Validation of a new questionnaire to assess the impact of Whiplash Associated Disorders: The Whiplash Activity and participation List (WAL)

Valid questionnaires for measuring functional limitations in patients with Whiplash Associated Disorders (WAD) are lacking, since existing measures are not suitable for addressing the specific limitations of these patients and because of cross contamination between theoretical constructs. The objective of this study was to evaluate dimensionality, test-retest reliability, measurement error, construct validity, and responsiveness of a new condition-specific questionnaire for WAD as well as to estimate the minimally important change score. Patients with WAD grade I or II were recruited from physical therapy practices and rehabilitation centers. Dimensionality was examined by internal consistency analysis (Cronbach's alpha) and factor analysis. Test-retest reliability was estimated by intraclass correlations and measurement error was calculated by the minimal detectable change (MDC) scores. Construct validity was investigated by testing predefined hypotheses on correlations of the WAL scores with generic health measures and by using the known group method. Responsiveness was expressed as the minimal clinically important change (MCIC)