Handscomb, Lucy
(2018)
A systematic evaluation of the cognitive behavioural model of tinnitus distress.
PhD thesis, University of Nottingham.
Abstract
Introduction & Aims
Tinnitus has long been known to be a much more distressing problem to some people than to others, and understanding the reasons for this is crucial to the development of tinnitus therapy. McKenna et al. (2014) developed a Cognitive Behavioural Model of Tinnitus Distress based on psychological theory- in particular, the Cognitive Model of Insomnia (Harvey, 2002)- existing evidence, and clinical experience. It attempts to explain how tinnitus distress arises and is then maintained in certain individuals. It proposes that interaction between negative thoughts, arousal and distress, attention and monitoring, behaviour and underlying beliefs makes tinnitus a psychologically distressing experience. A strength of this model is that it consists of several testable hypotheses. It makes a series of predictions about what the individual components of tinnitus distress are and how they relate to one another. The primary aim of this project was to test all these predictions using questionnaire data gathered from people with tinnitus and thereby to evaluate whether and to what extent the Cognitive Behavioural Model is supported by evidence. In some contexts, the model is used as a therapeutic tool to help people understand their own experience of tinnitus. The secondary aim of this project was therefore to investigate whether and to what extent people with tinnitus feel the model applies to them and whether they find it easy to understand.
Methods
Two studies were conducted in order to investigate the two project aims. In the first, volunteers with tinnitus were asked to fill in a survey online or on paper which consisted of a series of questionnaires (or parts of questionnaires) each of which was designed to assess an individual component of the Cognitive Behavioural Model. Questionnaire data were used first to conduct factor analysis of each questionnaire individually. The resulting factor scores were then used to evaluate the full model using path analysis. A series of models based on the original, theoretical model were created and tested and results were compared.
In the second study, tinnitus patients who had the Cognitive Behavioural Model explained to them in a therapy group were interviewed about their impressions of it. A focus group discussion about the model was also held with tinnitus therapists who were familiar with it. Interviews and the focus group were audio recorded, transcribed, and analysed using thematic analysis.
Results
Three hundred and forty-two adults with tinnitus completed the survey. Eleven tinnitus patients were interviewed and five therapists attended the focus group.
Examination of mean questionnaire scores indicated a strong correlation between each of the measures used and overall tinnitus distress, with the exception of a modified version of the illness perception questionnaire, which was used to measure tinnitus control beliefs. A robust factor structure was identified for all but one of the questionnaires used in the survey; the Fear of Tinnitus Questionnaire. This questionnaire was excluded from further analysis. Path analysis indicated that a number of configurations of the Cognitive Behavioural Model were a fairly good fit to the data obtained. The two best fitting models differed principally in the placement of tinnitus magnitude, which was seen as a product of attention in the first and as an independent variable in the second. Key fit indices for the two best fitting models were RMSEA = 0.061, 90% CI = 0.047-0.076, CFI = 0.984 and RMSEA = 0.055, 90% CI = 0.035-0.075, CFI = 0.993.
Results of qualitative analysis indicated that people with tinnitus are able to understand the Cognitive Behavioural Model and for the most part feel it broadly reflects their experience, although some people did not identify with certain parts of it. There were differing opinions amongst both patients and therapists as to how useful a part of tinnitus therapy it might be.
Conclusion
The Cognitive Behavioural Model of Tinnitus Distress is empirically supported by data obtained from a sample of people with tinnitus. Questions remain as to whether beliefs are important and what kind of beliefs influence tinnitus experience. The fact that different configurations of the model fit the data equally well and that people with tinnitus do not necessarily think that the model is a perfect reflection of their experience, indicate that there may in fact not be one universal model of tinnitus distress but several, some of which apply more to certain sub-groups of people with tinnitus than others. Further investigation of this is needed. This notwithstanding, this project indicates that the Cognitive Behavioural Model is a firm, evidence-based foundation on which to build psychological tinnitus therapies.
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