Letter to the Editor, "Reliability of Foot Posture Index individual and total scores for adults and older adults"

Cross-cultural adaptation and reliability of the Foot Posture Index (FPI-6) - French version

PURPOSE

The 6-item Foot Posture Index (FPI-6) is a reliable tool for the evaluation of foot deformities. Our aim was to translate and cross-culturally validate the FPI-6 for use in French-speaking countries and to determine the intra-rater and inter-rater reliability of the French version.

METHODS

Cross-cultural adaptation was performed according to guidelines. Two clinicians assessed the FPI-6 in 52 asymptomatic individuals. We evaluated intra- and inter-rater reliability with the intraclass correlation coefficients (ICC), correlations (p-value < 0.05) and Bland-Altman plots. Standard error of measurement (SEM) and minimum detectable change (MDC95) were determined.

RESULTS

For the cross-cultural adaptation, we modified several items of the FPI-6 user guide and added footnotes to ensure correct interpretation. ICC of the total FPI-6 scores were 0.94 to 0.96 for the intra- and inter-rater reliability for dominant and non-dominant lower limb. Correlations were significant (p < 0.001); r 0.88 to 0.92. Total score SEM was 0.68 to 0.78 and MDC95 was 1.58 to 1.82.

CONCLUSIONS

Intra- and inter-rater reliability of this French version of the FPI-6 was excellent for the total score and good to excellent for each item. The French FPI-6 can be used in French-speaking countries. The identification of SEM and MDC scores is useful for clinical interpretation.

Reliability of Different Clinical Techniques for Assessing Foot Posture

OBJECTIVE

The aim was to determine the interrater and intrarater reliability of navicular drop (NDP), navicular drift (NDT), and the Foot Posture Index-6 (FPI-6), and test-retest reliability of the static arch index (SAI) and dynamic arch index (DAI).

METHODS

Sixty healthy individuals were assessed for intrarater and test-retest reliability. From 60 participants, 30 individuals were assessed for interrater reliability. A digital caliper was used to measure NDP and NDT. Electronic pedography was used to calculate SAI and DAI. The FPI-6 was also performed. All assessments were performed on the dominant foot. The NDP, NDT, SAI, and DAI were repeated 3 times. The NDP and NDT were analyzed separately using both first measurement and the average, but the SAI and DAI were analyzed using only the average. The NDP, NDT, and FPI-6 were conducted by 2 raters to determine interrater reliability and were repeated by a single rater after 5 days from initial assessment to determine intrarater reliability. The SAI and DAI were also repeated after 5 days to determine test-retest reliability.

RESULTS

Intrarater intraclass correlation coefficients (ICCs) were 0.934 and 0.970 for NDP, 0.724 and 0.850 for NDT, and 0.945 for FPI. Interrater ICCs were 0.712 and 0.811 for NDP, 0.592 and 0.797 for NDT, and 0.575 for FPI. Test-retest ICCs of the SAI and DAI were 0.850 and 0.876, respectively.

CONCLUSION

Navicular drop is relatively more reliable than other traditional techniques. Also, the FPI-6 has excellent intrarater reliability, but only moderate interrater reliability. The results can provide clinicians and researchers with a reliable way to implement foot posture assessment.