The reliability, and discriminative ability of the identification of functional ankle instability questionnaire, Japanese version

Objective: To assess the discriminability as well as the reliability, and internal consistency of the Identification of Functional Ankle Instability questionnaire translated into Japanese (IdFAI-J). Design: Cross-sectional study. Setting: Collegiate athletic training/sports medicine clinic. Participants: Twenty bilingual and sixty-five collegiate athletes including participants with and without functional instability (FI). Main outcome measures: The sensitivity, specificity, test retest reliability, and internal consistency of IdFAI-J. Results: The optimal cutoff score between the FI and non-FI participants was >10, with an area under the curve of 0.92. We calculated high sensitivity (0.94) and specificity (0.77) at the cutoff point. For the testretest reliability, the intraclass correlation coefficient value of the IdFAI-J was 0.96; the standard error of measurement and minimal detectable change value was 1.69 and 3.60, respectively. Cronbach's a was 0.87; there was no improvement when a particular item was deleted from the scale. Conclusions: The IdFAI-J has excellent discriminability, test-retest reliability, and internal consistency. Hence, the IdFAI-J significantly contribute to clinical practice and future research related to ankle instability in Japan. (C) 2018 Elsevier Ltd. All rights reserved.