Transcultural Adaptation and Psychometric Evaluation of the Serbian Ankylosing Spondylitis Quality of Life (Asqol) Questionnaire and Its Correlations With Disease Activity (Asdas, Basdai) and Functional Status Indexes

Abstract

Abstract Background: The Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire gauges the impact of ankylosing spondylitis on individuals' overall well-being, shedding light on the quality of life challenges associated with this condition. The main goal of this study was to translate and adapt a Serbian version of the ASQoL questionnaire and to validate it with Serbian speaking AS patients. Methods: Three stages were accomplished in this study. First, the ASQoL questionnaire was translated using transcultural adaptation and its linguistic intelligibility and naturalness were assessed by a bilingual and a lay panel. Second, cognitive debriefing interviews were implemented to determine face and content validity. Third, psychometric properties of the ASQoL were assessed by construct validity (convergent validity by using NHP as a comparator scale, and known group validity by correlating with disease activity and overall health state), and reliability through the internal consistency and test-retest reliability. Finally, correlations of the ASQoL were evaluated with disease activity and functional status indexes. Results: The bilingual panel consisted of one male and five female Serbian professionals fluent in English, aged 25 to 35 years. The lay panel comprised two males and three females aged 28 to 65 years. Both panels were led by the same moderator. Cognitive debriefing interviews were conducted with 10 patients with a range of demographic backgrounds. The newly adapted questionnaire was evaluated as clear, precise and easy to understand and complete, and all of the questions were found to be valid and appropriate. Psychometric properties were tested on 60 randomly selected patients. Convergent validity was assessed by correlations of ASQoL and NHP domains of the pain (r =0.79), emotional reactions (r=0.78), physical activity (r=0.77) and energy (r=0.75) scales. Internal reliability measured by Cronbach’s alpha coefficient was 0.95 (1st administration) and 0.91 (2nd administration), test-retest reliability was 0.84, showing high correlations of the 1st and 2nd ASQoL administrations. Three independent regression analyses have shown significant relations (p<0.001) between ASQoL and ASDAS (R²=0.40), BASDAI (R²=0.56) and BASFI (R²=0.44). Conclusion: The Serbian ASQoL has demonstrated excellent psychometric properties, indicating that it is a valid and veracious instrument for use both in clinical studies and clinical practice.