AUTHOR=Armstrong Deborah , Alderson Alison J. , Davey Christopher J. , Elliott David B. 

TITLE=Development and Validation of the Vision-Related Dizziness Questionnaire

JOURNAL=Frontiers in Neurology

VOLUME=Volume 9 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2018.00379

DOI=10.3389/fneur.2018.00379

ISSN=1664-2295

ABSTRACT=Purpose: To develop and validate the first patient-reported outcome measure (PROM) to quantify vision-related dizziness. Dizziness is a common, multifactorial syndrome that causes reductions in quality of life and is a major risk factor for falls, but the role of vision is not well understood.
Methods: Potential domains and items were identified by literature review and discussions with experts and patients to form a pilot PROM, which was completed by 335 patients with dizziness. Rasch analysis was used to determine the items with good psychometric properties to include in a final PROM, to check undimensionality, differential item functioning and to convert ordinal questionnaire data into continuous interval data.  Validation of the final 25-item instrument was determined by its convergent validity, patient and item separation reliability and unidimensionality using data from 223 patients plus test-retest repeatability from 79 patients.
Results: 120 items were originally identified, then subsequently reduced to 46 to form a pilot PROM. Rasch analysis was used to reduce the number of items to 25 to produce the Vision-Related Dizziness or VRD-25. Two subscales of VRD-12-frequency and VRD-13-severity were shown to be unidimensional, with good psychometric properties. Convergent validity was shown by moderately good correlations with the Dizziness Handicap Inventory (r=0.75) and good test-retest repeatability with intra-class correlation coefficients of 0.88.
Conclusions: VRD-25 is the only PROM developed to date to assess vision-related dizziness.  It has been developed using Rasch analysis and provides a PROM for this under-researched area and for clinical trials of interventions to reduce vision-related dizziness.