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The Wheelchair Skills Test: a pilot study of a new outcome measure
R Lee Kirby1, Janneke Swuste, Debbie J Dupuis
1Division of Physical Medicine and Rehabilitation, Department of Medicine, Dalhousie University, Halifax, NS, Canada. kirby@is.dal.ca
Objective:
To evaluate the practicality, safety, reliability, validity, and usefulness of a new Wheelchair Skills Test (WST).
Design:
A pilot study with within-subject comparisons.
Setting:
Rehabilitation center.
Patients:
Twenty-four wheelchair users (11 with amputations, 4 with stroke, 3 with musculoskeletal disorders, 3 with spinal cord injury, 3 with neuromuscular disorders).
Intervention:
The WST.
Main Outcome Measures:
Subjects were videotaped while performing 33 skills twice (>10d apart). Their ability to perform each skill was rated on a 3-point ordinal scale. The test-retest, intra-, and interrater reliabilities were determined. Each subject's occupational therapist completed a visual analog scale (VAS), reflecting a global rating of the subject's manual wheelchair skills. We assessed validity by evaluating whether the WST detected expected changes (construct validity) and how well the total WST scores correlated with the occupational therapists' global ratings (concurrent validity). Each occupational therapist also used a VAS to quantify the usefulness of the WST.
Results:
The mean time required to administer the WST was 29 minutes. There were no adverse incidents. For the test-retest, intra-, and interrater reliabilities, the correlations for the total scores were .65 (P =.001), .96 (P <.001), and .95 (P <.001), respectively. The 9 therapists unanimously endorsed 30 (91%) of the 33 WST skills. The correlation between the mean changes in the WST and global rating scores was .45 (P <.05). There was a slight negative relationship between total WST score and age (P <.05). There were no significant differences related to the diagnoses accounting for wheelchair use. Wheelchair users with more than 3 weeks of experience with their wheelchairs scored higher than those with less experience (P =.0085). The correlations between the WST and global rating scores ranged from .40 to .54 (P <.05). Through Rasch analysis, we eliminated 6 skills, with the remaining skills comprising a unidimensional screening test of wheelchair ability. The mean VAS score for perceived usefulness was 59%.
Conclusions:
The WST is practical, safe, well tolerated, exhibits good to excellent reliability, excellent content validity, fair construct and concurrent validity, and moderate usefulness. This pilot study makes an important contribution toward meeting the need for a well-validated outcome measure of manual wheelchair ability.