Cognitive Behavior Therapy Based Self-help Delivered Via the Internet for Tinnitus Sufferers: Efficacy Trial in the U.S. Population
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 the United States: A 
randomized controlled trial protocol 
 
Clinical trial registration: NCT04004260 on 2 July 2019.  
 
Funding: 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-FY17-209). 
 
Document Date: June 22, 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).  
 
To overcome this barrier, an Internet-based CBT for tinnitus (ICBT; Andersson et al. 2002) 
has been developed. The efficacy of ICBT has been indicated in nine clinical trials across 
mainland Europe and the UK (for review see Beukes et al., 2019). No clinical trials,   
 
Study Objectives: 
1. To evaluate the efficacy of audiologist-delivered ICBT in reducing tinnitus distress 
compared with weekly monitoring of tinnitus in the US.  
2. To ascertain the efficacy of ICBT in reducing comorbidities associated with tinnitus. 
3. To assess the stability of ICBT intervention effects 2-months post-intervention. 
 
The hypothesis will be that patients with tinnitus would experience greater reduction of 
tinnitus distress and comorbidities after receiving ICBT compared to patients receiving 
weekly monitoring. 
 
Study Design 
A prospective two-arm delayed intervention efficacy trial with a 2-month follow-up is 
planned.  
 
Randomization 
Participants will be randomized to the Experimental Group and received the ICBT 
intervention for 8-weeks, or the Control Group whose participants will be monitored weekly 
during this 8-week period. During the first phase the experimental group will completed the 
intervention. Following this both groups  will complete T1 (post-treatment) outcome 
measures. During the second phase, the control group will receive the same ICBT 
intervention, after which both groups will complete T2 (2 month follow-up) outcomes. This 
study design, therefore, provided the opportunity to evaluate the intervention effects in two 
independent groups at three time points as shown in Figure 1.   
 
Study Population 
 
Study eligibility 
Inclusion criteria: 
§ Adults, aged 18 years and over, living in Texas in the US; 
§ The ability to read and type in English or Spanish; 
§ Access to a computer, the internet and able to email;   
§ Experiencing tinnitus for a minimum period of three months and 
§ A tinnitus severity score of 25 or greater on the Tinnitus Functional Index (TFI) 
indicating the need for an intervention. 
 
Exclusion criteria: 
§ Indication of significant depression (≥ 15) on the Patient Health Questionnaire (PHQ-9); 

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§ Indications of self-harm thoughts or intent, answering affirming on Question 10 of the 
PHQ-9 questionnaire;  
§ Reporting any medical or psychiatric conditions that could interfere with the treatment;  
§ Reporting pulsatile, objective or unilateral tinnitus, which has not been investigated 
medically or tinnitus still under medical investigation; and 
§ Undergoing any tinnitus therapy concurrent with participation in this study. 
 
Eligibility will be determined by a two-stage process as follows: 
§ An online screening questionnaire, which includes demographic information, health and 
mental health-related questions, and standardized outcome measures as shown in Table 1. 
§ A telephone interview during which the researcher will recheck eligibility, and provided 
the opportunity for potential participants to ask any questions related to the study. The 
study procedures will be explained, and motivational interviewing will be done to 
encourage participants to commit and engage in the intervention. 
§ Participants with a score of 15 or more on the PHQ-9 or indicated self-harm on question 
10 will receive a phone consultation from a clinical psychologist on the research team. 
This call will ensure that they are under care elsewhere or necessary resources and/or 
referrals can be provided. 
 
Recruitment Strategy 
Recruited will involve many strategies including  a television broadcast, promoting the study 
via tinnitus support groups in Texas and the American Tinnitus Association (ATA), and 
contracting the company “TrialFacts” to boost recruitment. Further recruitment strategies will 
involve the use of social media (e.g., Facebook and Twitter). Flyers and posters will be 
distributed to local communities and put up in clinic waiting rooms. Professionals such as 
audiologists and otolaryngologists in the state of Texas will be notified about the study and 
provided with leaflets to distribute to suitable patients. Those interested will  be directed to 
the study website (www.tacklingtinnitus.org) where they can read more about the study and 
register their interest in study participation.  Following registration, they will be invited to 
complete the screening questionnaire. They will be informed of their right to withdraw 
without penalty at any stage of the process. 
 
Sample Size, Power and Attrition  
Sample size estimation will be calculated using G*Power version 3.1.6 (Faul et al., 2007) and 
based on achieving a 13-point clinically meaning change between baseline and post-
intervention using the primary assessment measure, the TFI. Pilot data (Beukes et al., 
Submitted) indicated 26 participants per group with a 1:1 allocation to achieve 80% power to 
detect a between-group mean standardized difference effect size of d = 0.50 (a moderate 
effect size). As this will be fewer than the 58 participants suggested using data from previous 
RCTs of this intervention, (Beukes et al., 2018) we selected 58 per group. In addition, sample 
size will be inflated to account for missing data, estimated to be 20% from the US phase I 
trial data (Beukes et al., 2021b). The aim will be thus to recruit 146 participants with 73 in 
each arm (calculated as 58/0.8). 
 
Randomization 
Participants meeting the inclusion criteria will be randomly assigned in the ratio of 1:1 and 
enrolled to either the experimental or control group using a computer-generated 
randomization scheduled by an independent research assistant in blocks of varying sizes after 
participants are pre-stratified for language (English and Spanish).  
 

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Patient Public Partnership (PPI) 
A PPI will be established to include two individuals with tinnitus who had piloted the ICBT 
intervention, two audiologists, two researchers. Meetings will be held via video conferencing. 
The aim of the PPI will be to guide the study processes and input into the research strategy to 
boost recruitment and other elements of the study to ensure high compliance and 
engagement. 
 
Intervention 
The ICBT intervention content will be based on a CBT self-help program originally 
developed in Swedish (Andersson & Kaldo, 2004) and later adapted and translated in English 
(Abbott, et al., 2009). The intervention will be subsequently transformed into an 8-week 
interactive e-learning version suitable for a UK population (Beukes, et al., 2016) and then 
adapted linguistically and culturally to ensure suitability for a US population (Beukes, et al., 
2020). These adaptions prioritized accessibility of the intervention, such as lowering the 
readability to below the recommended 6th-grade level, as more than half the US adult 
population have low literacy skills  (Statistics, 2003). The intervention will be augmented by 
a module on mindfulness and more videos. The ICBT platform in the US application 
consisted of 22 modules with worksheets and quizzes (see Beukes et al., 2020; Beukes et al., 
2021a for more details).   
 
The intervention platform will be transferred from Sweden and housed in the US (Lamar 
University) to comply with the needed US data protection regulations. Prior to this feasibility 
trial, acceptability and functionality of this intervention for a US population will be first 
ensured (Manchaiah et al., 2020). Further details about the features, functionalities, and 
intervention components are presented in Manchaiah et al. (2020).  
 
Both groups will received the same intervention, only the timings regarding receiving the 
intervention will vary. The control group will receive the experimental intervention 8 weeks 
after the experimental group commenced the program. 
 
Audiology Guidance 
Guidance will be provided to support participants while undertaking the intervention. This 
will include monitoring progress, monitoring weekly scores, providing feedback on 
worksheets completed, outlining the content of new modules, and answering questions.  
 
Outcome Measures 
Primary Outcome Measure 
The primary outcome measure will be tinnitus severity as measured by the Tinnitus 
Functional Index (TFI; Meikle et al., 2012). The TFI has been translated into more than 15 
languages and been validated for several populations including Chinese, Dutch, Swedish and 
German (Henry et al., 2016). It will be selected over other tinnitus questionnaires as it will be 
specifically developed to measure tinnitus severity and assess responsiveness to treatment 
and for comparison purposes with previous trials (e.g., Beukes et al., 2018). Meikle et al. 
(2012) reported that meaningful changes occur when scores are reduced by 13 points or 
more. 
 
Secondary Outcome Measures 
Secondary outcome measures will assess anxiety, depression, insomnia, tinnitus cognitions, 
hearing-related difficulties, and health-related quality of life, as shown in Table 1. To reduce 
the assessment load, the Tinnitus and Hearing Survey (THS; Henry, et al., 2015) will be used 

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to identify hearing disability and hyperacusis as it only includes 10 questions. The section on 
tinnitus also served as a secondary tinnitus measure. The EQ-5D-5L (Herdman, et al., 2011) 
will be selected to measure general health-related quality of life. All questionnaires will be 
used with the required permissions and agreements will be set up for those that are not freely 
available to use. For Spanish speakers, validated Spanish translated versions will be used. 
Where these will be unavailable, validated translations will be undertaken (Manchaiah, et al., 
2020b). 
 
Weekly Monitoring During the Intervention 
Throughout the program, participants will be monitored weekly by means of the Tinnitus 
Handicap Inventory, Screening version (THI-S). The THI-S consists of a 10-item 
questionnaire and scores are comparable (r =.90) with the full version of the THI (Newman et 
al, 2008). The weekly scores will be also used to detect possible adverse effects. If scores 
increased by more than 10 points between two consecutive weeks, this will be noted as an 
adverse effect. Those indicating adverse effects will be contacted to address the identified 
problems. Participants will be also monitored by a newly developed Tinnitus Qualities 
Questionnaire (TQQ; Beukes et al., 2021a). The TQQ measures tinnitus qualities such as 
pitch, loudness, and the number of tones heard. The scores of TQQ can range between 0 to 
100 with higher scores indicating more problematic tinnitus.  
 
Intervention Variables 
Intervention compliance will be assessed by determining retention rates and compliance in 
completing outcome questionnaires. Intervention engagement will be assessed by the number 
of logins, the number of modules read, and the number of messages sent during the 
intervention. Adverse effects will be monitored by 1) Direct questioning in the outcome 
questionnaire regarding the presence of adverse effects 2) Adverse effects written in 
messages or worksheets 3) An increase of 10 points or more during weekly monitoring using 
the THI-S questionnaire. 
 
Questionnaire Administration 
Online questionnaires will be used throughout the study. All the measures will be completed 
at baseline, T1 (post-intervention for experimental group), T2 (post-intervention for the 
control group and at two-month follow-up for the experimental group). To have a measure of 
the control group 2 months post intervention, participants completed further outcome 
measures at T3. For data analysis purposes the T3 results for the control group and those at 
T2 for the experimental group will be compared in order to assess the invention effect at 
same experimental time point for both groups (i.e., 2 months post intervention). To maximize 
retention, 3 electronic reminders will be sent to participants who had not completed 
questionnaires, on the 3 consecutive days after the release of the questionnaire. A further 
reminder will be sent out via email and text message. If questionnaires will be still not 
completed participants will be telephoned to encourage questionnaire completion. 
Participants will be also phoned after completing the intervention to discuss the progress they 
had made and share their questionnaire results. 
 
Statistical Analysis Plan 
Statistical analyses will be performed using the Statistical Package for Social Sciences 
(SPSS) version 26.0. All statistical tests will be 2- tailed with an alpha set to .05. To account 
for missing data from participants not completing the post-intervention or follow-up 
intervention analysis an imputation analysis will be undertaken. Missing data will be handled 
through multiple imputation using the Markov Chain Monte Carlo approach (Jakobsen et al., 

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2017). For comparison, a complete case analysis will be also performed by analyzing only 
the completed questionnaire data without imputing missing data. As there will be substantial 
differences, statistical analysis using the imputed data are reported in the results section.    
 
The primary study outcome will be a change in TFI score between the groups at post-
intervention (T1). A difference in scores between T1–T2 for the experimental group will be 
used to assess the stability of intervention effects. According to recommendations for 
statistical analysis of internet interventions effect sizes, linear mixed effects models, and the 
reliable change index will be used to assess the primary and secondary outcomes (Hesser, 
2015). Changes from baseline to post-intervention will be compared within and between 
groups using the pre-post-test effect size (Cohen’s d) for all primary and secondary outcomes 
using the observed data. Effect sizes of d = 0.20 represent small effect sizes; those of d = 
0.50, medium effect sizes; and those equal or greater than d = 0.80, large effect sizes (Cohen, 
1992).  
 
A Linear Mixed Model (LMM), which provides unbiased results in the presence of missing 
data (using all available data), will be applied to analyze the intervention effect over time for 
each outcome measure. An unstructured-repeated effects and identify-random effects 
covariance structure provided the best model fit based on the Akaike’s Information Criterion 
(AIC). Time will be treated as a repeated and fixed effect. Restricted maximum likelihood 
estimation will be applied. The Type III F test sums of squares from the LMM will be 
calculated. As a sensitivity analysis, baseline tinnitus severity will be initially added as a 
covariate, but as it had no significant effect on the results it will be removed from the model.  
 
Another model will be run to test the differences during the course of the 8 weeks 
intervention for the weekly outcome measures. Post hoc time comparison will be carried out 
in the case of significant group differences to assess at which time points these differences 
occurred.  
 
In addition to statistical significant, clinical significance will also reported. A 13 point 
difference is recommended by the original developers of the TFI (Meikle et al, 2012) to 
indicate a meaningful change in scores. To handle study variability, the reliable change index 
(RCI) (Jacobson & Truax, 1991) is recommended as a means of calculating clinical 
significance for the TFI as the primary outcome. This will be calculated using the mean 
pretest-posttest score difference, the pretreatment standard deviation (17.49), and a test-retest 
reliability coefficient of 0.78, and as reported in the validation study  
 
Sample Characteristics  
Descriptive statistics including gender, age, ethnicity, race, tinnitus duration, hearing aid use, 
and professionals consulted, ease of computer use, veteran status, education and employment 
status will be used to describe the sample. The means and standard deviations will be 
reported for each outcome measure at each time point. Descriptive statistics will be also used 
to describe the sample and intervention engagement including the number of logins and 
modules read. A Chi square test of independence will be used to identify group differences 
regarding engagement and compliance rates. 

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Table 1. Study outcome measures used pre-intervention, post-intervention and at 2-months follow-up  
 
Dimension 
Outcome 
Measures  
Internal 
consistency 
Range of scores Levels of significance 
Timeframe
: T0 
(baseline) 
Timeframe: 
T1  
Timeframe: 
T2  
Timefra
me: T3 
Explanation 
 
 
 
 
 
Post-
intervention 
for the 
experimental 
group; post 
weekly 
monitoring 
for the control 
group 
2 month 
follow-up 
for 
experiment
al group, 
postinterve
ntion for 
the control 
group 
2 month 
follow-up 
for the 
control 
group 
 
 
Tinnitus distress 
Tinnitus 
Functional 
Index (TFI; 
Meikle et 
al, 2012)  
.97 
0-100 
A reduction of 
scores indicates 
improvement 
>25= mild (no need for 
intervention) 
26-50= significant 
(possible need for 
intervention) 
 50+ =severe (need for a 
more intense 
intervention) 
Both 
groups 
Both groups 
Both groups 
Control 
group 
only 
x 
x 
x 
x 
Generalized 
Anxiety 
Generalized 
Anxiety 
Disorder 
(GAD-7, 
Spitzer, 
Kroenke, 
Williams, et 
al., 2006) 
.89 
0-21 
A reduction of 
scores indicates 
improvement 
0-4= minimal anxiety 
5-9= mild anxiety 
10-14= moderate anxiety 
5-21= severe anxiety 
x 
x 
x 
x 

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Depression 
Patient 
Health 
Questionnai
re (PHQ-9; 
Spitzer, 
Kroenke, 
Williams, 
1999) 
.83 
0-27 
A reduction of 
scores indicates 
improvement 
5-9=mild depression 
10-14=moderate 
15-19=moderately severe 
20-18= severe depression 
x 
x 
x 
x 
Insomnia 
Insomnia 
Severity 
Index 
(ISI; 
Bastien, 
Vallières, & 
Morin, 
2001) 
.74 
0-28 
A reduction of 
scores indicates 
improvement 
0–7 = Not clinically significant  
8–14 = Subthreshold insomnia 
15–21 = Clinical insomnia 
 (moderate severity) 
22–28 = Clinical insomnia  
(severe degree) 
 
x 
x 
x 
x 
Tinnitus 
Cognitions 
Tinnitus 
Cognitions 
Questionnai
re (TCQ; 
Wilson & 
Henry, 
1998) 
.91 
0-104 
A reduction of 
scores indicates 
improvement 
Higher scores indicate a 
greater tendency to 
engage in negative 
cognitions in response to 
tinnitus 
x 
x 
x 
x 
Health-related 
quality of life 
EQ-5D-5L 
(Herdman, 
et al., 2011) 
.7-.85 
0-15 
A reduction of 
scores indicates 
improvement 
 
Measures 5 dimensions: 
mobility, self-care, usual 
activities, 
pain/discomfort, and 
anxiety/ depression 
x 
x 
x 
x 
Health-related 
quality of life 
EQ-5D-5L 
Visual 
Analogue 
Scale 
.7-.85 
0-100 
Higher scores 
indicates 
improved health 
VAS for overall health.  
x 
x 
x 
x 

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(VAS) 
(Herdman, 
et al., 2011) 
Short measure 
for tinnitus, 
hearing 
disability and 
hyperacusis 
Tinnitus 
and Hearing 
Survey 
(THS; 
Henry, et 
al., 2015) 
.86-.94 
Subscale for 
Tinnitus: 0-16 
Hearing: 0-16 
Sound tolerance: 
0-8 
 
 
x 
x 
x 
x 
Weekly monitoring 
 
 
 
 
Screening of 
tinnitus severity 
Tinnitus 
Handicap 
Inventory-
Screening 
(THI-S) 
(Newman, 
Sandridge, 
& Bolek, 
2008)   
.93 
0-40 
A reduction of 
scores indicates 
improvement 
>6 tinnitus handicap  
 
 
Weekly while 
undertaking 
the 8-week 
intervention 
 
 
Tinnitus percept 
Tinnitus 
Qualities 
Questionnai
re 
(TQQ; 
Beukes, 
Andersson, 
Manchaiah, 
& Kaldo, 
2021a) 
Not 
assessed 
0-100 
A reduction of 
scores indicates 
improvement 
Designed to determine 
whether tinnitus qualities 
such as loudness, pitch, 
the number of tones 
heard and so forth 
improves while 
undertaking an 
intervention. Higher 
scores indicate more 
bothersome aspects of 
tinnitus are present. 
 
Weekly while 
undertaking 
the 8-week 
intervention 
 
 
T0= preintervention; T1= 8 weeks after the experimental group started the intervention, prior to the control group starting; T2=8 weeks after the 
experimental group complete the intervention and at post-intervention for the control group. 

 

 
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