Test-retest reliability and agreement of the work ability index - single item in persons with physical disabilities

OBJECTIVE: To assess the test-retest reliability and agreement of the WAS in persons with a physical disability.

DESIGN: Test-retest study, with a 2-4 week interval. Test-retest reliability was computed using the intraclass correlation coefficient (ICC). The agreement was analyzed using Bland-Altman plots.

SETTING: Vocational rehabilitation department of a rehabilitation center.

PARTICIPANTS: Patients with a physical disability (spinal cord injury, acquired brain injury, neuromuscular disease, or other).

INTERVENTION: Not applicable MAIN OUTCOME MEASURE: The WAS consists of one question on self-reported current work ability compared to their highest work ability ever, rated on a 0-10 scale.

RESULTS: Data from 44 patients were available and 22 patients reported no changes in work or medical situation between the two measurements. After excluding one outlier in this subgroup (n=21), the ICC was 0.89 (95% CI 0.76 to 0.96), the mean test-retest difference was -0.05 points and the LoA were ± 2.4 points.

CONCLUSION: The WAS is reliable for measuring work ability in persons with a physical disability. Using the WAS could be valuable as a routine outcome measure in vocational rehabilitation for persons with a physical disability.