
==== Front
Resusc Plus
Resusc Plus
Resuscitation Plus
2666-5204
Elsevier

S2666-5204(24)00199-1
10.1016/j.resplu.2024.100748
100748
Short Paper
Survival of out-of-hospital cardiac arrest patients admitted to the hospital during the Tokyo Summer Olympic and Paralympic Games in Japan
Nishimura Takeshi t-nishimura@hemc.jp
⁎
Taira Takuya
Suga Masafumi
Ijuin Shinichi
Inoue Akihiko
Ishihara Satoshi
Department of Emergency and Critical Care Medicine, Hyogo Emergency Medical Center, Kobe City, Hyogo, Japan
⁎ Corresponding author at: Hyogo Emergency Medical Center, 1-3-1 Wakihamakaigan dori, Chuoku, Kobe city, Hyogo 651-0073, Japan. t-nishimura@hemc.jp
15 8 2024
9 2024
15 8 2024
19 1007484 6 2024
1 8 2024
5 8 2024
© 2024 The Author(s)
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Background

The influence of the Tokyo Summer Olympic/Paralympic Games on normal emergency medical system operations in Japan had not yet been fully elucidated. In this study, we examined whether out-of-hospital cardiac arrest (OHCA) patients treated during the Tokyo Olympic/Paralympic Games had differences in outcomes.

Methods

Using the nationwide JAAM-OHCA Registry, we evaluated the outcomes of OHCA patients admitted to the hospital during the Tokyo Olympic/Paralympic Games (July 23 to Aug. 8 and Aug. 24 to Sept. 5) in 2021, compared to those during same the dates in 2020 (Term 1: July 23 to Aug. 8 and Aug. 24 to Sept. 5), those during the pre-Olympic/Paralympic term during the same weekdays in the weeks before the event (Term 2: June. 18 to July. 4 and July. 6 to July. 18), and those during the post-Olympic/Paralympic term during the same weekdays in the weeks after the event (Term 3: Sept. 10 to Sept. 26 and Sept. 28 to Oct. 10). The primary outcome was 30-day survival, and multivariable logistic analysis was performed, adjusted for age and sex.

Results

A total of 3,111 OHCA patients were included in the study period (786 in the Olympic/Paralympic group, 774 in Term 1, 747 in Term 2, and 804 in Term 3). Crude 30-day survivals were 7.4% (58/786), 9.3% (72/774), 6.8% (51/747), and 8.2% (66/804), respectively. Using the Olympic/Paralympic group as a reference, multivariable logistic analysis revealed that 30-day survivals in Term 1 (OR 1.27 95% CI 0.88–1.83p = 0.20), Term 2 (OR 0.92 95% CI 0.62–1.36p = 0.67), and Term 3 (OR 1.10 95% CI 0.76–1.59p = 0.63) did not differ significantly.

Conclusions

No significant differences in 30-day survival for OHCA patients admitted during the Tokyo Summer Olympic/Paralympic Games were identified.

Keywords

Cardiac arrest
OHCA
Olympics
Paralympics
Sports event
Mass casualty
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pmcIntroduction

Out-of-hospital cardiac arrest (OHCA) is a major global public concern, and treatment of OHCA patients is one of the most challenging issues for an emergency medical system, even under normal circumstances.1 Japan hosted the Tokyo Summer Olympic/Paralympic Games in 2021 (July 23 to August 8 and August 24 to September 5).2 Mass gatherings are known to impose a burden on the daily operations of the emergency medical service system, as medical resources and attention are diverted to these events.3 Furthermore, the incidence of cardiac arrests and cardiovascular events may increase during such emotional events.4 Demanding sports events especially may affect the incidence of OHCA.5 However, the influence of the Olympic/Paralympic Games on the incidence of OHCA and normal emergency medical system operations has never been fully elucidated. Also, the Tokyo Olympic/Paralympic Games were held in the middle of the COVID-19 pandemic, which made this event exceptional and worth examining its influence in detail. Thus, in this study, we examined whether there were differences in outcomes for OHCA patients during the Tokyo Summer Olympic/Paralympic Games.

Methods

Study design and data collection

We utilized data from the JAAM-OHCA Registry, a multicenter, nationwide database in Japan. The JAAM-OHCA registry included data on OHCA patients transferred to registered hospitals.6 The registry includes pre-hospital data, in-hospital data, and outcomes for OHCA patients who were transported to the participating institutions. The emergency medical service (EMS) collected prehospital data using the standardized Utstein format,7 and the Fire and Disaster Management Agency in Japan verified the data. Clinical data administrators or clinicians at each institution recorded patient data during hospitalization using a standardized online form.

The Ethics Committee of Kyoto University, the corresponding institution, approved this registry, and each hospital approved the JAAM-OHCA Registry protocol. Our medical center institutional review board also approved this secondary analysis (local ref. no. 2023011). The local committee waived the requirement for patient consent.

The study included OHCA patients admitted to registered hospitals during the following study periods since OHCA patient outcomes could be influenced by the day of admission (weekend effect). Exclusion criteria were age under 18 years old or missing outcomes data. To detect the detailed changes and trends, we compared outcomes of OHCA patients during the Olympic/Paralympic Games to those during the same dates in 2020 (Term 1: July 23 to August 8 and August 24 to September 5 in 2020, “same dates in previous year”) (17 days + 13 days), and those in the pre-Olympic/Paralympic term, which was defined as the same weekdays in the weeks before the event (Term 2: June 18 to July 4 and July 6 to July 18, “just before the Olympic/Paralympic Games”) (17 days + 13 days), and those in the post-Olympic/Paralympic term, which was defined as the same weekdays in the weeks after the event (Term 3: September 10 to September 26 and September 28 to October 10, “just after the Olympic/Paralympic Games”) (17 days + 13 days), respectively.

The primary outcome was 30-day survival. Secondary outcomes were return of spontaneous circulation (ROSC) and 30-day favorable neurological outcomes at discharge (defined as Cerebral Performance Category scores of 1 or 2).

Data analysis

The study population was characterized using descriptive statistics. Continuous variables were described using median with interquartile range and analyzed using analysis of variance. Categorical variables were described using percentages and compared using the chi square test, and discrete variables were evaluated using the Kruskal-Wallis rank test.

Using OHCA patients in the Olympic/Paralympic group as a reference, a multivariable logistic regression analysis adjusted for age and sex was performed for 30-day survival, ROSC, and 30-day favorable neurological outcomes (Supplement). Since most of the events took place around Tokyo, there might have been differences between Tokyo and other prefectures. In the subgroup analysis, the same analysis for 30-day survival was performed for both the Tokyo area and other prefectures (regions other than Tokyo).

Statistical analyses were performed using logistic regressions with odds ratios (OR) and 95% confidence intervals (CI) using STATA/IC 15 (StataCorp, Lakeway, TX, USA).

Results

Patient flowchart & baseline characteristics

We included 3,111 OHCA patients in the study (786 in the Olympic/Paralympic group, 774 in Term 1, 747 in Term 2, and 804 in Term 3, Fig. 1). Patients’ backgrounds are shown in Table 1. Time from call to EMS arrival and time from call to EMS hospital arrival were similar in the four groups.Fig. 1 Flow chart for the patients analyzed in the study.

Table 1 Baseline patient characteristics.

		Olympic/Paralympic	Term 1	Term 2	Term 3		
		N = 786	N = 774	N = 747	N = 804	P-value	
Age (IQR)		77 (65–85)	74.5 (60–84)	76 (61–85)	75 (63–85)	0.31	
Sex (Male)		485 (61.7)	461 (59.6)	448 (60.0)	520 (64.7)	0.14	
Bystander CPR*	339 (43.1)	319 (41.2)	309 (41.4)	330 (41.0)	0.86	
Witnessed CA*	336 (42.7)	341 (44.1)	314 (42.0)	352 (43.8)	0.76	
ECG initial*	Shockable	50 (6.4)	63 (8.1)	53 (7.1)	64 (8.0)	0.51	
	PEA	204 (26.0)	186 (24.0)	168 (22.5)	195 (24.3)	0.47	
	Asystole	436 (55.5)	427 (55.2)	440 (58.9)	434 (54.0)	0.25	
	Other	36	32	27	46	−	
Prehospital AED*	82 (10.4)	90 (11.6)	85 (11.4)	104 (12.9)	0.32	
Prehospital adrenaline*	260 (33.1)	274 (35.4)	250 (33.5)	260 (32.3)	0.53	
Prehospital advanced airway management*	398 (50.6)	386 (49.9)	400 (53.5)	415 (51.6)	0.63	
Area	Tokyo	64 (8.1)	60 (7.8)	60 (8.0)	60 (7.5)	0.96	
	Other prefectures	722 (91.9)	714 (92.2)	687 (92.0)	744 (92.5)	−	
Origin	Heart	387 (49.2)	413 (53.4)	381 (51.0)	453 (56.3)	0.03	
	non Heart	398 (50.8)	361 (46.6)	366 (49.0)	351 (43.7)	0.03	
Time	call − EMS arrival*	8 (6–10)	8 (6–9)	8 (6–9)	8 (6–10)	0.39	
	call − hospital arrival*	34 (29–41)	33 (28–41)	35 (28–42)	335 (28–41)	0.30	
In-hospital							
ECG on hospital arrival	Shockable	33 (4.2)	32 (4.1)	32 (4.3)	27 (3.3)	0.77	
	PEA	178 (22.6)	159 (20.5)	160 (21.4)	183 (22.8)	0.67	
	Asystole	489 (62.2)	505 (65.2)	479 (64.1)	508 (63.2)	0.64	
	Other	0	0	0	0	−	
ETI		517 (65.8)	501 (64.7)	515 (68.9)	529 (65.8)	0.34	
Adrenaline*		569 (72.4)	566 (73.1)	530 (71.0)	586 (72.9)	0.50	
Defibrillation		78 (9.9)	80 (10.3)	69 (9.2)	90 (11.2)	0.64	
ECMO		24 (3.1)	39 (5.0)	25 (3.3)	33 (4.1)	0.18	
PCI		28 (3.6)	30 (3.9)	29 (3.9)	36 (4.5)	0.82	
IABP		13 (1.7)	34 (4.4)	20 (2.7)	29 (3.6)	0.01	
Abbreviations: IQR: interquartile range, CPR: cardiopulmonary resuscitation, CA: cardiac arrest, ECG: electrocardiography, AED: automated external defibrillator, EMS: emergency medical service, PEA: pulseless electrical activity, ETI: endotracheal intubation, ECMO: extracorporeal membrane oxygenation, PCI: percutaneous coronary intervention, IABP: intra-aortic balloon pump.

*Bystander CPR n = 250 missing.

*Witnessed CA n = 250 missing.

*ECG initial n = 250 missing.

*Prehospital AED n = 612 missing.

*Prehospital adrenaline n = 250 missing.

*Prehospital advanced airway management n = 658 missing.

*Time call − EMS arrival n = 255 missing.

*Time call − hospital arrival n = 251 missing.

*Adrenaline n = 105 missing.

Term 1: July 23 to Aug. 8 and Aug. 24 to Sept. 5 in 2020.

Term 2: June. 18 to July. 4 and July. 6 to July. 18.

Term 3: Sept. 10 to Sept. 26 and Sept. 28 to Oct. 10.

Primary and secondary outcomes are shown in Table 2. Crude 30-day survivals were 7.4% (58/786), 9.3% (72/774), 6.8% (51/747), and 8.2% (66/804), respectively (p = 0.30). ROSC [32.1% (252/786), 31.8% (246/774), 33.7% (252/747), 34.5% (227/804), p = 0.85] and 30-day favorable neurological outcomes [3.1% (24/786), 4.5% (35/774), 3.5% (26/747), 4.9% (39/804), p = 0.22] were similar, respectively. Multivariable logistic regression analysis revealed no significant differences in 30-day survival between the four groups (Term 1: OR 1.27, 95% CI, 0.588–1.83p = 0.20, Term 2: OR 0.92, 95% CI, 0.62–1.36p = 0.67, Term 3: OR 1.10, 95% CI, 0.76–1.59p = 0.63). ROSC and 30-day favorable neurological outcomes revealed no significant differences.Table 2 Primary and secondary outcomes are shown. Using OHCA patients in the Olympic/Paralympic group as a reference, multivariable logistic regression analysis was performed for 30-day survival, ROSC, and 30-day favorable neurological outcomes.

		Enrolled	OR (95% CI) *	p value	
30-day survival	Olympic/Paralympic	7.4% (58/786)	Reference	−	
	Term 1	9.3% (72/774)	1.27 (0.88–1.83)	0.20	
	Term 2	6.8% (51/747)	0.92 (0.62–1.36)	0.67	
	Term 3	8.2% (66/804)	1.10 (0.76–1.59)	0.63	
ROSC	Olympic/Paralympic	32.1% (252/786)	Reference	−	
	Term 1	31.8% (246/774)	0.98 (0.79–1.22)	0.88	
	Term 2	33.7% (252/747)	1.09 (0.88–1.35)	0.43	
	Term 3	34.5% (277/804)	1.11 (0.90–1.36)	0.34	
30-day favorable neurological outcome	Olympic/Paralympic	3.1% (24/786)	Reference	−	
	Term 1	4.5% (35/774)	1.46 (0.85–2.50)	0.17	
	Term 2	3.5% (26/747)	1.12 (0.63–1.98)	0.70	
	Term 3	4.9% (39/804)	1.60 (0.95–2.70)	0.08	
Term 1: July 23 to Aug. 8 and Aug. 24 to Sept. 5 in 2020.

Term 2: June. 18 to July. 4 and July. 6 to July. 18.

Term 3: Sept. 10 to Sept. 26 and Sept. 28 to Oct. 10.

* Adjusted with age, and sex.

Abbreviations: ROSC: return of spontaneous circulation, OR: odds ratio, 95% CI: 95% confidence interval, CA: cardiac arrest, CPR: cardiopulmonary resuscitation, EMS: emergency medical service, AED: automated external defibrillator, ECMO: extracorporeal membrane oxygenation.

In the subgroup analysis, there were no differences in 30-day survival between the Tokyo area (Term 1: OR 3.07, 95% CI, 0.86–11.0p = 0.08, Term 2: OR 2.01, 95% CI, 0.51–7.90p = 0.32, Term 3: OR 2.02, 95% CI, 0.51–8.10p = 0.32), and other prefectures (Term 1: OR 1.17, 95% CI, 0.79–1.71p = 0.43, Term 2: OR 0.86, 95% CI, 0.57–1.30p = 0.48, Term 3: OR 1.02, 95% CI 0.70–1.51p = 0.90), respectively (Table 3).Table 3 Subgroup analysis of primary outcome for OHCA patients in the Tokyo or other prefectures.

30-day survival		Enrolled	OR (95% CI)*	p value	
Tokyo	Olympic/Paralympic	6.3% (4/64)	Reference	−	
	Term 1	15.0% (9/60)	3.07 (0.86–11.0)	0.08	
	Term 2	10.0% (6/60)	2.01 (0.51–7.90)	0.32	
	Term 3	11.7% (7/60)	2.02 (0.51–8.10)	0.32	
Other prefectures	Olympic/Paralympic	7.5% (54/722)	Reference	−	
	Term 1	8.8% (63/714)	1.17 (0.79–1.71)	0.43	
	Term 2	6.6% (45/687)	0.86 (0.57–1.30)	0.48	
	Term 3	7.9% (59/744)	1.02 (0.70–1.51)	0.90	
Term 1: July 23 to Aug. 8 and Aug. 24 to Sept. 5 in 2020.

Term 2: June. 18 to July. 4 and July. 6 to July. 18.

Term 3: Sept. 10 to Sept. 26 and Sept. 28 to Oct. 10.

* Adjusted with age, and sex.

Abbreviations: OR: odds ratio, 95% CI: 95% confidence interval, CA: cardiac arrest, CPR: cardiopulmonary resuscitation, EMS: emergency medical service, AED: automated external defibrillator, ECMO: extracorporeal membrane oxygenation.

Dynamic trend of estimated probability of 30-day survival around Olympic/Paralympic Games was described using a spline curve (Supplement).

Discussion

We assumed that the Tokyo Summer Olympic/Paralympic Games might influence normal emergency system operations in Japan and examined the outcomes for OHCA patients during this big worldwide event compared to outcomes on the same dates in the previous year and those in the pre- and post-Olympic/Paralympic term. However, no significant differences were identified.

Mass gatherings may lead to a higher demand for EMS due to the temporary concentration of people in the area. Limitations to access to local EMS are regarded as a risk.8 Additionally, the high level of international interest in a mass gathering event like the Olympic/Paralympic Games is associated with the potential for mass casualty incidents.9, 10 Notably, the current study showed no difference in the time from call to EMS arrival and outcomes for OHCA patients, even in the limited area of Tokyo where most of the events took place. These results suggest that normal EMS operations were maintained during the Olympic/Paralympic Games.

Due to the COVID-19 pandemic, the International Olympic Committee, the Japanese Government, and the Tokyo Organizing Committee of the Olympic/Paralympic Games postponed the Tokyo 2020 Olympic/Paralympic Games until the summer of 2021. Despite the postponement, there was a resurgence of new COVID-19 cases in Tokyo and beyond, and many restrictions and countermeasures against the pandemic were announced. Furthermore, no spectators were allowed at any venues in Tokyo during the event. The Tokyo Olympic Games were attended by only 41,000 people compared to the usual 141,000 at a summer Olympics event.11 Shifting to a less-crowded and spectator-less event might help prevent worse outcomes for OHCA patients.

Cardiac arrests are expected to increase during an emotionally stressful event. A significant increase in the incidence of OHCA on the days of the sumo tournament in Tokyo was recognized.5 Similarly, watching a professional baseball championship might also pose the risk of cardiac arrest.12 The FIFA world cup, which may result in unfavorable physiological responses that adversely affect the heart, has led to adverse cardiac consequences.13 Conversely, lower mortality in French men caused by myocardial infarction on the day France won the 1998 World Cup of football was reported.14 Possible confounding factors and biases such as the intake of large amounts of alcohol, fatty foods, and use of illicit drugs and smoking should be considered.15 These topics are still debatable and inconclusive.

Public health planning requires co-ordination between local, regional, and national health-related agencies during the Olympic Games.16 To maintain normal public health system operations, the Academic Consortium on Emergency Medical Service and Disaster Medical Response, comprising 28 academic societies in Japan, launched a plan for the 2020 Tokyo Olympic/Paralympic Games in 2016.17 Associated academic organizations and societies led the development of a training program. During the Olympic/Paralympic Games, not only the COVID-19 pandemic,11, 18 but also heat illness was a major public health concern.19 Such training programs might develop medical assistants’ clinical skills and contribute to maintaining the quality of emergency systems throughout Japan.

Limitations

Unfortunately, this study had several limitations. This was a multicenter, retrospective analysis including different prehospital systems, emergency department systems, and intensive care management systems. Since treatment protocols for OHCA patients throughout Japan are different in each medical system and hospital, unified indications for advanced treatment options such as extracorporeal pulmonary resuscitation were not established. Furthermore, detailed information about OHCA patients such as socioeconomic status or incomes were unknown, which would make the results obscure. Second, this study did not include data on CPR quality, which might affect outcomes for OHCA patients. Third, the Olympic/Paralympic Games were held in the middle of the COVID-19 pandemic. To protect themselves from COVID-19 infection, EMS personnel prioritized airway protection over chest compression during the pandemic, which may have affected OHCA outcomes. Also, the many regulations against COVID-19 might have diluted the true influence of the Olympic/Paralympic Games on normal emergency medical system operations. However, this study highlights COVID-19 consequences and countermeasures during the Olympic/Paralympic Games in an island country. Although these situations were not typical and might be tough to apply simply to another county, this analysis could help with future international events, even in other nations.

Conclusions

We evaluated outcomes for OHCA patients admitted to the hospital during the Tokyo Olympic/Paralympic Games in Japan. No significant differences in 30-day survival, ROSC, and 30-day favorable neurological outcomes were identified. Further research to reveal the detailed association between the Olympic/Paralympic Games and OHCA outcomes with detailed information in different countries is warranted.

Disclosures

Informed consent: N/A.

Registry and the registration no. of the study/trial: 2023011. This study entitled “Survival in out-of-hospital cardiac arrest patients admitted during Tokyo Summer Olympic and Paralympic Games in Japan” was approved by our emergency medical center institutional review board (approval number: 2023011) on June 20, 2023.

Funding: The authors did not have any grant support for this study.

Animal studies: N/A.

CRediT authorship contribution statement

Takeshi Nishimura: Writing – original draft, Conceptualization. Takuya Taira: Writing – review & editing. Masafumi Suga: Writing – review & editing. Shinichi Ijuin: Writing – review & editing. Akihiko Inoue: Writing – review & editing. Satoshi Ishihara: Writing – review & editing.

Declaration of competing interest

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

Appendix A Supplementary material

The following are the Supplementary data to this article:Supplementary Fig. 1

Supplementary Fig. 2

Acknowledgements

We thank Christine Burr for editing the English writing.

Appendix A Supplementary data to this article can be found online at https://doi.org/10.1016/j.resplu.2024.100748.
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