Pan-Asian Resuscitation Outcomes Study Research Articles

Socioeconomic disadvantage and long-term survival duration in out-of-hospital cardiac arrest patients: A population-based cohort study

BackgroundSocioeconomic status (SES) is a well-established determinant of cardiovascular health. However, the relationship between SES and clinical outcomes in long-term out-of-hospital cardiac arrest (OHCA) is less well-understood. The Singapore Housing Index (SHI) is a validated building-level SES indicator. We investigated whether SES as measured by SHI is associated with long-term OHCA survival in Singapore. MethodsWe conducted an open cohort study with linked data from the Singapore Pan-Asian Resuscitation Outcomes Study (PAROS), and the Singapore Registry of Births and Deaths (SRBD) from 2010 to 2020. We fitted generalized structural equation models, calculating hazard ratios (HRs) using a Weibull model. We constructed Kaplan–Meier survival curves and calculated the predicted marginal probability for each SHI category. ResultsWe included 659 cases. In both univariable and multivariable analyses, SHI did not have a significant association with survival. Indirect pathways of SHI mediated through covariates such as Emergency Medical Services (EMS) response time (HR of low-medium, high-medium and high SHI when compared to low SHI: 0.98 (0.88–1.10), 1.01 (0.93–1.11), 1.02 (0.93–1.12) respectively), and age of arrest (HR of low-medium, high-medium and high SHI when compared to low SHI: 1.02 (0.75–1.38), 1.08 (0.84–1.38), 1.18 (0.91–1.54) respectively) had no significant association with OHCA survival. There was no clear trend in the predicted marginal probability of survival among the different SHI categories. ConclusionsWe did not find a significant association between SES and OHCA survival outcomes in residential areas in Singapore. Among other reasons, this could be due to affordable healthcare across different socioeconomic classes.

Machine learning prediction of refractory ventricular fibrillation in out-of-hospital cardiac arrest using features available to EMS

BackgroundShock-refractory ventricular fibrillation (VF) or ventricular tachycardia (VT) is a treatment challenge in out-of-hospital cardiac arrest (OHCA). This study aimed to develop and validate machine learning models that could be implemented by emergency medical services (EMS) to predict refractory VF/VT in OHCA patients. MethodsThis was a retrospective study examining adult non-traumatic OHCA patients brought into the emergency department by Singapore EMS from the Pan-Asian Resuscitation Outcomes Study (PAROS) registry. Data from April 2010 to March 2020 were extracted for this study. Refractory VF/VT was defined as VF/VT persisting or recurring after at least one shock. Features were selected based on expert clinical opinion and availability to dispatch prior to arrival at scene. Multivariable logistic regression (MVR), LASSO and random forest (RF) models were investigated. Model performance was evaluated using receiver operator characteristic (ROC) area under curve (AUC) analysis and calibration plots. Results20,713 patients were included in this study, of which 860 (4.1%) fulfilled the criteria for refractory VF/VT. All models performed comparably and were moderately well-calibrated. ROC-AUC were 0.732 (95% CI, 0.695 – 0.769) for MVR, 0.738 (95% CI, 0.701 – 0.774) for LASSO, and 0.731 (95% CI, 0.690 – 0.773) for RF. The shared important predictors across all models included male gender and public location. ConclusionThe machine learning models developed have potential clinical utility to improve outcomes in cases of refractory VF/VT OHCA. Prediction of refractory VF/VT prior to arrival at patient’s side may allow for increased options for intervention both by EMS and tertiary care centres.

Abstract 156: Incidence and Long-Term Outcomes of Acute Myocardial Infarction Among Survivors of Out-of-Hospital Cardiac Arrest

Introduction: Despite the increasing long-term survival after out-of-hospital cardiac arrest (OHCA), the risk of subsequent acute myocardial infarction (AMI) remains poorly understood. We aimed to determine the incidence, predictors, and long-term outcomes of AMI among OHCA survivors. Methods: We assembled a retrospective cohort of patients with OHCA who survived to 30 days or discharge from hospital regardless of time from index event between 2010-2019 by linking the Pan-Asian Resuscitation Outcomes Study (Singapore participants), Singapore Myocardial Infarction Registry, and the Singapore Registry of Births and Deaths. We calculated the risk of subsequent AMI defined as AMI occurring 30 days after index OHCA or following discharge from hospital post-OHCA, among OHCA survivors compared to the general population using age- and sex-specific standardised incidence ratios (SIR) and the cumulative incidence of subsequent AMI among OHCA survivors. We investigated predictors of subsequent AMI among OHCA survivors and whether AMI predicted mortality using Cox regression hazard ratios for time-to-event analyses. Results: In total, 882 OHCA survivors were analysed. OHCA survivors had an increased risk of subsequent AMI compared to the general population when matched for age and sex (SIR 4.64, 95% CI: 3.52-6.01). Age-specific risks of subsequent AMI for males (SIR 3.29, 95%CI: 2.39-4.42) and females (SIR 6.15, 95%CI: 3.27-10.52) were significantly increased. 7.2%, 8.3%, and 14.3% of OHCA survivors had subsequent AMI at 3 years, 5 years, and end of follow-up respectively. Age at OHCA (HR 1.04, 95%CI: 1.02-1.06) and past medical history of prior AMI, defined as any AMI preceding or during the index OHCA event (HR 1.84, 95%CI: 1.05-3.22), were associated with subsequent AMI. OHCA survivors with subsequent AMI had a higher risk of mortality (HR 1.58, 95%CI: 1.12-2.22) than those without. Conclusion: Long-term OHCA survivors have an increased risk of subsequent AMI, compared to the general population. Prior AMI significantly increases this risk and subsequent AMI predicts mortality. Intensive cardiovascular risk factor control and revascularisation may improve outcomes in selected patients with a cardiac etiology.

Technology activated community first responders in Singapore: Real-world care delivery & outcome trends

Background: Community first responders (CFRs) strengthen the Chain of Survival for out-of-hospital cardiac arrest (OHCA) care. Considerable efforts have been invested in Singapore’s CFR program, during the years 2016–2020, by developing an app-based activation system called myResponder. This paper reports on national CFR response indicators to evaluate the real-world impact of these efforts. Methods: We matched data from the Singapore Civil Defence Force’s CFR registry with the Pan Asian Resuscitation Outcomes Study (PAROS) registry data to calculate performance indicators. These included the number of CFRs receiving and accepting an issued alert per OHCA event. Also calculated were the fraction of OHCA events where CFRs received an issued alert, or accepted the alert, and arrived at the scene either before or after EMS. We also present trends of these indicators and compare the prevalence of these fractions between the CFR-attended and CFR-unattended OHCA events. Results: Of 6577 alerted OHCA events, 42.7% accepted an alert, 50% of these arrived at the scene and 71% of them arrived before EMS. Almost all CFR response indicators improved over time even for the pandemic year (2020). The fraction of OHCA events where >2 CFRs received an alert increased from 62% to 96%; the same figure for accepting an alert did not change much but >2 CFRs arriving at the scene increased from 0% to 7.5%. The fraction of OHCA events with an automated external defibrillator applied and defibrillation performed by CFR increased from 4.2% to 10.3% and 1.6% to 3%, respectively. Statistically significant differences were observed in these indicators when CFR-attended and CFR-unattended OHCA events were compared. Conclusion: This real-world study shows that activating CFRs using mobile technology can improve community response to OHCA and are bearing fruit in Singapore at a national level. Some targets for improvement and future research are highlighted in this report.

Does witness type affect the chance of receiving bystander CPR in out-of-hospital cardiac arrest?

ObjectivesThe relationship between the bystander witness type and receipt of bystander CPR (BCPR) is not well understood. Herein we compared BCPR administration between family and non-family witnessed out-of-hospital cardiac arrest (OHCA). BackgroundIn many communities, interventions in the past decade have contributed to an increased receipt of BCPR, for example in Singapore from 15% to 60%. However, BCPR rates have plateaued despite sustained and ongoing community-based interventions, which may be related to gaps in education or training for various witness types. The purpose of this study was to investigate the association between witness type and BCPR administration. MethodsSingapore data from 2010–2020 was extracted from the Pan-Asian Resuscitation Outcomes Study (PAROS) network registry (n = 25,024). All adult, layperson witnessed, non-traumatic OHCAs were included in this study. ResultsOf 10,016 eligible OHCA cases, 6,895 were family witnessed and 3,121 were non-family witnessed. After adjustment for potential confounders, BCPR administration was less likely for non-family witnessed OHCA (OR 0.83, 95% CI 0.75, 0.93). After location stratification, non-family witnessed OHCAs were less likely to receive BCPR in residential settings (OR 0.75, 95% CI 0.66, 0.85). In non-residential settings, there was no statistically significant association between witness type and BCPR administration (OR 1.11, 95% CI 0.88, 1.39). Details regarding witness type and bystander CPR were limited. ConclusionThis study found differences in BCPR administration between family and non-family witnessed OHCA cases. Elucidation of witness characteristics may be useful to determine populations that would benefit most from CPR education and training.

Association between Conversion to Shockable Rhythms and Survival with Favorable Neurological Outcomes for Out-of-Hospital Cardiac Arrests

Background The initial cardiac rhythm in out-of-hospital cardiac arrest (OHCA) portends different prognoses and affects treatment decisions. Initial shockable rhythms are associated with good survival and neurological outcomes but there is conflicting evidence for those who initially present with non-shockable rhythms. The aim of this study is to evaluate if OHCA with conversion from non-shockable (i.e., asystole and pulseless electrical activity) rhythms to shockable rhythms compared to OHCA remaining in non-shockable rhythms is associated with better survival and neurological outcomes. Method OHCA cases from the Pan-Asian Resuscitation Outcomes Study registry in 13 countries between January 2009 and February 2018 were retrospectively analyzed. Cases with missing initial rhythms, age <18 years, presumed non-medical cause of arrest, and not conveyed by emergency medical services were excluded. Multivariable logistic regression analysis was performed to evaluate the relationship between initial and subsequent shockable rhythm, survival to discharge, and survival with favorable neurological outcomes (cerebral performance category 1 or 2). Results Of the 116,387 cases included. 11,153 (9.6%) had initial shockable rhythms and 9,765 (8.4%) subsequently converted to shockable rhythms. Japan had the lowest proportion of OHCA patients with initial shockable rhythms (7.3%). For OHCA with initial shockable rhythm, the adjusted odds ratios (aOR) for survival and good neurological outcomes were 8.11 (95% confidence interval [CI] 7.62-8.63) and 15.4 (95%CI 14.1-16.8) respectively. For OHCA that converted from initial non-shockable to shockable rhythms, the aORs for survival and good neurological outcomes were 1.23 (95%CI 1.10-1.37) and 1.61 (95%CI 1.35-1.91) respectively. The aORs for survival and good neurological outcomes were 1.48 (95%CI 1.22-1.79) and 1.92 (95%CI 1.3 − 2.84) respectively for initial asystole, while the aOR for survival in initial pulseless electrical activity patients was 0.83 (95%CI 0.71-0.98). Prehospital adrenaline administration had the highest aOR (2.05, 95%CI 1.93-2.18) for conversion to shockable rhythm. Conclusion In this ambidirectional cohort study, conversion from non-shockable to shockable rhythm was associated with improved survival and neurologic outcomes compared to rhythms that continued to be non-shockable. Continued advanced resuscitation may be beneficial for OHCA with subsequent conversion to shockable rhythms.

Long term survival and disease burden from out-of-hospital cardiac arrest in Singapore: a population-based cohort study

Understanding the long-term outcomes and disability-adjusted life years (DALY) after out-of-hospital cardiac arrest (OHCA) is important to understand the overall health and disease burden of OHCA respectively, but data in Asia remains limited. We aimed to quantify long-term survival and the annual disease burden of OHCA within a national multi-ethnic Asian cohort. We conducted an open cohort study linking the Singapore Pan-Asian Resuscitation Outcomes Study (PAROS) and the Singapore Registry of Births and Deaths from 2010 to 2019. We performed Cox regression, constructed Kaplan-Meier curves, and calculated DALYs and standardised mortality ratios (SMR) for each year of follow-up. We analysed 802 cases. The mean age was 56.0 (SD 17.8). Most were male (631 cases, 78,7%) and of Chinese ethnicity (552 cases, 68.8%). At one year, the SMR was 14.9 (95% CI:12.5-17.8), decreasing to 1.2 (95% CI:0.7-1.8) at three years, and 0.4 (95% CI:0.2-0.8) at five years. Age at arrest (HR:1.03, 95% CI:1.02-1.04, p<0.001), shockable presenting rhythm (HR:0.75, 95% CI:0.52-0.93, p=0.015) and CPC category (HR:4.62, 95% CI:3.17-6.75, p<0.001) were independently associated with mortality. Annual DALYs due to OHCA varied from 304.1 in 2010 to 849.7 in 2015, then 547.1 in 2018. Mean DALYs decreased from 12.162 in 2010 to 3.599 in2018. OHCA survivors had an increased mortality rate for the first three years which subsequently normalised compared to that of the general population. Annual OHCA disease burden in DALY trended downwards from 2010 to 2018. Improved surveillance and OHCA treatment strategies may improve long-term survivorship and decrease its global burden. National Medical Research Council, Singapore, under the Clinician Scientist Award (NMRC/CSA-SI/0014/2017) and the Singapore Translational Research Investigator Award (MOH-000982-01).

Abstract 207: Performance Of The Universal Tor Rule For Out-of-hospital Cardiac Arrest Cases Not Witnessed By Ems Providers In The Pan Asian Resuscitation Outcomes Study

Introduction: In order to make effective use of limited medical resources in an aging society, ILCOR emphasizes the importance of considering the Termination of Resuscitation (TOR) rule in the prehospital setting. In Europe and the United States, the Universal TOR rule (no prehospital cardiac resumption, no witnessed by EMS, no shock at the scene) is utilized in the field. We used the Pan-Asian Resuscitation Outcomes (PAROS) data to examine cases of out-of-hospital cardiac arrest not witnessed by EMS providers in Singapore, Japan, Korea, and Taiwan. We also examined the validity of Universal TOR rule. Methods: This was a retrospective cohort study examining data from January 1, 2009 to June 31, 2018 of the Pan Asian Resuscitation Outcomes Study. We included patients with OHCA who were non-traumatic cardiac arrest and not witnessed by EMS providers. We examined the background of the patients, activities and response times of EMS, and survival outcomes. Then, we calculated the specificity, positive predictive value, etc. of cases that met the Universal TOR rule for poor neurological outcomes (CPC ≥ 3) . Results: The breakdown of cases was as follows: Singapore (10,976)/ Japan (117,814)/ Korea (17,926)/ Taiwan (17,063). Of these, Singapore 440 (4.0%)/ Japan 6,845 (5.8%)/ Korea 1,522 (8.5%)/ Taiwan 1,190 (7.0%) were discharged alive, and Singapore 263 (2.4%)/ Japan 3,791 (3.2%)/ Korea 679 (3.8%)/ Taiwan 457 (2.7%) were discharged alive for CPC 1 and 2. For CPC≥3 cases, the specificity of the universal TOR rule was Singapore 0.970/ Japan 0.912/ Korea 0.887/ Taiwan 0.742, and the positive predictive value was Singapore 0.999/ Japan 0.997/ Korea 0.995/ Taiwan 0.992. Conclusions: The positive predictive value for poor neurological prognosis at 1 month, among Universal TOR rule-compliant cases in the four countries was more than 99%. However, there were differences in the specificity of poor neurological outcome between countries.

Abstract 178: Development And Validation Of The Utstein-based Machine Learning Algorithms To Predict Neurological Outcomes After Out-of-hospital Cardiac Arrest: A Retrospective Analysis Of The Pan-asian Registry

Introduction: The proportion of favorable neurologic outcome from the survival after Out-of-Hospital Cardiac Arrest (OHCA) remains poor, esp. in the Asian communities. By using the machine learning (ML) approach, we aimed to develop and validate the the Utstein-based ML algorithms to predict neurological outcomes after OHCA in this population. Methods: We conducted a retrospective analysis of data collected from the registry of Pan Asian Resuscitation Outcomes Study (PAROS) Network, an international and multi-center cohort study of OHCA across 13 countries in this region. All adult (≥ 18 years) EMS-treated OHCA patients between Jan 2009 to May 2018 in the registry were included, with variables followed the Utstein recommendations and conform to a unified taxonomy established by the network. The primary outcome was defined as good neurological outcome with cerebral performance category 1 or 2. Random splitting was used to divide the dataset into the training/validation and testing cohorts at around 2-to-1 ratio. Four supervised ML models, including Random Forest (RF), Gradient Boosting (GB), Extra Trees (ET), and CatBoost (CB) classifiers were employed to construct the prediction models, and performances were evaluated and compared with traditional logistic regression (LR) by the area under the receiver operating characteristic curve (AUC) in the testing cohort. Results: We included 194,300 records for analysis. Of them, 6,342 (3.3%) achieved good neurologic outcome. Among the constructed ML models, RF obtained the best AUC performance (0.924, 95% CI: 0.917-0.932), followed by ET (0.922, 95% CI: 0.915-0.930), CB (0.922, 95% CI: 0.915-0.930), and GB (0.910, 95% CI: 0.901-0.920). Although there was no difference in performance between each ML models, RF performed significantly better than using the traditional LR. The top important features were first arrest rhythm, age, witnessed by EMS, event location, and duration from call to EMS arrival. Conclusions: The ML approach showed excellent discriminatory performance to predict good neurologic outcome for EMS-treated OHCA patients in the Pan-Asian communities. It has the potential to save more life or provide termination-of-resuscitation if successfully implemented in the EMS system.

Air quality and the risk of out-of-hospital cardiac arrest in Singapore (PAROS): a time series analysis

Previous studies have reported positive associations between out-of-hospital cardiac arrest (OHCA) and air pollutant concentrations, but there are inconsistencies across studies. We aimed to investigate the association between pollutant concentrations and the risk of OHCA in Singapore. We did a time series analysis of all cases of OHCA in Singapore reported between July 1, 2010, and Dec 31, 2018, to the Pan-Asian Resuscitation Outcomes Study (PAROS), a prospective, population-based registry. Using multivariable fractional polynomial modelling, we investigated the immediate (day 0) and lagged (up to 5 days after exposure) association between 10 μg/m³ increases in concentrations of particulate matter with a diameter of 2·5 μm or smaller (PM_2·5), particulate matter with a diameter of 10 μm or smaller (PM₁₀), ozone (O₃), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂) and 1 mg/m³ increase in carbon monoxide (CO) and relative risk (RR) of OHCA. We extracted data for 18 131 cases of OHCA. The median age of this cohort of cases was 65 years (IQR 56-80), 6484 (35·8%) were female, 11 647 (64·2%) were male, 12 270 (67·7%) were Chinese, 2873 (15·8%) were Malay, and 2010 (11·1%) were Indian. Every 10 μg/m³ increase in PM_2·5 was associated with increased risk of OHCA (RR 1·022 [95% 1·002-1·043]) over the next 2 days, which decreased over the subsequent 3 days (3-5 days after exposure; 0·976 [0·955-0·998]). For PM₁₀, O₃, NO₂, and SO₂, we did not observe any associations between increased concentration and risk of OHCA on day 0 or cumulative risk over time (ie, at 0-1 days, 0-2 days, 0-3 days, 0-4 days, 0-5 days, and 3-5 days after exposure). For CO, we observed a cumulative decreased risk of OHCA across 0-5 days after exposure (0·876 [0·770-0·997]) and at days 3-5 after exposure (0·810 [0·690-0·949]). We observed effect modification of the association between increasing PM_2·5 concentration and OHCA 0-2 days after exposure by cardiac arrest rhythm (non-shockable 1·027 [1·004-1·050] vs shockable 1·002 [0·956-1·051]) and location of OHCA (at home: 1·033 [1·008-1·057] vs not at home 0·955 [0·957-1·035]). In hypothetical modelling, the number of OHCA events associated with PM_2·5 could be reduced by 8% with a 1 μg/m³ decrease in PM_2·5 concentrations and by 30% with a 3 μg/m³ decrease in PM_2·5 concentrations. Increases in PM_2·5 concentration were associated with an initial increased risk of OHCA and a subsequent reduced risk from 3-5 days after exposure, suggesting a short-term harvesting effect. A decrease in PM_2·5 concentrations could reduce population demand for emergency health services. National Medical Research Council, Singapore, under the Clinician Scientist Award, Singapore and the Singapore Translational Research Investigator Award (MOH-000982-01).

The effect of building-level socioeconomic status on bystander cardiopulmonary resuscitation: a retrospective cohort study

Abstract Background/Introduction In out-of-hospital cardiac arrest (OHCA), bystander cardiopulmonary resuscitation (BCPR) increases survival [1]. Understanding the social determinants of BCPR receipt can inform the design of public health interventions to increase BCPR. The association of socioeconomic status (SES) with BCPR is generally poorly understood. Purpose We aimed to evaluate the effect of SES on BCPR in OHCA using a building-level SES marker. Methods This was a retrospective cohort study based on the Singapore cohort of the Pan-Asian Resuscitation Outcomes Study registry, an ongoing long-term prospective registry for OHCA in the Asia-Pacific region, between 2010 to 2018. We categorized patients into low, medium and high Singapore Housing Index (SHI) levels. The SHI, which appraises a residential property value on an ordinal scale of 1 to 7 (low to high), is a building-level marker that has a robust association with income and residence value [2]. The primary outcome was receipt of BCPR. The secondary outcomes were pre-hospital return of spontaneous circulation (ROSC) and survival – defined as survival to 30 days or hospital discharge, whichever occurred first. Results A total of 12,730 OHCA cases were included (Figure 1), the median age was 71 years and 58.9% were male. BCPR rate was 56.7%. OHCA patients in the low SHI tier were the youngest, most likely male, and least likely to have any medical co-morbidities (Table 1). Compared the low SHI category, those in the medium and high SHI categories were more likely to receive BCPR (medium SHI: adjusted odds ratio [aOR] 1.483, 95% CI 1.301–1.691, p&amp;lt;0.01; high SHI: aOR 1.933, 95% CI 1.669–2.240, p&amp;lt;0.01). As a continuous variable, every unit increase in SHI was associated with increased BCPR (aOR 1.142, 95% CI 1.110–1.174, p&amp;lt;0.001). High SHI patients had higher survival compared to low SHI patients on unadjusted analysis (OR 1.789, 95% CI 1.080–2.964) but not adjusted analysis (adjusted for age, sex, race, witness status, arrest time, past medical history of cancer, and first arrest rhythm). There were no significant differences in the proportion of ROSC across three categories of SHI (p=0.426). When comparing high with low SHI, females had larger increases in BCPR rates compared to males (ratio of OR 1.370, 95% CI 1.012–1.853). There were no significant associations between SHI and BCPR in the subgroups age ≥65 years, witnessed arrest, daytime arrest, and arrests after 2014, and no interaction effects were observed. Conclusions Lower building-level SES was independently associated with lower rate of BCPR. Higher SES was associated with higher 30-day survival on unadjusted analysis but not adjusted analysis, and this study may be under-powered for this outcome. Females were more susceptible to the effect of low SES on lower rate of BCPR, and community CPR training should focus on recognizing OHCA and performing BCPR in women in low SES communities. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Medical Research Council, Clinician Scientist Awards, Singapore (NMRC/CSA/024/2010, NMRC/CSA/0049/2013 and NMRC/CSA-SI/0014/2017) and Ministry of Health, Health Services Research Grant, Singapore (HSRG/0021/2012).

Long term survival and disease burden from out-of-hospital cardiac arrest: a population-based cohort study

Abstract Background Long-term outcomes of out-of-hospital cardiac arrest (OHCA) are important to evaluate the overall health burden of OHCA on society. The concept of disability-adjusted life years (DALY) have recently been utilised to measure disease burden in OHCA, but data in an Asian cohort remains limited. We aimed to quantify and identify predictors of long-term survival (up to 10 years follow up) in patients with OHCA, as well as to quantify the annual disease burden of OHCA estimated using DALY in a national multi-ethnic Asian cohort. Methods We conducted an open cohort study through the linkage of the Pan-Asian Resuscitation Outcomes Study and the Singapore Registry of Births and Deaths from 2010 to 2020 in Singapore [1]. We quantified long-term survival using the standardised mortality ratio (SMR) for each year of follow up and the annual disease burden using DALY. Predictors of long-term survival were identified using cox-proportional hazards models. Kaplan-Meier survival curves were constructed for the overall population, and by key characteristics. The proportion surviving (and 95% CI) was calculated for up to eight years post-OHCA. Results We included 802 cases in the analysis. The mean age was 56.0 (SD 17.8), 631 cases (78.7%) were male, and the majority (552 cases, 68.8%) were of Chinese ethnicity (Table 1). The proportion surviving at one year of follow up was 0.84 (95% CI: 0.81–0.87), at five years of follow up was 0.68 (95% CI 0.65–0.72), and at ten years of follow up was 0.62 (95% CI 0.57–0.67) (Figure 1). Age at arrest (HR 1.03, 95% CI: 1.02–1.04, p&amp;lt;0.001), shockable first arrest rhythm (HR 0.75, 95% CI: 0.52–0.93, p=0.015) and Cerebral Performance Category (CPC) (HR 4.62, 95% CI: 3.17–6.75, p&amp;lt;0.001) were independently associated with mortality (Figure 2, 3). At one year, the SMR was 14.9 (95% CI: 12.5–17.8), and this decreased to 1.2 (95% CI: 0.7–1.8) at three years, and 0.4 (95% CI: 0.2–0.8) at five years (Figure 4). The top three causes of death after OHCA based on ICD10 categories were pneumonia, chronic ischemic heart disease, and acute myocardial infarction. The total DALY increased from 304.1 in 2010 to 849.7 in 2015, followed by decreasing to 547.1 in 2018. The mean DALY decreased from 12.162 in 2010 to 3.599 in 2018. Conclusions Age at arrest and CPC category was independently associated with higher risk of mortality, while a shockable first arrest rhythm was independently associated with a lower risk of mortality in long-term OHCA survivors. Initial survivors of OHCA have an increased mortality rate compared to the general population for the first three years, but normalises to that of the general population subsequently, while the annual disease burden of OHCA quantified using DALY showed decreasing trends from 2010 to 2018. Further improvements in the surveillance and management of OHCA may be warranted to improve the long-term survivorship and decrease the burden of disease of OHCA globally. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Medical Research Council, Clinician Scientist Award, Singapore (NMRC/CSA/024/2010 and NMRC/CSA/0049/2013), Ministry of Health, Health Services Research Grant, Singapore (HSRG/0021/2012)

Characteristics and Outcomes of Traumatic Cardiac Arrests in the Pan-Asian Resuscitation Outcomes Study*

Objective Little is known about survival outcomes after traumatic cardiac arrest in Asia, or the association of Utstein factors with survival after traumatic cardiac arrests. This study aimed to describe the epidemiology and outcomes of traumatic cardiac arrests in Asia, and analyze Utstein factors associated with survival. Methods Traumatic cardiac arrest patients from 13 countries in the Pan-Asian Resuscitation Outcomes Study registry from 2009 to 2018 were analyzed. Multilevel logistic regression was performed to identify factors associated with the primary outcomes of survival to hospital discharge and favorable neurological outcome (Cerebral Performance Category (CPC) 1-2), and the secondary outcome of return of spontaneous circulation (ROSC). Results There were 207,455 out-of-hospital cardiac arrest cases, of which 13,631 (6.6%) were trauma patients aged 18 years and above with resuscitation attempted and who had survival outcomes reported. The median age was 57 years (interquartile range 39–73), 23.0% received bystander cardiopulmonary resuscitation (CPR), 1750 (12.8%) had ROSC, 461 (3.4%) survived to discharge, and 131 (1.0%) had CPC 1-2. Factors associated with higher rates of survival to discharge and favorable neurological outcome were arrests witnessed by emergency medical services or private ambulances (survival to discharge adjusted odds ratio (aOR) = 2.95, 95% confidence interval (CI) = 1.99–4.38; CPC 1-2 aOR = 2.57, 95% CI = 1.25–5.27), bystander CPR (survival to discharge aOR = 2.16; 95% CI 1.71–2.72; CPC 1-2 aOR = 4.98, 95% CI = 3.27–7.57), and initial shockable rhythm (survival to discharge aOR = 12.00; 95% CI = 6.80–21.17; CPC 1-2 aOR = 33.28, 95% CI = 11.39–97.23) or initial pulseless electrical activity (survival to discharge aOR = 3.98; 95% CI = 2.99–5.30; CPC 1-2 aOR = 5.67, 95% CI = 3.05–10.53) relative to asystole. Conclusions In traumatic cardiac arrest, early aggressive resuscitation may not be futile and bystander CPR may improve outcomes.

The predictive performance of current termination-of-resuscitation rules in patients following out-of-hospital cardiac arrest in Asian countries: A cross-sectional multicentre study.

BackgroundTermination-of-resuscitation rules (TORRs) in out-of-hospital cardiac arrest (OHCA) patients have been applied in western countries; in Asia, two TORRs were developed and have not been externally validated widely. We aimed to externally validate the TORRs using the registry of Pan-Asian Resuscitation Outcomes Study (PAROS).MethodsPAROS enrolled 66,780 OHCA patients in seven Asian countries from 1 January 2009 to 31 December 2012. The American Heart Association-Basic Life Support and AHA-ALS (AHA-BLS), AHA-Advanced Life Support (AHA-ALS), Goto, and Shibahashi TORRs were selected. The diagnostic test characteristics and area under the receiver operating characteristic curve (AUC) were calculated. We further determined the most suitable TORR in Asia and analysed the variable differences between subgroups.ResultsWe included 55,064 patients in the final analysis. The sensitivity, specificity, negative predictive value, positive predictive value, and AUC, respectively, for AHA-BLS, AHA-ALS, Goto, Shibashi TORRs were 79.0%, 80.0%, 19.6%, 98.5%, and 0.80; 48.6%, 88.3%, 9.8%, 98.5%, and 0.60; 53.8%, 91.4%, 11.2%, 99.0%, and 0.73; and 35.0%, 94.2%, 8.4%, 99.0%, and 0.65. In countries using the Goto TORR with PPV<99%, OHCA patients were younger, had more males, a higher rate of shockable rhythm, witnessed collapse, pre-hospital defibrillation, and survival to discharge, compared with countries using the Goto TORR with PPV ≥99%.ConclusionsThere was no single TORR fit for all Asian countries. The Goto TORR can be considered the most suitable; however, a high predictive performance with PPV ≥99% was not achieved in three countries using it (Korea, Malaysia, and Taiwan).

Evaluation of telephone-assisted cardiopulmonary resuscitation recommendations for out-of-hospital cardiac arrest

Aim of the studyWhile out-of-hospital cardiac arrest (OHCA) is associated with poor survival, early bystander CPR (B-CPR) and telephone CPR (T-CPR) improves survival from OHCA. American Heart Association (AHA) Scientific Statements outline recommendations for T-CPR. We assessed these recommendations and hypothesized that meeting performance standards is associated with increased likelihood of survival. Additional variables were analyzed to identify future performance measurements. MethodsWe conducted a retrospective cohort study of non-traumatic, adult, OHCA using the Singapore Pan-Asian Resuscitation Outcomes Study. The primary outcome was likelihood of survival; secondary outcomes were pre-hospital Return of Spontaneous Circulation (ROSC) and B-CPR. ResultsFrom 2012 to 2016, 2,574 arrests met inclusion criteria. Mean age was 68 ± 15; of 2,574, 1,125 (44%) received T-CPR with 5% (135/2574) survival. T-CPR cases that met the Lerner et al. performance metrics analyzed, demonstrated no statistically significant association with survival. Cases which met the Kurz et al. criteria, “Time for Dispatch to Recognize Need for CPR” and “Time to First Compression,” had adjusted odds ratios of survival of 1.01 (95% CI:1.00, 1.02; p = <0.01) and 0.99 (95% CI:0.99, 0.99; p = <0.01), respectively. Identified barriers to CPR decreased the odds of T-CPR and B-CPR being performed. Patients with prehospital ROSC had higher odds of B-CPR being performed. EMS response time < 8 minutes was associated with increased survival among patients receiving T-CPR. ConclusionAHA scientific statements on T-CPR programs serve as ideal starting points for increasing the quality of T-CPR systems and patient outcomes. More work is needed to identify other system performance measures.

Development and validation of an interpretable prehospital return of spontaneous circulation (P-ROSC) score for patients with out-of-hospital cardiac arrest using machine learning: A retrospective study

SummaryBackgroundReturn of spontaneous circulation (ROSC) before arrival at the emergency department is an early indicator of successful resuscitation in out-of-hospital cardiac arrest (OHCA). Several ROSC prediction scores have been developed with European cohorts, with unclear applicability in Asian settings. We aimed to develop an interpretable prehospital ROSC (P-ROSC) score for ROSC prediction based on patients with OHCA in Asia.MethodsThis retrospective study examined patients who suffered from OHCA between Jan 1, 2009 and Jun 17, 2018 using data recorded in the Pan-Asian Resuscitation Outcomes Study (PAROS) registry. AutoScore, an interpretable machine learning framework, was used to develop P-ROSC. On the same cohort, the P-ROSC was compared with two clinical scores, the RACA and the UB-ROSC. The predictive power was evaluated using the area under the curve (AUC) in the receiver operating characteristic analysis.Findings170,678 cases were included, of which 14,104 (8.26%) attained prehospital ROSC. The P-ROSC score identified a new variable, prehospital drug administration, which was not included in the RACA score or the UB-ROSC score. Using only five variables, the P-ROSC score achieved an AUC of 0.806 (95% confidence interval [CI] 0.799–0.814), outperforming both RACA and UB-ROSC with AUCs of 0.773 (95% CI 0.765–0.782) and 0.728 (95% CI 0.718–0.738), respectively.InterpretationThe P-ROSC score is a practical and easily interpreted tool for predicting the probability of prehospital ROSC.FundingThis research received funding from SingHealth Duke-NUS ACP Programme Funding (15/FY2020/P2/06-A79).

Validation of the CaRdiac Arrest Survival Score (CRASS) for predicting good neurological outcome after out-of-hospital cardiac arrest in an Asian emergency medical service system

BackgroundSurvival with favorable neurological outcomes is an important indicator of successful resuscitation in out-of-hospital cardiac arrest (OHCA). We sought to validate the CaRdiac Arrest Survival Score (CRASS), derived using data from the German Resuscitation Registry, in predicting the likelihood of good neurological outcomes after OHCA in Singapore. MethodsWe conducted a retrospective population-based validation study among EMS-attended OHCA patients (≥18 years) in Singapore, using data from the prospective Pan-Asian Resuscitation Outcomes Study registry. Good neurological outcome was defined as a cerebral performance category of 1 or 2. To evaluate the CRASS score in light of the difference in patient characteristics, we used the default constant coefficient (0.8) and the adjusted coefficient (0.2) to calculate the probability of good neurological outcomes. ResultsOut of 11,404 analyzed patients recruited between April 2010 and December 2018, 260 had good and 11,144 had poor neurological function. The CRASS score demonstrated good discrimination, with an area under the curve of 0.963 (95% confidence interval: 0.952–0.974). Using the default constant coefficient of 0.8, the CRASS score consistently overestimated the predicted probability of a good outcome. Following adjustment of the coefficient to 0.2, the CRASS score showed improved calibration. ConclusionCRASS demonstrated good discrimination and moderate calibration in predicting favorable neurological outcomes in the validation Singapore cohort. Our study established a good foundation for future large-scale, cross-country validations of the CRASS score in diverse sociocultural, geographical, and clinical settings.

Pre-hospital airway management and survival outcomes after paediatric out-of-hospital cardiac arrests

BackgroundPaediatric out-of-hospital cardiac arrest (OHCA) results in high mortality and poor neurological outcomes. We conducted this study to describe and compare the effects of pre-hospital airway management on survival outcomes for paediatric OHCA in the Asia-pacific region. MethodsWe performed a retrospective analysis of the Pan Asian Resuscitation Outcomes Study (PAROS) data from January 2009 to June 2018. PAROS is a prospective, observational, multi-centre cohort study from eleven countries. The primary outcomes were one-month survival and survival with favourable neurological status, defined as Cerebral Performance Category1 or 2. We performed multivariate analyses of the unmatched and propensity matched cohort. ResultsWe included 3131 patients less than 18 years in the study. 2679 (85.6%) children received bag-valve-mask (BVM) ventilations, 81 (2.6%) endotracheal intubations (ETI) and 371 (11.8%) supraglottic airways (SGA). 792 patients underwent propensity score matching. In the matched cohort, advanced airway management (AAM: SGA and ETI) when compared with BVM group was associated with decreased one-month survival [AAM: 28/396 (7.1%) versus BVM: 55/396 (13.9%); adjusted odds ratio (aOR), 0.46 (95% CI, 0.29 – 0.75); p = 0.002] and survival with favourable neurological status [AAM: 8/396 (2.0%) versus BVM: 31/396 (7.8%); aOR, 0.22 (95% CI, 0.10 – 0.50); p < 0.001]. For SGA group, we observed less 1-month survival [SGA: 24/337 (7.1%) versus BVM: 52/337 (15.4%); aOR, 0.41 (95 %CI, 0.25–0.69), p = 0.001] and survival with favourable neurological status. ConclusionIn children with OHCA in the Asia-Pacific region, pre-hospital AAM was associated with decreased one-month survival and less favourable neurological status.

The Effect of Building-Level Socioeconomic Status on Bystander Cardiopulmonary Resuscitation: A Retrospective Cohort Study

Objective Understanding the social determinants of bystander cardiopulmonary resuscitation (CPR) receipt can inform the design of public health interventions to increase bystander CPR. The association of socioeconomic status with bystander CPR is generally poorly understood. We evaluated the relationship between socioeconomic status and bystander CPR in cases of out-of-hospital cardiac arrest (OHCA). Methods This was a retrospective cohort study based on the Singapore cohort of the Pan-Asian Resuscitation Outcomes Study registry between 2010 and 2018. We categorized patients into low, medium, and high Singapore Housing Index (SHI) levels—a building-level index of socioeconomic status. The primary outcome was receipt of bystander CPR. The secondary outcomes were prehospital return of spontaneous circulation and survival to discharge. Results A total of 12,730 OHCA cases were included, the median age was 71 years, and 58.9% were male. The bystander CPR rate was 56.7%. Compared to patients in the low SHI category, those in the medium and high SHI categories were more likely to receive bystander CPR (medium SHI: adjusted odds ratio [aOR] 1.48, 95% CI 1.30–1.69; high SHI: aOR 1.93, 95% CI 1.67–2.24). High SHI patients had higher survival compared to low SHI patients on unadjusted analysis (OR 1.79, 95% CI 1.08–2.96), but not adjusted analysis (adjusted for age, sex, race, witness status, arrest time, past medical history of cancer, and first arrest rhythm). When comparing high with low SHI, females had larger increases in bystander CPR rates than males. Conclusions Lower building-level socioeconomic status was independently associated with lower rate of bystander CPR, and females were more susceptible to the effect of low socioeconomic status on lower rate of bystander CPR.

Gender disparities among adult recipients of layperson bystander cardiopulmonary resuscitation by location of cardiac arrest in Pan-Asian communities: A registry-based study.

SummaryBackgroundBystander cardiopulmonary resuscitation (BCPR) is a critical component of the 'chain of survival' in reducing mortality among out-of-hospital cardiac arrest (OHCA) victims. Inconsistent findings on gender disparities among adult recipients of layperson BCPR have been reported in the literature. We aimed to fill this knowledge gap by investigating the extent of gender disparities in a cross-national setting within Pan-Asian communities.MethodsWe utilised data collected from the Pan-Asian Resuscitation Outcomes Study (PAROS), an international, multicentre, prospective study conducted between 2009 and 2018. We included all OHCA cases with non-traumatic arrest aetiology transported by emergency medical services and excluded study sites that did not consistently collect information about the location of cardiac arrest. Logistic regression was used to analyse the association between gender and BCPR, stratified by location.FindingsWe analysed a cohort of 56,192 OHCA cases with an overall BCPR rate of 36.2% (20,329/56,192). At public locations, the BCPR rate was 31.2% (631/2022) for female and 36.4% (3235/8892) for male OHCA victims; while at home, the rate was 38.3% (6838/17,842) for females and 35.1% (9625/27,436) for males. Controlling for site differences and several factors in multivariable logistic regression, we found females less likely to receive BCPR than males in public locations (odds ratio [OR]=0.89, 95% confidence interval [CI]: 0.70–0.99), but more likely to receive BCPR at home (OR=1.16, 95% CI: 1.11–1.21).InterpretationIn Pan-Asian communities, gender differences exist in adult recipients of BCPR and differ between home and public locations. Future studies should account for additional information on bystanders and societal factors to identify targets for interventions.FundingThe study was supported by grants from the National Medical Research Council (NMRC/CSA/0049/2013) and Laerdal Foundation (20040).