Validation of Utstein-Based score to predict return of spontaneous circulation (UB-ROSC) in patients with out-of-hospital cardiac arrest.

BACKGROUND AND AIMS: The Utstein Based-ROSC (UB-ROSC) score has been developed to predict ROSC in OHCA victims. Aim of the study was to validate the UB-ROSC score using two Utstein-based OHCA registries: the SWiss REgistry of Cardiac Arrest (SWISSRECA) and the Lombardia Cardiac Arrest Registry (Lombardia CARe), northern Italy. METHODS: Consecutive patients with OHCA of any etiology occurring between January 1st, 2019 and December 31st 2021 were included in this retrospective validation study. UB-ROSC score was computed for each patient and categorized in one of three subgroups: low, medium or high likelihood of ROSC according to the UB-ROSC cut-offs (≤-19; -18 to 12; ≥13). To assess the performance of the UB-ROSC score in this new cohort, we assessed both discrimination and calibration. The score was plotted against the survival to hospital admission. RESULTS: A total of 12.577 patients were included in the study. A sustained ROSC was obtained in 2.719 patients (22%). The UB-ROSC model resulted well calibrated and showed a good discrimination (AUC 0.71, 95% CI 0.70-0.72). In the low likelihood subgroup of UB-ROSC, only 10% of patients achieved ROSC, whereas the proportion raised to 36% for a score between -18 and 12 (OR 5.0, 95% CI 2.9-8.6, p < 0.001) and to 85% for a score ≥13 (OR 49.4, 95% CI 14.3-170.6, p < 0.001). CONCLUSIONS: UB-ROSC score represents a reliable tool to predict ROSC probability in OHCA patients. Its application may help the medical decision-making process, providing a realistic stratification of the probability for ROSC.

Association Between Postresuscitation 12-Lead ECG Features and Early Mortality After Out-of-Hospital Cardiac Arrest: A Post Hoc Subanalysis of the PEACE Study.

Background Once the return of spontaneous circulation after out-of-hospital cardiac arrest is achieved, a 12-lead ECG is strongly recommended to identify candidates for urgent coronary angiography. ECG has no apparent role in mortality risk stratification. We aimed to assess whether ECG features could be associated with 30-day survival in patients with out-of-hospital cardiac arrest. Methods and Results All the post-return of spontaneous circulation ECGs from January 2015 to December 2018 in 3 European centers (Pavia, Lugano, and Vienna) were collected. Prehospital data were collected according to the Utstein style. A total of 370 ECGs were collected: 287 men (77.6%) with a median age of 62 years (interquartile range, 53-70 years). After correction for the return of spontaneous circulation-to-ECG time, age >62 years (hazard ratio [HR], 1.78 [95% CI, 1.21-2.61]; P=0.003), female sex (HR, 1.5 [95% CI, 1.05-2.13]; P=0.025), QRS wider than 120 ms (HR, 1.64 [95% CI, 1.43-1.87]; P<0.001), the presence of a Brugada pattern (HR, 1.49 [95% CI, 1.39-1.59]; P<0.001), and the presence of ST-segment elevation in >1 segment (HR, 1.75 [95% CI, 1.59-1.93]; P<0.001) were independently associated with 30-day mortality. A score ranging from 0 to 26 was created, and by dividing the population into 3 tertiles, 3 classes of risk were found with significantly different survival rate at 30 days (score 0-4, 73%; score 5-7, 66%; score 8-26, 45%). Conclusions The post-return of spontaneous circulation ECG can identify patients who are at high risk of mortality after out-of-hospital cardiac arrest earlier than other forms of prognostication. This provides important risk stratification possibilities in postcardiac arrest care that could help to direct treatments and improve outcomes in patients with out-of-hospital cardiac arrest.

End-tidal carbon dioxide (ETCO2) at intubation and its increase after 10 minutes resuscitation predicts survival with good neurological outcome in out-of-hospital cardiac arrest patients.

AIM: To evaluate whether end-tidal carbon dioxide (ETCO2) value at intubation and its early increase (10 min) after intubation predict both the survival to hospital admission and the survival at hospital discharge, including good neurological outcome (CPC 1-2), in patients with out-of-hospital cardiac arrest (OHCA). METHODS: All consecutive OHCA patients of any etiology between 2015 and 2018 in Pavia Province (Italy) and Ticino Region (Switzerland) were considered. Patients died before ambulance arrival, with a "do-not-resuscitate" order, without ETCO2 value or with incomplete data were excluded. RESULTS: The study population consisted of 668 patients. An ETCO2 value at intubation > 20 mmHg and its increase 10 min after intubation were independent predictors (after correction for known predictors of OHCA outcome) of survival to hospital admission and survival at hospital discharge. Relative to hospital discharge with good neurological outcome, ETCO2 at intubation and its 10-min change were confirmed predictors both individually and in a bivariable analysis (OR 1.83, 95 %CI 1.02-3.3; p = 0.04 and OR 3.9, 95 %CI 1.97-7.74; p < 0.001, respectively). This was confirmed also when accounting for gender, age, etiology and location. After further adjustment for bystander and CPR status, presenting rhythm and EMS arrival time, the ETCO2 change remained an independent predictor. CONCLUSIONS: ETCO2 value > 20 mmHg at intubation and its increase during resuscitation improve the prediction of survival at hospital discharge with good neurological outcome of OHCA patients. ETCO2 increase during resuscitation is a more powerful predictor than ETCO2 at intubation. A larger prospective study to confirm this finding appears warranted.

Physical activity and quality of cardiopulmonary resuscitation: A secondary analysis of the MANI-CPR trial.

INTRODUCTION: The association between the level of physical activity and quality of cardio-pulmonary resuscitation (CPR) performed by laypeople is unclear. The aim of this study was to evaluate the associations between physical activity level and laypeople performance during an eight-minute scenario of CPR. MATERIALS AND METHODS: This study was a secondary analysis of the MANI-CPR Trial. The entire cohort of participants was grouped based on the level of physical activity assessed using the International Physical Activity Questionnaire (IPAQ) into a "low-moderate" level group and a "high" level group. Descriptive statistics were used for unadjusted analysis and multivariate logistic and linear regression models were also performed. RESULTS: A total of 492 participants who reached the score of "Advanced CPR performer" at the 1-min final test monitored by Laerdal Resusci Anne QCPR were included in this analysis; 224 with a low-moderate level and 268 with a high level of physical activity. A statistically significant difference was found for the outcome of percentage of compressions with adequate depth (low-moderate group: 87.8% [41·4%-99·3%], high group: 97% [63·2%-100%]; P = 0·003). No associations remained significant after controlling for biometric characteristics of the participants, compression protocols and sex. CONCLUSION: Adequate quality CPR may not need high baseline level of physical activity to be performed by a lay rescuer.

Out-of-hospital cardiac arrests and mortality in Swiss Cantons with high and low COVID-19 incidence: A nationwide analysis.

AIMS: Many countries reported an increase of out-of-hospital cardiac arrests (OHCAs) and mortality during the COVID-19 pandemic. However, all these data refer to regional settings and national data are still missing. We aimed to assess the OHCA incidence and population mortality during COVID-19 pandemic in whole Switzerland and in the different regions (Cantons) according to the infection rate. METHODS: We considered OHCAs and deaths which occurred in Switzerland after the first diagnosed case of COVID-19 (February 25th) and for the subsequent 65 days and in the same period in 2019. We also compared Cantons with high versus low COVID-19 incidence. RESULTS: A 2.4% reduction in OHCA cases was observed in Switzerland. The reduction was particularly high (-21.4%) in high-incidence COVID-19 cantons, whilst OHCAs increased by 7.7% in low-incidence COVID-19 cantons. Mortality increased by 8.6% in the entire nation: a 27.8% increase in high-incidence cantons and a slight decrease (-0.7%) in low-incidence cantons was observed. The OHCA occurred more frequently at home, CPR and AED use by bystander were less frequent during the pandemic. Conversely, the OHCAs percentage in which a first responder was present, initiated the CPR and used an AED, increased. The outcome of patients in COVID-19 high-incidence cantons was worse compared to low-incidence cantons. CONCLUSIONS: During the COVID-19 pandemic in Switzerland mortality increased in Cantons with high-incidence of infection, whilst not in the low-incidence ones. OHCA occurrence followed an opposite trend showing how variables related to the health-system and EMS organization deeply influence OHCA occurrence during a pandemic.

European Resuscitation Council Guidelines 2021: Systems saving lives.

The European Resuscitation Council (ERC) has produced these Systems Saving Lives guidelines, which are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. The topics covered include chain of survival, measuring performance of resuscitation, social media and smartphones apps for engaging community, European Restart a Heart Day, World Restart a Heart, KIDS SAVE LIVES campaign, lower-resource setting, European Resuscitation Academy and Global Resuscitation Alliance, early warning scores, rapid response systems, and medical emergency team, cardiac arrest centres and role of dispatcher.

Smartphone-based dispatch of community first responders to out-of-hospital cardiac arrest - statements from an international consensus conference.

BACKGROUND: Over the past decade Smartphone-based activation (SBA) of Community First Responders (CFR) to out-of-hospital cardiac arrests (OHCA) has gained much attention and popularity throughout Europe. Various programmes have been established, and interestingly there are considerable differences in technology, responder spectrum and the degree of integration into the prehospital emergency services. It is unclear whether these dissimilarities affect outcome. This paper reviews the current state in five European countries, reveals similarities and controversies, and presents consensus statements generated in an international conference with the intention to support public decision making on future strategies for SBA of CFR. METHODS: In a consensus conference a three-step approach was used: (i) presentation of current research from five European countries; (ii) workshops discussing evidence amongst the audience to generate consensus statements; (iii) anonymous real-time voting applying the modified RAND-UCLA Appropriateness method to adopt or reject the statements. The consensus panel aimed to represent all stakeholders involved in this topic. RESULTS: While 21 of 25 generated statements gained approval, consensus was only found for 5 of them. One statement was rejected but without consensus. Members of the consensus conference confirmed that CFR save lives. They further acknowledged the crucial role of emergency medical control centres and called for nationwide strategies. CONCLUSIONS: Members of the consensus conference acknowledged that smartphone-based activation of CFR to OHCA saves lives. The statements generated by the consensus conference may assist the public, healthcare services and governments to utilise these systems to their full potential, and direct the research community towards fields that still need to be addressed.

Association of Timing of Electrocardiogram Acquisition After Return of Spontaneous Circulation With Coronary Angiography Findings in Patients With Out-of-Hospital Cardiac Arrest.

Importance: Electrocardiography (ECG) is an important tool to triage patients with out-of-hospital cardiac arrest (OHCA) after return of spontaneous circulation (ROSC). An immediate coronary angiography after ROSC is recommended only in patients with an ECG that is diagnostic of ST-segment elevation myocardial infarction (STEMI). To date, the benefit of this approach has not been demonstrated in patients with a post-ROSC ECG that is not diagnostic of STEMI. Objective: To assess whether the time from ROSC to ECG acquisition is associated with the diagnostic accuracy of ECG for STEMI. Design, Setting, and Participants: This retrospective, multicenter cohort study (the Post-ROSC Electrocardiogram After Cardiac Arrest study) analyzed consecutive patients older than 18 years who were resuscitated from OHCA between January 1, 2015, and December 31, 2018, and were admitted to 1 of the 3 participating centers in Europe (Pavia, Italy; Lugano, Switzerland; and Vienna, Austria). Exposure: Only patients who underwent coronary angiography during hospitalization and who acquired a post-ROSC ECG before the angiography were enrolled. Patients with a nonmedical cause of OHCAs were excluded. Main Outcomes and Measures: The primary end point was false-positive ECG findings, defined as the percentage of patients with post-ROSC ECG findings that met STEMI criteria but who did not show obstructive coronary artery disease on angiography that was worthy of percutaneous coronary angioplasty. Results: Of 586 consecutive patients who were admitted to the 3 participating centers, 370 were included in the analysis (287 men [77.6%]; median age, 62 years [interquartile range, 53-70 years]); 121 (32.7%) were enrolled in the participating center in Pavia, Italy; 38 (10.3%) in Lugano, Switzerland; and 211 (57.0%) in Vienna, Austria. The percentage of false-positive ECG findings in the first tertile of ROSC to ECG time (≤7 minutes) was significantly higher than that in the second (8-33 minutes) and third (>33 minutes) tertiles: 18.5% in the first tertile vs 7.2% in the second (odds ratio [OR], 0.34; 95% CI, 0.13-0.87; P = .02) and 5.8% in the third (OR, 0.27; 95% CI, 0.15-0.47; P < .001). These differences remained significant when adjusting for sex (≤7 minutes: reference; 8-33 minutes: OR, 0.32; 95% CI, 0.12-0.85; P = .02; >33 minutes: OR, 0.26; 95% CI, 0.14-0.47; P < .001), age (≤7 minutes: reference; 8-33 minutes: OR, 0.34; 95% CI, 0.13-0.89; P = .03; >33 minutes: OR, 0.27; 95% CI, 0.15-0.46; P < .001), number of segments with ST-elevation (≤7 minutes: reference; 8-33 minutes: OR, 0.35; 95% CI, 0.15-0.81; P = .01; >33 minutes: OR, 0.28; 95% CI, 0.15-0.52; P < .001), QRS duration (≤7 minutes: reference; 8-33 minutes: OR, 0.35; 95% CI, 0.14-0.87; P = .02; >33 minutes: OR, 0.27; 95% CI, 0.15-0.48; P < .001), heart rate (≤7 minutes: reference; 8-33 minutes: OR, 0.35; 95% CI, 0.13-0.93; P = .04; >33 minutes: OR, 0.29; 95% CI, 0.15-0.55; P < .001), epinephrine administered (≤7 minutes: reference; 8-33 minutes: OR, 0.35; 95% CI, 0.13-0.98; P = .045; >33 minutes: OR, 0.27; 95% CI, 0.16-0.48; P < .001), shockable initial rhythm (≤7 minutes: reference; 8-33 minutes: OR, 0.35; 95% CI, 0.13-0.96; P = .04; >33 minutes: OR, 0.26; 95% CI, 0.15-0.46; P < .001), and 3 or more shocks administered (≤7 minutes: reference; 8-33 minutes: OR, 0.36; 95% CI, 0.13-1.00; P = .05; >33 minutes: OR, 0.27; 95% CI, 0.16-0.48; P < .001) in bivariable analyses. Conclusions and Relevance: This study suggests that early ECG acquisition after ROSC in patients with OHCA is associated with a higher percentage of false-positive ECG findings for STEMI. It may be reasonable to delay post-ROSC ECG by at least 8 minutes after ROSC or repeat the acquisition if the first ECG is diagnostic of STEMI and is acquired early after ROSC.

A Multicenter International Randomized Controlled Manikin Study on Different Protocols of Cardiopulmonary Resuscitation for Laypeople: The MANI-CPR Trial.

BACKGROUND: Compression-only cardiopulmonary resuscitation (CPR) is a suggested technique for laypeople facing out-of-hospital cardiac arrest (OHCA). However, it is difficult performing high-quality CPR until emergency medical services arrival with this technique. We aimed to verify whether incorporating intentional interruptions of different frequency and duration increases laypeople's CPR quality during an 8-minute scenario compared with compression-only CPR. METHODS: We performed a multicenter randomized manikin study selecting participants from 2154 consecutive laypeople who followed a basic life support/automatic external defibrillation course. People who achieved high-quality CPR in 1-minute test on a computerized manikin were asked to participate. Five hundred seventy-six were enrolled, and 59 were later excluded for technical reasons or incorrect test recording. Participants were randomized in an 8-minute OHCA scenario using 3 CPR protocols (30 compressions and 2-second pause, 30c2s; 50 compressions and 5-second pause, 50c5s; 100 compressions and 10-second pause, 100c10s) or compression-only technique. The main outcome was the percentage of chest compressions with adequate depth. RESULTS: Five hundred seventeen participants were evaluated. There was a statistically significant difference regarding the percentage of compressions with correct depth among the groups (30c2s, 96%; 50c5s, 96%; 100c10s, 92%; compression only, 79%; P = 0.006). Post hoc comparison showed a significant difference for 30c2s (P = 0.023) and for 50c5s (P = 0.003) versus compression only. Regarding secondary outcome, there were a higher chest compression fraction in the compression-only group and a higher rate of pauses longer than 10 seconds in the 100c10s. CONCLUSIONS: In a simulated OHCA, 30c2s and 50c5s protocols were characterized by a higher rate of chest compressions with correct depth than compression only. This could have practical consequences in laypeople CPR training and recommendations.Clinical Trial Registration: NCT02632500.

Spatio-temporal prediction model of out-of-hospital cardiac arrest: Designation of medical priorities and estimation of human resources requirement.

AIMS: To determine the out-of-hospital cardiac arrest (OHCA) rates and occurrences at municipality level through a novel statistical model accounting for temporal and spatial heterogeneity, space-time interactions and demographic features. We also aimed to predict OHCAs rates and number at municipality level for the upcoming years estimating the related resources requirement. METHODS: All the consecutive OHCAs of presumed cardiac origin occurred from 2005 until 2018 in Canton Ticino region were included. We implemented an Integrated Nested Laplace Approximation statistical method for estimation and prediction of municipality OHCA rates, number of events and related uncertainties, using age and sex municipality compositions. Comparisons between predicted and real OHCA maps validated our model, whilst comparisons between estimated OHCA rates in different yeas and municipalities identified significantly different OHCA rates over space and time. Longer-time predicted OHCA maps provided Bayesian predictions of OHCA coverages in varying stressful conditions. RESULTS: 2344 OHCAs were analyzed. OHCA incidence either progressively reduced or continuously increased over time in 6.8% of municipalities despite an overall stable spatio-temporal distribution of OHCAs. The predicted number of OHCAs accounts for 89% (2017) and 90% (2018) of the yearly variability of observed OHCAs with prediction error ≤1OHCA for each year in most municipalities. An increase in OHCAs number with a decline in the Automatic External Defibrillator availability per OHCA at region was estimated. CONCLUSIONS: Our method enables prediction of OHCA risk at municipality level with high accuracy, providing a novel approach to estimate resource allocation and anticipate gaps in demand in upcoming years.

Out-of-hospital cardiac arrest across the World: First report from the International Liaison Committee on Resuscitation (ILCOR).

BACKGROUND: Since development of the Utstein style recommendations for the uniform reporting of cardiac arrest, increasing numbers of national and regional out-of-hospital cardiac arrest (OHCA) registries have been established worldwide. The International Liaison Committee on Resuscitation (ILCOR) created the Research and Registries Working Group and aimed to systematically report data collected from these registries. METHODS: We conducted two surveys of voluntarily participating national and regional registries. The first survey aimed to identify which core elements of the current Utstein style for OHCA were collected by each registry. The second survey collected descriptive summary data from each registry. We chose the data collected for the second survey based on the availability of core elements identified by the first survey. RESULTS: Seven national and four regional registries were included in the first survey and nine national and seven regional registries in the second survey. The estimated annual incidence of emergency medical services (EMS)-treated OHCA was 30.0-97.1 individuals per 100,000 population. The combined data showed the median age varied from 64 to 79 years and more than half were male in all 16 registries. The provision of bystander cardiopulmonary resuscitation (CPR) and bystander automated external defibrillator (AED) use was 19.1-79.0% in all registries and 2.0-37.4% among 11 registries, respectively. Survival to hospital discharge or 30-day survival after EMS-treated OHCA was 3.1-20.4% across all registries. Favorable neurological outcome at hospital discharge or 30 days after EMS-treated OHCA was 2.8-18.2%. Survival to hospital discharge or 30-day survival after bystander-witnessed shockable OHCA ranged from 11.7% to 47.4% and favorable neurological outcome from 9.9% to 33.3%. CONCLUSION: This report from ILCOR describes data on systems of care and outcomes following OHCA from nine national and seven regional registries across the world. We found variation in reported survival outcomes and other core elements of the current Utstein style recommendations for OHCA across nations and regions.

Survival after out-of-hospital cardiac arrest in Europe - Results of the EuReCa TWO study.

BACKGROUND: The epidemiology and outcome after out-of-hospital cardiac arrest (OHCA) varies across Europe. Following on from EuReCa ONE, the aim of this study was to further explore the incidence of and outcomes from OHCA in Europe and to improve understanding of the role of the bystander. METHODS: This prospective, multicentre study involved the collection of registry-based data over a three-month period (1st October 2017 to 31st December 2017). The core study dataset complied with the Utstein-style. Primary outcomes were return of spontaneous circulation (ROSC) and survival to hospital admission. Secondary outcome was survival to hospital discharge. RESULTS: All 28 countries provided data, covering a total population of 178,879,118. A total of 37,054 OHCA were confirmed, with CPR being started in 25,171 cases. The bystander cardiopulmonary resuscitation (CPR) rate ranged from 13% to 82% between countries (average: 58%). In one third of cases (33%) ROSC was achieved and 8% of patients were discharged from hospital alive. Survival to hospital discharge was higher in patients when a bystander performed CPR with ventilations, compared to compression-only CPR (14% vs. 8% respectively). CONCLUSION: In addition to increasing our understanding of the role of bystander CPR within Europe, EuReCa TWO has confirmed large variation in OHCA incidence, characteristics and outcome, and highlighted the extent to which OHCA is a public health burden across Europe. Unexplained variation remains and the EuReCa network has a continuing role to play in improving the quality management of resuscitation.

An Utstein-based model score to predict survival to hospital admission: The UB-ROSC score.

AIMS: To develop and validate a multi-parametric practical score to predict the probability of survival to hospital admission of an out-of-hospital cardiac arrest (OHCA) victim by using Utstein Style-based variables. METHODS: All consecutive OHCA cases occurring from 2015 to 2017 in two regions, Pavia Province (Italy) and Canton Ticino (Switzerland) were included. We used random effect logistic regression to model survival to hospital admission after an OHCA. We computed the model area under the ROC curve (AUC ROC) for discrimination and we performed both internal and external validation by considering all OHCAs occurring in the aforementioned regions in 2018. The Utstein-Based ROSC (UB-ROSC) score was derived by using the coefficients estimated in the regression model. The score value was obtained adding the pertinent score components calculated for each variable. The score was then plotted against the probability of survival to hospital admission. RESULTS: 1962 OHCAs were included (62% male, mean age 73 ± 16 years). Age, aetiology, location, witnessed OHCA, bystander CPR, EMS arrival time and shockable rhythm were independently associated with survival to hospital admission. The model showed excellent discrimination (AUC 0.83, 95%CI 0.81-0.85) for predicting survival to hospital admission, also at internal cross-validation (AUC 0.82, 95%CI 0.80-0.84). The model maintained good discrimination after external validation by using the 2018 OHCA cohort (AUC 0.77, 95%CI 0.74-0.80). CONCLUSIONS: UB-ROSC score is a novel score that predicts the probability of survival to hospital admission of an OHCA victim. UB-ROSC shall help in setting realistic expectations about sustained ROSC achievement during resuscitation manoeuvres.

Real-life time and distance covered by lay first responders alerted by means of smartphone-application: Implications for early initiation of cardiopulmonary resuscitation and access to automatic external defibrillators.

AIM OF THE STUDY: To investigate the distance covered by lay first responders (LFR) alerted for an out-of- hospital cardiac arrest (OHCA), evaluate the time elapsed between mission acceptance and arrival at the OHCA site, as well as the distance between the LFRs to the closest automatic external defibrillator (AED). METHODS: The LFR route, thus time, distance information, and the average speed of each responder were estimated. The same methodology was used to calculate the distance between the closest AED and the LFRs, as well as the distance between the AED and OHCA site. RESULTS: Between June 1st, 2014 and December 31st, 2017, the LFR network was activated in occasion of 484 suspected OHCAs. 710 LFRs were automatically selected by the application and accepted the mission. On average 1.5 LFRs arrived at the OHCA site. LFRs covered a distance of 1196 m (IQR 596-2314) at a median speed of 6.9 m/s (IQR 4.5-9.8) or 24.8 Km/h. In 4.4% of the cases the speed of the LFRs was compatible with a brisk walk activity (<1.5 m/sec). The total intervention time of an LFR, who first retrieved an AED and then went to the OHCA site, was longer (275 s, IQR: 184 s-414 s) compared to the total intervention time of a LFR (197 s, IQR: 120 s-306 s; p < 0.001), who went to the OHCA site directly without retrieving an AED. CONCLUSIONS: The dispatch of LFRs directly to the OHCA site instead of first retrieving the AED, significantly decreases the time to CPR initiation. More studies are needed to assess the prognostic implications on survival and neurological outcome.

Validation of the return of spontaneous circulation after cardiac arrest (RACA) score in two different national territories.

BACKGROUND: The likelihood of return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest (OHCA) is influenced by unmodifiable (gender, aetiology, location, the presence of witnesses and initial rhythm) and modifiable factors (bystander CPR and the time to EMS arrival). All of these have been included in the ROSC After Cardiac Arrest (RACA) score. PURPOSE: To test the ability of the RACA score to predict the probability of ROSC in two different regions with different local resuscitation networks: the Swiss Canton Ticino and the Italian Province of Pavia. METHODS AND RESULTS: All OHCAs occurred between January 1st 2015 and December 31st 2017 were included. The original regression coefficients for all RACA score variables were applied. The probability to obtain the ROSC as measured with the RACA score was divided in tertiles. Overall, 2041 OHCAs were included in the analysis. The RACA score showed good discrimination for ROSC (AUC 0.76) and calibration, without interaction (p 0.28) between the region and the probability of ROSC. The probability of ROSC was 15% for RACA scores <0.28, 20% for RACA scores between 0.28 and 0.42, increasing to 55% for RACA scores >0.42. CONCLUSIONS: The application of the RACA score reliably assess the probability to obtain the ROSC, with equal effectiveness in the two regions, despite different organization of the resuscitation network. Patients with a RACA score >0.42 had more than 50% probability to obtain ROSC.