Cross-Cultural Adaptation and Validation of the Voice Handicap Index into Thai.

BACKGROUND: The voice handicap index (VHI) is one of the most utilized instruments for measuring a patient's self-assessment of voice severity. The VHI has been translated into several languages, but not in Thai.

OBJECTIVE: To examine the psychometric properties of a Thai translation of the voice Handicap Index (VHI) and assess the applicability in the screening diagnosis.

MATERIAL AND METHOD: After receiving permission from the American Speech Language Hearing Association (ASHA), the original VHI had been translated and adapted to Thai by forward and backward standard translation. Eighty-five patients with voice disorders, divided in four groups according to the etiology of the diseases (neurogenic, structural, functional, and inflammatory), and 30 asymptomatic subjects were included in the present study. Internal consistency was analyzed through Cronbach's a coefficient. For the VHI test-retest reliability analysis, the Thai VHI was completed twice by 22 patients and assessed through the intraclass correlation coefficient. For clinical validity evaluation, the VHI scores from the pathological group were compared with the control group and compared among the four different pathological groups. The cutoff point for distinguishing the normal from the patient group was assessed by ROC analysis. Effects of age and gender on VHI scores were also evaluated.

RESULTS: The Thai VHI showed a significant high internal consistency and test-retest reliability (Cronbach's α = 0.96 and r = 0.843, respectively). Mann-Whitney U test was used to compare the control group and pathological groups and revealed significant difference in total scores and its three domains scores (p < 0.001). ROC analysis demonstrated that a VHI score of 13 should be considered the threshold for revealing the impact of quality of life in voice disorder patients. Age and gender were not affect the VHI scores in both control and patient groups.

CONCLUSION: The Thai VHI has high reliability and validity. The Thai version of VHI is considered to be a self-assessment tool for the severity of voice disorders in Thai patients.