Sensitivity, Specificity, and Cutoff Point at Vocal Tract Discomfort Scale in the Assessment of Patients with Muscle Tension Dysphonia

Background and Objective:According to the literature, self-assessment instruments can be used as competent tools to distinguish dysphonic subjects from vocally healthy population. Recently, authors have been interested to study discriminant value of voice self-assessment instruments.One of these self-rating instruments for evaluation of voice disorders is Vocal Tract Discomfort (VTD) scale. The VTD scale,previously has been cross-culturally adapted to polish, Portuguese, Dutch, Persian, German and Italian languages. The purpose of this cross-sectional, nonrandomized and prospective study is to evaluate ability of the Persian version of vocal tract discomfort scale(VTDp)as a diagnostictool in the discrimination of patients with muscle tension dysphonia (MTD) from vocally healthy individuals.Materials and Methods:The clinical data were gathered from a total of 181 participants. The paitent group was 131 patients with MTD (62 male and 69 female), aged between 20 and 60 years. All patients were diagnosed by an otorhinolaryngologist and a speech and language pathologist (SLP) based on the voice history information, voice self-assessment, and videostroboscopic examination. The control group comprised 50 healthy volunteers (26 men and 24 women), aged between 22 and 60 years who were screened with the videostroboscopic examination made by an otorhinolaryngologist, taking voice history made by an SLP as well as voice self-assessment.To measure the sensitivity and specificity of the VTDp scale, both patient and healthy groups completed the scale in a quiet room. The participants asked to complete the questionnaire on 8 symptoms concerning the vocal tract by two separate subscales of frequency and severity. In this way, participants quantified both frequency and severity of their individual throat discomfort in the scale range from 0 to 6.Total scores for the VTDp subscales were analyzed by descriptive statistics in both patient and healthy groups. To measure sensitivity and specificity of the VTDp scale, receiver-operating characteristic (ROC) curve analysis was used.Findings:The ROC curve test determined the cutoff point at VTDp frequency subscale as equal to 7.5, with 0.87 sensitivity and 0.96 specificity. For the severity subscale the best cutoff score appeared to be equal to 7.5, with 0.90 sensitivity and 0.96 specificity. Therefore, VTDp scale indicates the presence of MTD if the score of frequency and severity subscales is above 7.5 and the absence of MTD if the score of frequency and severity subscales is less than or equal to 7.5.Conclusion:The VTDp scale can be used as a discriminativetool to diagnose MTDpatients from healthy subjects in theresearch and clinical practice inPersian-speaking population.

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Words:Vocal tract discomfort , Sensitivity , Specificity , Cutoff point , Muscle tension dysphonia , Persian language