Results
A total of 18 participants were included, with a mean age of 45.77 (SD: 11.87) years; 12 were female (66.67 %) and 6 were male (33.33%). Half of the participants experienced tinnitus in their left ear and half in their right. The mean pure-tone average (PTA), considering values measured at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz, was 29.34 (SD: 8.08) dB-HL in the affected ear. The main scores obtained on each questionnaire (THI and Sp-TFI) are plotted in Figure 1.
Assessing the internal consistency of the Sp-TFI, we obtained a standard Cronbach’s α for the overall score of 0.83 (taking the THI score as the gold standard). Table 1 details the other standard Cronbach’s α values calculated in this study, namely, those for the Sp-TFI subscales and VAS. Analyzing the temporal stability of the Sp-TFI, we found an ICC(2,1) for the overall score of 1 (CI: 0.99 – 1). ICC(2,1) values for THI, Sp-TFI subscales and VAS scores also calculated are detailed in Table 2. Bland and Altman plots (graphical concordance analysis) are shown in Figure 2 for paired test-retest scores of the Sp-TFI and THI. A positive correlation was found between the THI and Sp-TFI, r= 0.71 (CI: 0.36 - 0.88, p < 0.01).
Among the demographic and audiological characteristics and test scores studied, the stepwise backward/forward variable selection method with a Bayesian information criterion step value of 38.59 indicated that the variables that should be included in the linear model were: age, sex, laterality, history of contralateral ear surgery, PTA, VAS R subscale score, overall Sp-TFI score and SL, R, I, C, and A subscale scores. Exploring the predictive value of variables included in the linear model, the ANOVA Wald test showed a statistically significant predictive effect of the following variables on THI score: sex (p < 0.01), PTA (p = 0.03), overall Sp-TFI score (p = 0.02), and Sp-TFI SL, R, and A subscale scores (p = 0.03, p = 0.03 and p < 0.01, respectively). Figure 3 is an effect plot of the variables found to be statistically significant predictors of THI score with the ANOVA Wald test.