Measuring outcome from vestibular rehabilitation, part II: refinement and validation of a new self-report measure.

A prototype self-report measure of vestibular rehabilitation outcome is described in a previous paper. The objectives of the present work were to identify the most useful items and assess their psychometric properties. Stage 1: One hundred fifty-five participants completed a prototype 36-item Vestibular Rehabilitation Benefit Questionnaire (VRBQ). Statistical analysis demonstrated its subscale structure and identified redundant items. Stage 2: One hundred twenty-four participants completed a refined 22-item VRBQ and three established questionnaires (Dizziness Handicap Inventory, DHI; Vertigo Symptom Scale short form, VSS-sf; Medical Outcomes Study short form 36, SF-36) in a longitudinal study. Statistical analysis revealed four internally consistent subscales of the VRBQ: Dizziness, Anxiety, Motion-Provoked Dizziness, and Quality of Life. Correlations with the DHI, VSS-sf, and SF-36 support the validity of the VRBQ, and effect size estimates suggest that the VRBQ is more responsive than comparable questionnaires. Twenty participants completed the VRBQ twice in a 24-hour period, indicating excellent test-retest reliability. The VRBQ appears to be a concise and psychometrically robust questionnaire that addresses the main aspects of dizziness impact.