Translation, cross-cultural adaptation, and reliability of the Foot Posture Index (FPI-6) – Brazilian version

Background: The Foot Posture Index (FPI) is a quick, easy, and reliable clinical assessment for measuring foot posture variation in different environments. The aim of the study was to translate the FPI into Brazilian Portuguese and assess its inter and intra-observer reliability.
Methods: The cross-cultural adaptation of the 6-item version of the FPI (FPI-6) was accomplished using standard guidelines. Forty-two volunteers participated in the reliability process, assessed by two examiners and at three different occasions, evaluated using the intraclass correlation coefficient (ICC). The agreement between reliability assessments was investigated by the standard error of measurement (SEM) and the minimal detectable change (MDC90).
Results: The Brazilian version of the FPI-6 showed excellent inter and intraobserver reliability for the dominant (ICC = 0.91 and 0.90) and nondominant lower limb (ICC = 0.94 and 0.92). The agreement was considered excellent for SEM with values representing less than 5% in relation to the total FPI-6 score. The MDC90 showed that changes in the score greater than 1.82 (for interobserver) and 1.90 (for intraobserver) can be considered as clinical changes in foot posture.
Conclusion: The Brazilian version of the FPI-6 has proved reliable in terms of inter and intraobserver reliability and can therefore be used both in clinical practice and in scientific research.

背景：足部姿势指数（Foot Posture Index, FPI）是一种快速、简便且可靠的临床评估工具，用于评估不同环境下的足部姿势变异。本研究旨在将FPI翻译为巴西葡萄牙语，并评估其观察者间与观察者内信度。
方法：本研究遵循标准流程完成了FPI的6条目版本（FPI-6）的跨文化调适。共有42名志愿者参与信度检验流程，由2名检查者分别在3个不同时间点进行评估，并采用组内相关系数（intraclass correlation coefficient, ICC）进行分析。通过标准测量误（standard error of measurement, SEM）与最小可检测变化量（minimal detectable change, MDC90）对信度评估的一致性进行考察。
结果：巴西葡萄牙语版FPI-6在优势侧下肢（ICC=0.91、0.90）与非优势侧下肢（ICC=0.94、0.92）均展现出优异的观察者间及观察者内信度。SEM值占FPI-6总得分的比例不足5%，提示其一致性表现优异。MDC90结果显示，当得分变化量超过1.82（观察者间）与1.90（观察者内）时，可认为足部姿势出现了具有临床意义的改变。
结论：巴西葡萄牙语版FPI-6已被证实具备优异的观察者间与观察者内信度，因此可应用于临床实践与科学研究。