Resuscitation

Bystander basic life support and survival after out-of-hospital cardiac arrest: A propensity score matching analysis

a b s t r a c t

Introduction and objectives: In out-of-hospital cardiac arrest, early recognition, calling for emergency medical as- sistance, and early cardiopulmonary resuscitation are acknowledged to be the three most important components in the Chain of survival. However, bystander basic life support (BLS) initiation rates remain low. The objective of the present study was to evaluate the association between bystander BLS and survival after an out-of-hospital cardiac arrest (OHCA).

Methods: We conducted a retrospective cohort study of all patients with OHCA with a medical etiology treated by a mobile intensive care unit (MICU) in France from July 2011 to September 2021, as recorded in the French National OHCA registry (ReAC). Cases in which the bystander was an on-duty fire fighter, paramedic, or emer- gency physician were excluded. We assessed the characteristics of patients who received bystander BLS vs. those who did not. The two classes of patient were then matched 1:1, using a propensity score. conditional logistic regression was then used to probe the putative association between bystander BLS and survival.

Results: During the study, 52,303 patients were included; BLS was provided by a bystander in 29,412 of these cases (56.2%). The 30-day survival rates were 7.6% in the BLS group and 2.5% in the no-BLS group (p < 0.001). After matching, bystander BLS was associated with a greater 30-day survival rate (odds ratio (OR) [95% confi- dence interval (CI)] = 1.77 [1.58-1.98]). Bystander BLS was also associated with greater short-term survival (alive on hospital admission; OR [95%CI] = 1.29 [1.23-1.36]).

Conclusions: The provision of bystander BLS was associated with a 77% greater likelihood of 30-day survival after OHCA. Given than only one in two OHCA bystanders provides BLS, a greater focus on life saving training for lay- people is essential.

(C) 2023

  1. Introduction

Abbreviations: BLS, basic life support; OHCA, out-of-hospital cardiac arrest; MICU, mobile intensive care unit; ReAC, Registre Electronique des Arrets Cardiaques; OR, odds ratio; CI, confidence interval; CPR, cardiopulmonary resuscitation; ALS, advanced life support; ROSC, return of spontaneous circulation; CPC, cerebral performance category; IQR, interquartile range.

* Corresponding author at: ULR 2694 – METRICS: Evaluation des technologies de sante et des pratiques medicales, Institute of Health Engineering of Lille, University of Lille, 42, rue Ambroise Pare, F-59120 Loos, France.

E-mail address: [email protected] (M. Lafrance).

Out-of-hospital cardiac arrest (OHCA) is a major health issue. The overall incidence of OHCA is reportedly 84.0 per 100,000 person-years in Europe and 61.5 per 100,000 person-years in France, which corre- sponds to approximately 46,000 OHCAs per year in the latter country [1,2]. The 30-day survival rate is 7.6% worldwide and 4.9% in France [2,3]. OHCAs are generally managed according to the “chain of survival” concept, which comprises the following prehospital four steps: (i) early recognition, (ii) early cardiopulmonary resuscitation (CPR), (iii) Early defibrillation, and (iv) advanced care [4]. The first three links in the

https://doi.org/10.1016/j.ajem.2023.02.028

0735-6757/(C) 2023

chain of survival (corresponding to basic life support (BLS)) are based on bystander action and are the most important for the survival of an OHCA victim [5]. BLS must be provided as soon as possible because the no-flow duration (i.e. the time interval between collapse and the initiation of CPR) is one of the most important survival factors [6,7]. Bystander intervention before the arrival of a mobile intensive care unit (MICU) is therefore also a key survival factor [3,8-11]. According to the literature data, the bystander BLS initiation rate varies markedly from one country to another. In Europe, the rate ranges from 6% in Romania to 50% in France and over 70% in the Netherlands [12]. Given the low BLS initiation rates in most European countries and the associ- ated loss of chance for survival, the European Resuscitation Council has encouraged member countries to organize and implement more training in life saving [13]. France intends to respond to this call, and the present study is one of the steps in this process. The study’s primary objective was to assess the efficacy of bystander BLS on survival follow- ing an OHCA in France. The secondary objectives were to describe the characteristics of the BLS and the bystanders who provided BLS.

  1. Method
    1. Study setting

In France, the emergency medical service (including OHCA manage- ment) has two components. The first paramedic response and BLS are usually provided by the fire department. Advanced life support is usually then provided by a MICU, coordinated by a medical dispatch center [14]. The French emergency medical services provide details of all OHCAs to the French National cardiac arrest registry (Registre Electronique des Arrets Cardiaques – ReAC). A specific ReAC form is used to collect data on the victim, Bystander interventions, intervention times, the provision of medical support, and the victim’s survival status immediately after the cardiac arrest. The ReAC form is structured ac- cording to the Utstein template [15]. The data on the form are entered in the ReAC’s secure database (www.registreac.org). A follow-up report is filed 30 days after the OHCA or upon hospital discharge.

    1. Study population and data

We assessed ReAC data registered between July 1, 2011, and September 1, 2021. These data included the context of the OHCA, the year, the location (home or otherwise), the bystander-witnessed status (yes/no) defined as the presence of bystander at the time of collapse, the type of bystander (family member, first aid professional, healthcare pro- fessional, or other) and each bystander’s level of training in BLS. We also assessed the victim’s baseline clinical characteristics, sex, age, and med- ical history, along with bystander CPR, first documented rhythm, no- flow and low-flow durations, the provision of ALS (including intubation and epinephrine injection), return of spontaneous circulation (ROSC), vital status upon admission to hospital, and 30-day (D30) follow-up data (vital status and neurological outcome). All the definitions of col- lected data were based on the international Utstein-style template [15].

    1. Inclusion and exclusion criteria

We included all OHCAs with one or more bystanders but we ex- cluded cases in which the bystander was an on-duty fire fighter, para- medic, or emergency physician. We also excluded victims who were found dead (Rigor mortis), victims not treated by a MICU, victims whose cardiac Rhythm status was unknown, victims with spontaneous Cardiac activity upon the MICU’s arrival and without any previous rhythm recorded and OHCAs with a non-medical etiology. A medical etiology was defined (according to the Utstein template) as cases in which the cause of the cardiac arrest is presumed to be cardiac or other medical cause (e.g, respiratory disease, neurological disease, ana- phylaxis, asthma, and gastrointestinal bleeding) and there is no other

obvious cause of the cardiac arrest [15]. Victims with a no-flow duration

>60 min when the MICU arrived and victims with missing data for study variables were also excluded.

    1. Main exposure

The main exposure of this study was bystander BLS. We define by- stander BLS as the initiation of CPR (chest compression and/or ventila- tion) and/or the use of an Automated external defibrillator .

    1. Endpoints

The primary endpoint was patient survival 30 days after OHCA or upon hospital discharge (if sooner). The secondary endpoints were ROSC, survival upon admission to hospital, and the neurological out- come globally and for patients alive at D30 (according to the Cerebral Performance Category score [16]).

    1. Statistical analysis

We first described the study population and then compared patients who had received bystander BLS (the BLS group) with those who had not (the no-BLS group) with regard to the OHCA context, care, and out- come. Lastly, we calculated a propensity score, matched patients in the no-BLS group with a patient in the BLS group, and assessed the differ- ence in survival.

      1. Description and comparison

Categorical variables were quoted as the number (percentage). For continuous variables, the normality of the data distribution was assessed using the Kolmogorov Smirnov test, and they were described as the median [interquartile range (IQR)] or mean (standard deviation) as appropriate. Bivariate analysis was performed using the Pearson chi- squared test for qualitative variables and the Mann-Whitney U test for quantitative variables.

      1. Calculation of the propensity score and the matching method

We used a multiple logistic regression model to calculate a propen- sity score. First, we selected 14 covariates with clinical or methodologi- cal relevance: the year of OHCA, the patient’s sex, the patient’s age, OHCA location, first documented rhythm, the patient’s medical history (heart disease, respiratory disease, diabetes, end-of-life scenario, other, or none), witnessed OHCA (yes/no), type of bystander, and no- flow duration. The dependent variable was BLS initiation. We attempted 1:1 nearest-neighbor propensity score matching without replacement, within a caliper of 15% of the standard deviation [17-19].

      1. Conditional weighted logistic regression

We performed a logistic regression to estimate a nonadjusted odds ratio (OR) and a conditional weighted logistic regression to estimate an adjusted OR (reference: no-BLS) [20,21]. The threshold for statistical significance was set to p < 0.05. Statistical analyses were performed with R software (version 4.0.3) [22] plus the survival package for condi- tional logistic regression [23] and the MatchIt package for sequential matching [24].

    1. Ethics

The study was approved as a medical assessment registry without a requirement for patient consent. In line with the French legislation on retrospective studies of anonymous registry data, the study protocol was approved by a hospital committee with competency for research not requiring authorization by an institutional review board. The study protocol was registered with the French National Data Protection Commission (Commission nationale de l’informatique et des libertes (Paris, France); reference: 910946, dated April 6, 2012, and the French

Advisory Committee on Information Processing in Health Research (Comite Consultatif sur le Traitement de l’Information en matiere de Recherche dans le domaine de la Sante (Paris, France); reference: 10.326Ter, dated October 14, 2010).

  1. Results
    1. Description of the study population

During the study period, 131,195 patients were recorded in the ReAC (Fig. 1). Of these, 78,892 met at least one exclusion criterion, and so 52,303 patients were included in the study: 29,413 (56.2%) in the BLS group and 22,890 (43.8%) in the no-BLS group. The majority of OHCA victims were male (69.4%), and the median age was 67 years (IQR: [56,78]). A history of a cardiovascular disease was frequent (48.1%), and the OHCA had occurred at home in 75.2% of cases. In the majority of cases, a witness was present at the time of collapse (73.9%). The by- stander was one of the victim’s family member in 69.1% of cases and a healthcare professional in 12.1%. The median of no- and low-flow dura- tions were 9 (IQR: [3,15]) and 35 (IQR: [24,47]) minutes, respectively, and the first documented rhythm was shockable in 22.9% of cases. With regard to ALS, 92.7% of victims were intubated at some point, and 90.1% received epinephrine (Table 1).

    1. Comparison of the BLS and no-BLS groups
      1. The unadjusted (nonmatched) population

In the BLS group, the patients were significantly younger (66 years (IQR: [55,77]), vs. 69 years (IQR: [58,79]) in the no-BLS group; p < 0.001) and were less likely to have a history of cardiovascular dis- ease (47.0% vs. 49.6%, respectively; p < 0.001) (Table 1). OHCA in the BLS group occurred less often at home (67.9%, vs. 84.5% in the no-BLS group; p < 0.001) but was more likely to have been witnessed (80.7% vs. 65.2%, respectively; p < 0.001). In the BLS group, the bystander was less frequently one of the victim’s family member (59.5%, vs.

81.5% in the no-BLS group; p < 0.001). Compared with the no-BLS group, the median no-flow duration was shorter in the BLS group (11 min. (IQR: [7,17]) vs. 5 min. (IQR: [0,14]), respectively; p < 0.001) and the low-flow duration was longer (33 min. (IQR: [23,45]) vs. 36 min. (IQR: [25,50]), respectively; p < 0.001). Patients in the BLS group were more likely to be intubated (93.2%, vs. 92.0% in the no-BLS group; p < 0.001) and less likely to receive epinephrine (89.6% vs. 90.7%, respectively; p < 0.001).

Lastly, patients in the BLS group had a greater incidence of ROSC (32.0%, vs. 22.9% in the no-BLS group; p < 0.001) and higher survival rates upon admission to hospital (27.9% vs. 17.5%, respectively; p < 0.001) and at D30 (7.6% vs. 2.5%, respectively; p < 0.001, respec- tively). When considering D30 survivors, members of the BLS group were more likely to have a good neurological outcomes (84.8%, vs. 75.5% in the no-BLS group; p < 0.001). Globally, members of the BLS group were more likely to have a good neurological D30 survival (6.4% vs. 1.9% in the no-BLS group; p < 0.001).

      1. The matched population

After using a propensity score with 14 covariates to match the pa- tients, we obtained absolute standardized mean differences <10% for each variable and thus validated the matching process (Fig. 2). Hence, each of 17,211 patients in the no-BLS group were matched with a corre- sponding patient in the BLS group. Bystander BLS was associated with higher survival at both timepoints. Patients having received BLS were

1.77 times more likely to survive at D30 than those who did not (sur- vival rate: 5.2% vs. 3.0% respectively; OR [95% confidence interval (CI)] = 1.77 [1.58-1.98]). A positive effect of BLS was also observed for ROSC (28.2%, vs. 24.8% in the no-BLS group, OR [95%CI] = 1.21 [1.16-1.27]) and survival upon admission to hospital (23.6% vs. 19.6%, respectively; OR [95%CI] = 1.29 [1.23-1.36]). The difference in the pro- portion of 30-day survivors with a good neurological outcome was not significant (82.3% in the BLS group vs. 75.8% in the no-BLS group; OR [95%CI] = 1.40 [0.44-4.41]). However, bystander BLS was associated with higher global proportion of good neurological D30 survival (4.2%

Fig. 1. Flowchart.

BLS = basic life support; MICU = mobile intensive care unit; OHCA = out-of-hospital cardiac arrest.

Table 1

Characteristics of the population as a whole and the BLS and no-BLS groups.

after the OHCA. Moreover, 80% of the bystander who did not initiate BLS were family members of the victim.

Characteristics Study population

Comparison

BLS No-BLS p

In line with Lei et al.’s meta-analysis, we did not observe a sex differ- ence in the frequency of bystanders BLS [25]. However, sex differences have been observed in older studies [26,27]. As suggested by Lei et al.,

(n = 52,303) (n = 29,413) (n = 22,890)

Cases per yearu

<0.001

2011

398

(0.8)

224

(0.8)

174

(0.8)

2012

3321

(6.3)

1595

(5.4)

1726

(7.5)

2013

6301

(12.0)

3134

(10.7)

3167

(13.8)

2014

6269

(12.0)

3274

(11.1)

2995

(13.1)

2015

6172

(11.8)

3332

(11.3)

2840

(12.4)

2016

5706

(10.9)

3109

(10.6)

2597

(11.3)

2017

5433

(10.4)

3137

(10.7)

2296

(10.0)

2018

5510

(10.5)

3284

(11.2)

2226

(9.7)

2019

5396

(10.3)

3397

(11.5)

1999

(8.7)

2020

4952

(9.5)

3115

(10.6)

1837

(8.0)

2021

2845

(5.4)

1812

(6.2)

1033

(4.5)

Sex (male)

36,298

(69.4)

20,499

(69.7)

15,799

(69.0)

0.100

Age (years)

67

[56,78]

66

[55,77]

69

[58,79]

<0.001

Medical history

Heart disease

25,180

(48.1)

13,823

(47.0)

11,357

(49.6)

<0.001

Respiratory

disease

7573

(14.5)

3874

(13.2)

3699

(16.2)

<0.001

Diabetes

8104

(15.5)

4275

(14.5)

3829

(16.7)

<0.001

End-of-life

scenario

492

(0.9)

229

(0.8)

263

(1.1)

<0.001

Other

17,472

(33.4)

9608

(32.7)

7864

(34.4)

<0.001

None

6107

(11.7)

3636

(12.4)

2471

(10.8)

<0.001

OHCA location

(home)

39,312

(75.2)

19,972

(67.9)

19,340

(84.5)

<0.001

Witnessed OHCA

38,661

(73.9)

23,742

(80.7)

14,919

(65.2)

<0.001

First documented

rhythm

(shockable)

11,970

(22.9)

8019

(27.3)

3951

(17.3)

<0.001

Bystander type

<0.001

Family member

36,148

(69.1)

17,489

(59.5)

18,659

(81.5)

First aid

professional

1868

(3.6)

1707

(5.8)

161

(0.7)

Healthcare

professional

6307

(12.1)

5575

(19.0)

732

(3.2)

Other

7980

(15.3)

4642

(15.8)

3338

(14.6)

Trained

bystander?

1234

(77.4)

989

(77.0)

245

(79.0)

0.481

No-flow duration

(min)

9

[3,15]

5

[0,14]

11

[7,17]

<0.001

Low-flow duration

(min) 35

[24,47]

36

[25,50]

33

[23,45]

<0.001

Intubation

48,485

(92.7)

27,416

(93.2)

21,069

(92.0)

<0.001

Epinephrine

47,103

(90.1)

26,339

(89.6)

20,764

(90.7)

<0.001

ROSC

14,654

(28.0)

9423

(32.0)

5231

(22.9)

<0.001

Alive at hospital

admission

12,206

(23.3)

8202

(27.9)

4004

(17.5)

<0.001

Alive at D30

2793

(5.3)

2229

(7.6)

564

(2.5)

<0.001

If alive, CPC 1-2 at

D30

2317

(83.0)

1891

(84.8)

426

(75.5)

<0.001

CPC 1-2 at D30

2317

(4.4)

1891

(6.4)

426

(1.9)

<0.001

BLS = basic life support; CPC = Cerebral performance category score; D30 = survival 30 days after OHCA or upon hospital discharge (if sooner); OHCA = out-of-hospital car- diac arrest; ROSC = return of spontaneous circulation.

Data are expressed as n (%) for categorical variables and the median [interquartile range] for continuous variables.

u Year 2011 is from July to December and year 2021 is from January to September.

* 50,708 missing values.

in the BLS group vs. 2.3% in the no-BLS group; OR [95%CI] = 1.90 [1.67-2.15]) (Fig. 3).

  1. Discussion

Here, we studied patients who suffered an OHCA in the presence of a bystander and were resuscitated by a MICU. Patients who received by- stander BLS were 20% more likely to have ROSC, 30% more likely to be alive on admission to hospital, and 77% more likely to be alive 30 days

this disparity might reflect changing stereotypes and changes in society; if this is true, our results are encouraging.

However, we identify several factors that appeared to reduce the fre- quency of bystander BLS. In line with the literature data, we found that family bystanders are the least likely to provide BLS [28-31]. There are several possible explanations for this finding. Firstly, the stress of the event can create a psychological barrier that impedes the family mem- ber from reacting [32]. Secondly, the fear of injuring the victim is a known barrier to bystander BLS [33,34] and is accentuated by an emo- tional link between the victim and the bystander. Thirdly, a lack of self-confidence [33,35] and a lack of knowledge [32,34] are known bar- riers to the provision of bystander BLS. All these factors are directly re- lated to the general public’s lack of training in basic life support. Lastly, the bystander is often a family member for OHCAs that occur at home [29,36]; this can also be a barrier to the initiation of bystander BLS. The need for training laypeople in BLS appear clear. That’s why the European Resuscitation Council initiated the Kids Save Lives project with the objective to train schoolchildren in BLS earlier as possible dur- ing their schooling [37].

Hence, patients who did not receive bystander BLS were more likely to have cardiac arrest at home. Many studies have reported similar re- sults [28,38,39]. These findings support Hasselqvist et al.’s suggestion

[40] that when an OHCA occurs at home, the bystander is more likely

to be an elderly person who is not aware of or trained in BLS or is not physically able to provide BLS. Another possible explanation is that vic- tims of an OHCA at home are more likely to be alone in a specific room at the time of the arrest, which could delay recognition of the event. In- deed, we found in our study that when a bystander had not witnessed the collapse, he/she was less likely to perform BLS. This observation is in line with the literature data on infrequent BLS initiation due mainly to a lack of BLS training [33,38,41].

In our matched population, we observed a favorable effect of by- stander BLS on survival variables (ROSC, being alive on admission to hospital, and D30 survival). However, bystander BLS did not appear to have an impact on the neurological outcome of D30 survivors. In a pro- pensity score matching study of the Swedish OHCA Registry between 1990 and 2011, Hasselqvist-Ax et al. [40] compared the 30-day survival rates for OHCA victims having received (or not) bystander CPR. The re- searchers found that the D30 survival rate for victims having received bystander CPR was almost three times greater than that for victims who had not (vs. 1.77 times greater in our study). Our results are also in line with the beneficial effect of bystander CPR on 30-day survival ev- idenced in observational studies of cardiac arrest registry data from the USA, Australia, and Korea by Geri et al. [42], Doan et al. [43] and Lee et al. [44], respectively.

Few studies have focused on ROSC. However, Geri et al. [42] or Lee et al. [44] found a higher incidence of ROSC in victims having received bystander CPR. As in the present study, Geri et al. [42] and Doan et al.

[43] also found a beneficial effect of bystander CPR on survival upon ad- mission to hospital. In our study, bystander CPR did not appear to have an impact on neurological outcomes in 30-day survivors; this contrasted with Lee et al.’s [44] study in a similar study population. This disparity might be due to differences in ALS provided by the MICU or in in-hospital care.

Our overall findings are in line with the literature: bystander CPR is associated with greater survival after an OHCA. These results notably emphasize the importance of the bystander in the first three links in the chain of survival, including immediate alerting, cardiac massage, and early defibrillation. Accordingly, Deakins et al. [5] found that the links in the chain of survival do not all carry the same weight in terms

Image of Fig. 2

Fig. 2. Absolute standardized mean differences.

Healthcare Prof. = Healthcare Professional; OHCA = out-of-hospital cardiac arrest.

of patient survival; immediate alerting and cardiac massage were the most critical for survival of an OHCA.

    1. Limitations

Our study had some limitations. Firstly, participation in the French National Cardiac Arrest Registry (ReAC) is voluntary; and a small pro- portion (<10%) of the MICUs in France did not contribute to ReAC

during the study period. However, the registry’s broad geographical coverage and the nevertheless large number of centers indicate that its data are representative of the population and practices in France. Sec- ondly, our study did not have a randomized, controlled design. How- ever, it is ethically and logistically complicated to set and conduct a randomized study of BLS. Although a propensity score does not provide the Level of evidence associated with a randomized, controlled design, the methodology used here is an excellent, cheaper alternative for

Outcomes Models

OR [95% CI]

Nonmatched 1.62 [1.56-1.68]

In favor of no- BCPR

In favor of BCPR

ROSC

Alive at hospital admission

Alive at D30

If alive, CPC 1-2 at D30

CPC 1-2 at D30

Matched 1.21 [1.16-1.27]

Nonmatched 1.85 [1.77-1.93]

Matched 1.29 [1.23-1.36]

Nonmatched 3.25 [2.97-3.57]

Matched 1.77 [1.58-1.98]

Nonmatched 1.76 [1.40-2.19]

Matched 1.40 [0.44-4.41]

Nonmatched 3.60 [3.25-4.01]

Matched 1.90 [1.67-2.15]

0 1 2 3 4

Fig. 3. Comparison of study endpoints.

removing identified sources of confounding biases. Additionally, some pre-existing confounding factors could have been unmeasured which could have an impact on the matching process. Moreover, this study only included pre-hospital data and do not consider post-resuscitation care which might be a cofounding in the study outcomes. Additionally, the registry enable us to know the implementation or not of BLS. How- ever, we didn’t assess the quality and efficacy of bystander chest com- pression. Thus, some BLS could have been of suboptimal quality but this did not prevent us from studying the impact of an active bystander who enabled the various links in the chain of survival to be set up. Lastly, we studied bystanders in France, and so our findings cannot necessarily be generalized to other countries and healthcare systems.

  1. Conclusion

Our present results showed that in France, bystander BLS is associ- ated with greater survival after OHCA. However, only one in two by- standers initiated BLS. Our results therefore highlight the importance and usefulness of the bystander and his/her action but also the low in- tervention rate by the general public. The low bystander Intervention rates are known to be related to a lack of knowledge and self- confidence. Hence, our results also emphasize the importance of the in- ternational guidelines on the role of bystanders in OHCA and on the im- portance of training in BLS [13,45]. The European “Kids Save Lives” educational project [37] should be therefore implemented in France in order to evaluate the impact of BLS training in schoolchildren and im- prove bystander BLS initiation rates.

CRediT authorship contribution statement

Martin Lafrance: Writing – review & editing, Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Morgan Recher: Writing – review & editing, Validation, Methodology, Conceptualization. Francois Javaudin: Writing – review & editing, Visu- alization, Validation, Investigation. Tahar Chouihed: Visualization, Val- idation, Investigation. Eric Wiel: Visualization, Validation, Investigation. Gerard Helft: Visualization, Validation, Investigation. Herve Hubert: Writing – review & editing, Validation, Methodology, Conceptualization. Valentine Canon: Writing – review & editing, Validation, Supervision, Methodology, Conceptualization.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influ- ence the work reported in this paper.

Acknowledgement

The French National Cardiac Arrest Registry is funded by the French Society of Emergency Medicine (SFMU), the Federation Francaise de Cardiologie (FFC), the Mutuelle Generale de l’Education Nationale, Lille University, the Hauts-de-France Regional Council, and (via the European Regional Development Fund) the European Union.

The members of the French National Out-of-Hospital Cardiac Arrest Registry study group are Drs. Diego Abarrategui, Mohamed Abdeljaouad, Sami Abdelkhalek, Lila Abdelli, Romain Adam, Fabrice Agbemebia, Jean-Marc Agostinucci, Terence Ahui, Tesnim Aiouaz, Afandi Al Bassem, Anas Al Tabchi, Pierre Alba, Fabrice Alcouffe, Elodie Allemandet, Mona Allers, Yohan Altervain, Francois-Xavier Amelon, Eryk Amiens, Loic Amizet, Antoine Andre, Fanny Andre, Paul Andregnette, Florian Andriamirado, Bastien Anette, Anne-Claire Laquerbe, Celia Antonic-Ravaut, Jerome Antouard, Aurelie Armand, Aurelie Arnaud, Gaelle Arnaud, Idriss Arnaudet, Xavier Arrot, Gaele Aubert, Raphael Aubert, Antoine Aubrion, Thomas Audra, Claudie Audrain, Yannick Auffret, Harold Auger, Isabelle Aune, Jean-Christophe

Auneau, Aurelie Avondo, Sonia Ayllon-Milla, Thierry Babet, Clement Babin, Florence Bages-Limoges, Anne Baina, Joseph Balland, Celine Bal- let, Claire Ballet, Pierre Banwarth, Christian Bar, Patrick Barandiaran, Christophe Barberis, Adele Barbery, Romain Bardelay, Philippe Bargain, Ruxandra Barrault, Morgane Barret, Benjamin Barry-Colin, Francois- Xavier Barthelemy, Jean-Claude Bartier, Karen Barukh, Marielle Basty- Ghuysen, Martin Bataille, Marine Baudin, Stan Bawejski, Cyril Bazzoli, Placido Beaka, Max Beal, Adeline Beaudoin, Zaher Beayni, Sarah Bedini, Aurelie Begaudeau, Julien Beharelle, Matthieu Belin, Marielle Bellet, Marie-Camille Belli, Tobola Bellow, Josiane Benaniba, Amandine Benard, Imane Benaziz, Sylvain Benenati, Yony Benguigui, Clement Benoit, Cecile Berard, Julie Berger, Patricia Bernadet, Sandra Bernard, Emmanuel Bernigaud, Antoine Berthelon, Frederic Berthier, Hedi Bertille, Benoit Bertrand, Pascale Bertrand, Philippe Bertrand, Sylvie Besnier, Paulin Besserve, Veronique Beunas, Roland Bianchi, Laurianne Billier, Cecilia Billiou, Tania Bintener, Pascal Bissolokele, Stephane Blain, Gilles Blaquiere, Romain Blondet, Emmanuel Blottiaux, Clio Bohler, Rozenn Bois, Jennifer Bois-De-Fer, Romain Bokobza, Maxime Bollani, Cecile Bonhomme, Lucie Bonnet, Daniel Bonnieux, Jeremy Bontemps, Guil- laume Boon, Juliane Bosc, Severine Boucard, Celia Bouchel, Olivia Boudard, Philippe Bouffard, Emmanuel Bouhey, Guillem Bouilleau, Bertrand Boulanger, Chloe Boulanger, Guillaume Boulestein, Nadia Bourayou, Marike Bouret, Arthur Bourg, Anna Bourreau, Marion Boursier, Catherine Boussarie, Florent Bouteloup, Celia Boutin, Celine Boutry, Simon Bouvier, Romain Boyer, Cecile Bracq, Fabienne Branche, Francois Brau, Mathieu Brazy, Stephanie Bredel, Samia Bregigeon, Apolline Briatte, Nicolas Briole, Etienne Brisson, Romain Brocheux, Lara Brosset, Lucile Bruere, Amandine Bruneau, Romain Brunschwig, Laure Brus, Cecile Bujon, Clement Buleon, Laura Buscaglia, Olivia Busi, Geraldine Butin, Laurent Cabanne, Camille Cahuzac, Dominique Cailloce, Charles Noel Camard, Leila Camboni-Pineau, Guillaume Campagne, Val- entine Canon, Florian Canu, Olivier Capel, Pierre Caprini, Elvira Capuano, Christophe Caralp, Maud Carcaille, Marion Caresmel, Olivier Carle, Alain Carreres, Chloe Carruesco, Alexis Casalonga, Denis Casanova, Olivier Cassone, Margot Cassuto, Francois Castera, Sophie Cathelin, Vincent Cattin, Pascale Cavalli, Margaux Chabannon, Asceline Chabaud, Fabien Chadelaud, Anne Champenois, Vanessa Champenois, David Chanel, Gauthier Chantrel, Anais Chapelle, Amelie Charbon, Adeline Chardin, Alexandre Charney, Carine Chassery, Coralie Chassin, Guillaume Chatenet, Arthur Chatrenet, Claude Cheminat, Anne-Sophie Chesneau, Marine Chesnoy, Guillaume Chevrier, Eric Chiale, Julien Chiche, Mahado Chirwa, Hendricks Chomono, Laure Chopard, Pierre-Amaury Chopinaud, Mikhael Chouraqui, Jean-Francois Cicala, Philippe Ciocca, Khadidiatou Cissokho, Emmelyne Clauw, Maxens Clauzel, Bonnet Clem- entine, Berenice Cluzel, Pierre Coffin, Rudy Cohen, Mauro Coletta, Valery Collet, Amandine Collin, Pierre-Etienne Colot, Camille Colson, Pascal Conan, Alice Conio, Loik Connan, Lucile Constant, Samuel Constant, Vincent Coppin, Carole Cornaglia, Mathieu Cornuault, Laure Corradi, Alexandra Corsia, Aurelie Costa, Charlotte Cotronis, Bastien Coulon, Hubert Courcoux, Cecile Couteux, Sylvain Crindal, Maximilien Cruc, Clarysse Crusoe, Anne-Dominique Curunet-Raoul, Emelyne Cwicklinski, Alain Cys, Sami Dabbagh, Amira Dabri, Ludovic Daby, Elodie Dagoret, Christian Daguerre, Antoine Daisey, Xavier Daligaud, David Dall’acqua, Amelie Danet, Dizae Dansou, Alix Dattin, Geoffroy David, Morgane Da- vid, Olivier David, Sandy David, Serrano David, Camille Davost, Philippe De Boerio, Hugo De Carvalho, Laurene De Dinechin, Helene De Facq, Marie-Alix De Schlichting, Aurelien Debelle, Eric Deberdt, Sandra Decker, Julie Decloitre, Alice Decoster, Marie-Pierre Degos, Marc- Antoine Dehouck, Sophie Delage, Cyril Delangue, Hubert Delarue, Cath- erine Delattre, Julie Delaunay, Marine Delbergue, Marc Delbos, Amelie Delcourt, Thibault Delemar, Romain Delespierre, Stephanie Deleu, Amel Delli, Thierry Delmas, Thomas Delomas, Adrien Delprat, Ingrid Demarle, Geoffroy Denoray, Melanie Desangles, Nicolas Desaveines, Claire Desbuards, Jean-Philippe Desclefs, Benoit Deslais, Segolene Desoubeyran, Marie Desroziers, Arnaud Dessaint, Florian Deuez, Arnaud Devillard, Stephane Dhalluin, marion Dhers, Christophe Dhote, Hassen

Didane, Olivier Diez, Francois Dissait, Lynda Djebbar, Beatrice Doco, Sandrine Dojat, Mathieu Doukhan, Samia Draoua, Matthieu Drouard, Marie Druet, Marc Du Besset, Josephine Dubeaux, Manon Dubernat, Camille Dubois, Marie Dubourg, Pierre Ducasse, Caroline Duchier, Antoine Duconge, Yves Duffait, Sebastien Dufraise, Edouard Dugat, Franck Dumas, Jean-Baptiste Dumont, Nathalie Dumont, Julie Dumouchel, Yann Duperron, Aurelie Dupin, Thomas Dupuy, Marion Durand, Olivier Durand, Sandrine Durand, Alice Durand-Perdriel, Emilie Durieux, Sebastien Dussoulier, Benoit Duval, Nicolas Duytsche, Mohamed Dyani, Malek Echeikh, Claire Edange, Gerald Egmann, Sebastien Ehrminger, Mounir El Abdi, Imane El Kadiri, Ugo Ellena, Em- manuel Duval, Emmanuel Vilbois, Anne Emonet, David Emsallem, Jose- phine Escutnaire, Vincent Etienne, Yoann Evain, Gregoire Evrard, Caroline Faivre-Pierret, Aurelie Falvard, Armelle Fanchon, Guillaume Fatscher, Zoe Faure, Laura Federici, Meriem Ferhati, Martin Ferquel, Juliette Ferre, Justine Ferreira, Anne-Laure Ferri, Guillaume Ferrier, Jean-Baptiste Fezard, Nasri Fiani, Marie-Laurence Fievet, Olivier Fillatre, Maud Flambard, Marie Flandinette, Elodie Flauder, Thomas Fleuchot, Kleeve Fleurival, Amandine Fleury, Jonathan Florentin, Bertin Fogang, Maxime Foiret, Julien Foly, Alban Forel, Lahcene Foudi, Helene Foulgoc, Emmanuelle Fournier, Marc Fournier, Philippe Fradin, Virginie France, Herve Frances, Marie Frei, Regis Frenais, Louis Fresse, Jerome Frey, Emmanuelle Fritsch, Isaure Fromont, Dora Furnon, Celine Fuseau, Pat- rick Fuster, Matthieu Gaget, Florence Gaillard, Nancy Gaillard, Michel Galinski, Eva Gallais, Michel Gallon, Veronique Galtier, Thierry Gamin, Pauline Gantois, Zahia Gaoui, Emilie Garay, Carolina Garcia, Lea Garcia, Franck Garden-Breche, Matthias Garidou, Claire Gast, Patrick Gatin, Julien Gaubert, Vincent Gauclere, Anais Gaufrer, Lise Gautier, Julien Gay, Sylvain Geffroy, Emilie Gelin, Anne-Sophie Genain-Soulier, Sarah Gendraud, Paul-Henri Gendre, Stephane Gennai, Angelie Gentilhomme, Benoit Genuyt, David Gerault, Renaud Getti, Vincent Gevrey, Nawel Gharnaout, Louise Giaume, Stephane Gillet, Lucie Ginoux, Cecile Girard, Sabrina Giraud, Fabrice Girault, Frank Goes, Mathieu Goichon, Adrien Goldstein, Charles Gomes De Mattos, Coralie Gondret, Corinne Gonet- Dubois, Denis Gonzalez, Geraldine Gonzalez, Lola Gonzalez, Marion Gornet, Pierre Gosset, Christine Potiron-Goubet, Julie Gouges, Nathalie Goulois, Virginie Goulvin, Melanie Goument, Claire Gradel, Cyril Grandjon, Sarah Grar, Charlene Grard, Cecile Graux, Eric Grave, Fabrice Gregoire, Jean-Luc Greingor, Gauthier Gress, Emma Grigahcine, Oceane Grignon, Aude Grigoletto, Philippe Grippon, David Grua, Annaig Guegan, Pierre-Alban Guenier, Magali Guerin, Thomas Guerin, Carole Guery, Charlene Guez, Durand Guillaume, Frederic Guillaumee, Aline Guillet, Alain Guillon, Philippe Guillot, Sollweig Guinard, Olivier Guiot, Adrien Habay, Laurent Halbout, David Hamdan, Kheir-Eddine Hamdi, Najat Hammouti, Tom Handwerk, David Harel, Alexa Harguindeguy, Laure Harle, Gaelle Haziza, Manon Hebrard, Christine Hecker, Karina Heleniak, Meriem Hellal, Jonathan Hennache, Raymond Henry, Laurent Herkelmann, Gilles Hernandez, Aurelien Herpin, Virginie Heydel, Pascale Hiller, Timothee Hiriart, Michael Hoang, Stephanie Hoareau, Julie Hoff, Laure Hoffman, Eric Hollecker, Arthur Honorez, Nicolas Hourdin, Vanessa Houze-Cerfon, Priscilia Hsing, Loic Huet, Delphine Hugenschmitt, Thomas Hullin, Amr Ibrahim, Line Jacob, Renaud Jacquemin, Deborah Jaeger, Laure Jainsky, Guillaume Jammes, Benoit Jardel, Coline Jaud-Fischer, Charline Jauneau, Francois Javaudin, Yoann Jeanmasson, Joel Jenvrin, Alexandre Jeziorny, Guillaume Joannesse, Ma- rie Jobert, Geraldine Joliet, Marc Joly, Sebastien Jonquet, Ignasi Jubert, Mathilde Jung, Roger Kadji, Jean-Philippe Kahn, Isabelle Kaliszczak, Mariam Kamara, Mounir Kamboua, Clotilde Kamga, Cyrille Kamga, Claire Kany, Christian Kassasseya, Elodie Katz, Romain Kazmierczak, Helene Kermorgant, Cecile Kernaleguen, Mounir Khiter, Carine Kindle, Sebastien Kirsch, Amelie Klein, Stephane Klimas, Vincent Kottmann, Etienne Kras, Tarek Kribeche, Vincent Kuczer, Franck Labarrere, Benedicte Labbens, Stephane Labed, Francois-Xavier Laborne, Anne Laboure, Melanie Lacaze, Julien Lacoste, Arnaud Lacroix, Marina Lafay, Blandine Lafitte, Jean Lafon, Armelle Lafontaine, Steven Lagadec, Kelly Laggia, Sana Lahmar, Xavier Lakermance, Sara Lakhal, Jessica Lalande,

Yacine Lamarche-Vadel, Elisa Lamazou, Christophe Lambert, Julia Lam- bert, Marion Lamothe, Charles Lamourere, Michael Lamy, Pascale Lamy, Virgine Lancon, Yankel Landau, Alice Landel, Frederick Langeron, Mathilde Lannes, Melanie Laot, Elodie Larchanche, Fanny Larcher, Manon Lartaud, Thomas Laterrade, Audrey Launay, Paris Laurenne, Adrien Lauvray, Loic Lavaill, Jeanne Lavielle, Julien Lazar, Victor Lazard, Celine Le Beuan, Aurelie Le Goff, Arnaud Le Jan, Etienne Le Joubioux, Thomas Le Normand, Olivier Le Pennetier, Philippe Le Pimpec, Thomas Le, Antoine Lebail, Cecile Lebrun, Nathalie Lecadet, Aurelie Lechevrel, Gilles Leclerc, Maxence Leclerc, Romain Lecomte, Julien Lecoz, Aurelien Leduc, Cyndie Lefebvre, Stephanie Lefeuvre, Nathalie Lefevre, Alexandra Lefort, Delphine Lefranc, Valentin Lefrancois, Lea Legay, Estelle Legeard, Kevin Legendre, Gregory Legrand, Cathelle Lemarchand, Remy Lemarchand, Claire Lenne, Laurence Lepage, Alexandra Lepeve, Anne- Laure Lepori, Thierry Leraitre, Pierre Leroux, Antoine Leroy, Julien Lesaca, Christine Lespiaucq, Jean-Yves Letarnec, Emilie Letourneur, Gregory Letur, Pascale Leurent, Marion Leveau, Brice Levelu, Eleonore Levet, Pascaline Levrard, Patrick Levy, Raffaello Li Crapi, Caroline Line, Sebastien Line, Laura Lis, Laetitia Livernois, Mathilde Loirat, Sara Lomberty, Celine Longo, Lea Loquet, David Lorain, Sarah Lorge, Thomas Lory, Yannick Loslier, Richard Loubert, Aurelie Louchet, Jean-Paul Lougnon, Stephanie Louisot, Marie Loze, Anne-Sophie Lucas, Remy Lu- cas, Yannick Macabre, Camille Machet, Edouard Magimel-Pelonnier, Aurore Mahe, Zakaria Mahi, Olivier Maigre, Michel Maille, Gwenaelle Majoufre, Gilles Majour, Domitille Malange, Anne-Sophie Malaquin, Arnaud Malbranque, Nadia Mansouri, Bruno Maquaire, Pierre Marais, Jean-Baptiste Marc, Pauline Marchand, Sebastien Marchasson, Joelle Marchegay, Jacques Marchi, Julien Mariage, Dubois Marina, Heloise Marinoni, Paul Maroteix, Faycal Marrakchi, Paul-Louis Martin, Thibault Martin, Arnaud Martinage, Nathalie Mascarenc, Sylvie Massacrier, Juliette Masse, Solene Masse, Caroline Masson, Loic Masson, Melanie Mathe, Clement Mathie, Benedicte Mathieu, Laure Maugein, Marion Maurel, Sophie May, Guillaume Mazetier, Andre Mazille, Margherita Mazzoldi, Marie-Fleur Megard, Oussama Megherbi, Isabelle Megy- Michoux, Laure Melin, Marion Menay, Pascal Menot, Elise Menu, Elsie Menu, Catherine Mercier, Heloise Merle, Adil Mesli, Caroline Mesplede, Alexis Messieux, Jacques Metzger, Juliette Meunier, Stephanie Meunier, Daniel Meyran, Laurianne Michelland, Corinne Michenet, Sandrine Michenet, Guilhem Milhaud, Audrey Millot, Frederic Minko, Jerome Minost, Julie Miquelestorena, Celine Miranda, Albrice Moine, Linda Moine, Claudine Molly, Jean-Baptiste Monange, Franck Monchard, Martine Moneron, Thomas Monneret, Melanie Monribot, Francois- Xavier Montagnon, Emmanuel Montassier, Romain Moquay, Alice Morat, Jean-Charles Morel, Emanuel Morel-Marechal, Maria Elena Moreno-Maestre, Fanny Moulinet, Valerie Mozzi, Alain Mpela, Johanna Mroueh, Uriel Munoz, Sebastien Mur, Davy Murgue, Margaux Muteaud, Myriam Van Tricht, Marie Naban, Bertille Naegels, Sophie Narcisse, Jean- Ely Nardy, Julien Naud, Florence Naux, Sophie Nave, Florian Negrello, Eloi Nenert, Marie-Yves Ngonga, Natacha Ngoyi, Arsene Nguessan, Kim Nguyen, Ophelie Nicolats, Leandre Nicolin, Sarah Nixdorf, Magaly Noel, Camille Nussbaum, Mathieu Oberlin, Kirill Oganov, Stephanie Ol- ive, Larissa Oliveira, Francois Orcival, Frederic Orhon, Gerard Oriot, Jennifer Ospital, Maud Outrequin, Younes Ouyachchi, Mariane Ovtcharenko, Philippe Pamart, Agathe Pancher, Marc-Antoine Pangallo, Gregory Pansin, Francois Pantaloni, Annelaure Paquet, Rahman Paquirimoidine, Xavier Paringaux, Benoit Paris, Laurenne Paris, Sarah Parisot, Pierre Parsis, Clemence Pascalon, Nicolas Pauchet, Serge Paula Palma, Laure Pavageau, Laurent Pecout, Julien Pegeot, Vincent Pegoraro, Aurelie Pegorier, Olivier Peguet, Brandon Peixoto, Elodie Pelletier, Claudia Pelsy, Tanguy Peluchon, Yann Penverne, Oceane Pernin, Thomas Pernot, Philippe Pes, Caroline Petit, Olivia Petitdemange, Etienne Petitdidier, Martin Petitprez, Oceane Pettinotti, Sylvie Peyrat, Ludovic Piboule, Daniel Pic, Jeanne Picart, Mailis Piccardi, Dorine Pichon, Jessica Picot, Gil Pierre, Ambre Pignol, Natacha Pilati, Virginie Pinaud, Flore Pineau, Lauren Pinel, David Pinero, Camille Pioch, Sarah Pires, Perrine Planet, Cecile Plenier, Elodie Pocholle, Fabien Poher, geraldine Poincet,

Sebastien Poincet, Delphine Pointaire, Christian Poirel, Stephanie Polini, Nathalie Polisset, Soisic Pommier, Stephane Potriquier, Jeremie Poulet, Patrick Poupart, Catherine Pradeau, Anne-Lise Pradel, Nicolas Pradignac, Jean-Baptiste Pretalli, Sophie Prieur, Stevens Prineau, Christina Prouve, Florence Prudor, Aurelien Puchois, Thomas Quibel, Dominique Quilliet, Mathilde Quinty, Maria Rachidi, Julien Raconnat, Dorothee Radenac, Raphaelle Rahmani, Jean-Louis Rakotonirina, Martin Rallu, Thierry Ramaherison, Noel Ramaniraka, Solo Randriamalala, Camille Raynaud, Olivier Rebet, Laurent Rebillard, Claudine Remakel, Annabelle Remond, Emilie Resplandy, Francois Revaux, Franck Reydy, Yassine Rharif, Agnes Ricard-Hibon, Ghislain Richard, Jean-Dominique Risser, Robert Ristovski, Jean-Christophe Robart, Damien Robert, Frederique Robert, Helene Robert, Samuel Robert, Florent Roche, Annabelle Rocheteau, Pierre Rodriguez, Juliette Roger-Sename, Pierre-Julien Rogez, Jerome Rojas, Didier Roland-Billecart, Julie Rosenblatt, Yann Roth, Julie Rotival, Nicolas Roucaud, Nathalie Roudiak, Christelle Rouet, Louis Rouffilange, Jean Rouffineau, Jimmy Rouquet, Charlotte Rousselon, Nicolas Roux, Celine Royer, Guillaume Roze, Gautier Ruellan, Solene Ruiz, Phloy Rungsawad, Laure Saada, Sebastien Sabbat, Sonia Sadoune, Benoit Sahuc, Amelie Saint-Paul, Stephane Saintonge, Beatrice Salaun, Julie Salignon, Marie San Miguel, Caroline Sanchez, Oriana Sanchez, Chantal Sanjuan, Aurelie San-Miguel, David Sapir, Jean-Louis Saucede, Irina Sauder, Geraldine Sauvaget, Jean-Remy Savineau, Alexandru Savu, Jas- mine Sawadogo, Michel Scherpereel, Thibault Schillig, Anne-Catheirne Schmit, Valerie Schmitt, Sophie Schvahn, Christelle Sciacca, Pierre Scuotto, Salim Sebai, Julien Segard, Lionel Segard, Gerald Sejourne, Alienor Senez, Patrice Serre, Marine Serres, Julian Serrurier, Marta Sigarteu, Antoine Sigaux, Isabelle Simeon, Ciprian Simisdean, Benoit Si- mon, Bruno Simonnet, Allison Singier, Perrine Sobocinski, Moihedja Soulaimana, Marie Soulat, Audrey Spriet, Sophie Staes, Laurence Steenbeke, Virginie Stefanski-Serniclay, Teddy Sturiale, Pauline Suhas, Myriam Sussat, Roux Sylvie, Eric Sztil, Trung Hung Ta, Julien Tabarly, Romain Tabary, Pierre-Emmanuel Tabourin, Bertrand Tahon, frederic Tasei, Victor Tasteyre, Samuel Taxis, Jean-Francois Techer, Eric Tellier, Robin Tellier, Eric Tentillier, Lucie Teyssier, Odile Theurey, Eric Thibaud, Klein Thibaut, Michel Thicoipe, Romain Thiriat, Sylvain Thiriez, Agnes Thivellier, Fabien Thomas, Marie Thomas, Loan Thuong, Jean-Sebastien Top, Florian Torreton, Karim Toumert, Cedric Touquet, Eve Trebouet, Justine Treels, Sarah-Laure Trialoup, Bruno Trogoff, Helene Trouvain, Veronique Uchlinger, Cecile Ursat, Rishad Vally, Elyse Valser, Gregory Vancoillie, Carine Vanderstraeten, Ludivine Vanparys, Paul Vara, Laurene Vasseur, Isabelle Vassor, Pierre-Olivier Vautrin, Laetitia Velly, Valentinne Vendois, Laurent Vercher, Guillaume Verge, Muriel Vergne, Vanessa Verhaeghe, Stephanie Verissimo, Celine Vermersch, Jean- Pierre Vernet, Gregoire Versmee, Michael Vial, Marie-Sophie Viallard, Marie Viciana, Guillaume Vidal, Elodie Vidil, Frederic Vignaud, Claire Vigneau, Laurent Villain-Coquet, Maxime Villard, Barbara Villoing, Rayane Vincent, Mathieu Violeau, Clelia Viratelle, Corinne Wassong, Olivier Watrelot, Melanie Watremez, Eva Weinzorn, Claire-Marie Weyer, Marc Witte, Florine Wojcieszak, Marion Wrobel, Vassilis

Wurtz-Gress, Geoffrey Wyckaert, Samraa Yahiaoui, Matthieu Yali,

Quentin Yvetot, Guillaume Zamparini, Maria Zemouri, Badia Zeribi, Laila Zitouni.

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