Translation and validation of the Turkish version of the Ankylosing Spondylitis Quality of Life (ASQOL) questionnaire

Abstract

The Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire is a disease-specific measure of needs-based quality of life developed in the UK and the Netherlands. This study describes translation, validation, and reliability of the scale into Turkish population. The ASQoL was translated into Turkish using the dual-panel process. Content validity was assessed via cognitive debriefing interviews with ankylosing spondylitis (AS) patients. Patients with AS according to modified New York criteria were recruited into the study from 12 hospitals of all part of Turkey. Psychometric and scaling properties were assessed via a two administration survey involving the ASQoL, the Nottingham Health Profile (NHP), Bath AS Functional Index (BASFI), and Bath AS Disease Activity Index (BASDAI). Classical psychometrics assessed reliability, convergent validity (correlation of ASQoL with NHP, BASFI, and BASDAI) and discriminative validity (correlation of ASQoL with perceived AS-severity and general health). Cognitive debriefing showed the new Turkish ASQoL to be clear, relevant, and comprehensive. Completed survey questionnaires were received from 277 AS patients (80% Male, mean age 42.2/SD 11.6, mean AS duration 9.4 years/SD 9.4). Test-retest reliability was excellent (0.96), indicating low random measurement error for the scale. Correlations of ASQoL with NHP sections were low to moderate (NHP Sleep 0.34; NHP Emotional Reactions 0.83) suggesting the measures assess related but distinct constructs. The measure was able to discriminate between patients based on their perceived disease severity (p < 0.0001) and self-reported general health (p < 0.0001). The Turkish version of ASQoL has good reliability and validity properties. It is practical and useful scale to assess the quality of life in AS patients in Turkish population.