
==== Front
Int J Emerg Med
Int J Emerg Med
International Journal of Emergency Medicine
1865-1372
1865-1380
Springer Berlin Heidelberg Berlin/Heidelberg

679
10.1186/s12245-024-00679-1
Research
Incidence, characteristics, and prehospital outcomes of out-of-hospital cardiac arrest in Qatar: a nationwide gender-based investigation
Awad Emad 123
Farhat Hassan 45
Shami Rakan 2
Gholami Nooreh 2
Mortada Bothina 2
Rumbolt Niki 2
Azizurrahman Adnaan 2
Arabi Abdul Rahman 6
Alinier Guillaume GAlinier@hamad.qa

4789
1 grid.223827.e 0000 0001 2193 0096 Dept of Emergency Medicine, School of Medicine, University of Utah, Salt Lake City, UT USA
2 https://ror.org/041ddxq18 grid.452189.3 0000 0000 9023 6033 College of Health Science, University of Doha for Science and Technology, Doha, Qatar
3 https://ror.org/03rmrcq20 grid.17091.3e 0000 0001 2288 9830 Department of Emergency Medicine, University of British Columbia, Vancouver, Canada
4 https://ror.org/02zwb6n98 grid.413548.f 0000 0004 0571 546X Hamad Medical Corporation Ambulance Service (HMCAS), Hamad Medical Corporation, Doha, Qatar
5 https://ror.org/00dmpgj58 grid.7900.e 0000 0001 2114 4570 Faculty of Medicine “Ibn El Jazzar”, University of Sousse, Sousse, Tunisia
6 https://ror.org/02zwb6n98 grid.413548.f 0000 0004 0571 546X Heart Hospital, Hamad Medical Corporation, Doha, Qatar
7 grid.416973.e 0000 0004 0582 4340 Weill Cornell Medicine – Qatar, Doha, Qatar
8 https://ror.org/0267vjk41 grid.5846.f 0000 0001 2161 9644 School of Health and Social Work, University of Hertfordshire, Hatfield, UK
9 https://ror.org/049e6bc10 grid.42629.3b 0000 0001 2196 5555 Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
2 9 2024
2 9 2024
2024
17 10522 1 2024
2 4 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

Research on incidence and characteristics of Out-of-Hospital Cardiac Arrest (OHCA) in the Middle East is limited. We assessed the incidence, prehospital characteristics, and outcomes of OHCA in Qatar, a Middle Eastern country. Subsequently, we performed gender-specific analysis.

Methods

This was a retrospective examination of data obtained from the OHCA registry at Hamad Medical Corporation (HMC) in Qatar from 2017 to 2022. We included adults, non-traumatic, EMS-treatment OHCA. We calculated the incidence of adult OHCA and conducted descriptive analyses for prehospital characteristics, and prehospital outcomes presented by return of spontaneous circulation (ROSC). We evaluated gender differences in prehospital characteristics and ROSC using Student’s t-test and the Chi-Square test as appropriate. Furthermore, we conducted a multivariable logistic regression analysis to investigate the correlation between gender and achieving ROSC.

Results

We included 4,306 adult OHCA patients, with 869 (20.2%) being females. The mean annual incidence of adult OHCA was 27.4 per 100,000 population-year. Males had a higher annual incidence of OHCA than females. Among all cases, 36.3% occurred in a public location, 25.8% had an initial shockable rhythm, and 28.8% achieved ROSC. Males had a higher proportion of bystander CPR, arrests in public locations, and initial shockable rhythms. While unadjusted analysis showed no significant gender differences in achieving ROSC, adjusted analysis revealed that male gender was associated with higher odds of achieving ROSC (adjusted OR male vs. female 1.38, 95% CI 1.15–1.66, p < 0.001).

Conclusions

Approximately 720 adults undergo non-traumatic OHCA in Qatar every year, with a higher incidence observed in males. Male gender was associated with higher odds of achieving ROSC. Further gender-specific research in OHCA intervention and outcome in the Middle East is required.

Keywords

OHCA
Incidence
Gender
ROSC
Qatar
Middle East
http://dx.doi.org/10.13039/100007458 Qatar Foundation UREP29-195-3-061 UREP29-195-3-061 UREP29-195-3-061 issue-copyright-statement© Springer-Verlag GmbH Germany, part of Springer Nature 2024
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pmcIntroduction

Out-of-hospital cardiac arrest (OHCA) constitutes a crucial public health concern leading to millions of deaths worldwide [1]. Existing data reveal noteworthy variations in both OHCA incidence and survival rate [2–5] across populations and regions. Recently reported OHCA incidence rates were approximately 93 per 100,000 person-years in the USA [6], 89 per 100,000 person-years in Europe [5], and 95.7 per 100,000 person-years in China [7]. Survival rates also vary across regions, ranging from 15,8% in the USA [6], 8% in England [8], and 12.0% in Australia and New Zealand [9]. OHCA incidence and outcomes not only differ across regions but also exhibit variations based on gender [10–12]. Previous data from western societies consistently reported lower incidence in females and inconsistent survival rate results [13–16]. Gender-related differences in the OHCA interventions [17] may contribute to the reported disparities in OHCA survival outcomes.

While OHCA incidence and gender differences in interventions and outcomes have been well investigated in Western countries, research on these topics is deficient in developing countries, particularly in the Middle East. This study’s objective was to quantify the incidence of non-traumatic OHCA in Qatar and investigate gender differences in OHCA incidence, prehospital characteristics, and short-term outcomes.

Design and setting

We conducted a population-based investigation using data from the Hamad Medical Corporation (HMC) OHCA registry in Qatar. Qatar, a Middle Eastern country, with a total population of approximately three million people, with around 2,614,000 adults aged 18 years and older [18]. HMC serves as the primary public healthcare provider in Qatar [19]. Prehospital emergency care for OHCA across the entire country is provided by HMC Ambulance Service (HMCAS), which has a modern fleet of fully equipped vehicles distributed nationally based on a hub and spoke model to ensure a rapid response to all emergency calls [20, 21]. Ambulances and rapid response cars are respectively crewed by two ambulance paramedics or a critical care paramedic and critical care assistant, all of whom are trained in advanced cardiopulmonary life support (ACLS). Clinicians undertake a rigorous training program upon joining HMCAS, irrespective of their previous qualification as they come for a variety of countries. [22]. In order to better meet the population’s needs and prevent communication issues, crews in each vehicle are always mixed so they can speak a minimum of three languages in total [23, 24]. Further, HMCASs ensure the medical management of emergency cases for those who call 999 based on the clinical practice guidelines (CPGs), which recapitulate the operational response flowcharts for all potential emergencies that can occur in the prehospital environment. In addition, unless there exists a definitive objection from the patient regarding transportation, HMCAS advocates for hospital transport for all encountered patients [25]. This helps minimize patients’ call-back and enhances patients’ outcomes. The average EMS response time to OHCA ranges from 5 to 10 min [26]. The HMC OHCA registry contains data collected on all Emergency Medical Services (EMS)-attended OHCA victims.

To achieve the goal of this study, we analyzed data collected between December 2017 and December 2022 from all regions of Qatar [19]. The data included valuable information on patient demographics, arrest location, bystander cardiopulmonary resuscitation (CPR), initial cardiac rhythm, EMS-provided treatments, and return of spontaneous circulation (ROSC). This study obtained ethical approval from the Institutional Review Board (IRB) of HMC Medical Research Center (MRC-01-22-501).

Study population

Using the HMC OHCA registry, we generated an analytical dataset comprising adult patients who experienced OHCA and received treatment from EMS. We excluded patients under 18 years of age, those with traumatic cardiac arrest, and cases with missing data.

Variable of interest

The primary outcomes of interest were OHCA characteristics, including age per year, arrest location (public vs. private), witnessed status (witnessed by bystanders vs. witnessed by EMS personnel), initiation of immediate CPR: classified into three categories: no CPR initiated, bystander-initiated CPR, or CPR performed by EMS personal), initial heart rhythm (shockable vs. non-shockable), arrest period: OHCA cases were categorized based on whether they occurred during the COVID-19 pandemic or outside of the pandemic period. The secondary outcome was achieving ROSC, defined as “the restoration of a spontaneous perfusing rhythm, resulting in a palpable pulse” [27], prior to arrival at the hospital’s ED and sustained until the patient’s admission to the ED.

Data analysis

We calculated the annual incidence of adult OHCA for each year between 2017 and 2022 for the full cohort and separately for each gender using the formula: Incidence rate = (number of new cases in a specific year/ population at risk in that year) *100,000. Subsequently, we extrapolated the mean annual incidence rate overall and for each gender.

We conducted descriptive statistics for OHCA pre-hospital characteristics in the entire cohort. We employed Student’s t-test for continuous variables and the Chi-Square test for categorical variables to analyze the bivariate associations between gender and ROSC. To further examine association between gender and ROSC while accounting for variables known to influence ROSC [27], we used multivariable logistic regression analysis. We built multiple regression models using forward variable selection technique and used − 2 loglikelihood (deviance) values to assess the goodness of fit of the competing models. We repeated the multivariable analysis within two subgroups (patients with shockable rhythms and those with non-shockable rhythms). Before conducting the multivariable analyses, we checked for logistic regression assumptions including absence of multicollinearity. All analyses were performed using IBM SPSS version 29, Armonk, NY.

Results

Incidence

We initially had a total population of 5.084 individuals. Among these, 57 individuals under the age of 18 and 693 cases with traumatic OHCA were excluded. Additionally, 28 cases were omitted due to missing data on key variables. The remaining 4,306 individuals were included in the analytic dataset (Fig. 1). Their mean age was 54.0 ± 17.9 years. Of the total, 3,434 (79.8%) were males, and 869 (20.2%) were females. The mean annual incidence of adult OHCA was 27.4 per 100,000 population, corresponding to 717 cases a year. The gender-specific annual incidence was higher in males (30.1 per 100,000 male population) than in females (20.4 per 100,000 female population).

Fig. 1 Study flow chart

Baseline characteristics

Among the 4,306 OHCA cases, 1,582 (36.3%) occurred in public locations, 1,110 (25.8%) had an initial shockable rhythm, and 1,241 (28.8%) achieved ROSC (Table 1). The male-female unadjusted comparison revealed several significant differences. Males were younger than females, with a mean age of 50.7 compared to 64.2 years. Males had significantly higher proportions of OHCA in public locations (42.4% vs. 14.5%), bystander CPR (35.4% vs., 31.0%), and shockable initial rhythm (28.8% vs. 13.8%), compared to females. No statistically significant difference was observed in ROSC (28.5% vs. 30.3%, p = 0.29). Table 1 summarizes the pre-hospital characteristics for the entire cohort and differences by gender.

Table 1 OHCA baseline characteristics for the full cohort and stratified by gender

Variable	Total
N = 4306	Male
3437 (79.8%)	Female
869 (20.2%)	P value	
Age (years)	54.0 ± 17.8	50.7 ± 16.4	64.2 ± 19.1	< 0.001	
Arrest location					
Private	2,724 (63.3%)	1,981 (57.6%)	743 (85.5%)	< 0.001	
Public	1,582 (36.7%)	1,456 (42.4%)	126 (14.5%)		
Witness status					
Bystander-witnessed	3,598 (83.6%)	2,900 (84.4%)	698 (80.3%)	0.004	
EMS-witnessed	708 (16.4%)	537 (15.6%)	171 (19.3%)		
Bystander CPR					
Not provided	2,235 (51.9.%)	1,685 (49.0%)	429 (49.4%)	0.02	
Bystander CPR	1,363 (31.7%)	1,215 (35.4%)	269 (31.0%)		
EMS CPR	708 (16.4%)	537 (15.6%)	171 (19.6%)		
Initial rhythm					
Non-shockable	3,196 (74.2%)	2,447 (71.2%)	749 (86.2%)	< 0.001	
Shockable	1,110 (25.8%)	990 (28.8%)	120 (13.8%)		
Arrest period					
Non-pandemic	2,954 (68.6%)	1,071 (31.2%)	281 (32.3%)	0.60	
Pandemic	1,352 (31.4%)	2,366 (68.8%)	588 (67.7%)		
ROSC

Not achieved

	3,065 (71.2%)	2,459 (71.5%)	606 (69.7%)	0.29	
Achieved	1,241 (28.8%)	978 (28.5%)	263 (30.3%)		

Multivariable analysis: full cohort

Overall, 1,241 (28.8%) patients in the cohort achieved ROSC. The proportion of males who achieved ROSC compared to females was 28.5% vs. 30.3% (p = 0.29). The crude odds of ROSC was not significant (crude OR males vs. females 1.09, 95% Confidence Interval (CI) 0.93–1.28, p = 0.31). However, after adjusting for variables known to influence ROSC, males had significantly higher odds of ROSC than females (adjusted OR 1.38, 95% CI 1.15–1.66, p < 0.001) (Table 2). The final model (Table 2) had a lower deviance value compared to all other models and had. No VIF value was > 2.5, suggesting absence of multicollinearity among the explanatory variables.

Table 2 Association between gender and ROSC: logistic regression analysis (N = 4306)

Variable	OR	(95% C I)	P value	
Male gender (crud)	1.09	0.93–1.28	0.31	
Male gender (adjusted)	1.38	1.15–1.66	< 0.001	
Age	1.01	0.99–1.01	0.13	
Public location	1.30	1.11–1.52	0.002	
Bystander CPR	1.38	1.18–1.62	< 0.001	
EMS CPR	4.74	3.96–5.68	< 0.001	
EMS-witnessed	3.58	2.99–4.29	< 0.001	
Initial Rhythm	4.75	4.05–5.54	< 0.001	
Non-pandemic period	1.35	1.17–1.57	< 0.001	

Subgroup 1 analysis (patients with shockable rhythm)

Of the total cohort (N = 4,306), 1,110 (25.8%) had initial shockable rhythms (including 28.8% [990/3,437] of the males in the cohort and 13.8% [120/869] of the females). Results of this subgroup analysis were similar to the full cohort. The crude odds of ROSC was not significant (crude OR males vs. females 1.33, 95% CI 0.91–1.96, p = 0.15), and the adjusted odds was in favour of males (adjusted OR 1.59, 95% CI 1.05–2.41, p < 0.001) (Table 3).

Subgroup 2 analysis (patients with non-shockable rhythm)

Of the total cohort (N = 4,306), 3,196 (74.2%) had initial non-shockable rhythms (including 71.2% [2,447/3,437] of the males in the cohort and 86.2% [749/869] of the females). Results of this subgroup analysis showed that the crude odds of ROSC was significantly greater in males (crude OR males vs. females 1.52, 95% CI 1.25–1.84, p = 0.15). After adjustment, the odds of ROSC remained significantly higher in males (adjusted OR 1.33, 95% CI 1.08–2.56, p < 0.001) (Table 3).

Table 3 Association between gender and ROSC: subgroup analyses

	Subgroup 1: Patients with shockable
Rhythm (N = 1110)		Subgroup 2: Patients with non-shockable rhythm (N = 3196)	
Variable	OR	(95% C I)	P value		OR	(95% C I)	P value	
Male gender (crude)	1.33	0.91–1.96	0.15		1.52	1.25–1.84	< 0.001	
Male gender (adjusted)	1.59	1.05–2.41	0.03		1.33	1.08–1.65	0.01	
Age	0.99	0.98–1.01	0.36		1.01	1.01–1.01	0.001	
Public location	1.16	0.90–1.51	0.03		1.44	1.18–1.76	0.02	
Bystander CPR	0.90	0.69–1.15	0.20		1.31	1.06–1.61	0.01	
EMS CPR	0.93	0.70–1.20	0.26		0.82	0.63– 1.14	0.30	
EMS-witnessed	4.42	3.65–8.04	< 0.001		3.80	2.96–4.90	< 0.001	
Non-pandemic period	1.04	0.80–1.35	0.79		1.53	1.28–1.84	< 0.001	

Discussion

We analyzed data from 4,306 adults with non-traumatic OHCA in the State of Qatar and calculated the annual incidence of non-traumatic OHCA for the population and for each gender. We also assessed gender differences in OHCA characteristics and ROSC.

Our study found that the annual incidence of non-traumatic OHCA in Qatar is 27.4 per 100,000 population. This is higher than that reported of 23.5 per 100,000 population in Qatar for the year 2013–2014 when the country’s population was around 1.9 million inhabitants [28]. It was lower than the annual global incidence (55 per 100,000) [29], lower than that reported in the USA (93 per100,000) [6], Australia (72.39 per 100,000) [30], and England (53 per 100,000) [8]. The lower incidence in Qatar compared to other societies can perhaps be explained by differences in the population’s characteristics. Compared to Western societies, Qatar has a relatively younger population with a median age of approximately 34 years, largely due to the substantial number of expatriate male workers [31]. This distinction may have contributed to the lower occurrence of OHCA in Qatar. Our findings also indicated that the annual incidence of OHCA was higher among males than females, which aligns with previous studies [30, 32].

Our results additionally revealed significant differences in the OHCA pre-hospital characteristics predictive of ROSC, in favour of males. Specifically, males showed a higher incidence of OHCA in public locations and a higher proportion of shockable rhythm. Previous studies consistently reported similar advantages in males [13, 16, 33–39]. Despite these favorable characteristics, our initial analysis did not detect a significant difference in crude ROSC rates between males and females. This finding contradicted our initial expectation of females having lower crude odds of ROSC based on their unfavorable pre-hospital characteristics. One possible explanation for this unexpected result is the potential positive effect of female estrogen hormones on achieving ROSC [40]. However, after accounting for variables known to be associated with ROSC, our analysis revealed that males had higher odds of achieving ROSC. Our findings align with those reported in recently published studies [16, 41]. This favorable ROSC in males could partially be due to the males’ advantages in OHCA prehospital characteristics [38]. Recent studies have reported that females are less likely to receive prehospital interventions including bystander CPR, perhaps due to a fear of being accused of inappropriate touch [42, 43]. This issue may be even more pronounced in a Middle Eastern cultural context.

The results of our subgroup 1 analyses (patients with shockable rhythm) were very similar to the findings observed in the full cohort. In subgroup 2 (those with non-shockable rhythm), the crude and adjusted odds of ROSC were in favour of males, suggesting shorter time to providing CPR to males or differences in the intensity of treatment provided to males. Other possible explanations for this gender differences in achieving ROSC could be due to variations in underlying causes of arrest or physiological variances between males and females that influence the response to CPR efforts. Nevertheless, subgroup adjusted analyses revealed greater odds of ROSC and OHCA occurring at a younger age in male. These findings strengthen the evidence that male gender is associated with higher odds of ROSC.

This study has some limitations. First, the analyses were limited to OHCA data from Qatar and the results may not be generalizable to other regions worldwide. Second, the underlying causes of OHCA among females may differ systematically from those among males, potentially having substantial impacts on outcomes. Third, data on some variables, such as EMS response time, prehospital interventions, ethnicity, and comorbidities were incomplete in the dataset, and subsequently were not included in the analyses. Finally, no data was available for survival to hospital discharge. Quantifying gender differences in survival to hospital discharge would provide more comprehensive information. Further studies specifically investigating gender differences in survival to hospital discharge in Qatar are required.

Conclusion

The incidence of adult, non-traumatic OHCA in Qatar is 27.4 per 100,000 population, corresponding to approximately 720 cases every year, with a lower occurrence in females than males. OHCA baseline characteristics were advantageous for males. Male gender was associated with higher odds of achieving ROSC. This advantage for males was observed in the full cohort and within both shockable and non-shockable rhythm subgroups. This study highlights the need for additional gender-specific research in pre-OHCA care and survival outcome in the Middle East.

Acknowledgements

The authors thank HMCAS for their support and collaboration in this research. The authors also thank HMCAS EMS staff for their efforts in providing prehospital resuscitation to OHCA patients in Qatar.

Author contributions

All authors contributed to the study’s conception and design. Material preparation and data collection were completed by Hassan Farhat, Bothina Mortada, Adnaan Azizurrahman, and Abdul Rahman Arabi. Data analyses were performed by Emad Awad, Guillaume Alinier, Bothina Mortada, Adnaan and Nooreh Gholami. The first draft of the manuscript was written by Emad Awad and revised by Niki Rumbolt and Rakan Shami. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

This research was supported by Qatar National Research Fund (QNRF) provided by Qatar Foundation under UREP project (UREP29-195-3-061). The funding agency had no role in the study design, data analysis and interpretation, or in writing the manuscript. The University of Doha for Science and Technology funded the publication of this article.

Data availability

The data that support the results of this study are available from the OHCA registry at Hamad Medical Corporation (HMC), but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. However, data are available from the authors upon reasonable request and with permission of HMC.

Declarations

Ethics approval and consent to participate

Ethics approval for this study was obtained from the Research Ethics Board of Hamad Medical Corporation Medical Research Center (MRC-01-22-501). We certify that the study was performed in accordance with the Declaration of Helsinki ethical standards. No written informed consent was obtained from patients as this was a secondary analysis of deidentified data. The study meets all requirements for exemption from informed consent.

Consent for publication

Not applicable.

Conflict of interest

This research was supported by Qatar National Research Fund (QNRF) provided by Qatar Foundation under UREP project (UREP29-195-3-061). The funding agency had no role in the study design, data analysis and interpretation, or in writing the manuscript. The authors affirm that the research was conducted in an unbiased manner, and the results and interpretations presented in this manuscript are not influenced by any conflicting interests. The authors declare no other conflicts of interest.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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References

1. Myat A Song KJ Rea T Out-of-hospital cardiac arrest: current concepts Lancet 2018 391 10124 970 9 10.1016/S0140-6736(18)30472-0 29536861
Myat A, Song KJ, Rea T. Out-of-hospital cardiac arrest: current concepts. Lancet. 2018;391(10124):970–9.29536861 10.1016/S0140-6736(18)30472-0
2. Ong MEH Shin S De Do NNA Tanaka H Nishiuchi T Song KJ Outcomes for out-of-hospital cardiac arrests across 7 countries in Asia: the Pan Asian Resuscitation outcomes Study (PAROS) Resuscitation 2015 96 100 8 10.1016/j.resuscitation.2015.07.026 26234891
Ong MEH, Shin S, De Do NNA, Tanaka H, Nishiuchi T, Song KJ, et al. Outcomes for out-of-hospital cardiac arrests across 7 countries in Asia: the Pan Asian Resuscitation outcomes Study (PAROS). Resuscitation. 2015;96:100–8.26234891 10.1016/j.resuscitation.2015.07.026
3. Dyson K Brown SP May S Smith K Koster RW Beesems SG International variation in survival after out-of-hospital cardiac arrest: a validation study of the Utstein template Resuscitation 2019 138 168 81 10.1016/j.resuscitation.2019.03.018 30898569
Dyson K, Brown SP, May S, Smith K, Koster RW, Beesems SG, et al. International variation in survival after out-of-hospital cardiac arrest: a validation study of the Utstein template. Resuscitation. 2019;138:168–81.30898569 10.1016/j.resuscitation.2019.03.018
4. Yan S Gan Y Jiang N Wang R Chen Y Luo Z The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis Crit Care 2020 24 1 61 10.1186/s13054-020-2773-2 32087741
Yan S, Gan Y, Jiang N, Wang R, Chen Y, Luo Z, et al. The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis. Crit Care. 2020;24(1):61.32087741 10.1186/s13054-020-2773-2
5. Gräsner JT Herlitz J Tjelmeland IBM Wnent J Masterson S Lilja G European Resuscitation Council guidelines 2021: epidemiology of cardiac arrest in Europe Resuscitation 2021 161 61 79 10.1016/j.resuscitation.2021.02.007 33773833
Gräsner JT, Herlitz J, Tjelmeland IBM, Wnent J, Masterson S, Lilja G, et al. European Resuscitation Council guidelines 2021: epidemiology of cardiac arrest in Europe. Resuscitation. 2021;161:61–79.33773833 10.1016/j.resuscitation.2021.02.007
6. Cardiac Arrest Registry to Enhance Survival (CARES). 2021 annual report. Incidence and demographic. 2021.
7. Mellett-Smith A, Couper K. Establishing an out-of-hospital cardiac arrest registry in China: a key first step to improving outcomes. The Lancet Public Health. Volume 8. Elsevier Ltd; 2023. pp. e908–9.
8. Hawkes C Booth S Ji C Brace-McDonnell SJ Whittington A Mapstone J Epidemiology and outcomes from out-of-hospital cardiac arrests in England Resuscitation 2017 110 133 40 10.1016/j.resuscitation.2016.10.030 27865775
Hawkes C, Booth S, Ji C, Brace-McDonnell SJ, Whittington A, Mapstone J, et al. Epidemiology and outcomes from out-of-hospital cardiac arrests in England. Resuscitation. 2017;110:133–40.27865775 10.1016/j.resuscitation.2016.10.030
9. Beck B Bray J Cameron P Smith K Walker T Grantham H Regional variation in the characteristics, incidence and outcomes of out-of-hospital cardiac arrest in Australia and New Zealand: results from the Aus-ROC Epistry Resuscitation 2018 126 49 57 10.1016/j.resuscitation.2018.02.029 29499230
Beck B, Bray J, Cameron P, Smith K, Walker T, Grantham H, et al. Regional variation in the characteristics, incidence and outcomes of out-of-hospital cardiac arrest in Australia and New Zealand: results from the Aus-ROC Epistry. Resuscitation. 2018;126:49–57.29499230 10.1016/j.resuscitation.2018.02.029
10. Lei H Hu J Liu L Xu D Sex differences in survival after out-of-hospital cardiac arrest: a meta-analysis Crit Care 2020 24 1 613 10.1186/s13054-020-03331-5 33076963
Lei H, Hu J, Liu L, Xu D. Sex differences in survival after out-of-hospital cardiac arrest: a meta-analysis. Crit Care. 2020;24(1):613.33076963 10.1186/s13054-020-03331-5
11. Kotini-Shah P Del Rios M Khosla S Pugach O Vellano K McNally B Sex differences in outcomes for out-of-hospital cardiac arrest in the United States Resuscitation 2021 163 6 13 10.1016/j.resuscitation.2021.03.020 33798627
Kotini-Shah P, Del Rios M, Khosla S, Pugach O, Vellano K, McNally B, et al. Sex differences in outcomes for out-of-hospital cardiac arrest in the United States. Resuscitation. 2021;163:6–13.33798627 10.1016/j.resuscitation.2021.03.020
12. Awad EM Humphries KH Grunau BE Christenson JM Premenopausal-aged females have no neurological outcome advantage after out-of-hospital cardiac arrest: a multilevel analysis of north American populations Resuscitation 2021 166 58 65 10.1016/j.resuscitation.2021.06.024 34271125
Awad EM, Humphries KH, Grunau BE, Christenson JM. Premenopausal-aged females have no neurological outcome advantage after out-of-hospital cardiac arrest: a multilevel analysis of north American populations. Resuscitation. 2021;166:58–65.34271125 10.1016/j.resuscitation.2021.06.024
13. Awad E Humphries K Grunau B Besserer F Christenson J The effect of sex and age on return of spontaneous circulation and survival to hospital discharge in patients with out of hospital cardiac arrest: a retrospective analysis of a Canadian population Resusc Plus 2021 5 100084 10.1016/j.resplu.2021.100084 34223350
Awad E, Humphries K, Grunau B, Besserer F, Christenson J. The effect of sex and age on return of spontaneous circulation and survival to hospital discharge in patients with out of hospital cardiac arrest: a retrospective analysis of a Canadian population. Resusc Plus. 2021;5:100084.34223350 10.1016/j.resplu.2021.100084
14. Auricchio A Caputo ML Baldi E Klersy C Benvenuti C Cianella R Gender-specific differences in return-to-spontaneous circulation and outcome after out-of-hospital cardiac arrest: results of sixteen-year-state-wide initiatives Resusc Plus 2020 4 100038 10.1016/j.resplu.2020.100038 34223315
Auricchio A, Caputo ML, Baldi E, Klersy C, Benvenuti C, Cianella R, et al. Gender-specific differences in return-to-spontaneous circulation and outcome after out-of-hospital cardiac arrest: results of sixteen-year-state-wide initiatives. Resusc Plus. 2020;4:100038.34223315 10.1016/j.resplu.2020.100038
15. Luc G Baert V Escutnaire J Genin M Vilhelm C Di Pompéo C Epidemiology of out-of-hospital cardiac arrest: a French national incidence and mid-term survival rate study Anaesth Crit Care Pain Med 2019 38 2 131 5 10.1016/j.accpm.2018.04.006 29684654
Luc G, Baert V, Escutnaire J, Genin M, Vilhelm C, Di Pompéo C, et al. Epidemiology of out-of-hospital cardiac arrest: a French national incidence and mid-term survival rate study. Anaesth Crit Care Pain Med. 2019;38(2):131–5.29684654 10.1016/j.accpm.2018.04.006
16. Rob D, Kavalkova P, Smalcova J, Franek O, Smid O, Komarek A et al. Gender differences and survival after out of hospital cardiac arrest. Am J Emerg Med [Internet]. 2022;55:27–31. https://linkinghub.elsevier.com/retrieve/pii/S0735675722001176.
17. Zheng J Lv C Zheng W Zhang G Tan H Ma Y Incidence, process of care, and outcomes of out-of-hospital cardiac arrest in China: a prospective study of the BASIC-OHCA registry Lancet Public Health 2023 8 12 e923 32 10.1016/S2468-2667(23)00173-1 37722403
Zheng J, Lv C, Zheng W, Zhang G, Tan H, Ma Y, et al. Incidence, process of care, and outcomes of out-of-hospital cardiac arrest in China: a prospective study of the BASIC-OHCA registry. Lancet Public Health. 2023;8(12):e923–32.37722403 10.1016/S2468-2667(23)00173-1
18. Qatar Planing and Statistics. Monthly figures on total population. 2023.
19. Dept CC. 2022. 2022. Hamad Medical Corporation. https://www.hamad.qa/EN/About-Us/Our-Organization/Pages/default.aspx.
20. Hutton D, Alinier G. Ambulance service operational improvement. Int Paramedic Pract. 2013;3(3):61–3.
21. Wilson P, Alinier G, Reimann T. Influential factors on urban and rural response times for emergency ambulances in Qatar. Mediterr J Emerg Med 2018:8–13.
22. Demir S, Tunçbilek Z, Naidoo V, Morris T, Alinier G. Paramedic education in Qatar as seen by academics from Turkey. Int Paramedic Pract. 2023;13(1):2–8.
23. Gangaram P, Alinier G, Menacho AM. Crisis resource management in emergency medical settings in Qatar. Int Paramedic Pract. 2017;7(2):18–23.
24. Demir S, Tunçbilek Z, Alinier G. Prehospital emergency health services in Qatar. J Paramedic Pract. 2022;14(11):456–62.
25. Farhat H Alinier G El Aifa K Athemneh K Gangaram P Romero R Quality improvement tools to manage emergency callbacks from patients with diabetes in a prehospital setting BMJ Open Qual 2023 12 1 e002007 10.1136/bmjoq-2022-002007 36599502
Farhat H, Alinier G, El Aifa K, Athemneh K, Gangaram P, Romero R, et al. Quality improvement tools to manage emergency callbacks from patients with diabetes in a prehospital setting. BMJ Open Qual. 2023;12(1):e002007.36599502 10.1136/bmjoq-2022-002007
26. Wilson PAGRT. Influential factors on urban and rural response times for emergency ambulances in Qatar. Mediterranean J Emerg Med. 2018;8–13.
27. Nolan JP, Berg RA, Andersen LW, Bhanji F, Chan PS, Donnino MW et al. Cardiac arrest and cardiopulmonary resuscitation outcome reports: update of the utstein resuscitation registry template for in-hospital cardiac arrest: a consensus report from a aask force of the international liaison committee on resuscitation. Circulation. 2019;140(18).
28. Irfan FB Bhutta ZA Castren M Straney L Djarv T Tariq T Epidemiology and outcomes of out-of-hospital cardiac arrest in Qatar: a nationwide observational study Int J Cardiol 2016 223 1007 13 10.1016/j.ijcard.2016.08.299 27611569
Irfan FB, Bhutta ZA, Castren M, Straney L, Djarv T, Tariq T, et al. Epidemiology and outcomes of out-of-hospital cardiac arrest in Qatar: a nationwide observational study. Int J Cardiol. 2016;223:1007–13.27611569 10.1016/j.ijcard.2016.08.299
29. Berdowski J Berg RA Tijssen JGP Koster RW Global incidences of out-of-hospital cardiac arrest and survival rates: systematic review of 67 prospective studies Resuscitation 2010 81 11 1479 87 10.1016/j.resuscitation.2010.08.006 20828914
Berdowski J, Berg RA, Tijssen JGP, Koster RW. Global incidences of out-of-hospital cardiac arrest and survival rates: systematic review of 67 prospective studies. Resuscitation. 2010;81(11):1479–87.20828914 10.1016/j.resuscitation.2010.08.006
30. Pemberton K Bosley E Franklin RC Watt K Epidemiology of pre-hospital outcomes of out‐of‐hospital cardiac arrest in Queensland, Australia Emerg Med Australasia 2019 31 5 821 9 10.1111/1742-6723.13354
Pemberton K, Bosley E, Franklin RC, Watt K. Epidemiology of pre-hospital outcomes of out‐of‐hospital cardiac arrest in Queensland, Australia. Emerg Med Australasia. 2019;31(5):821–9.10.1111/1742-6723.13354
31. Qatar Planing and Statistics. Monthly figures on total population [Internet]. 2023. https://www.psa.gov.qa/en/statistics1/pages/topicslisting.aspx?parent=General&child=QIF
32. Bolijn R Sieben CHAM Kunst AE Blom M Tan HL van Valkengoed IGM Sex differences in incidence of out-of-hospital cardiac arrest across ethnic and socioeconomic groups: a population-based cohort study in the Netherlands Int J Cardiol 2021 343 156 61 10.1016/j.ijcard.2021.09.007 34509532
Bolijn R, Sieben CHAM, Kunst AE, Blom M, Tan HL, van Valkengoed IGM. Sex differences in incidence of out-of-hospital cardiac arrest across ethnic and socioeconomic groups: a population-based cohort study in the Netherlands. Int J Cardiol. 2021;343:156–61.34509532 10.1016/j.ijcard.2021.09.007
33. Goto Y Funada A Maeda T Okada H Goto Y Sex-specific differences in survival after out-of-hospital cardiac arrest: a nationwide, population-based observational study Crit Care 2019 23 1 263 10.1186/s13054-019-2547-x 31345244
Goto Y, Funada A, Maeda T, Okada H, Goto Y. Sex-specific differences in survival after out-of-hospital cardiac arrest: a nationwide, population-based observational study. Crit Care. 2019;23(1):263.31345244 10.1186/s13054-019-2547-x
34. Awad EM Humphries KH Grunau BE Norris CM Christenson JM Predictors of neurological outcome after out-of-hospital cardiac arrest: sex-based analysis: do males derive greater benefit from hypothermia management than females? Int J Emerg Med 2022 15 1 43 10.1186/s12245-022-00447-z 36064329
Awad EM, Humphries KH, Grunau BE, Norris CM, Christenson JM. Predictors of neurological outcome after out-of-hospital cardiac arrest: sex-based analysis: do males derive greater benefit from hypothermia management than females? Int J Emerg Med. 2022;15(1):43.36064329 10.1186/s12245-022-00447-z
35. Blewer AL, McGovern SK, Schmicker RH, May S, Morrison LJ, Aufderheide TP et al. Gender disparities among adult recipients of bystander cardiopulmonary resuscitation in the public. Circ Cardiovasc Qual Outcomes. 2018;11(8).
36. Lee GT Hwang SY Jo IJ Kim TR Yoon H Cha WC Gender difference in the clinical outcomes of patients with out-of-hospital cardiac arrest Medicine 2021 100 48 e27855 10.1097/MD.0000000000027855 35049187
Lee GT, Hwang SY, Jo IJ, Kim TR, Yoon H, Cha WC, et al. Gender difference in the clinical outcomes of patients with out-of-hospital cardiac arrest. Medicine. 2021;100(48):e27855.35049187 10.1097/MD.0000000000027855
37. Karlsson V Dankiewicz J Nielsen N Kern KB Mooney MR Riker RR Association of gender to outcome after out-of-hospital cardiac arrest – a report from the International Cardiac arrest Registry Crit Care 2015 19 1 182 10.1186/s13054-015-0904-y 25895673
Karlsson V, Dankiewicz J, Nielsen N, Kern KB, Mooney MR, Riker RR, et al. Association of gender to outcome after out-of-hospital cardiac arrest – a report from the International Cardiac arrest Registry. Crit Care. 2015;19(1):182.25895673 10.1186/s13054-015-0904-y
38. Awad E Alinier G Farhat H Rumbolt N Azizurrahman A Mortada B Provision of bystander CPR for out-of-hospital cardiac arrest in the Middle East: a retrospective gender-based analysis Int J Emerg Med 2023 16 1 63 10.1186/s12245-023-00537-6 37752462
Awad E, Alinier G, Farhat H, Rumbolt N, Azizurrahman A, Mortada B, et al. Provision of bystander CPR for out-of-hospital cardiac arrest in the Middle East: a retrospective gender-based analysis. Int J Emerg Med. 2023;16(1):63.37752462 10.1186/s12245-023-00537-6
39. Liu N, Ning Y, Ong MEH, Saffari SE, Ryu HH, Kajino K et al. Gender disparities among adult recipients of layperson bystander cardiopulmonary resuscitation by location of cardiac arrest in Pan-Asian communities: A registry-based study. EClinicalMedicine [Internet]. 2022;44:101293. https://linkinghub.elsevier.com/retrieve/pii/S2589537022000232.
40. Johnson MA Haukoos JS Larabee TM Daugherty S Chan PS McNally B Females of childbearing age have a survival benefit after out-of-hospital cardiac arrest Resuscitation 2013 84 5 639 44 10.1016/j.resuscitation.2012.09.011 22986061
Johnson MA, Haukoos JS, Larabee TM, Daugherty S, Chan PS, McNally B, et al. Females of childbearing age have a survival benefit after out-of-hospital cardiac arrest. Resuscitation. 2013;84(5):639–44.22986061 10.1016/j.resuscitation.2012.09.011
41. Malik A Gewarges M Pezzutti O Allan KS Samman A Akioyamen LE Association between sex and survival after non-traumatic out of hospital cardiac arrest: a systematic review and meta-analysis Resuscitation 2022 179 172 82 10.1016/j.resuscitation.2022.06.011 35728744
Malik A, Gewarges M, Pezzutti O, Allan KS, Samman A, Akioyamen LE, et al. Association between sex and survival after non-traumatic out of hospital cardiac arrest: a systematic review and meta-analysis. Resuscitation. 2022;179:172–82.35728744 10.1016/j.resuscitation.2022.06.011
42. Perman SM Vogelsong MA Del Rios M Is all bystander CPR created equal? Further considerations in sex differences in cardiac arrest outcomes Resuscitation 2023 182 109649 10.1016/j.resuscitation.2022.11.015 36436692
Perman SM, Vogelsong MA, Del Rios M. Is all bystander CPR created equal? Further considerations in sex differences in cardiac arrest outcomes. Resuscitation. 2023;182:109649.36436692 10.1016/j.resuscitation.2022.11.015
43. Blom MT, Oving I, Berdowski J, van Valkengoed IGM, Bardai A, Tan HL. Women have lower chances than men to be resuscitated and survive out-of-hospital cardiac arrest. Eur Heart J. 2019.
