Measurement properties of the Wheelchair Skills Test - Questionnaire for powered wheelchair users

Purpose: To evaluate the test-retest reliability, concurrent validity and responsiveness of the Wheelchair Skills Test - Questionnaire (WST-Q) Version 4.1 for powered wheelchair users. Methods: A volunteer sample of 72 community-dwelling, experienced powered wheelchair users, ranging in age from 50 to 77 years, participated in this study. Participants completed measures at baseline and 1 month later. Results: Mean +/- standard deviation total percentage WST-Q scores at baseline and 1 month were 83.7% +/- 10.9 and 86.3% +/- 10.0 respectively. Cronbach's alpha was 0.90 and the 1 month test-retest intraclass correlation coefficient (ICC1,1) was 0.78 (confidence interval: 0.68-0.86). There were no floor or ceiling effects. Percentages of agreement between baseline and 1 month for individual skills ranged from 72.2% to 100%. The correlations between the WST-Q and the objective Wheelchair Skills Test (WST), WheelCon and Life Space Assessment were r = 0.65, r = 0.47 and r = 0.47 respectively. The standard error of measurement (SEM) and smallest real difference (SRD) were 5.0 and 6.2 respectively. Conclusion: The WST-Q 4.1 has high internal consistency, strong test-retest reliability and strong support for concurrent validity and responsiveness.