Validation of the Brazilian Scale of Perceived Control Over Voice in the Present using Item Response Theory

this study aims to verify the stages of evidence of validity of the voice-adapted present perceived control scale (V-APPCS) in its translated and cross-culturally adapted version for the Brazilian Portuguese "Voice-Adapted Present Perceived Control Scale" and to estimate the psychometric measurements of the properties of its items based on the item response theory (IRT).

the instrument underwent a process of translation and cross-cultural adaptation for the Brazilian Portuguese, the process was carried out by two qualified translators, native in the destination language, and fluent in the language and culture of origin. The first translated version of the protocol was forwarded to a back-translation, performed by a third bilingual Brazilian translator. The translations were analyzed and compared by a committee composed of five speech therapists who are specialists in voice and with proficiency in the English language. The empirical study used data from 168 individuals, 127 had voice problems and 41 vocally healthy ones. For the stages of validity evidence, the following analyses were performed: Cronbach's alpha, exploratory factor analysis, confirmatory factor analysis and IRT.

The stages of translation and cross-cultural adaptation allowed linguistic adjustments to be made so that the items were understandable and suitable for use in Brazil. The adequacy, structure, and application of the items were confirmed through the application of the final version of the scale in twenty individuals in a real context. The instrument in its Brazilian version presented good internal consistency, with bifactorial structure the exploratory factor analysis, besides presenting satisfactory values in the adjustment indexes of the model, confirming the structure of the confirmatory factor Analysis. The IT was applied to evaluate the parameters discrimination (a) and difficulty (b) of the items of the instrument; item 5 "I have control over my day-to-day reactions to the voice problem." Presented itself as a more discriminative item and item 8 "My reaction to the voice problem is not under my control." As an item of greater difficulty.

The V-APPCS, translated, cross-culturally adapted, and validated, is robust and adequate to represent the construct in the Brazilian versions.