Wheelchair casters fail frequently in the field causing multiple user consequences and wheelchair breakdowns. To inform caster design improvement, there exists no validated tools that can collect caster failures. This need motivated the development of a user-reported, caster failure inspection tool (C-FIT).
To develop C-FIT, a multistep design and testing approach was used which included face validity testing, test-retest reliability testing and expert review. Reliability testing was conducted with two independent cohorts of wheelchair professionals who inspected caster failures physically and online through pictures. The tool was revised based on testing outcomes and expert feedback. For preliminary data collection and evaluating usability, C-FIT was piloted at wheelchair service centers in Scotland, Indonesia and Mexico.
Caster failure items reported in the literature were screened to develop the initial list of C-FIT items. Face validity testing conducted through surveys with wheelchair experts (n = 6) provided 14 items for C-FIT inclusion. The test-retest reliability was found to be high for 10 items with physical failure inspections (n = 12). For each of these items, 75% or more participants had substantial to almost perfect agreement scores (κ = 0.6–1.0). Lower reliability scores were found with online failure inspections (n = 11). C-FIT received positive usability feedback from study participants and data collectors in the field. Pilot field data (n = 31) included comprehensive details about failures useful for manufacturers, designers and researchers to improve caster designs.
The C-FIT tool developed in this study has substantial reliability and can be used for documenting caster failures at wheelchair service centers.