The development and validation of the vestibular activities and participation measure.

ABSTRACT

OBJECTIVES: To develop and validate a new self-report outcome measure named the Vestibular Activities and Participation (VAP) for people with vestibular disorders to examine their activities and participation according to the International Classification of Functioning Disability and Health. DESIGN: Delphi iterative survey for the development of the VAP and validation study. SETTING: Tertiary balance clinic. PARTICIPANTS: A panel of worldwide experts (n=17) in vestibular dysfunction participated in the development of the VAP, and patients (N=58) with vestibular disorders were enrolled in the validation of the VAP. INTERVENTION Not applicable. MAIN OUTCOME MEASURES: For the development of the VAP, an Internet-based survey of 55 activities and participation items was presented to the panel of experts and the percentage agreement per item was calculated. For the validation of the VAP, the VAP was completed twice to examine the test-retest reliability, the World Health Organization Disability Assessment Schedule II (WHODAS II) was used to examine the concurrent validity with the VAP, and the Dizziness Handicap Inventory (DHI) was used to examine the convergent validity of the VAP. RESULTS: After 2 rounds of the Delphi technique, the VAP was developed. The VAP total score had excellent test-retest reliability (intraclass correlation coefficient=.95; confidence interval=.91-.97) and good to excellent agreement per item indicated by the unweighted kappa (.41-.80) and the weighted kappa (.58-.94). The minimum detectable change at 95% confidence level of the VAP score was .58. The VAP had strong correlation (ρ=.70; P<.05) with the WHODAS II and moderate to strong correlations (ρ=.54-.74) with the DHI subscale and total scores. After adjustment for age, we found sex and self-reported imbalance to be independent explanatory variables of the transformed VAP total score. CONCLUSIONS: The VAP measure was developed to examine the disabling effect of vestibular disorders on people's activities and participation based on a standardized framework (the International Classification of Functioning Disability and Health). The VAP demonstrated excellent reliability and was validated with external instruments in people with vestibular disorders.