The Influence of Injury Definition on Injury Burden in Preprofessional Ballet and Contemporary Dancers.

Study Design Cohort study. Background Multiple operational definitions of injury exist in dance research. The influence that these different injury definitions have on epidemiological estimations of injury burden among dancers warrants investigation. Objective To describe the influence of injury definition on injury prevalence, incidence, and severity in preprofessional ballet and contemporary dancers. Methods Dancers registered in full-time preprofessional ballet (n = 85; 77 female; median age, 15 years; range, 11-19 years) and contemporary (n = 60; 58 female; median age, 19 years; range, 17-30 years) training completed weekly online questionnaires (modified Oslo Sports Trauma Research Centre questionnaire on health problems) using 3 injury definitions: (1) time loss (unable to complete 1 or more classes/rehearsals/performances for 1 or more days beyond onset), (2) medical attention, and (3) any complaint. Physical therapists completed injury report forms to capture dance-related medical attention and time-loss injuries. Percent agreement between injury registration methods was estimated. Injury prevalence (seasonal proportion of dancers injured), incidence rates (count of new injuries per 1000 dance-exposure hours), and severity (total days lost) were examined across each definition, registration method, and dance style. Results Questionnaire response rate was 99%. Agreement between registration methods ranged between 59% (time loss) and 74% (injury location). Depending on definition, registration, and dance style, injury prevalence ranged between 9.4% (95% confidence interval [CI]: 4.1%, 17.7%; time loss) and 82.4% (95% CI: 72.5%, 89.8%; any complaint), incidence rates between 0.1 (95% CI: 0.03, 0.2; time loss) and 4.9 (95% CI: 4.1, 5.8; any complaint) injuries per 1000 dance-hours, and days lost between 111 and 588 days. Conclusion Time-loss and medical-attention injury definitions underestimate the injury burden in preprofessional dancers. Accordingly, injury surveillance methodologies should consider more inclusive injury definitions. J Orthop Sports Phys Ther 2018;48(3):185-193. Epub 13 Dec 2017. doi:10.2519/jospt.2018.7542 Level of Evidence Symptom prevalence study, level 1b.