Factorial Analysis of the Brazilian Version of the Vocal Tract Discomfort Scale in patients with dysphonia

Abstract

Objectives: To investigate the psychometric properties of the Brazilian version of the Vocal Tract Discomfort Scale, known as Escala de Desconforto do Trato Vocal (EDTV), based on factor analysis, in patients with dysphonia.

Methods: This was a retrospective documentary and cross-sectional study. The study database contained sociodemographic variables, laryngeal diagnosis, auditory-perceptual evaluation and EDTV items. All of these variables were extracted from the medical records of 310 patients seen at the Integrated Laboratory of Voice Studies. A descriptive statistical analysis, exploratory factor analysis (EFA), and confirmatory factor analysis (CFA) were performed.

Results: The sample consisted of patients of both sexes with a mean age of 39.36 (SD = 15.80) years; the majority were female and were nonvoice professionals. The EFA grouped the EDTV items into four factors according to the interitem correlations. The CFA grouped the EDTV items into three factors because the last two factors found in the EFA were correlated and constituted a single factor. Thus, the CFA revealed that the EDTV was organized as follows: Factor 1, "Hybrid," comprised the items corresponding to the frequency and severity of the symptoms of burning, sore, and irritated throat; Factor 2, "Inflammatory process/tissue lesion," comprised the items related to throat itching and throat sensitivity; and Factor 3, "Muscle discomfort," comprised the items related to symptoms of tightness, dryness, and the sensation of a lump in the throat. Item responses are dichotomous (High/Low), and the result is determined by the sum of the responses, in which high frequency/severity is assigned two points and reduced frequency/severity assigned one point.

Conclusions: The CFA allows the proposal of an adjustment to the EDTV and suggests that the described changes be made to the instrument to make it a scale with three factors that behave differently but are related.

Keywords: Dysphonia; Factor analysis; Protocols; Self-assessment; Signs and symptoms; Voice.