Cross-cultural Adaptation and Validation of the Italian Version of the Vocal Tract Discomfort Scale (I-VTD)

Abstract

To evaluate the reliability and validity of the Italian version of the VTD scale (I-VTD scale). Cross-sectional, nonrandomized, prospective study with controls. For the item generation, a cross-cultural adaptation and translation process was performed following the back translation process (phase 1). For reproducibility analysis (phase 2), 102 patients with dysphonia were recruited (internal consistency analysis); 57 of them completed the I-VTD scale twice (test-retest reliability analysis). Seventy-three vocally healthy participants completed the I-VTD scale for normative data generation (phase 3). For validity analysis (phase 4), the scores obtained by patients with dysphonia and by vocally healthy participants were compared (construct validity analysis); in addition, 45 patients with dysphonia completed both the I-VTD scale and the Italian version of the Voice Handicap Index for criterion validity analysis. Finally, for responsiveness analysis (phase 5), a cohort of 30 patients with muscle tension dysphonia was recruited, and scores of the I-VTD scale before and after voice therapy were compared. Both the internal consistency and the test-retest reliability of the I-VTD scale were satisfactory. The scores obtained by patients with dysphonia and vocally healthy participants were significantly different. Moderate correlations between the Italian version of the Voice Handicap Index and the I-VTD scores were found. Finally, the scores of the I-VTD scale obtained in pretreatment conditions appeared to be significantly higher than those obtained after successful voice therapy. The I-VTD scale appears a reliable and valid instrument for the assessment of vocal tract discomfort in Italian-speaking patients.