Transcultural adaptation and testing psychometric properties of the Korean version of the Foot and Ankle Outcome Score (FAOS)

This study was performed to translate and transculturally adapt the English version of the Foot and Ankle Outcome Score (FAOS) into a Korean version, and to test psychometric properties of the Korean FAOS in terms of internal consistency, test–retest reliability, convergent validity, and dimensionality. Translation and transcultural adaptation of FAOS into a Korean version was performed according to internationally recommended guidelines. Internal consistency (N = 294) and test–retest reliability (N = 21) were evaluated. Convergent validity was analyzed using correlation with pain visual analogue scale (VAS) score. All subscales, except for the quality of life (Q) subscale (Cronbach’s alpha, 0.615), showed satisfactory internal consistency (Cronbach’s alpha > 0.7). Cronbach’s alpha of function in daily living (ADL) was highest (0.962), which might represent the redundancy of the items. All five subscales showed satisfactory reliability with ADL subscale showing the highest ICC (intraclass correlation coefficient; 0.851) and Q subscale the lowest ICC (0.718). Pain VAS score showed the highest correlation with pain (P) subscale of FAOS (r = 0.675, p < 0.001) and the lowest correlation with Q subscale (r = 0.495, p < 0.001). In the dimensionality test, a factor analysis was performed using the total items to rank their relative significance, which showed seven components solution. Considerable portion of the items showed a similar dimension according to their original subscales, except for ADL items. Translation and transcultural adaptation of FAOS into the Korean language was performed successfully. The items were understandable, and the subscales showed satisfactory test–retest reliability. Some minor revision might be needed to enhance the internal consistency of Q subscale and reduce the redundancy of ADL subscale.