The Tinnitus Functional Index (TFI) is considered the gold standard in measuring tinnitus severity. The aim of the study was to establish reference values to improve the interpretability of TFI scores.
Results from 1114 patients with tinnitus were retrospectively analyzed. The participants were consecutive patients who attended our tertiary referral Ear, Nose, and Throat Center. The eligibility criteria were: at least 18 years old, persistent tinnitus, completed pure-tone audiometry, and answered all 25 items on the TFI. Hearing status (normal hearing vs. hearing impairment) was established according to the recommendation of the Bureau International d’Audiophonologie. Means (M) and SD on the TFI were the basis for grading tinnitus severity on four levels: low, lower moderate, upper moderate, and high. To gauge individual scores in clinical practice, percentiles are also proposed.
All 1114 patients (586 women and 528 men) were Caucasian and aged from 19 to 87 years (M = 50.96; SD = 13.10 years). Tinnitus duration ranged from 0.5 to 50 years (M = 7.17; SD = 7.71 years). There were 258 patients with normal hearing and 856 patients with hearing loss. A score of above 65 points on TFI was established as the cutoff point for diagnosing high tinnitus severity. A regression model associating tinnitus severity with gender, age, tinnitus duration, and hearing loss was statistically significant: F(4,1109) = 8.99; p < 0.001, but the effect was very small (R2adj = 0.028) and only gender and age were associated with TFI global score, while tinnitus severity was not related to tinnitus duration or hearing loss.
The reference values proposed here support those reported previously by Meikle et al. They are empirically based and can be used as benchmarks in clinical practice and scientific research. They make it possible to assess tinnitus severity, evaluate individual scores, and categorize individuals with tinnitus. This allows researchers to set inclusion or exclusion criteria when assigning patients to specific groups during clinical trials involving tinnitus intervention strategies.