Objectives: Ankylosing spondylitis (AS) is a chronic condition with significant impact on quality of life. The objective was to cross-culturally adapt into French and validate the ASQoL, an 18-item disease-specific self-report questionnaire.
Methods: Cross-cultural adaptation according to published guidelines used forward and backward translations, with an emphasis on expert committee informed decision making. A sample of active AS French patients answered the questionnaire twice, two weeks apart. A transition question helped identify those with no or some change over time.
Results: Cross-cultural adaptation resulted in rewording outcome categories from yes/no into true/false to better suit the French context. In 139 patients (mean age 40.9 years, 54.6% males) with active disease (mean BASDAI 4.8), the mean ASQoL score was 10.0. A 2-parameter Rasch model confirmed unidimensionality (chi-square fit p=0.86) with good item discrimination. Internal consistency was high (Cronbach's alpha 0.9). Convergent validity was ascertained by high correlation of ASQoL score with disease activity measures (r=0.57 to 0.79). Test-retest reproducibility was satisfactory (ICC 0.89). Responsiveness was moderate (SRM 0.44) in patients improving and good (SRM 0.68) in patients worsening over the period.
Conclusions: These results show equivalence in content and validity of the cross-culturally adapted ASQoL for French speaking settings.