Development and psychometric validation of a vestibular symptom severity scale

To develop the Self-Perception of Vestibular Symptom Severity Scale (EGV) and to evaluate the validity and reliability of the interpretations derived from its scores.

This methodological validation study included 100 adults with vestibular symptoms. Instrument development involved an exploratory literature review, item construction through a Delphi panel, and content validation by expert judges. Structural validity was examined separately for the frequency and intensity subscales using exploratory and confirmatory factor analyses. Internal consistency was assessed using Cronbach's alpha. Test-retest reliability (7- and 14-day intervals) was analyzed using the Intraclass Correlation Coefficient (ICC). Measurement error was estimated through the standard error of measurement and smallest detectable change. Construct validity was evaluated through hypothesis testing by examining associations between EGV scores and validated instruments measuring functional impact, physical activity, autonomy, and attentional awareness.

All items demonstrated satisfactory content validity (coefficients ≥0.80). Exploratory factor analysis supported a unidimensional structure in both subscales (KMO > 0.94; Bartlett's test p < 0.001), with factor loadings ranging from 0.84 to 0.95. Confirmatory factor analysis indicated adequate model fit. Internal consistency was excellent (α > 0.90). Test-retest reliability showed high stability at 14-days (ICC ≥ 0.80). Higher EGV scores were significantly associated with greater functional limitation, lower physical activity levels, increased dependence, and reduced attentional awareness.

The EGV demonstrated evidence supporting structural validity, reliability, and construct validity, supporting its clinical applicability for measuring vestibular symptom severity. The scale provides a standardized framework for monitoring symptom progression in clinical practice and research.