[Validation of the German Version of Tinnitus Functional Index (TFI)]

Tinnitus belongs to seriously debilitating auditory conditions and is often complicated by comorbidities such as insomnia, difficulties with concentration, depression, frustration and irritability. To facilitate the grading of symptoms and the effects of therapeutic strategies, we validated a German-version Tinnitus Functional Index (TFI) in 229 subjects suffering from chronic tinnitus. Outcome validity was assessed using the Tinnitus Questionnaire (TQ, German adaptation by Goebel u. Hiller [1998]). Construct validity was assessed using the "Hamburger Allgemeine Depressionsskala" (HADS). The German TFI featured excellent internal consistency (total score Cronbach's α=0.93). Factor analysis disclosed eight TFI subscales as proposed earlier by Meikle et al. [2012]. Intercorrelations were strong both between the TFI and the TQ (r=0.83), and between the TFI and the HADS (depression r=0.49, anxiety r=0.51). The German-version TFI qualifies as a rapid and statistically robust tool for grading the impact of tinnitus on daily living and for the measurements of therapeutic effects. Regarding depressive symptomatology, sensitivity of the TFI was comparable to that of the TQ.