Translation, cross-cultural adaptation and validation of the French version of the Knee Outcome Survey-Activities of Daily Living Scale

Abstract

Purpose: The Activities of Daily Living Scale of the Knee Outcome Survey (KOS-ADLS) is a joint-specific questionnaire measuring functional limitation experienced by individuals with knee disorders. The original English version of the KOS-ADLS has been shown to be highly reliable and responsive to change. The purpose of this study was to perform a translation and cross-cultural adaptation of the original version of the KOS-ADLS questionnaire into French and to validate this French version of the questionnaire.

Method: In accordance with standard procedure, the original version of the KOS-ADLS was translated and cross-culturally adapted into French. Once the final French version of the KOS-ADLS was developed, it was subjected to further psychometric evaluation with 76 individuals with knee disorders. Each participant completed the KOS-ADLS on three occasions: at baseline, two days later to evaluate test-retest reliability, and four weeks later to evaluate responsiveness. Symptoms and function-oriented construct questions were also completed to evaluate construct-convergent and known-group validity.

Results: The cross-cultural adaptation procedure revealed no major problems with content or language. The French version of the KOS-ADLS showed excellent test-retest reliability with low measurement error (intraclass correlation coefficient = 0.92, minimal detectable change = 8.3), as well as high responsiveness (standardized response mean = 1.41; clinically important difference = 13.6). Further, it discriminates between different levels of self-rated or clinician-rated knee function.

Conclusions: The French version of the KOS-ADLS is a reliable, valid and responsive questionnaire for the assessment of functional limitation in individuals with musculoskeletal knee disorders.

Keywords: Knee; outcome assessment; questionnaires; reliability and validity; responsiveness to change.