Cross-Cultural Adaptation and Validation of the Italian Version of the Voice Symptom Scale (I-VoiSS)

Objectives: To evaluate the reliability and validity of the Italian Voice Symptom Scale (I-VoiSS). Study Design: Cross-sectional, nonrandomized, prospective study with controls. Methods: The study consisted of five phases: item generation, reliability analysis, normative data generation, validity and responsiveness analysis. A group of 113 dysphonic patients was enrolled for the internal consistency analysis. Seventy-three of them completed the I-VoiSS twice, 2 weeks apart, for test-retest reliability analysis. A group of 150 vocally healthy participants completed the I-VoiSS for normative data generation. I-VoiSS scores obtained by dysphonic and vocally healthy participants were compared for validity analysis. I-VoiSS scores were correlated with those of the Italian version of the Voice Handicap Index (I-VHI) in 49 dysphonic patients for criterion validity analysis. I-VoiSS scores obtained in a group of 37 nonsmoker dysphonic patients before and after surgical treatment for vocal fold polyps were compared for responsiveness analysis. Finally, the cutoff value of the I-VoiSS was calculated. Results: All the enrolled participants managed to complete the I-VoiSS autonomously. Internal consistency and test-retest were satisfactory (α = 0.92 and r = 0.91). A significant difference in the I-VoiSS scores between the dysphonic and vocally healthy participants was found (p = 0.001). Positive significant correlations were found between I-VoiSS and I-VHI scores (r = 0.85). I-VoiSS scores obtained in the pretreatment condition were significantly higher than those obtained after surgery (p = 0.001). The cutoff value of I-VoiSS was 15.5. Conclusion: I-VoiSS is reliable, valid, responsive to changes, and recommended for clinical practice and outcome research.