Validation of the Ankylosing Spondylitis Quality of Life questionnaire in Tunisian language

Background: The Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire is a Wide-world used, unidimensional, disease-specific measure of quality of life. Arabic or Tunisian versions of ASQoL or any other quality of life index are not provided. Aim: To adapt the Ankylosing Spondylitis Qhality of life Questionnaire (ASQoL) for use in Tunisian and to test its reliability and validity. Methods: 99 patients who fulfilled the modified New York criteria for ankylosing spondylitis (AS) were included in this study (84 male and 15 female). The translation process included the recent guidelines for cross-cultural adaptation. Reliability of the Tunisian version of the ASQoL was assessed by test-retest method (day 1 and day 10) and internal consistency using Cronbach's alpha coefficient. For construct validity, ASQoL scores were correlated with specific instruments of AS. Results: The mean age of patients was 38.35 years ± 12.26 (18- 73) and the mean disease duration was 11.3 years ± 9.4 (0.6 - 40). The mean time to complete the questionnaire was 5 minutes. Reproducibility was good with no significant difference between ASQoL0 (mean score = 9.8 ± 5.04) and ASQoL10 (mean score = 9.46 ± 5.89) as well as the statically significant positive correlation intra-class coefficient: 0.87 (IC 95%: 0.79-0.92). Internal consistency was good (Cronbach: 0.933; IC95%=0.86-0.95). ASQoL was significantly correlated with BASDAI (p<0.001), BASFI (p<0.001), BASG-s (p<0.001), BASMI (p=0.026), MASES (p=0.024) and all items of SF-36. Conclusion: Validation of the ASQoL for use in Tunisia was successful. The results of the present study indicate that the Tunisian version for ASQoL is reliable and valid.