A new measure for assessing the health-related quality of life of patients with vertigo, dizziness or imbalance: the VDI questionnaire.

Vertigo, dizziness and imbalance are frequent symptoms among patients in clinical practice. We present the development of a new multipurpose measure specific to patients with these symptoms: the VDI questionnaire. Items of the VDI questionnaire were generated through an international panel of clinicians, in-depth interviews with 25 patients and an extensive literature search. Items were reduced by qualitative and quantitative methods. Psychometric properties were tested in 130 patients recruited in primary care general practices, neurologists and ENT out-patient clinics. Patients were clinically evaluated and administered several specific and generic health status instruments: the Balance Scale, the SF-12 Health Survey and the General Health Questionnaire 12 items. The VDI symptoms and the VDI health related quality of life (HRQoL) scales were administered during the visit and some weeks after. Correlation and confirmatory factor analysis were used. Reliability of the VDI was high (0.92 for VDI HRQoL scale and 0.86 for VDI symptoms). VDI scores were more correlated with Balance Scale scores than with mental health indicators. All factor loadings were significantly different from zero and confirmed the expected relations. In the second administration, VDI scores showed a deterioration among those reporting a worsening in their symptoms and an improvement among those reporting feeling better. The data presented suggest that the VDI questionnaire is a reliable, valid and responsive instrument for patients with vertigo, dizziness or imbalance. The VDI questionnaire could be a useful complement of the clinical evaluation of these patients at both group and individual level.