Measurement properties of patient-specific instruments measuring physical function.

OBJECTIVE To identify patient-specific self-assessment instruments, which measure physical function in patients with musculoskeletal disorders and to evaluate the descriptive properties and the psychometric qualities of these instruments. STUDY DESIGN AND SETTING After a systematic search, included instruments were evaluated psychometrically by the checklist "quality criteria for measurement properties of health status instruments." RESULTS Twenty-three studies were included, referring to 12 instruments. Nine different versions of the Patient-Specific Functional Scale (PSFS) were identified. The practical elaboration of the different versions of the PSFS varied widely. None of the instruments were tested on all psychometric quality criteria of the checklist. The PSFS described by Cleland et al. was most extensively investigated and obtained exclusively positive scores. Overall, construct validity, reliability, and responsiveness were evaluated most frequently. CONCLUSION The descriptive properties and psychometric quality of patient-specific instruments measuring physical function are only partly investigated. The PSFS was the most investigated instrument: nine different versions have been evaluated psychometrically. The version of Cleland et al. was most extensively investigated, obtained exclusively positive scores following the quality criteria by Terwee et al., and could be recommended for clinical use therefore. Future research will be necessary to confirm the psychometric quality of patient-specific instruments measuring physical function in patients with musculoskeletal disorders.