Background The influence of injury definition on the interpretation of epidemiological outcomes of injury risk has not been previously evaluated in a dance population.

Objective To determine the influence of injury definition (i.e., time loss, medical attention, all complaints) on the prevalence and rate of musculoskeletal injuries in pre-professional ballet and contemporary dancers.

Design Prospective cohort.

Setting Pre-professional ballet school; university dance program.

Participants Dancers registered in full-time pre-professional ballet [n=85, 77 females, median (range) age 15 yrs (11–19 yrs)] and contemporary [n=60, 58 females, 19 yrs (17–30 yrs)] training.

Main Outcome Measurements Dancers completed a weekly online questionnaire (modified Oslo Sports Trauma Research Centre's Questionnaire on Health Problems) using three definitions for dance-related injuries: (1) time loss (an inability to complete one or more classes, rehearsals or performances one or more days beyond onset); (2) medical attention; and (3) any complaint. Physiotherapists completed injury report forms, capturing dance-related medical attention and time loss injuries. Percent agreement was estimated between injury registration methods. Descriptive statistics [proportions, 95% confidence intervals (95% CI)] summarized injury prevalence (IP; seasonal proportion of dancers injured). Injury incidence rates (IIR; number of new injuries/1000 dance exposure hours) were examined for each definition, registration method, and dance style.

Results Dancer questionnaire response rate was 98.99%. Agreement between injury registration methods ranged between 58.82% (time loss) and 72.94% (medical attention). Depending on definition, registration, and dance style, IP varied from 9.41% (95% CI: 4.15, 17.71; time loss) to 82.35% (95% CI: 72.56, 89.77; all complaint), and IIRs spanned 0.09 (95% CI: 0.01, 0.17; time loss) to 4.89 (95% CI: 4.04, 5.74; all complaint) injuries/1000 dance hours.

Conclusions Injuries resulting in time loss and medical attention underestimate the burden of injury in a pre-professional dance population. To understand the full impact of injury on a dance population, it is imperative that registration methodologies consider definitions that capture all injuries.