Prospective cohort study on injuries and health problems among circus arts students

Subjects

We invited all first, second and third-year students (n=44) of the Bachelor Circus Arts of Codarts Rotterdam, the Netherlands. The students are enrolled in a 4-year educational programme, resulting in a Bachelor of Arts. They study a wide range of circus disciplines, ranging from juggling to acrobatics, and choose a specialisation in their first year in which they wish to excel. Codarts School of Circus Arts is an international school in which students from more than 16 different nationalities are enrolled. All students were informed about the procedure and provided written informed consent. Our data were routinely collected for management purposes and for educational purposes and not for the purpose of this particular study. Therefore, The Dutch Central Committee on Research Involving Human Subjects (CCMO) stated that no medical ethical approval was necessary for this questionnaire study, as stated in the Dutch Medical Research Involving Human Subjects Act (http://www.ccmo.nl/nl/toetsingscommissie-ccmo-of-metc?55a37b93-dd8c-4bf8-8883-2d30c35ff8ba).

Procedures

At the beginning of the academic year (end of August 2016), height and body weight were recorded by the research team of Codarts Rotterdam. An intake questionnaire was administered, which included items on age, year of education and previous injuries (ie, injuries lasting at least 1 week in the previous year).

All first, second and third year students were prospectively followed during the entire 2016/2017 academic year. Students who were injured at the start of the academic year, as well as students who dropped out of the programme during the academic year (n=3), were included in the study. The time they were enrolled in the programme was taken into account in the analyses. Every month, all students were asked to complete questionnaires by using a web-based system (Performing Artist and Athletes Health Monitor (PAHM)). PAHM was developed by Codarts Rotterdam and used to monitor physical and mental health in performing artists and athletes. This system consists of several questionnaires and items (ie, visual analogue scale (VAS) pain scale; VAS stress scale; Self-Estimated Functional Inability because of Pain questionnaire;13 Oslo Sports Trauma Research Centre Questionnaire on Health Problems;9 mental complaints;14 15 injury characteristics (location, history and acute or overuse onset16–18 ); items on sleep quality, mental energy, feelings and emotions, satisfaction with rehearsals and performances, taking distance and exposure (minutes spend on different activities)). Every month, students automatically received a link to the questionnaire by email. A reminder was sent to all students who did not respond on the questionnaire after 1 week.

In PAHM, the Dutch translation of the Oslo Sports Trauma Research Centre (OSTRC) Questionnaire on Health Problems11 12 was included. The original9 and Dutch OSRTC questionnaire11 12 consisted of four key questions on the consequences of health problems on participation, training volume and performance as well as the degree to which the student perceived symptoms. All items ranged from 0 (no problem, no reduction, no effect or no symptoms) to 25 (cannot participate at all or severe symptoms). Questions 1 and 4 were scored on a four-point scale (0–8–17–25), while questions 2 and 3 were scored on a five-point scale (0–6–13–19–25). The severity of a health problem was calculated on a scale of 0 (no health problem) to 100 (cannot participate at all due to sever health problems) by summing the score of the four questions, according to the method proposed by Clarsen and colleagues.9 If the severity score was 0, the questionnaire was finished for that month. However, if a symptom was reported, the students were asked whether they referred to a physical injury, mental problem or an illness. For physical injuries, the student was automatically directed to an injury registration form based on an international consensus statement on injury surveillance methodology for football to collect further details (eg, location, history and acute or overuse onset).16–18

Students were defined to be substantially injured if they reported problems leading to moderate or severe reductions (value ≥13 on question 2 or 3 of the OSTRC) in training volume, or moderate or severe reductions in performance or complete inability to participate in activities at least once during follow-up.8 If a student reported the same type of health problem on two or more consecutive months, this was counted as one case of a (fluctuating) problem.12

Statistical analysis

Statistical analyses were conducted using SPSS (SPSS V.24.0), and statistical significance level was set at an alpha level >0.05. Descriptive statistics were used to describe baseline characteristics of all participants using means and SD or number and percentages (%). Injury incidence rate was calculated as the number of injuries per 1000 hours spending on physical circus activities.19 The corresponding 95% CIs were obtained using the following formula: (#injuries/exposure±1.96 SE) * 1000.19 The (substantial) injury incidence proportion (IP) for one academic year was calculated by dividing the number of students that reported at least one (substantial) injury during the academic year by the number of respondents19 The (substantial) IP per month was calculated by dividing the number of students that reported at least one (substantial) injury during that month by the number of respondents in that same month. The proportion of all injuries that affect a particular body part was calculated by dividing the number to the location into the total number of injuries affecting that particular body part and multiplying it with 100, resulting in a percentage. The severity of all injuries was calculated by the mean duration in days, the median and the SD.

Response and baseline characteristics

All circus students agreed to participate and were consequently included in the present study. The cohort comprised of 44 circus students (females=47.7%), the mean age was 22.0 years (2.8) and mean BMI was 22.1 kg/m² (1.8). Fourteen first-year (31.8%), 18 second-year (40.9%) and 12 third-year (27.3%) students were included in the present study. In total, 421 questionnaires were sent to the students and 349 were completed, resulting in a response rate of 82.9%.

Health problems

During the academic year, all (100%) students reported a health problem. In the 10 monthly questionnaires, a total of 261 health problems were reported consisting of 184 injuries (70.5%), 51 illnesses (19.5%), 15 mental problems (5.0%) and 11 other health problems (3.1%). The 44 students reported on average 5.9 (2.1) health problems during the academic year with a minimum of 1 and a maximum of 10 health problems. Figure 1 shows that between 44.7% and 94.7% of the students reported a health problem on a monthly basis, and between the 13.2% and 47.4% of the students reported a substantial health problem on a monthly basis. Figure 2 shows that students with health problems reported monthly severity scores between 28.1 and 43.1.

Injuries

During the academic year, 42 (95.5%) students reported in total 184 injuries. Of these, 130 were unique cases. The remaining 54 injuries were subsequent injuries. These injuries were reported in at least two consecutive questionnaires and therefore did not calculate as a unique injury.

The 14 first-year circus students and 18 second-year students spend on average 25 hours per week on physical circus activities, resulting in a total exposure of 32 000 hours during the data collection of 40 weeks. However, two second-year students dropped out of the educational programme after 4 months. Adjusting for this dropped out results in a total exposure for the first-year and second-year students of 30 800 hours. The 12 third-year students spend on average 19 hours on physical circus activities, resulting in a total exposure of 9120. However, one third-year student dropped out of the educational programme after 3 months. Adjusting for this dropped out results in a total exposure for third-year students of 8588 hours. The total exposure of all circus students was 39 388 hours. The total time equates to an injury incidence rate of 3.3 injuries per 1000 hours (95% CI 2.7 to 3.9).

The 42 students reported on average 4.4 (1.6) injuries during the academic year with a minimum of one and a maximum of eight injuries. Figure 3 shows that the monthly incidence proportion of all injuries ranged from 31.6% to 69.0% and from 6.8% to 34.1% for substantial injuries. Figure 2 shows that students with injuries reported monthly severity scores between 23.6 and 46.1. The shoulder (n=51; 27.7%), lower back (n=29; 15.8%), wrist (n=26; 14.1%) and ankle (n=17; 9.2%) were the most reported anatomical injury locations in the 10 questionnaires. The average duration of the injuries was 6.9 days (15.0) with a minimum of 0 and a maximum of 134 days. The median was 2.0 days.

Strengths of the study

One major strength of this study is the response rate of the monthly questionnaire of 82.9%. There are several reasons that might explain the high response rate. First, we used adequate guidance during the data collection to increase involvement of students and teachers. Second, we used PAHM to give students visual feedback of the collected data to improve their commitment to this study. Third, we asked for feedback from our students to improve PAHM. The feedback was incorporated in the new versions of PAHM. We recommend to use this approach when using similar registration methods.

A unique aspect of the current study is that all students were enrolled in a circus educational programme. A thorough investigation on the severity and magnitude of self-reported injury problems in this group is lacking. Although the sample size is relatively small, the presented data are accurately measured, and the response rate is high, which suggests that the results are representative for this specific target population.

Limitations of the study

In this study, we used student-reported outcomes. This methodology exposes a potential limitation. Most circus students lack medical expertise. Therefore, we were unable to record specific diagnoses for the reported injuries and profound onset mechanisms. We recommend that future studies include a follow-up from the medical staff during the data collection period to gain more insight in the injury type and aetiology.

A second limitation is that students recorded a questionnaire every month, instead of every week, as proposed by Clarsen and colleagues.8 This may have led to a slight underestimation of injuries, as students may forget a physical problem that occurred 2 weeks earlier. However, Clarsen and colleagues8 showed that the average prevalence and severity of health problems was not affected by the sampling frequency up to a frequency of one sample every 4 weeks. We therefore believe that students are able to provide reliable information about a health problem from 1 month back.

Third, the used methodology implies that the problem’s severity is constant between two recordings. It is therefore unclear at what specific day the severity of the injury was the highest. However, due to this method, the students were not overloaded with questionnaires every week, leading to a high compliance.