Development and measurement properties of the Orthotics and Prosthetics Users' Survey (OPUS): a comprehensive set of clinical outcome instruments.

The need to measure and evaluate orthotics and prosthetics (O&P) practice has received growing recognition in the past several years. Reliable and valid self-report instruments are needed that can help facilities evaluate patient outcomes. The objective of this project was to develop a set of self-report instruments that assess functional status, quality of life, and satisfaction with devices and services that can be used in an orthotics and prosthetics clinic. Selecting items from a variety of existing instruments, the authors developed and revised four instruments that differentiate patients with varying levels of lower limb function, quality of life, and satisfaction with devices and services. Evidence of construct validity is provided by hierarchies of item difficulty that are consistent with clinical experience. For example, with the lower limb function instrument, running one block was much more difficult than walking indoors. The instruments demonstrate adequate internal consistency (0.88 for lower limb function, 0.88 for quality of life, 0.74 for service satisfaction, 0.78 for device satisfaction). The next steps in their research programme are to evaluate sensitivity and construct validity. The Orthotics and Prosthetics Users' Survey (OPUS) is a promising self-report instrument which may, with further development, allow orthotic and prosthetic practitioners to evaluate the quality and effectiveness of their services as required by accreditation standards such as those of the American Board for Certification in Orthotics and Prosthetics that mandate quality assessment.