poor outcomes in many conditions. It is unknown whether these disparities extend to individuals presenting with dyspnoea. We aimed to evaluate the relationship between SES and incidence, care quality and outcomes among patients attended by emergency medical services (EMS) for dyspnoea.

METHODS

This population-based cohort study included consecutive patients attended by EMS for dyspnoea between 1 January 2015 and 30 June 2019 in Victoria, Australia. Data were obtained from individually linked ambulance, hospital and mortality datasets. Patients were stratified into SES quintiles using a composite census-derived index.

RESULTS

A total of 262 412 patients were included. There was a stepwise increase in the age-adjusted incidence of EMS attendance for dyspnoea with increasing socioeconomic disadvantage (lowest SES quintile 2269 versus highest quintile 889 per 100 000 person years, ptrend<0.001). Patients of lower SES were younger and more comorbid, more likely to be from regional Victoria or of Aboriginal or Torres Strait Islander heritage and had higher rates of respiratory distress. Despite this, lower SES groups were less frequently assigned a high acuity EMS transport or emergency department (ED) triage category and less frequently transported to tertiary centres or hospitals with intensive care unit facilities. In multivariable models, lower SES was independently associated with lower acuity EMS and ED triage, ED length of stay>4 hours and increased 30-day EMS reattendance and mortality.

CONCLUSION

Lower SES was associated with a higher incidence of EMS attendances for dyspnoea and disparities in several metrics of care and clinical outcomes.

Association of socioeconomic status in the incidence, quality-of-care metrics, and outcomes for patients with cardiogenic shock in a pre-hospital setting

AIMS

The relationship between lower socioeconomic status (SES) and poor cardiovascular outcomes is well described; however, there exists a paucity of data exploring this association in cardiogenic shock (CS). This study aimed to investigate whether any disparities exist between SES and the incidence, quality of care or outcomes of CS patients attended by emergency medical services (EMS).

METHODS AND RESULTS

This population-based cohort study included consecutive patients transported by EMS with CS between 1 January 2015 and 30 June 2019 in Victoria, Australia. Data were collected from individually linked ambulance, hospital, and mortality datasets. Patients were stratified into SES quintiles using national census data produced by the Australian Bureau of Statistics.A total of 2628 patients were attended by EMS for CS. The age-standardized incidence of CS amongst all patients was 11.8 [95% confidence interval (95% CI), 11.4-12.3] per 100 000 person-years, with a stepwise increase from the highest to lowest SES quintile (lowest quintile 17.0 vs. highest quintile 9.7 per 100 000 person-years, P-trend < 0.001). Patients in lower SES quintiles were less likely to attend metropolitan hospitals and more likely to be received by inner regional and remote centres without revascularization capabilities. A greater proportion of the lower SES groups presented with CS due to non-ST elevation myocardial infarction (NSTEMI) or unstable angina pectoris (UAP), and overall were less likely to undergo coronary angiography. Multivariable analysis demonstrated an increased 30-day all-cause mortality rate in the lowest three SES quintiles when compared with the highest quintile.

CONCLUSION

This population-based study demonstrated discrepancies between SES status in the incidence, care metrics, and mortality rates of patients presenting to EMS with CS. These findings outline the challenges in equitable healthcare delivery within this cohort.

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.

Variation in Health Care Processes, Quality and Outcomes According to Day and Time of Chest Pain Presentation via Ambulance

BACKGROUND

Previous studies examining temporal variations in cardiovascular care have largely been limited to assessing weekend and after-hours effects. We aimed to determine whether more complex temporal variation patterns might exist in chest pain care.

METHODS

This was a population-based study of consecutive adult patients attended by emergency medical services (EMS) for non-traumatic chest pain without ST elevation in Victoria, Australia between 1 January 2015 and 30 June 2019. Multivariable models were used to assess whether time of day and week stratified into 168 hourly time periods was associated with care processes and outcomes.

RESULTS

There were 196,365 EMS chest pain attendances; mean age 62.4 years (standard deviation [SD] 18.3) and 51% females. Presentations demonstrated a diurnal pattern, a Monday-Sunday gradient (Monday peak) and a reverse weekend effect (lower rates on weekends). Five temporal patterns were observed for care quality and process measures, including a diurnal pattern (longer emergency department [ED] length of stay), an after-hours pattern (lower angiography or transfer for myocardial infarction, pre-hospital aspirin administration), a weekend effect (shorter ED clinician review, shorter EMS off-load time), an afternoon/evening peak period pattern (longer ED clinician review, longer EMS off-load time) and a Monday-Sunday gradient (ED clinician review, EMS offload time). Risk of 30-day mortality was associated with weekend presentation (Odds ratio [OR] 1.15, p=0.001) and morning presentation (OR 1.17, p<0.001) while risk of 30-day EMS reattendance was associated with peak period (OR 1.16, p<0.001) and weekend presentation (OR 1.07, p<0.001).

CONCLUSIONS

Chest pain care demonstrates complex temporal variation beyond the already established weekend and after-hours effect. Such relationships should be considered during resource allocation and quality improvement programs to improve care across all days and times of the week.

Healthcare cost burden of acute chest pain presentations

BACKGROUND

This study aimed to estimate the direct healthcare cost burden of acute chest pain attendances presenting to ambulance in Victoria, Australia, and to identify key cost drivers especially among low-risk patients.

METHODS

State-wide population-based cohort study of consecutive adult patients attended by ambulance for acute chest pain with individual linkage to emergency and hospital admission data in Victoria, Australia (1 January 2015-30 June 2019). Direct healthcare costs, adjusted for inflation to 2020-2021 ($A), were estimated for each component of care using a casemix funding method.

RESULTS

From 241 627 ambulance attendances for chest pain during the study period, mean chest pain episode cost was $6284, and total annual costs were estimated at $337.4 million ($68 per capita per annum). Total annual costs increased across the period ($310.5 million in 2015 vs $384.5 million in 2019), while mean episode costs remained stable. Cardiovascular conditions (25% of presentations) were the most expensive (mean $11 523, total annual $148.7 million), while a non-specific pain diagnosis (49% of presentations) was the least expensive (mean $3836, total annual $93.4 million). Patients classified as being at low risk of myocardial infarction, mortality or hospital admission (Early Chest pain Admission, Myocardial infarction, and Mortality (ECAMM) score) represented 31%-57% of the cohort, with total annual costs estimated at $60.6 million-$135.4 million, depending on the score cut-off used.

CONCLUSIONS

Total annual costs for acute chest pain presentations are increasing, and a significant proportion of the cost burden relates to low-risk patients and non-specific pain. These data highlight the need to improve the cost-efficiency of chest pain care pathways.

Epidemiology, outcomes and predictors of mortality in patients transported by ambulance for dyspnoea: A population-based cohort study

OBJECTIVES

There are currently limited data to inform the management of patients transported by emergency medical services (EMS) with dyspnoea. We aimed to describe the incidence, aetiology and outcomes of patients transported by EMS for dyspnoea using a large population-based sample and to identify factors associated with 30-day mortality.

METHODS

Consecutive EMS attendances for dyspnoea in Victoria, Australia from January 2015 to June 2019 were included. Data were individually linked to hospital and mortality records to determine incidence, diagnoses, and outcomes. Factors associated with 30-day mortality were assessed using multivariable logistic regression.

RESULTS

During the study period, there were 2 505 324 cases attended by EMS, of whom 346 228 (14%) met inclusion criteria for dyspnoea. The incidence of EMS attendances for dyspnoea was 1566 per 100 000 person-years, and was higher in females, older patients and socially disadvantaged areas. Of the 271 204 successfully linked cases (median age 76 years; 51% women), 79% required hospital admission with a 30-day mortality of 9%. The most common final diagnoses (and 30-day mortality rates) were lower respiratory tract infection (13%, mortality 11%), chronic obstructive pulmonary disease (13%, mortality 6.4%), heart failure (9.1%, mortality 9.8%), arrhythmias (3.9%, mortality 4.4%), acute coronary syndromes (3.9%, mortality 9.5%) and asthma (3.2%, mortality 0.5%). Predictors of mortality included older age, male sex, pre-existing chronic kidney disease, heart failure or cancer, abnormal respiratory status or vital signs and pre-hospital intubation.

CONCLUSION

Dyspnoea is a common presentation with a broad range of causes and is associated with high rates of hospitalisation and death.

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.

Outcomes of paediatric patients who are not transported to hospital by Emergency Medical Services: a data linkage study

BACKGROUND

Data on the safety of non-transport decisions for paediatric patients attended by Emergency Medical Services (EMS) are lacking. We describe the characteristics and outcomes of paediatric non-transported patients in Victoria, Australia.

METHODS

A retrospective data linkage study of consecutive paediatric (aged <18 years) non-transported patients between January 2015 and June 2019. Patients were linked to ED, hospital admission and death records. Multivariable logistic regression analyses were used to determine factors associated with EMS recontact, ED presentation, hospital admission and an adverse event (death/cardiac arrest, intensive care unit admission or highest ED triage category) within 48 hours of the initial emergency call.

RESULTS

In total, 62 975 non-transported patients were included. The mean age was 7.1 (SD 6.0) years and 48.9% were male. Overall, 2.2% recontacted the EMS within 48 hours, 13.7% self-presented to a public ED, 2.4% were admitted to hospital and 0.1% had an adverse event, including two deaths. Among patients with paramedic-initiated non-transport (excluding transport refusals and transport via other means), 5.6% presented to a public ED, 1.1% were admitted to hospital and 0.05% had an adverse event. In the overall population, an abnormal vital sign on initial assessment increased the odds of hospital admission and an adverse event. Among paramedic-initiated non-transports, cases occurring in the early hours of the morning (04:00-08:00 hours) were associated with increased odds of subsequent hospital admission, while the odds of ED presentation and hospital admission also increased with increasing prior exposure to non-transported cases.

CONCLUSION

Adverse events were rare among paramedic-initiated non-transport cases. Vital sign derangements and attendance by paramedics with higher prior exposure to non-transports were associated with poorer outcomes and may be used to improve safety.

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.

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.

Mastering Linked Datasets: The Future of Emergency Health Care Research

Objectives: The aim of this work is to describe routine integration of prehospital emergency health records into a health master linkage file, delivering ongoing access to integrated patient treatment and outcome information for ambulance-attended patients in Queensland.Methods: The Queensland Ambulance Service (QAS) data are integrated monthly into the Queensland Health Master Linkage File (MLF) using a linkage algorithm that relies on probabilistic matches in combination with deterministic rules based on patient demographic details, date, time and facility identifiers. Each ambulance record is assigned an enduring linkage key (unique patient identifier) and further processing determines whether each record matches with a corresponding hospital emergency department, admission or death registry record. In this study, all QAS electronic ambulance report form (eARF) records from October 2016 to December 2018 where at least 1 key linkage variable was present (n = 1,771,734) were integrated into the MLF.Results: The majority of records (n = 1,456,502; 82.2%) were for transported patients, and 90.1% (n = 1,312,176) of these transports were to public hospital facilities. Of these transport records, 93.9% (n = 1,231,951) matched to emergency department (ED) records and 59.3% (n = 864,394) also linked to admitted patient records. Of ambulance non-transport records integrated into the MLF, 23.6% (n = 74,311) matched with ED records.Conclusion: This study demonstrates robust linkage methods, quality assurance processes and high linkage rates of data across the continuum of care (prehospital/emergency department/admitted patient/death) in Queensland. The resulting infrastructure provides a high-quality linked dataset that facilitates complex research and analysis to inform critical functions such as quality improvement, system evaluation and design.

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

AIMS

Non-traumatic chest pain is one of the most common reasons for calls for emergency assistance and places a significant burden on health services. This study aimed to determine age- and sex-specific 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, with substantial differences according to age and sex. Almost half of patients are discharged from hospital with a diagnosis of non-specific pain and low rates of mortality.