Adaptation and validation of the Singing Voice Handicap Index into Polish

Objective: To translate and adapt the original Singing Voice Handicap Index (SVHI) for the Polish population and to evaluate the psychometric properties of the Polish SVHI version, such as internal consistency, reliability and construct validity in different groups of dysphonic singers. Study design: Prospective case-control study. Setting: Patients treated at a single institute. Participants: Sixty singers with voice disorders and 57 healthy singers completed the SVHI and the Voice Handicap Index (VHI). Thirty singers completed the SVHI twice within a 2-to 4-week interval. Main outcome measures: Internal consistency, test-retest reliability, discriminant validity, criterion-related validity Results: A strong Cronbach's alpha coefficient (0.96) indicates that the SVHI items are measuring the same construct. Evaluating the test-retest reliability, the r-Spearman correlation coefficient was r = 0.797 for the total score of SVHI, which shows a good level of reproducibility. There were significant differences between the control group (CG) and patients with benign vocal fold lesions (P < 0.001), CG and singers with muscle tension dysphonia (P < 0.001), CG and coexistence of muscle tension dysphonia and chronic laryngitis (P < 0.001). There was a positive statistically significant correlation between SVHI and VHI (r = 0.753, P = 0.000*). Conclusions: The Polish version of SVHI serves as a valid health status instrument, as well as discriminating between singers with voice disorders and singers without voice problems. The SVHI is easy to perform in clinical practice.