Internet-based Cognitive Behavioural Therapy for Spanish Tinnitus Sufferers: A Global Pilot Trial
Phase: NA
Conditions: Tinnitus
Sponsor: Lamar University

 
 
 
 
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Study Protocol and Statistical Analysis Plan 
 
 
Study Title: Internet-based Cognitive Behavioral Therapy for tinnitus in Spanish: A global 
feasibility trial 
 
 
Clinical trial registration: NCT04335929 on April 06, 2020.  
 
Funding: This study was partly funded by the National Institute on Deafness and 
Communication Disorders (NIDCD) of the National Institute of Health (NIH) under the award 
number R21DC017214. 
 
Ethical approval: Institutional Review Board at Lamar University, Beaumont, Texas, US (IRB-
FY20-200). 
 
Document Date: June 24, 2021 
 
 
 

 
 
 
 
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Background 
Tinnitus, characterized by the perception of sound in the absence of an external stimulus, is one 
example of such a condition. Managing tinnitus is notoriously challenging as there is often not a 
curable medical cause. The intervention with strongest research evidence is cognitive behavioral 
therapy (CBT) for tinnitus. CBT is psychological intervention addressing unhelpful thought 
patterns and emotional reactions caused by tinnitus (Andersson, 2002). Despite the evidence 
base, accessibility to CBT for tinnitus is limited due to a dearth of healthcare providers with the 
knowledge and expertise to provide CBT to this population (Bhatt et al., 2016; Henry et al., 
2019). However, no previous trials on Spanish population exist.  
 
Objectives 
The aim of the present study was to run a small-scale study to inform feasibility of ICBT in 
Spanish to inform the protocol of a implementing a larger randomized clinical trials (RCT). The 
specific objects were to investigate the recruitment, compliance, engagement, acceptance, and 
outcome feasibility in reducing tinnitus distress and tinnitus associated problems, using ICBT for 
Spanish speakers with tinnitus.  
 
Study Design 
A single-group pretest posttest design was used to determine the feasibility of ICBT for Spanish 
communities and refine the protocol for larger studies. This was intended to be an initial small-
scale study (n =32) without a control group to test the protocol prior to allocating resources to a 
larger scale study. Such studies are an important initial part of clinical trials designs for complex 
interventions and considered as the Phase 1 trial.  
 
Intervention 
The ICBT intervention content was based on a CBT self-help program originally developed in 
Swedish (Andersson & Viktor, 2004). This intervention has been translated into German (Jasper 
et al., 2014) and English (Abbott, et al., 2009) and adapted into an interactive 8-week interactive 
e-learning version (Beukes, et al., 2016). For the purposes of this study the intervention was 
translated into Spanish, ensuring readability at below the recommended 6th-grade level (Beukes, 
et al., 2020) and functionality of the platform housed in the US was established (Manchaiah, et 
al., 2020a). The ICBT program employed 22 modules with videos, worksheets and quizzes 
(Beukes et al., 2021a).  
 
To minimize the resources required, on-support guidance was offered to participants. There was 
an encrypted two-way messaging system enabling participants to ask questions about the 
program. These messages were monitored by a Spanish-speaking doctoral audiology student who 
responded in Spanish. If required, further support was available from a specialist tinnitus 
audiologist or a licensed CBT therapist. 
 
Outcome Measures 
The primary outcome was Tinnitus severity as measured by the Tinnitus Functional Index (TFI) 
(Meikle et al., 2012). Secondary outcomes included measures of anxiety, depression, insomnia, 
tinnitus cognitions, hearing-related difficulties, and health-related quality of life. Spanish 
translations (Manchaiah et al., 2020b) of all outcome measures are listed below. 
 

 
 
 
 
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Primary Outcome Measure 
The primary outcome measure was tinnitus severity as measured by the TFI (Meikle et al., 
2012). It was selected over other tinnitus questionnaires as it was specifically developed to 
measure tinnitus severity and assess responsiveness to treatment and for comparison purposes 
with similar trials in the UK and the US (Beukes et al., 2017, 2018, 2021b). 
 
Secondary Outcome Measures 
The following secondary measures were incorporated to assess commonly reported 
tinnitus-related difficulties:  
§ The Generalized Anxiety Disorder–7 (GAD-7; Spitzer et al., 2006) assessed symptoms of 
generalized anxiety disorder.  
§ The PHQ-9 (Spitzer, Kroenke, Williams, 1999) indicated symptoms of depression. 
§ The Insomnia Severity Index (ISI; Bastien, Vallières, & Morin, 2001) assessed the presence 
of insomnia. 
§ The Tinnitus Cognitions Questionnaire (TCQ; Wilson & Henry, 1998) was used to measure 
negative tinnitus cognitions. 
§ The EQ-5D-5L (Herdman et al., 2011) measured general health-related quality of life. 
§ The Tinnitus and Hearing Survey (THS; Henry et al., 2015) was used as a short measure to 
identify participants’ tinnitus severity, hearing disability, and hyperacusis. 
 
To monitor participants tinnitus severity while undertaking the intervention, the screening 
version of the Tinnitus Handicap Inventory (THI-S; Newman et al, 2008) was completed weekly 
during the course of the 8 week intervention. If scores increased by more than 10 points between 
two consecutive weeks, the participant was contacted to discuss presenting difficulties. 
Participants were also monitored weekly by a newly developed Tinnitus Qualities Questionnaire 
(TQQ; Beukes et al., 2021a). The TQQ measures psychoacoustic tinnitus qualities such as pitch, 
loudness, and the number of tones heard. 
 
Online questionnaires were used throughout the study. All the measures were completed pre- and 
post-intervention, and at two-month follow-up. To maximize retention, 3 electronic reminders 
were sent to participants who had not completed questionnaires. 
 
Recruitment  
We aimed to recruit participants across the globe without any geographical barrier. To recruit 
Spanish speakers, a range of strategies were used to disseminate information, including social 
media (Facebook and Twitter), emails, forums. As uptake was low a company “TrialFacts” were 
contracted to boost recruitment.  The main recruitment period was between 1 March to 20 April 
2020. Those interested were directed to the study website, where all the information was 
available to read in Spanish regarding what the study entailed and how to register. Study 
eligibility was determined as follows: 
§ Spanish speakers, adults, aged 18 years and over from any location; 
§ Access to a computer, the internet and the ability to email;   
§ Experiencing tinnitus for a minimum period of three months; 
§ A tinnitus severity score of 25 or greater on the TFI indicating the need for an 
intervention; 

 
 
 
 
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§ Not undertaking any other therapies or interventions that may interfere with the current 
study; and 
§ Not presenting with any serious health conditions that may prevent undertaking the 
intervention. 
 
Statistical Analysis Plan 
Statistical analyses were performed using the Statistical Package for Social Sciences (SPSS) 
version 26.0. The study outcomes of interest were retention, feasibility, and effect size at post-
intervention. For all analyses, the goal of this pilot was to estimate the pre-post-test effect size 
for all primary and secondary outcomes; however 2-sided p-values using alpha = 0.05 are also 
reported. Missing data were handled through multiple imputation using the Markov Chain Monte 
Carlo approach as they were missing at random (Little’s MCAR test X2 = 17.50  (24) = .83). For 
comparison purposes a completer’s only analysis was also done. The data that support the 
findings of this study are openly available in Figshare at 
http://doi.org/10.6084/m9.figshare.13718896. 
 
Effect Sizes and Statistical Modelling 
Effect sizes (Cohen’s d) at post-intervention were calculated by dividing the differences in pre- 
and post-intervention means by the pooled standard deviations. The reliable change index (RCI) 
(Jacobson & Truax, 1991) was used as a means of calculating clinical significance for the TFI as 
the primary outcome. This was calculated using the mean pretest posttest score difference, the 
pre-intervention standard deviation, and a test-retest reliability coefficient of 0.78, and as 
reported in the validation study (Meikle et al, 2012). Finally, linear mixed models (LMM) using 
maximum likelihood with random intercept for participants were used to account for repeated 
measures and incorporate all available data points in the analysis. The models were used to 
determine the effect of the pre-intervention scores on follow-up scores. The LMM induces a 
scaled identity covariance structure. Bonferroni-corrected pairwise post hoc tests were applied to 
determine which timepoints were significantly different, for each variable.  
 
Sample Characteristics  
Descriptive statistics including gender, age, tinnitus duration, hearing aid use, and professionals 
consulted, were used to describe the sample. The mean and standard deviation were reported for 
each outcome measure at each time point. Descriptive statistics were also used to describe 
intervention adherence and engagement including the number of logins and modules read.  
 
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