Test–retest reliability of the Swedish version of the Orthotics and Prosthetics Users’ Survey

Abstract

The Orthotics and Prosthetics Users' Survey consists of five modules to assess outcomes of orthotic and prosthetic interventions: lower extremity functional status, upper extremity functional status, client satisfaction with device, client satisfaction with services and health-related quality of life. To investigate the test-retest reliability and calculate the smallest detectable difference for all modules of the Swedish Orthotics and Prosthetics Users' Survey. Test-retest reliability study design. A total of 69 patients at a Department of Prosthetics and Orthotics completed Orthotics and Prosthetics Users' Survey on two occasions separated by a 2-week interval, giving 18 answers on lower extremity functional status, 41 on upper extremity functional status, 53 on client satisfaction with device, 12 on client satisfaction with services and 67 answers on health-related quality of life. Raw scores were converted into Orthotics and Prosthetics Users' Survey units on a 0-100 scale. Intra-class correlation coefficients, Bland-Altman plots, common person linking plots and t-tests of person mean measures were used to investigate the reliability. The 95% confidence level smallest detectable differences were calculated. The intra-class correlation coefficients ranged from 0.77 to 0.96 for the modules, and no systematic differences were detected between the response occasions. The smallest detectable differences ranged from 7.4 to 16.6 units. The test-retest reliability was satisfactory for all Orthotics and Prosthetics Users' Survey modules. The smallest detectable difference was large on all modules except the health-related quality of life module. The Orthotics and Prosthetics Users' Survey modules are reliable and, thus, can be recommended for repeated measurements of patients over time. Relatively large changes are needed to achieve statistical significance when assessing individual patients.