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

Abstract

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.

Implications for Rehabilitation

• The French version of the 6-item Foot Posture Index (FPI-6) can be used in clinical practice in French-speaking countries

• Intra- and inter-rater reliability of total FPI score are excellent

• We provide minimal detectable change value for clinical interpretation (1.58 to 1.82)

Keywords:

• Foot Posture Index
• cross-cultural adaptation
• foot deformities
• reliability
• validation study

Acknowledgements

The authors thank Johanna Robertson for language assistance and constructive criticism, and the University of Leeds for supplying the original FPI-6.

Author contributions

Cédric Blouin: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing - Original Draft, Writing - Review & Editing, Visualization, Supervision, Project administration François Genêt: Conceptualization, Methodology, Validation, Visualization, Supervision, Writing - Original Draft, Writing - Review & Editing, Project administration, Funding acquisition Wilfrid Graff: Methodology, Validation, Writing - Original Draft, Writing - Review & Editing, Visualization, Supervision, Project administration Céline Bonnyaud: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing - Original Draft, Writing - Review & Editing, Supervision, Project administration Antoine Perrier: Conceptualization, Methodology, Validation, Investigation, Writing - Original Draft, Writing - Review & Editing, Supervision, Project administration

Disclosure statement

The authors report there are no competing interests to declare.

Additional information

Funding

This research was supported by the Agence Régionale de Santé Île-de-France and the Institut de Santé Parasport Connecté (ISPC).