Italian Vocal Fatigue Index: Cross-Cultural Adaptation and Validation

Background: Vocal fatigue involves self-perceived vocal symptoms and reduced physiological capacity. This study aimed to adapt and validate the Vocal Fatigue Index (VFI), a tool originally designed to distinguish between patients with vocal fatigue and vocally healthy individuals, for Italian speakers. Method: A four-step translation and validation process was employed. First, four bilingual clinicians specializing in voice disorders translated the English VFI into Italian. An expert committee of six bilingual Italian-English voice disorder specialists then reviewed and refined these translations, leading to a preliminary Italian version. This version was then back-translated into English by one of the authors, ensuring semantic equivalence with the original. Finally, the resulting Italian VFI (VFI-I) was pretested in a study involving 669 participants (386 normal voices and 283 disordered voices) from diverse regions. Results: Nonparametric tests showed significantly higher VFI-I scores for all factors among participants with voice disorders compared with participants with healthy voices. The VFI-I showed good internal consistency and reliability, with Cronbach alpha coefficients ranging from 0.92 to 0.97. Treatment-induced changes were captured, showing a significant decrease in Factor-1 scores post therapy. Convergent validity analysis indicated moderate correlations between VFI-I factors and VHI-I subscales. Multivariate analysis confirmed the association of VFI-I factors with diagnosed voice disorders. Conclusion: This study established the VFI-I as a reliable and valid tool for identifying Italian speakers with vocal fatigue, with good sensitivity to clinical diagnosis, and the ability to track treatment progress highlighting its potential for improving voice care in Italian-speaking populations.