Tinnitus Heterogeneity

Tinnitus is a heterogeneous disease. This heterogeneity presents methodological challenges in tinnitus research into effective therapies. The aim of this thesis was to explore tinnitus heterogeneity. In chapter 2 we assessed which outcome measures are important for tinnitus patients with a discrete choice experiment. Four attributes (tinnitus loudness, tinnitus acceptance, quality of sleep and concentration) were assessed with three different levels (increased, decreased, similar). The choice of therapy was affected significantly by all levels in all outcome measures, apart from a similar level in concentration and tinnitus acceptance. We identified tinnitus loudness to be the most important. Two different classes of preference were identified. In chapter 3 we assessed the prevalence of tinnitus in the Dutch general population with different cutoffs for definition. We assessed the prevalence of tinnitus with different criteria ( n=932). We found that 36% of our sample experienced tinnitus for an undefined amount of time during the past year. 23% of our sample met our definition of having pathologic tinnitus, of those 48.7% had a TFI score of 18 or higher. This chapter illustrated the difficulties with defining tinnitus, and stressed the importance of a uniform definition. In chapter 4 we describe a study that assessed the difference in characteristics between people with tinnitus that seek help and those that do not. 34% of those with tinnitus were identified as tinnitus help seekers. We described differences between help-seekers and non-help-seekers in tinnitus- and audiological characteristics. In chapter 5 we describe the results of a study in 963,880 people, of those 8050 were defined as tinnitus patients. We explored the primary health care consumption of patients with tinnitus and people without tinnitus. We concluded that, compared to people without tinnitus, patients with tinnitus had a higher average amount of consultations, were more often referred to medical specialists and received more prescriptions. In chapter 6 we describe associations between different variables and the TFI. We performed univariable and multivariable regression analyses to assess these associations with the TFI. We concluded that audiological variables such as hearing problems and hyperacusis have the largest association with tinnitus impact. In chapter 7 we describe a systematic review on prediction models for tinnitus presence and the impact of tinnitus.. We included 21 studies, that described 31 different predictions models. 17 studies described a prediction model for tinnitus impact, 3 for tinnitus presence and 1 study described one on each. Depression or anxiety were mostly used as predictors in models on tinnitus impact. For models on tinnitus experience demographic factors were most commonly used as predictor candidates. We noticed a high risk of bias and poor reporting in all studies. In chapter 8 we developed and internally validated a prediction model on tinnitus presence. The model was derived on 122.884 participants from the Lifelines database, 6.5% of them experienced tinnitus. 24 candidate predictors on different domains were used to predict tinnitus presence. From 24 candidate predictors, the final model included nine. This study highlighted the value of co-morbidities, especially hearing related co-morbidities.