Lower limb orthoses (LLOs) are often prescribed to facilitate mobility in individuals with functional impairments. The Orthotic Patient-Reported Outcomes - Mobility (OPRO-M) is a self-report instrument developed recently to measure LLO users' perceived mobility with an orthosis. An observational, prospective, psychometric validation study was conducted to evaluate the construct validity and test-retest reliability of the OPRO-M 12- and 20-item short forms. LLO users were recruited from orthotic clinics across the United States. Participants were administered four self-report instruments (OPRO-M, Orthotic and Prosthetic Users Survey - Lower Extremity Functional Status, Lower Extremity Functional Scale, and Patient-Reported Outcomes Measurement Information System - Physical Function) and three performance-based instruments (10-meter Walk Test, Timed Up and Go Test, and Two-Minute Walk Test) during an in-person assessment. Self-report instruments were re-administered via an online survey sent to participants 7 days later. Convergent validity was assessed by comparing OPRO-M scores to those from co-administered self-report and performance-based instruments. Known groups validity was evaluated by comparing scores from patients grouped by clinician-assigned mobility level. Test-retest reliability was assessed by comparing scores from the in-person and follow-up assessments. Standard error of measurement (SEM) and smallest detectable change (SDC) were derived from test-retest reliability coefficients. A total of 104 LLO users (51% male, mean age = 53 years) completed both assessments. OPRO-M short form scores correlated strongly with those from self-report (ρ = 0.84-0.91) and performance-based (|ρ| = 0.73-0.83) instruments. OPRO-M short form scores also effectively differentiated all mobility groups except household and limited community ambulators. The OPRO-M short forms showed excellent test-retest reliability (ICC = 0.93-0.94) and low measurement error (SEM = 2.4-2.6, SDC = 5.5-6.0). These results provide sound evidence of the OPRO-M short forms' validity and reliability when used to measure mobility in LLO users. These instruments are promising, population-specific alternatives to generic surveys with psychometric performance comparable to or better than established self-report instruments.
Copyright: © 2025 Balkman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.