Objective: To translate, culturally adapt, and validate the psychometric characteristics of the Italian version of the Dance Functional Outcome Survey (DFOS-IT) in adult dancers.
Design: Clinical measurement study.
Methods: The DFOS-IT was forward translated, reconciled, backward translated, and reviewed by an expert committee to establish optimal correspondence with the original English DFOS. We examined test-retest reliability in 58 dancers within a 10-day period, using intraclass correlation coefficients (ICC2,1). In a sample of 265 healthy and injured dancers, the following were examined: 1) construct validity, comparing the DFOS-IT to SF-36 using Pearson correlations; 2) exploratory factor analysis and internal consistency; and 3) sensitivity, by generating receiver operating characteristic curves and determining area under the curve (AUC). In a subgroup of 44 dancers, we determined internal responsiveness across three time-points using repeated measures ANOVA (p<0.05). Injured dancers' scores were analyzed for floor and ceiling effects.
Results: The DFOS-IT demonstrated very high test-retest reliability (ICC≥0.98). Single-factor loading in exploratory factor analysis supported unidimensionality of the scale, with high internal consistency (a=0.93). DFOS-IT total, activities of daily living (ADL), and Dance Technique scores had strong construct validity compared with scores on the SF-36 PCS (r≥0.71). There was excellent sensitivity, with high AUC values (AUC≥0.80). There were significant differences across time for DFOS-IT scores (p<0.001), demonstrating responsiveness to change, and no floor or ceiling effects.
Conclusion: The DFOS-IT is a valid, reliable, and responsive tool that can be used as an outcome and screening measure for Italian adult ballet and modern dancers following lower extremity or low back injury.
Trial registration: ClinicalTrials.gov NCT03918876.