Development of a candidate item bank for measuring mobility of lower limb orthosis users

Orthoses are often prescribed to improve mobility of people with chronic health conditions that affect lower limb function. Patient-reported survey instruments can be used to measure aspects of mobility that cannot be easily assessed in clinical or research settings. A population-specific item bank could be designed to measure aspects of mobility that are most important to lower limb orthosis users and used to evaluate the effects of orthoses.

To develop items for a new survey instrument to measure mobility of lower limb orthosis users.

Survey items were developed using a qualitative item review process.

Focus groups were held by video conferencing. Cognitive interviews were conducted by telephone.

Focus group and cognitive interview participants were adults with at least 6 months of experience using a lower limb orthosis that extended from the foot to a level above the ankle.

Research methods included focus groups with lower limb orthosis users, an item generation and reduction process that involved a stakeholder advisory panel, and cognitive interviews with target respondents.

A total of 1180 extant items were identified in a literature review. Focus group participants (n = 29) provided feedback that informed the suitability of a construct definition and conceptual model. An advisory panel contributed to the selection of 118 candidate items for measuring orthotic mobility. Feedback from cognitive interview participants (n = 30) informed removal or revision of problematic items, resulting in a candidate bank of 100 mobility items.

The rigorous qualitative methods applied here resulted in a large set of candidate items that spanned a range of situations relevant to moving with a lower limb orthosis. Next steps include administration of the candidate items to a large sample of lower limb orthosis users and calibration of the item bank.