The chronic ankle instability scale: Clinimetric properties of a multidimensional, patient-assessed instrument

Objective: To construct the chronic ankle instability scale (CAIS) and evaluate its clinimetric properties. Design/setting: Validation study. The test procedure was conducted at the University Hospital of the Vrije Universiteit Brussel, Brussels, Belgium. Participants: Twenty-nine patients with chronic ankle instability (CAI) were selected. Main outcome measures: Content validity, test-retest reliability, internal consistency, floor-ceiling effects, construct validity and the minimal detectable change of the CAIS were investigated. Results: After final item reduction, the CAIS contains 14 items. Weighted kappa coefficients of the items ranged from .50 to .94. The intraclass correlation coefficient for the total score was .84 (p <.05). The standard error of measurement of the total score was 2.7 points; the minimal detectable change 4.7 points. Cronbach alpha coefficients for the subscales ranged from .62 to .80. The "impairments" subscale score of the CAIS did not correlate significantly with talar tilt values (Rho respectively -.05 and -.07; p >.05). The "disabilities" subscale score of the CAIS correlated significantly with both the timed test performance (Rho respectively -.38 and -.40; p <.05) and the perceived difficulty of the multiple hop test (Rho respectively -.41 and -.49; p <.05). Conclusion: The CATS is a valid and reliable instrument for quantifying the multidimensional profile of patients with CAI. Future research should investigate the responsiveness of the CAIS and determine its minimally clinical important difference. (c) 2008 Elsevier Ltd. All rights reserved.