Linguistic and Cultural Adaptation and Validation of the Vocal Fatigue Index into Polish

• Published in: Journal of voice 2022-10
• Main Authors: Morawska, Joanna, Niebudek-Bogusz, Ewa, Pietruszewska, Wioletta
• Format: Article
• Language: English
• ISSN: 0892-1997; 1873-4588
• DOI: 10.1016/j.jvoice.2022.09.012

The purpose of the present study was the cross-cultural and linguistic adaptation and validation of the Vocal Fatigue Index (VFI) in the Polish language. The Vocal Fatigue Index was adapted into Polish and was administered to 323 subjects (216 with voice disorders, and 107 without voice disorders). One hundred and four participants with voice disorders completed the VFI a second time to evaluate test-retest reliability. VFI was assessed for internal consistency, test-retest reliability, discriminant validity, criterion validity, and sensitivity and specificity. The Polish VFI exhibited satisfactory psychometric properties. A high Cronbach's alpha coefficient for the three factors (α=0.971 for Factor 1, α=0.929 for Factor 2, α=0.930 for Factor 3) was obtained. Significantly higher scores were revealed in subjects with voice disorders (48.88±11.73 [mean±SD]) in comparison with vocally healthy subjects (12.25±6.75 [mean±SD]) in the total VFI score as well as in the three factors (all P-values < 0.01). The best cut-off for VFI Total Score was set at a 32.5 score with sensitivity of 0.931 and specificity of 0.991. The translated version of the VFI is a valid and reliable tool for identifying vocal fatigue symptoms in the Polish-speaking population.