Initial Development of a Patient-Reported Item Bank to Assess Mobility of People Who Use Lower Limb Orthoses

Abstract

Item banks are contemporary health survey instruments used to efficiently measure patient-reported outcomes that may be difficult to observe in a clinical or research setting. Item banks designed specifically for measuring outcomes among people who receive a specific intervention often include survey questions that are relevant to the individual and expected to change as a result of the intervention. Lower limb orthotic interventions are designed to improve users’ mobility in a range of environments and real-world situations. An item bank designed to assess mobility of lower limb orthosis users does not currently exist. Such an instrument could be an effective tool for rehabilitation professionals interested in orthotic mobility outcomes. An orthosis user-specific item bank could also benefit the global community of orthotic patient care professionals, as a means by which mobility outcomes data can be collected, pooled, and/or compared across different regions and cultures. Given the need for an orthosis user-specific item bank, the studies in this dissertation aimed to (1) better understand how orthosis users conceptualize mobility, (2) construct a candidate item bank for orthosis users, and (3) develop and apply a process for translating condition-specific item banks into other languages. This body of work represents the initial development of a new item bank and a model for future language translation efforts. The first chapter is a qualitative study designed to explore how lower limb orthosis users describe their mobility using focus groups and thematic analysis. Insights from participants suggest that orthosis users with a variety of underlying health conditions experience many of the same benefits and challenges associated with using a lower limb orthosis. Also, orthosis users can often choose to modify their mobility in different situations by using or not using their orthosis and/or other mobility aid(s). Gaining an understanding of a measurement construct of interest, in this case, mobility of orthosis users, is the first step toward developing a new PRO instrument. The second chapter describes additional steps taken to identify items applicable to orthosis users’ mobility and evaluate their suitability for inclusion in a candidate item bank. Results of this study further clarify the need for an item bank specific to this population as many of the activities and situations described by orthosis users as being important are not included in existing PRO instruments. The candidate items are now ready for further testing in a future study outside the scope of this dissertation. The third chapter is a language translation and linguistic validation study that describes a model for translating condition-specific item banks. As a result of this study, a Japanese translation of the Prosthetic Limb Users Survey of Mobility (PLUS-M) is now available, and a model is prepared for translating the new item bank to other languages in the future. Collectively, the chapters of this dissertation describe insights gained from orthosis users’ perspectives on mobility, initial development of an item bank to designed for measuring mobility of people who receive orthotic interventions, and a model for translating a condition-specific item bank to other languages. These research findings also lay the groundwork for future research efforts, including calibration and psychometric evaluation of the new item bank, and translation of the instrument into other languages to facilitate international efforts to collect orthotic mobility outcomes data.