The Rugby World Cup, Olympics, and Paralympics were recently hosted in Japan as large-scale sporting events. The Tokyo 2020 Summer Olympics involved 11,420 athletes and 312,883 officials from 206 countries [1], while the 2019 Rugby World Cup attracted 1,704,443 spectators, averaging 37,877 spectators per game [2]. These large-scale sporting events are viewed as mass gatherings with a potential for injuries and illnesses [3]. Therefore, stadium emergency medical systems must be prepared to handle not only athletes, but also spectators and officials [4]. To establish an adequate emergency medical system, it is crucial to understand the patterns of injuries and illnesses that occur among athletes and spectators.

Kiyohara et al. [5] reported on sports-related emergency transports that took place in Osaka over the past 3 years. Out of the 2,642 transports, 701 (25.5%) were due to fractures/bone contusions, making them the most common, followed by 667 (24.2%) cases of bruises. Hirschhorn et al. [6] analyzed sports injuries requiring emergency transport among high school and college students across the United States. Of the 485 case visits, 82 (16.9%) were fractures, the most common injury, followed by 73 (15.1%) concussions. There are numerous reports of sports injuries both in Japan and globally, where athletes were injured during competition and required emergency transport [6].

Conversely, Tajima et al. [4] conducted a study focusing on spectators, finding that 15.8% of spectators who were rushed to the hospital during the tournament suffered from heat stroke and fractures and/or dislocations respectively. The highest incidence was among men in their 70s, followed by men in their 80s [2]. Additionally, the most frequent transport time was just before the start of the game [2]. However, to develop an emergency medical system that includes spectators, it is necessary to have epidemiological information not only for a specific period but also for the entire year. Moreover, Tajima et al. [2] did not report on the locations of injuries and illnesses. Therefore, to build an emergency medical system that includes not only athletes but also spectators and related parties, it is necessary to understand the detailed characteristics of emergency patients throughout the entire sports stadium.

Between January 1, 2015, and December 31, 2019, a total of 26,710,631 patients were registered in the emergency transport database. Of these, 29,536 patients met the criteria for inclusion in this study. These patients were categorized into two groups: SrETi (n=14,078; 47.7%) and NSrETi (n=15,458; 52.3%), as shown in Fig. 1. The characteristics of these patients are detailed in Table 1. The highest number of incidents occurred during the summer, accounting for 10,550 (35.7%) of the total incidents. Of these, 5,209 (37.0%) were SrETi and 5,341 (34.6%) were NSrETi. The most common time for call entries was between noon and the afternoon, with 15,766 (53.4%) calls. Of these, 7,645 (54.3%) were SrETi, and 8,121 (52.5%) were NSrETi. Males made up the majority of the cases (n=21,096; 71.4%). In the SrETi group, the largest patient demographic (n=6,464; 45.9%) was between 13 and 22 years old. In contrast, the NSrETi group had the highest number of patients (n=5,311; 34.4%) who were over 64 years old. For SrETi incidents, the most common location was the sports ground (n=8,164; 58.0%), followed by the gymnasium and dojo (n=4,110; 29.2%). Similarly, 4,415 (28.6%) of NSrETi incidents occurred on sports grounds, and 2,788 (18.0%) took place in gymnasiums and dojos. However, unlike the SrETi group, NSrETi incidents also occurred in corridors (n=881; 5.7%), on stairways (n=222; 1.4%), in toilets (n=172; 1.1%), and in bathrooms (n=557; 3.6%). The NSrETi group had more severe cases, including 92 deaths (0.6%) and 17 serious illnesses (0.1%), compared to the SrETi group, which had nine deaths (0.06%) and four serious illnesses (0.03%).

In the SrETi group, there were 71 instances of severe or greater illnesses and injuries, while the NSrETi group had 621 such cases. Conversely, SrETi reported 2,429 cases of moderate or minor illnesses and injuries, and NSrETi reported 4,084 cases (Figs. 2, 3). Due to missing values in the disease and injury data from FDMA, percentages were calculated based on the total patient count. Table 2 provides a summary of the characteristics of SrETi and NSrETi where the initial physician rated the severity as severe or greater. In this context, SrETi accounted for 326 cases (24.8%), and NSrETi accounted for 991 cases (75.2%). The most common severe or greater illnesses and injuries in SrETi and NSrETi were non-union fractures (35.2%) and brain diseases (45.6%), respectively. On the other hand, the most common moderate or minor illnesses and injuries in SrETi and NSrETi were bruises (39.2%) and brain diseases (16.1%), respectively.

The results of the multivariable logistic regression analysis are displayed in Table 3. NSrETi were found to be significantly associated with severity (AOR, 1.52; 95% CI, 1.29–1.76) when compared to SrETi. Patients who were less than 13 years old (AOR, 0.10; 95% CI, 0.07–0.14), between 13 and 22 years old (AOR, 0.20; 95% CI, 0.17–0.25), between 23 and 35 years old (AOR, 0.36; 95% CI, 0.29–0.44), and between 36 and 64 years old (AOR, 0.75; 95% CI, 0.65–0.87) were significantly more associated with severity than patients who were older than 64 years. The locations of a toilet (AOR, 1.84; 95% CI, 1.09–3.12), swimming pool (AOR, 3.67; 95% CI, 2.83–4.77), and other unspecified locations (AOR, 1.26; 95% CI 1.08–1.46) were also significantly associated with severity when compared to the sports ground.

Multivariable logistic regression analysis demonstrated a significantly higher occurrence of severe or greater illnesses and injuries in toilets, swimming pools, and other locations. Fig. 4 illustrates the proportion of NSrETi cases in these places. In swimming pools, cardiac disease accounted for the greatest number of cases (n=38; 45.8%), followed by brain disease (n=30; 36.1%). Similarly, in other locations, cardiac disease was the most common cause of incidents (n=108; 33.2%), followed by brain disease (n=103; 31.7%). In toilets, brain disease was the most common cause of incidents (n=10; 58.8%), followed by cardiac disease (n=2; 11.8%).

To the best of our knowledge, this is the first study to examine the characteristics of patients transported from sports stadiums and facilities using FDMA emergency transport data. The results indicated that SrETi patients were more frequently rushed to the hospital due to injuries, while NSrETi patients were more often transported due to illnesses. Moreover, SrETi cases were primarily classified as moderate or minor, and not directly life-threatening. In contrast, NSrETi cases encompassed more severe and potentially life-threatening illnesses, which were more common in swimming pools, toilets, and other locations. The epidemiology of diseases occurring at athletic fields and sports facilities, as identified by this study, could enhance the prognosis of injured and ill patients when athletic trainers, physicians, and EMS are actively providing emergency medical care.

The findings of this study suggest that serious emergency medical incidents at athletic fields and stadiums are more frequently non-sports-related than sports-related. Traditionally, sports-related emergency medical systems and AED placement have been viewed as relief strategies primarily for athletes [13]. However, in line with the suggestions made by Borjesson et al. [14], the results of our study underscore the necessity for emergency medical systems that cater to non-athletes, including staff and spectators, at large-scale sporting events. Besides injuries, illnesses are also prevalent among spectators. Given that spectators are typically older than athletes and are more likely to have complex medical histories, they are at a heightened risk. As evidenced by the Tokyo 2020 Olympics, first aid preparedness in athletic stadiums and sports facilities should account for both injuries among competitors and non-sports participants.

This study found that the incidence of NSrETi was significantly higher in toilets and other locations. The elevated incidence in toilets is thought to be due to the rapid rise in blood pressure that occurs during straining for urination and defecation, which can trigger acute coronary syndrome and subarachnoid hemorrhage [15]. Out-of-hospital cardiac arrests (OHCA) that occur in toilets often result in delayed patient discovery, leading to a poorer neurological prognosis [16]. An increased incidence was also observed in spectator seating areas. The rate of OHCA rose during sports viewing [17-21], and the emotional stress experienced while watching sports can precipitate acute cardiovascular events [22-26]. The findings of this study underscore the importance of promoting awareness of relief in toilets and spectator seating areas. Furthermore, AEDs should be strategically positioned in locations that are easily accessible from toilets and spectator seating areas.

Furthermore, the results of this study revealed that the incidence of severe disease significantly increased with age. As most cases of heart disease (n=108; 33.2%) were classified as severe and occurred in various locations, it is crucial to consider the rising number of spectators with age-related heart disease.

This study had several limitations. First, as an observational study utilizing secondary emergency transport data, there may have been confounding effects. Second, the cross-sectional nature of the study precludes the identification of causal relationships. Third, the study's generalizability to other countries and regions may be limited, given that it was conducted using emergency transport data from Japan. Fourth, the FDMA defines accidents resulting from athletic events as "accidents that occur during the conduct of athletic events and that involve the direct conduct of athletic events, referees, and related personnel" [7]. As such, some non-athletes were included in the SrETi group.

In conclusion, this study investigated the characteristics of patients requiring emergency transport from athletic stadiums and sports facilities in Japan and found that the SrETi group mostly involved moderate and minor non-life-threatening sports injuries. In contrast, the NSrETi group tended to include life-threatening illnesses and injuries, many of which occurred in swimming pools, toilets, or other locations. These results underscore the importance of developing emergency medical systems not only for athletes but also for staff and spectators, as well as strategic AED placement near toilets and spectator seating.