Psychometric Properties of the Wheelchair Skills Test and the Wheelchair Skills Test-Questionnaire: Validity, Reliability, and Responsiveness in Children and Young Adults With Cerebral Palsy—Exploratory Study

To explore the concurrent validity and responsiveness of the Wheelchair Skills Test-Questionnaire (WST-Q) caregiver proxy, and the inter- and intra-rater reliability of the Wheelchair Skills Test (WST) in children and young adults with cerebral palsy (CP). Concurrent validity and responsiveness of the WST-Q caregiver proxy were assessed in 12 participants with CP (mean age 15 years; SD: 3 years 6 months); power wheelchair users. Concurrent validity of the WST-Q was determined using Pearson's correlation coefficients, and responsiveness with linear regression. Inter- and intra-rater reliability of the WST were assessed with intraclass correlation coefficients (ICC) (n = 4). The WST-Q caregiver proxy showed good concurrent validity with WST total scores (r = 0.623, p < 0.001). No acceptable responsiveness was found for the WST-Q caregiver proxy (R2 = 0.317, p = 0.071). Inter-rater reliability for the WST total scores was good (ICC = 0.864, p < 0.001); and intra-rater reliability ranged from good to excellent (Rater 1 ICC = 0.857; Rater 2 ICC = 0.904; Rater 3 ICC = 0.923, all p < 0.001). The WST-Q caregiver proxy appears to be valid for assessing levels of wheelchair skills in children and young adults with CP, however, it lacks suitability to measure intervention effects due to its poor responsiveness. The WST appears reliable for measuring wheelchair skills in young adults with CP.