Validation of the voice handicap index by assessing equivalence of European translations.

OBJECTIVE We aimed to assess the equivalence of translations of the Voice Handicap Index (VHI). PATIENTS AND METHODS Confirmatory factor analysis was used to assess equivalence of the US version and several translations including (1) Dutch, (2) Flemish Dutch (Belgium), (3) UK English, (4) French, (5) German, (6) Italian, (7) Portuguese and (8) Swedish. VHI questionnaires were gathered from 1,281 subjects. Patients were classified into 11 voice lesion categories. Patients with incomplete response (4%) and patients within voice lesion categories with small numbers were excluded from further analyses, leaving a cohort of 1,052 patients from 8 countries. RESULTS The internal consistency of the VHI proved to be good. Confirmatory factor analysis across countries revealed that a 3-factor fixed measurement model best fitted the data; the 3 subscales appeared to highly intercorrelated, especially in the US data. The underlying structure of the VHI was also equivalent regarding various voice lesions, but distinct groups were recognized with respect to the height of the VHI scores, indicating that various voice lesions lead to a diversity of voice problems in daily life. CONCLUSION The US VHI and the translations appeared to be equivalent, which means that the results from studies from the various included countries can be compared.