Validation of the Japanese Version of the Singing Voice Handicap Index.

PURPOSE: The aim of the present study was to translate the Singing Voice Handicap Index (SVHI) into Japanese and validate the Japanese version of the SVHI. METHODS: The SVHI was translated into Japanese from the validated original version, and the questionnaire was administered to 102 singers with voice problems and 88 healthy singers. Internal consistency and test-retest methods were implemented to evaluate the reliability of this index. The internal consistency method assessed validity via Cronbach's α, and test-retest reliability was analyzed by the intraclass correlation coefficient (ICC) and limits of agreement (LoA) according to the Bland Altman method. Construct validity was verified by confirming correlations between SVHI scores and visual analog scale (VAS) scores for disability in singing using Spearman correlation. Discriminant validity was evaluated by comparing SVHI scores between singers with voice problems and healthy singers using t tests. Using the Tukey's honestly significant difference (HSD) test, we also compared the Voice Handicap Index (VHI) and SVHI scores among three groups: healthy singers, singers with voice problems solely during singing, and singers with voice problems during both speaking and singing. RESULTS: The Japanese version of the SVHI showed excellent internal consistency (Cronbach's α = 0.981) and test-retest reliability (ICC: 0.93). The 95 percent LoA was calculated to be between -20.8 and 33.9. Construct validity was verified through correlated SVHI and VAS scores (r = 0.736, P < 0.001). Discriminant validity was verified as the SVHI scores of singers with voice problems were higher than those of healthy singers (77.8±37.5 vs. 30.0±26.5, P < 0.001). There were no statistically significant differences in VHI scores between singers with voice problems solely during singing and healthy singers; however, the SVHI scores of singers with voice problems solely during singing were significantly higher than those of healthy singers (63.4±36.8 vs. 30.0±26.5, P < 0.001). CONCLUSION: We confirmed that the Japanese version of the SVHI is a valid and reliable self-rated questionnaire for measuring the patient-perceived impact of singing voice problems among Japanese singers.