Materials and Methods
This study was a prospective, non-interventional, observational trial in
patients experiencing tinnitus. The study was approved by the ethics
committee of (Name of the hospital blinded for review) Hospital
and all participants gave written informed consent. The study was
performed in accordance with the ethical principles laid down in the
Declaration of Helsinki of 1975, as revised in 2008. We followed the
recommendations of the World Health Organization for the translation and
adaptation of instruments and those of Guillemin et al. for the
cross-cultural adaptation of health-related quality of life measures.[11,12] Moreover, we followed the STROBE statement for
cross-sectional studies. [13]
The Spanish version of the TFI (Sp-TFI) was obtained in the following
way. Stage I: the original TFI was translated by two independent
otolaryngologists - head & neck surgeons who were both bilingual in
English and Spanish. Stage II: The Spanish versions obtained were
combined in a single document and sent to a panel of six experts in
otology at our Otorhinolaryngology Department for comments. It was
agreed that there were only very minor (non-meaningful) differences
between the two translations and a general consensus was reached on a
single version. Stage III: This agreed Spanish version was sent to a
third otorhinolaryngology - head & neck surgeon bilingual in English
and Spanish for back-translation to English and no meaningful
differences were found with respect to the original version. Stage IV:
the translated questionnaire was piloted in a group of patients to test
its comprehensibility, ensuring that the patients understood the items
as intended. Stage V: The panel of experts reviewed the patients’
responses, and as there was a consensus that the patients had understood
the questions well, agreed that the questionnaire piloted could be
definitive version (Supplementary figure).
The TFI was developed to provide a rating of tinnitus severity and the
impact of its severity, and also a responsive measure of change in
severity. It is composed of 25 items divided into eight subscales:
intrusiveness (I), sense of control (SC), cognition (C), sleep (SL),
auditory (A), relaxation (R), quality of life (Q), and emotional
distress (E).[5]
The THI is a 25-item self-reported questionnaire that has been widely
used in tinnitus clinical practice and research to assess distress and
disability associated with tinnitus. In this instrument, the 25 items
are grouped into three subscales: functional (disability affecting daily
life); emotional (anxiety and mental stress); and catastrophic
(hopelessness, loss of control, and inability to cope with the problem).
Three response options are provided for each item: yes, sometimes or no,
awarded scores of 4, 2, and 0, respectively. Consequently, the THI total
score ranges from zero to 100, higher total scores indicating more
severe handicap related to tinnitus. The validity and reliability of the
Spanish version have been confirmed.[14]
Additionally, the loudness and annoyance related to tinnitus can be
evaluated using VAS.[6,15]
To assess the reliability of the Sp-TFI, patients with tinnitus symptoms
who came to an otology consultation, between May 2019 and March 2020,
were asked to complete this new questionnaire, and also the THI and two
VAS. [6,14] Specifically, using the VAS, patients were
asked to rate their self-perceived tinnitus loudness and their annoyance
on an 11-point Likert scale from 0-10. Lastly, they were asked to
indicate which ear was affected by the tinnitus. The same patients were
asked to complete the same questionnaires at 3 weeks and again at 6
months after the first consultation.
At baseline, patients were screened for cognitive impairment through an
interview and by reviewing their medical records. Data on clinical and
demographic characteristics were also obtained from the medical records
of each participant. To explore convergent validity, we assessed
correlations between scores on Sp-TFI, THI and VAS.
We prospectively included all patients who were Spanish native speakers,
older than 18 years old, and had at least a 1-month history of tinnitus.
Exclusion criteria were previous otology surgery on the same side as the
tinnitus and/or a diagnosis of malignancy of the ear, as well as refusal
to participate or insufficient cognitive skills to complete the
questionnaires.
Statistical analysis was conducted using R 4.1.2 statistical language
software (R Core Team (2021). R: A language and environment for
statistical computing. R Foundation for Statistical Computing, Vienna,
Austria. URL
(https://www.R-project.org/)
with standard CRAN libraries. The internal consistency of the Sp-TFI was
assessed with standard Cronbach’s α, considering the THI score the gold
standard, and the temporal stability of the test with the intraclass
correlation coefficient (ICC) type 2,1 in the nomenclature of Shrout and
Fleiss. [16, 17] Specifically, ICC (2,1) was calculated in
R using the psych package version 2.1.9 (Revelle, W. (2021) psych:
Procedures for Personality and Psychological Research, Northwestern
University, Evanston, Illinois, USA.
https://CRAN.R-project.org/package=psych). [18]
A linear model was used to identify statistically significant influences
and interactions between the variables studied, considering THI score
the predicted (dependent) variable. The model equation was developed
using a stepwise backward/forward (independent) variable selection
method based on the Bayesian information criterion.[19]Statistical significance of the interactions detected in the model was
evaluated using analysis of variance (ANOVA) Wald Type II tests.
A p value under 0.05 was considered statistically significant for this
study. For both Cronbach’s α and ICC (2,1), values of 0.8 or above were
considered target values to validate temporal stability (test-retest)
and internal consistency of the Sp-TFI. [20, 21]