The Cumberland ankle instability tool: a report of validity and reliability testing.
OBJECTIVE
To test the Cumberland Ankle Instability Tool (CAIT), a 9-item 30-point scale, for measuring severity of functional ankle instability.


METHODS
Cross-sectional study.


METHODS
General community.


METHODS
Volunteer sample of 236 subjects.


METHODS
Not applicable.


METHODS
Concurrent validity by comparison with the Lower Extremity Functional Scale (LEFS) and a visual analog scale (VAS) of global perception of ankle instability by using the Spearman rho. Construct validity and internal reliability with Rasch analysis using goodness-of-fit statistics for items and subjects, separation of subjects, correlation of items to the total scale, and a Cronbach alpha equivalent. Discrimination score for functional ankle instability by maximizing the Youden index and tested for sensitivity and specificity. Test-retest reliability by intraclass correlation coefficient, model 2,1 (ICC(2,1)).


RESULTS
There were significant correlations between the CAIT and LEFS (rho=.50, P<.01) and VAS (rho=.76, P<.01). Construct validity and internal reliability were acceptable (alpha=.83; point measure correlation for all items, >0.5; item reliability index, .99). The threshold CAIT score was 27.5 (Youden index, 68.1); sensitivity was 82.9% and specificity was 74.7%. Test-retest reliability was excellent (ICC(2,1)=.96).


CONCLUSIONS
CAIT is a simple, valid, and reliable tool to measure severity of functional ankle instability.
Hiller
Claire E
CE
School of Physiotherapy, University of Sydney, Lidcombe, Australia.
Refshauge
Kathryn M
KM
Bundy
Anita C
AC
Herbert
Rob D
RD
Kilbreath
Sharon L
SL
D000328:Adult; D016512:Ankle Injuries / Q000145:classification*; D003430:Cross-Sectional Studies; D006801:Humans; D015601:Injury Severity Score; D007593:Joint Instability / Q000145:classification*; D012372:ROC Curve; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires