[Translation, Cultural Adaptation and Validation of the Tinnitus Functional Index to European Portuguese]

Tinnitus is defined as the conscious perception of an auditory sensation in the absence of any corresponding external stimulus. It is associated with significant negative consequences across multiple domains of an individual's life, namely physical, psychological, cognitive, auditory, social, and financial. Several questionnaires can be used to measure its impact on quality of life, however, these instruments are not sensitive in quantifying possible treatment-related changes. Therefore, the Tinnitus Functional Index (TFI) was developed, allowing the evaluation not only of tinnitus severity, but also of changes triggered by a clinical intervention. The aim of this study was the translation, validation and cultural adaptation of the TFI into European Portuguese for later use in intervention studies.

This cross-sectional study was carried out in a Portuguese tertiary hospital center and conducted in two stages: translation and cultural adaptation; analysis of internal consistency and validation. A total of 30 participants were included. The internal consistency of the questionnaire was assessed using Cronbach's alpha coefficient. Convergent validity was assessed using the Spearman correlation coefficient between the TFI and the Tinnitus Handicap Inventory (THI).

The European Portuguese version was obtained through a process of initial translation, synthesis of translations, back-translation and review by a panel of professionals. The 30 participants were aged between 26 and 80 years (57 ± 11.5 years), and 19 were female. The European Portuguese version of the TFI showed a strong correlation (rho = 0.823, p < 0.001) with the THI. Internal consistency was high, with a Cronbach's alpha of 0.96.

The validation of the TFI scale for European Portuguese showed strong internal consistency, correlation with the THI scale, and similarity to the positive results obtained in other studies and the original scale. Therefore, this translation is considered an instrument supported by evidence of adequacy and validity, useful for assessing tinnitus severity and for monitoring the effect of clinical interventions.