Validation of the orthotics and prosthetics user survey upper extremity functional status module in people with unilateral upper limb amputation

Objective: To evaluate the measurement properties of the Upper Extremity Functional Status module of the Orthotics and Prosthetics User Survey (OPUS). Design: Methodological research on an outcome measure administered by clinical interview. Patients: A convenience sample of 61 adults who had unilateral upper limb amputations and completed rehabilitation at the Institute for Rehabilitation in Ljubljana, Slovenia, at least one year prior to interview. Thirty-four patients had undergone amputation of the dominant hand. Four patients did not use a prosthesis. Methods: Rating scale analysis (Rasch model) was used to evaluate functioning of the rating scale categories, the validity of the measure by examining fit of items to the latent trait, and the hierarchy of item difficulties compared with expectations of the construct. Results: Rasch analysis allowed us to improve the Upper Extremity Functional Status by rescoring to reduce the response categories from 5 to 4, and identifying 19 of 23 items that are useful to measure upper extremity function. The results allow us to have high confidence in the consistency of both person-ability and item-difficulty estimates. Conclusion: This revised Upper Extremity Functional Status is a promising instrument to measure the degree of manual functioning after a unilateral upper limb amputation.