Trends in sports-related emergency department visits in the Netherlands, 2009–2018

Data source

Sports-related ED visits in the Netherlands were extracted from the Dutch Injury Surveillance System (DISS). The DISS data set is composed of a representative sample of injuries treated at 14 geographically distributed EDs in the Netherlands since 1986.⁸ Despite the availability of the DISS data set since 1986, in the current study, data are used from 2009 until 2018. This time period was chosen as it represents the current state of affairs in the field of nationwide sports injuries, which in turn can guide current policy development, aimed at preventative efforts. The DISS data set represents 16% of all EDs in the Netherlands and includes general and academic hospitals that provide emergency services 24 hours a day. When a patient visits one of the participating EDs, an employee of the ED (eg, a doctor or nurse) registers the basic data in an administrative system.

When the patient requires treatment for an injury, detailed information about the circumstances of the accident is recorded. In this process, it is determined whether the injury was caused while taking part in a sport, where sport is defined as physical activity which is practised within an organised or unorganised setting, such as competitive or recreational sport.⁹ All data on injuries that are registered by the EDs are provided anonymously to VeiligheidNL (VNL), and records are converted—by a data manager—into uniform codes and variables. In the case of open text fields, conversion is carried out by means of automatic text recognition. A random check is performed manually on the data to determine whether the data conversions were performed correctly.

Because VNL is an organisation that conducts scientific research, an appeal can be made to the exemption clause of the Medical Treatment Contracts Act (WGBO) for the use of patients’ medical data for scientific research (Article 7: 458 of the Dutch Civil Code). Therefore, no explicit consent of patients was needed (Article 7: 457 of the Dutch Civil Code). Patients were informed about the existence of the surveillance system, and about the possibility to object to the inclusion of their data in the surveillance system.

The sample of 14 EDs can be extrapolated to nationwide estimates, while the age distribution, the type of hospital and other demographics are representative of all EDs in the Netherlands.^{10 11–13} An extrapolation factor was calculated as follows: (No. of ED visits in the sample×No. hospital admissions in all hospitals)/No. of hospital admission in the sample.¹⁴

Severe injury

In the Netherlands, minor injuries are often treated by a general practitioner during same-day visits. Furthermore, minor (overload) injuries are often treated at a physiotherapy centre (without a medical referral). Outside working hours, patients can be treated at a general practice centre, usually situated in a hospital. Severe injuries are often treated at an ED, which can be visited all hours of the day and is situated in a hospital. In the past 10 years, new policies have been adopted in the Netherlands aimed at improving the efficiency of emergency care. This has resulted in minor injuries being treated even more often outside EDs by the general practitioner, whereas severe injuries are still treated in the EDs.¹⁰ As minor injuries were more likely to be treated outside EDs, it was decided in the current study to only report the number of severe sports-related ED visits from the DISS data set that were treated between 2009 and 2018. It is assumed that, by doing this, a more reliable description of the incidence of sports-related ED visits in the Netherlands can be provided.

To select the severe sports-related ED visits, a derivative of the Maximum Abbreviated Injury Scale (MAIS) was used.¹⁵ The score on this scale runs from 1 (minor) to 6 (maximum) and represents the severity of the injury.¹⁶ A MAIS score was generated for the injuries in DISS by transforming 39 injury groups to corresponding categories in the International Classification of Diseases, 10th Revision.¹⁷ An overview of the MAIS classification of injury diagnoses is presented in online supplemental table S1. In the current study, severe injury is defined as one with a MAIS score of at least 2.¹⁸

Data analysis

The absolute numbers and time trends of severe sports-related ED visits were specified for age, gender, sports activity and injury diagnosis for each individual year from 2009 to 2018. As the ED data were extrapolated, all absolute numbers were rounded to the nearest integer. In addition, 95% CIs were calculated. For the calculation of time trends, absolute numbers of injuries were standardised by correcting for changes in population composition between 2009 and 2018. Standardisation was performed by direct standardisation, in which one weight was applied to all age-specific rates, irrespective of the age distribution of the population.¹⁹ Data on changes in population composition were obtained from Statistics Netherlands.²⁰

Injuries were specified for the following age groups: 0–17, 18–34, 35–54 and ≥55 years. These age groups are conventional within the DISS data set. In general, the agroup 0–17 years represents youth athletes, 18–34 years represents senior athletes, 35–54 years represents master athletes, and ≥55 years represents elderly athletes.

In the DISS data set, a total of 65 sports activities are coded (online supplemental table S2). Sports activities averaging less than 500 severe sports-related ED visits a year (between 2009 and 2018) were not included in the current analyses. This cut-off was applied as the ED data were extrapolated, resulting in sports activities with less than 500 ED visits a year being less representative for the Netherlands. Therefore, only the following sports activities were included: basketball, combat sports, field hockey, fitness, futsal, gymnastics, horse riding, ice-skating, inline/roller skating, motorcycle racing, mountain bike racing, physical education, road cycle racing, running, skateboarding, skiing, snowboarding, soccer, swimming, tennis and volleyball.

Severe sports-related injury diagnoses identified in the EDs less than 500 times a year (between 2009 and 2018) were not included in the current study either. Again, this cut-off was applied as the ED data were extrapolated, resulting in injury diagnoses identified less than 500 times a year being less representative for the Netherlands. Therefore, only the following severe sports-related injuries were included: knee distortion (ie, a dislocation, sprain, or strain of joint and ligaments of the knee), fractured ankle, fractured collarbone/shoulder, fractured elbow, fractured foot, fractured forearm, fractured hand, fractured hip, fractured knee, fractured lower leg, fractured ribs/chest, fractured spine/spinal cord injury, fractured upper arm, fractured wrist, knee luxation, mild traumatic brain injury, muscle/tendon injury in hand/finger, muscle/tendon injury in lower leg and severe traumatic brain injury.

To analyse the statistical significance of the trends over time, a logistic regression model was used. Both the linear and the quadratic association were tested based on standardised data, as the trend was corrected for changes in population composition between 2009 and 2018. A p value below 0.05 was considered statistically significant. The absolute percentage of the change over time and the 95% CI are reported. All analyses were performed using IBM SPSS Statistics version 25.

Patient and public involvement

This research was done without patient involvement. Patients were not invited to comment on the study design and were not consulted to develop patient-relevant outcomes or interpret the results. Patients were not invited to contribute to the writing or editing of this document for readability or accuracy.

Gender and age group

An overview of the absolute number of severe sports-related ED visits in the Netherlands from 2009 to 2018 is presented by gender and age group in table 1. Figure 1 presents the trends over time. The number of severe sports-related ED visits has significantly decreased by 14% (95% CI −19% to −9%). This was also the case among men (−12%; 95% CI −18% to −6%) and women (−19%; 95% CI −26% to −11%). Even though the number of ED visits decreased for all age groups between 2009 and 2018, a significant decrease was seen only among individuals aged 18–34 years (−19%; 95% CI −28% to −10%).

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Sports activity

Table 2 presents the absolute number of severe sports-related ED visits, for the 10 sports activities with, on average, the highest number of ED visits (between 2009 and 2018). This includes soccer, physical education, horse riding, ice-skating, road cycle racing, inline/roller skating, motorcycle racing, field hockey, mountain bike racing and gymnastics. The time trends of these 10 sports activities are presented in figure 2. The number of severe sports-related ED visits has significantly decreased over time in soccer (−15%; 95% CI −24% to −6%), ice-skating (−80%; 95% CI −85% to −73%) and in inline/roller skating (−38%; 95% CI −55% to −15%). The number of ED visits has significantly increased over time in road cycle racing (+135%; 95% CI +85% to +198%) and in mountain bike racing (+80%; 95% CI +32% to +146%). The full data of the other 11 sports are provided in online supplemental table S3.

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Injury diagnosis

Table 3 presents the absolute number of severe sports-related ED visits, for the 10 injuries that, on average, were diagnosed in the EDs most often (between 2009 and 2018). This includes fractured wrist, fractured collarbone/shoulder, fractured ankle, fractured hand, knee distortion, fractured foot, fractured forearm, mild traumatic brain injury, fractured elbow and fractured lower leg. The time trends of these 10 injuries are presented in figure 3. The injury diagnoses of fractured wrist (−15%; 95% CI −24% to −5%), fractured hand (−37%; 95% CI −49% to −21%), knee distortion (−66%; 95% CI −74% to −55%) and fractured lower leg (−38%; 95% CI −55% to −14%) have significantly decreased between 2009 and 2018. The full data of the other 11 injuries are provided in online supplemental table S4.

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Comparison with other studies

To date, a study describing the nationwide trends of severe sports-related ED visits has not been performed in the Netherlands. In contrast, previous studies have investigated time trends of sports-related ED visits in other countries. Namely, an Australian study reported an increase in sports injury-related ED visits between 2012 and 2015.²¹ Furthermore, an American study on sports-related ED visits among individuals aged 5–18 years reported an increase in sports-related injuries between 2009 and 2013,⁶ whereas we found a decrease among individuals aged 0–17 years between 2009 and 2018. This difference could be explained by the fact that in the current study only severe sports-related ED visits are included. Similar to the promising reduction in ED visits reported in our study, a Swedish study reported a decrease in sports injury-related ED visits between 2004 and 2007.²² However, an Australian study reported a significant annual increase in sport-related major trauma between 2001 and 2007.²³ Differences between these studies could be explained due to differences in time periods, healthcare systems and healthcare policy.

Interpretation of results

The reduction in severe sports-related ED visits could be explained by new policies that have been adopted in the Netherlands aimed at improving the efficiency of emergency care. The number of individuals participating in sports on a weekly basis has slightly increased in the Netherlands over the years, but significant differences exist across sports activities.²⁴ Therefore, this cannot be an explanation for the general reduction in severe sports-related ED visits. Interestingly, when the trends in severe sports-related ED visits are compared with all severe ED visits or with other specific ED visits in the Netherlands, differences become evident. Namely, the number of all severe ED visits and severe work-related ED visits has stayed the same between 2009 and 2018.¹⁸ In addition, the number of severe traffic-related ED visits has increased over time.

The current study shows a decreasing trend of ED visits over time in soccer, ice-skating and in inline/roller skating. The decreasing trend in soccer could be explained by mandating the use of shin guards, resulting in significant decreases in lower leg fractures.²⁵ In addition, the decreasing trend in ice-skating could be explained by milder winters, resulting in fewer individuals ice-skating outside.

In contrast, ED visits for road cycle racing and mountain bike racing increased between 2009 and 2018. One possibility for the increased ED visits could be that exposure hours of road cycle racing or mountain bike racing have changed in the past decade. A national questionnaire on accidents and exercise among Dutch inhabitants—between 2009 and 2014—found that exposure hours slightly increased for road cycle racing but stayed the same for mountain bike racing.²⁶ However, no information about exposure hours of these sports is available for 2015 through 2018.

Strengths and limitations

A strength of the current study is the use of the DISS data set. This data set is composed of a representative sample of nationwide sports-related ED visits. Furthermore, the current study extensively describes the number of severe sports-related ED visits on different age groups, gender, sports activities and injury diagnoses over a period of 10 years. A limitation is that this study does not provide a complete picture of nationwide sports injuries, as only severe sports-related ED visits were included in the analyses. Including low-risk activities (ie, minor injuries) in the analyses could give a better overview of sports injuries, aimed to look at preventative efforts. Another limitation of the study is that injury data are not corrected for exposure hours as this information is unavailable in the Netherlands. In the current study, a correction was made for changes in population composition between 2009 and 2018.