Translation and cultural adaptation of the Persian version of Vestibular Disorders Activities of Daily Living scale (VADL): a validity and reliability study

Background: Vestibular disorders can lead to functional limitations and deficits in performing routine daily life tasks. The Vestibular Disorders Activities of Daily Living scale (VADL) is a useful tool for impact assessment level of functional limitations in patients with vestibular disorders. Objective: Translation, cultural adaptation and evaluation of the reliability and validity of VADL to Persian. Methods: In this analytical-descriptive study, VADL was translated based on the native protocol of the International Quality of Life questionnaire and adapted to the conditions found in Iranian culture. Upon confirmation of face validity, this scale was performed on 90 Persian patients with vestibular disorders (aged between 25 and 85 years). After one week, 53 participants were asked to complete the questionnaire again. Finally, reliability was evaluated with both methods of internal consistency and test-retest reproducibility. Results: Five items out of 28 were modified to adapt the scale to the culture of Iranians, and they were approved by the original designer of the questionnaire. Internal consistency was confirmed by Cronbach's alpha coefficient of 0.94, and repeatability was confirmed by the Interclass Correlation Coefficient of 0.97. Conclusion: The Persian version of VADL was relatively equivalent to the original content and it was in compliance with the terms of Persian culture with high validity and reliability. Therefore, it may be a useful tool for the assessment of functional limitation in some patients with vestibular disorders.