Translation and French Linguistic Validation of the Bath Ankylosing Spondylitis Functional Index and the Bath Ankylosing Spondylitis Global Score in Patients with Axial Spondyloarthritis

Background: Axial spondyloarthritis (axSpA) may lead to functional and physical disturbances. Self-administered questionnaires can measure functional limitations associated to axSpA. If these questionnaires are currently used in clinical practice and research, the French version of these questionnaires has not been validated. The aim of this study was to translate and perform a linguistic validation of the Bath Ankylosing Spondylitis Functional Index (BASFI) and the Bath Ankylosing Spondylitis Global score (BAS-G) in French. Methods: The study has been approved by local ethic committee and is registered in Clinical Trial (NCT04212806). The translation process was performed through a forward/backward validation process, followed by clinician experts validation and patient cognitive interviews. Results: The two questionnaires were translated into a French version by two independent translators. Translators then agreed on sentences being different between the two translations. The backward translation was equivalent to the initial English version except for two questions. Five French clinician experts on rheumatology made essential changes in sentences constructions of the translated questionnaire. The last version of the questionnaires was presented to 5 patients with axSpA which all found them clear and understandable. Conclusion: BASFI and BAS-G would be a generally reliable instrument for patients with axSpA. These questionnaires can be widely used in clinical practice and research in French-speaking population. The use of these questionnaires is expected to have a positive impact on patient care to better understand physical consequences of axSpA.