The assessment of work-related functioning is a key process in vocational rehabilitation to identify specific domains of disability that can be considered within return to work strategies. The Work Rehabilitation Questionnaire (WORQ) was developed to evaluate work-related functioning based on the International Classification of Functioning, Disability, and Health (ICF) framework and is available in different languages. The aim of this study was to assess the French version of the WORQ using item response theory to further validate the scale. Rasch analysis of WORQ and the WORQ-BRIEF (a brief version of the WORQ) was performed using a calibration sample of 221 persons with musculoskeletal injuries. A four-testlet solution indicated the unidimensionality of WORQ, with no differential item functioning for age, education, physical job demands, and injury severity. Reliability was 0.969 and 0.918 for WORQ and WORQ-BRIEF, respectively. The minimal detectable change was calculated to be 4.2% of its operational range for WORQ and 8.5% for WORQ-BRIEF. Consequently, the French version of WORQ can be considered a good measure of work-related functioning in musculoskeletal conditions. WORQ can be used in rehabilitation practice to comprehensively identify the disability and guide clinical decision making and intervention planning. Further studies are needed to evaluate the psychometric properties of WORQ in other health conditions.

BACKGROUND: In the last few years the International Classification of Functioning, Disability and Health (ICF) has become a widely known and useful reference classification in vocational rehabilitation. It would be equally important to know which asp