The Singing Voice Handicap Index (SVHI): Validation and Adaptation Into Persian.

The aim of the present study is to develop, validate, and assess the reliability of the Persian version of Singing Voice Handicap Index (SVHIp) as a self-reported questionnaire for singers with voice disorders that measure the patient's self-perceived voice handicap. This is a cross-sectional study. During this study, the Persian version of singing voice handicap index was administered to 115 singers (90 male and 25 female, age range: 22-45 years). Voice disorder was confirmed by video-stroboscopic evidences in 48 participants, while 67 were healthy without any voice disorders. To assess the content validity, the prefinal questions were given to 15 experts to comment on its content applicability and relevance through a Likert scale. Seventy five singers rated its importance to detect face validity. To evaluate the concurrent validity, the same 75 participants completed both the SVHIp as well as a visual analog scale. The SVHI total scores of the singers with diagnosed voice disorder and of the healthy singers were compared to test the clinical validity (discriminant validity). Also, internal consistency reliability was assessed using Cronbach α coefficient. The relative reliability was calculated by asking 40 of all singers to complete the SVHIp twice, with a week of interval between the first and the second times. To detect the absolute reliability, Standard Error of Measurement and Smallest Detected Change were calculated. Responsiveness was measured for the Persian version of SVHI by comparing the individual patient scores before and after the treatment. The SVHI was favorably accepted with no deletions. Discriminative validity differed significantly between singers with and without voice disorder. There was a significant correlation between the SVHIp and visual analog scale total scores (P < 0.05). The internal consistency was confirmed (Cronbach α = 0.78). The test-retest reliability was excellent (intraclass correlation coefficient = 0.95). The Standard Error of Measurement and Smallest Detected values were acceptable (0.39 and 1.08), respectively. The Cohens' d effect size indicates the high responsiveness for SVHIp. The Persian SVHI was demonstrated to be a valid and reliable self-rated questionnaire for use in Persian-singers.

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