Validation and translation of the Dutch tinnitus functional index

Several questionnaires are used to survey how tinnitus affects quality of life, making comparisons across studies difficult. The questionnaires also are used to measure treatment outcome but were not designed for this purpose. To address these issues, a new questionnaire has been suggested, the tinnitus functional index (TFI), which is highly responsive to treatment-related change. The current study aim was to translate and validate the TFI for a Dutch-speaking population. Factor analysis was performed to characterize the TFI profile in a large tinnitus population.

The questionnaire was translated using a translation-back translation procedure, and 263 patients in the ENT department of Antwerp University Hospital with tinnitus-related complaints completed it. Factor structure was assessed using exploratory analysis with oblique rotation and compared with the original questionnaire. Internal consistency was measured using Cronbach's alpha coefficient. Spearman correlations with the percentage of time aware of the tinnitus and the visual analogue scales (VAS) for maximum tinnitus loudness and mean tinnitus loudness were calculated to investigate convergent validity.

The original eight-factor structure could be confirmed in the Dutch version of the TFI. Internal consistency (a=0.96) and convergent validity showed good results. Statistically significant correlations were found with the VAS for maximum loudness (r=0.59; p<0.001), VAS for mean loudness (r=0.66; p<0.001), and percentage of time aware of tinnitus (r=0.58; p<0.001).

The Dutch version of the TFI is suitable for measuring in clinical and research settings how tinnitus affects daily life, with psychometric properties in line with the original version.