Acceptance of Tinnitus As an Independent Correlate of Tinnitus Severity Hugo Hesser,1 Ellinor Bånkestad,1 and Gerhard Andersson1,2 Objectives: Tinnitus is the experience of sounds without an identified external source, and for some the experience is associated with significant severity (i.e., perceived negative affect, activity limitation, and participation restriction due to tinnitus). Acceptance of tinnitus has recently been proposed to play an important role in explaining heterogeneity in tinnitus severity. The purpose of the present study was to extend previous investigations of acceptance in relation to tinnitus by examining the unique contribution of acceptance in accounting for tinnitus severity, beyond anxiety and depression symptoms.
Although some people with tinnitus suffer greatly, most do not. Thus, tinnitus is not normally a disabling condition. In fact, many individuals live healthy and productive lives, despite having tinnitus (Henry et al. 2005). It was noted early on that psychological variables might act as mediating links between sound perception of tinnitus and the experienced disability (Fowler & Fowler 1955; Hallam et al. 1984). Indeed, numerous studies have shown strong correlations between anxiety and depression symptoms and subjective reports of tinnitus severity (i.e., perceived negative affect, activity limitation, and participation restriction due to tinnitus) in clinical samples (see for reviews, Andersson 2002; Langguth et al. 2011). Patients’ avoidance of the tinnitus sounds and of associated internal experiences (distressing thoughts, emotional reactions, bodily sensations) have been proposed to be key contributors to tinnitus severity (Hesser et al. 2009a). Avoidance can take on many forms. For example, an individual may excessively use background sounds to avoid hearing tinnitus or may use mental distraction techniques (e.g., suppression) to keep thoughts about tinnitus out of mind. Specifically, an individual’s coping responses of suppressing or controlling the experience of and the response to tinnitus (i.e., using avoidance strategies to avoid tinnitus-related thoughts and emotions or the tinnitus sound per se) may temporarily produce relief but will most likely produce a greater preoccupation with the sounds and make the individual more disturbed by tinnitus over time (Hesser et al. 2013). Individuals who excessively strive to control tinnitus or responses to tinnitus may lock into a self-amplifying negative spiral in which unsuccessful efforts to control the sounds produce more distress, which, in turn, prompts more attempts of avoidance. Ultimately, individuals with tinnitus may become trapped in an avoidance cycle. Psychological acceptance is the theorized opposite of such a detrimental process (Hayes et al. 1996). Acceptance is defined as a willingness to experience internal events, such as physical sensations, emotions, and thoughts, without attempts of controlling, changing, or avoiding them (Hayes et al. 2011). It is an active stance in which an individual observes and evaluates internal experiences, such as tinnitus, openly and without judgment. It is important to note that acceptance of disturbing experiences is not an end in itself but is used as a way to persist or engage in effective actions to pursue valued goals in life. Thus, in the context of tinnitus, acceptance is the process of changing behavior patterns so that they are less tied to controlling the sounds and more focused on healthy living in the presence of tinnitus (Westin et al. 2008a; Hesser et al. 2012). The concept of acceptance is gaining increasing attention within clinical psychology. It has been suggested to be part of a new emerging trend within behavioral and cognitive psychotherapies (Hayes et al. 2011). Acceptance and commitment therapy (ACT) is one of the most researched of these new treatment approaches (Hayes et al. 2011). ACT is designed to treat a broad
Design: In a cross-sectional study, 362 participants with tinnitus attending an ENT clinic in Sweden completed a standard set of psychometrically examined measures of acceptance of tinnitus, tinnitus severity, and anxiety and depression symptoms. Participants also completed a background form on which they provided information about the experience of tinnitus (loudness, localization, sound characteristics), other auditory-related problems (hearing problems and sound sensitivity), and personal characteristics. Results: Correlational analyses showed that acceptance was strongly and inversely related to tinnitus severity and anxiety and depression symptoms. Multivariate regression analysis, in which relevant patient characteristics were controlled, revealed that acceptance accounted for unique variance beyond anxiety and depression symptoms. Acceptance accounted for more of the variance than anxiety and depression symptoms combined. In addition, mediation analysis revealed that acceptance of tinnitus mediated the direct association between self-rated loudness and tinnitus severity, even after anxiety and depression symptoms were taken into account. Conclusions: Findings add to the growing body of work, supporting the unique and important role of acceptance in tinnitus severity. The utility of the concept is discussed in relation to the development of new psychological models and interventions for tinnitus severity. Key words: Acceptance, Anxiety, Avoidance, Depression, Tinnitus disability. (Ear & Hearing 2015;36;e176–e182)
INTRODUCTION Tinnitus is the experience of sounds in the ears without a recognized external source and is a highly prevalent condition, affecting between 10% and 15% of the adult population (Baguley et al. 2013). The condition can be a serious health concern, and for a substantial proportion of individuals (approximately 2% to 3% of the general population), sleep, mood, and the ability to perform everyday tasks are affected to a significant degree (Henry et al. 2005). There is also growing evidence that the negative consequences of disabling tinnitus can be observed at the level of society. For example, a recent nationwide cohort study in Sweden showed that sick leave due to tinnitus was associated with increased risk of disability pension compared with sick leave due to nonaudiological diagnoses (Friberg et al. 2012). Department of Behavioural Sciences and Learning, Linköping University, Linköping, Sweden; and 2Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm, Sweden.
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array of problems and is based on a contextual model of human suffering and health. Although part of the behavioral and cognitive psychotherapy tradition (i.e., cognitive behavioral therapy [CBT]), ACT differs from traditional forms of CBT in a significant way (Hayes et al. 2013). Rather than focusing on altering the form or frequency of maladaptive cognitions and emotions as done in CBT, ACT seeks to alter the function of thoughts and feelings by changing the relationship with these experiences. Context is hence emphasized over content or form. Hayes et al. (1999) expressed the difference in the following way: “the relevant question is no longer how do we change undesirable thoughts and feelings but what context produces the most useful thought-behavior or emotion-behavior relationship?” (p. 34). In ACT, individuals are instructed to approach inner experiences (bodily sensations, thoughts, feelings) openly without defense, to be able to respond effectively in stressful situations without getting caught in unhelpful emotional reactions and judgments. An individual’s willingness to stay in contact with difficult internal (or subjective) experiences can free resources. By doing so, an individual may make life choices and accomplish goals that are meaningful. Moreover, psychological acceptance is proposed to counteract the negative long-term effects associated with avoidance of internal experiences, so-called experiential avoidance (Hayes et al. 1996). That is, avoidance of internal experiences may, in certain circumstances, exacerbate the very sensation one is trying to avoid (e.g., Wegner 2009) and acceptance of the sensation may be one way to eliminate or reduce such negative effects. This psychological approach has been found to be particularly helpful for chronic medical conditions, such as chronic pain (e.g., McCracken & Vowles 2008; McCracken 2010), and there are emerging data to support ACT as efficacious for anxiety and depression disorders (e.g., Forman et al. 2007; Arch et al. 2012). Given the similarities between tinnitus and chronic pain and the fact that anxiety and depression often accompany distressing tinnitus (Henry et al. 2005), the concept of acceptance may have utility in psychological models of adjustment to tinnitus. There is now a growing body of work that supports acceptance of tinnitus as inversely related to tinnitus severity. Crosssectional and longitudinal studies have shown that scores on measures of acceptance—or its theoretical opposite, experiential avoidance (Hayes et al. 1996)—are correlated with scores on measures of severity due to tinnitus (Davis & Morgan 2008; Westin et al. 2008a; Hesser & Andersson 2009; Kleinstäuber et al. 2013; Weise et al. 2013). A few experimental studies have also found support for the utility of the concept of acceptance in tinnitus (Westin et al. 2008b; Hesser et al. 2009a, 2013). Furthermore, studies have shown that ACT can be effective in alleviating tinnitus severity (Westin et al. 2011; Hesser et al. 2012) and that these effects can, at least in part, be explained by changes in acceptance processes (Hesser et al. 2009b, 2014). The purpose of the present study was to extend previous findings from the investigations of the role of psychological acceptance—as defined earlier and used in the underlying ACT model of health and functioning—in relation to tinnitus severity. Despite the evidence supporting the potential important role of this form of acceptance in tinnitus, to our knowledge no study to date has examined whether acceptance is uniquely associated with tinnitus severity beyond depression and anxiety symptoms in a clinical sample of individuals with tinnitus. Thus, the first
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aim of this study was to examine the relative contribution of acceptance of tinnitus in explaining variation in tinnitus severity when anxiety and depression symptoms were taken into account. We hypothesized that acceptance of tinnitus would explain unique variance in tinnitus severity beyond depression and anxiety symptoms. The second aim was to investigate a previously observed pattern of associations in which acceptance of tinnitus would mediate the direct association between selfrated loudness of the sounds and tinnitus severity (see Fig. 1; Weise et al. 2013). Here, we predicted that loudness would be negatively associated with acceptance (a-path), which in turn would be inversely related to tinnitus severity (b-path), and that the mediated pathway (ab-path) would be significantly different from zero, even when anxiety and depression symptoms would be statistically taken into account.
MATERIALS AND METHODS Participants Data were collected retrospectively from an ENT clinic at a university hospital. The clinic uses a stepped-care approach to the management of tinnitus. All patients who are referred to the clinic for tinnitus receive information about tinnitus in group-format, but depending on their needs, patients also receive additional medical and psychological treatments. The following inclusion criteria were used: patients had to have a confirmed diagnosis of tinnitus as attested by the medical files (International Classification of Diseases, Tenth Revision, code H 93.1), be at least 18 years old, and have sought treatment and/ or further information about tinnitus at the clinic between the years 2004 and 2012. No other inclusion/exclusion criteria were applied. All patients fulfilling these criteria were mailed the survey at home (n = 634) and were asked to complete and return it by e-mail. The postal survey contained a set of psychometrically validated self-report measures (see Measures). In addition to these measures, the survey included a background form on which participants provided information about their tinnitus experience and other auditory-related problems, as well as information about their personal characteristics (e.g., age, work status, and sex). A letter containing information about the purpose of the research and how data were going to be used accompanied the survey. Patients were asked to sign and return a written informed consent along with the postal survey by e-mail. A reminder was sent to patients after 3 weeks. The study followed the ethical principles as outlined in the Declaration of Helsinki, and the regional ethics committee at Linköping University, Linköping, Sweden, approved the study protocol.
Fig. 1. A schematic diagram of the mediator model explored in the study. The mediated effect is the product of the regression coefficients associated with the a-path and b-path in the model. TAQ, Tinnitus Acceptance Questionnaire; THI, Tinnitus Handicap Inventory.
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Measures Acceptance of tinnitus was measured with the 12-item Tinnitus Acceptance Questionnaire (TAQ; Westin et al. 2008a). It includes two factors, activity engagement (i.e., ability to engage in value-based activities despite presence of tinnitus) and suppression (i.e., cognitive avoidance strategies to avoid tinnitusrelated thoughts and emotions; scale is reversed in scoring), but it is generally recommended to combine scores from both scales to provide a single measure of psychological acceptance. All items are rated on a 0 (never true) to 6 (always true) scale and are summed to calculate the total score of a maximum of 72 points. Higher scores on the instruments reflect greater acceptance. The TAQ has demonstrated satisfactory psychometric properties, including good internal consistency, temporal stability, and factor structure (Westin et al. 2008a; Weise et al. 2013). Tinnitus Handicap Inventory (THI; Newman et al. 1996) was used to assess global tinnitus severity. The THI is one of the more widely used instruments to assess severity and handicap due to tinnitus and consists of 25 items; each rated on a threepoint graded response categorical scale. Scores on the instrument are summed to create an index of global tinnitus severity. The instrument has repeatedly demonstrated satisfactory internal consistency, temporal stability, concurrent validity, and a unidimensional factor structure (Newman et al. 1998; Baguley et al. 2000; Hesser & Andersson 2014). The 14-item Hospital Anxiety and Depression Scale (HADS; Zigmond & Snaith 1983) was used to assess anxiety and depression symptoms. The HADS is commonly used to assess depression and anxiety symptoms among patients with somatic illness (Herrmann 1997). The two-factor solution has been confirmed, and adequate reliability, sensitivity, and specificity have been demonstrated (Herrmann 1997). The satisfactory psychometric properties of the HADS have also been established in samples of individuals with tinnitus (Andersson et al. 2003; Svedlund et al. 2003).
Data Analytic Approach We first present descriptive statistics in the form of means, standard deviations, Cronbach’s alpha, and unadjusted bivariate correlations (zero-order correlations) for primary study variables (TAQ, HADS, THI). Multiple ordinary least square regression analysis was used to address the primary aims of the study. To examine the relative contribution of acceptance of tinnitus in explaining variation in tinnitus severity beyond anxiety and depression symptoms, we conducted two hierarchical regression analyses. All independent variables included in the regression model were grand mean centered (i.e., the variable mean was subtracted from each individual score to create a deviation score) to avoid problems with multicollinearity. In the first step of the first analysis, we added demographic and audiological characteristics that had a significant zero-order correlation with THI (p < 0.05). In the second step, both HADS subscales were entered into the regression model. In the final step, we entered TAQ in the model. Thus, this first regression analysis allowed us to test the independent contribution of acceptance to the criterion variable after all other variables in the model were taken into account. In the second analysis, the order of entry for the HADS subscales and TAQ was reversed, that is, TAQ was entered in the second step and the HADS subscales were entered in the third and final step. This procedure allowed us to
test the independent contribution of TAQ in explaining variation in THI scores relative to HADS. To examine whether acceptance mediated the association between self-rated loudness of tinnitus and tinnitus severity (see Fig. 1), mediation analysis using regression was performed and the indirect effect was formally tested with a bootstrapped extension of the Sobel test (see for further details, Preacher & Hayes 2004, 2008). The Sobel test examines whether the crossproduct of a and b paths (ab-product; see Fig. 1) in mediation analysis is significantly different from zero by dividing the point estimate of the product with its standard error. As the product of two random variables are only normally distributed in rare cases and given that the traditional Sobel test relies on normal theory assumptions, resampling methods (i.e., bootstrapping) are often recommended to test whether the ab-product is significantly different from zero in finite samples (Preacher & Hayes 2004, 2008). In the current bootstrap extension of the Sobel test, the point estimate of the ab-product is the mean of the ab-estimates calculated in each of 5000 random samples, and the empirical distribution of estimates are used to calculate a standard error and a bias-corrected confidence interval (CI) for hypothesis testing of the point estimate. If the upper limit (UL) and lower limit (LL) of the bootstrapped bias-corrected CI (95%) does not contain zero, the indirect effect is significantly different from zero at the specified alpha level (i.e., 0.05).
RESULTS Descriptive Statistics The sample included in the present study consisted of 362 participants, of which 52% were men. Mean age was 59.6 years (SD = 11.6). About half of the participants were employed, 49.6%, or retired, 42% (long-term sick leave, 3.9%, student/ other, 4.5%). Average length of time with tinnitus was 12.5 years (SD = 9.4). About half of the participants reported hearing tinnitus in both ears/head, 45.4% (left, 33.8%, right, 20.8%). A significant proportion reported that tinnitus changed in pitch, location, and character (fluctuating tinnitus: “Does your tinnitus change in terms of pitch, level and/or character?”), 91.3%, that they were sensitive to everyday sounds (noise sensitivity: “Are you sensitive to everyday sounds?”), 83.5%, and that they had hearing problems, 78.9% (hearing problems: “Do you have any hearing difficulties?”). Average self-rated loudness of tinnitus, as rated on a Likert-like scale from 0 to 100, was 54.7 (SD = 22.5). About half experienced more than one tinnitus sound, 43.9%, and reported problems with dizziness, 51.5%. Some participants had missing data at the item level on the psychometrically examined self-report measurements (TAQ, HADS, and THI). We calculated a score on these measures if the missing items did not exceed 20% of the items in the scale. Missing items were in these cases replaced with the mean of the item responses from the individual on that scale. Results from correlation analyses of scores on measures of acceptance of tinnitus (TAQ), depression, anxiety symptoms (HADS), and tinnitus severity (THI) and descriptive statistics for these variables are shown in Table 1. All primary study variables were significantly correlated in the expected directions. The TAQ displayed the strongest zero-order correlation with tinnitus severity (r = −0.74). Greater acceptance was associated with less tinnitus severity, as well as less severe anxiety and depression symptoms.
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TABLE 1. Descriptive statistics and intercorrelations for primary study variables Variable
N*
M
SD
Cronbach’s Alpha†
1.
2.
3.
4.
1. Tinnitus Handicap Inventory 2. Tinnitus Acceptance Questionnaire 3. Hospital Anxiety and Depression Scale–depression 4. Hospital Anxiety and Depression Scale–anxiety
361 356 360 361
39.15 42.76 4.42 5.58
22.20 11.96 3.97 4.25
0.93 0.88 0.86 0.88
— −0.74‡ 0.60‡ 0.59‡
— −0.59‡ −0.54‡
— 0.72‡
—
*Number of individuals who completed a sufficient number of items on the scale to calculate a total score. We calculated a score on a scale if the missing responses did not exceeded more than 20% of the items in the scale. Missing items were in these cases replaced with the mean of the responses from the individual on that scale. †Alpha is based on participants who completed all items on the scale/questionnaire. ‡p < 0.001.
Acceptance As an Independent Correlate of Tinnitus Severity Table 2 shows the results of the first regression analysis in which the TAQ was entered in the third and final step. In the first step, age of participant and audiological characteristics (i.e., subjective report of sound sensitivity, tinnitus loudness, and complex tinnitus sound, which all had significant zeroorder correlations with the criterion) accounted for 31% of the total variation in tinnitus severity, and all predictors in this first step had a significant independent contribution to the regression model. Self-rated tinnitus loudness was the strongest predictor in the first step. In the second step, both HADS subscales had an independent contribution and together they explained more than 25% of the variance in THI after demographic and audiological characteristics of participants were taken into account. In the final step, TAQ had a significant contribution, explaining almost 13% of the variance beyond depression and anxiety symptoms as measured with the HADS subscales. In the second regression analysis in which the order of entry was reversed, TAQ accounted for 34% of the variance in
THI after demographic and audiological variables were taken into account, F(1, 310) = 300.25, p < 0.001. The HADS subscales also had a significant contribution in the final step, F(2, 308) = 21.73, p < 0.001, but accounted for only 4% of the variance beyond the variance explained by TAQ. Thus, the relative contribution of acceptance of tinnitus was larger than the combined contribution of anxiety and depression symptoms.
Acceptance As a Mediator Between Loudness of Sounds and Tinnitus Severity In the mediation analysis (see Fig. 1), self-rated loudness of tinnitus had a significant negative association with TAQ (a-path), b = −0.21 (SE = 0.03), p < 0.001, and TAQ was significantly and negatively correlated with THI after the direct effect of self-rated loudness was taken into account (b-path), b = −1.27 (SE = 0.07), p < 0.001. The cross-product of these estimates (ab = 0.27) was significantly different from zero as evaluated with the normal theory test of the Sobel, z = 7.10, p < 0.001, as well as with the biascorrected CI method (i.e., bootstrapping), 95% CI LL = 0.20, UL = 0.35. This inference was not altered when anxiety and
TABLE 2. Hierarchical regression analysis predicting scores on the Tinnitus Handicap Inventory Unstandardized Coefficients Step
Predictor
B
SE
Standardized Coefficients β
p
1 Age Complex sound Tinnitus loudness Sound sensitivity
−0.27 6.95 0.48 7.96
0.09 2.17 0.05 2.95
−0.14 0.16 0.49 0.13
0.004 0.001
Although some people with tinnitus suffer greatly, most do not. Thus, tinnitus is not normally a disabling condition. In fact, many individuals live healthy and productive lives, despite having tinnitus (Henry et al. 2005). It was noted early on that psychological variables might act as mediating links between sound perception of tinnitus and the experienced disability (Fowler & Fowler 1955; Hallam et al. 1984). Indeed, numerous studies have shown strong correlations between anxiety and depression symptoms and subjective reports of tinnitus severity (i.e., perceived negative affect, activity limitation, and participation restriction due to tinnitus) in clinical samples (see for reviews, Andersson 2002; Langguth et al. 2011). Patients’ avoidance of the tinnitus sounds and of associated internal experiences (distressing thoughts, emotional reactions, bodily sensations) have been proposed to be key contributors to tinnitus severity (Hesser et al. 2009a). Avoidance can take on many forms. For example, an individual may excessively use background sounds to avoid hearing tinnitus or may use mental distraction techniques (e.g., suppression) to keep thoughts about tinnitus out of mind. Specifically, an individual’s coping responses of suppressing or controlling the experience of and the response to tinnitus (i.e., using avoidance strategies to avoid tinnitus-related thoughts and emotions or the tinnitus sound per se) may temporarily produce relief but will most likely produce a greater preoccupation with the sounds and make the individual more disturbed by tinnitus over time (Hesser et al. 2013). Individuals who excessively strive to control tinnitus or responses to tinnitus may lock into a self-amplifying negative spiral in which unsuccessful efforts to control the sounds produce more distress, which, in turn, prompts more attempts of avoidance. Ultimately, individuals with tinnitus may become trapped in an avoidance cycle. Psychological acceptance is the theorized opposite of such a detrimental process (Hayes et al. 1996). Acceptance is defined as a willingness to experience internal events, such as physical sensations, emotions, and thoughts, without attempts of controlling, changing, or avoiding them (Hayes et al. 2011). It is an active stance in which an individual observes and evaluates internal experiences, such as tinnitus, openly and without judgment. It is important to note that acceptance of disturbing experiences is not an end in itself but is used as a way to persist or engage in effective actions to pursue valued goals in life. Thus, in the context of tinnitus, acceptance is the process of changing behavior patterns so that they are less tied to controlling the sounds and more focused on healthy living in the presence of tinnitus (Westin et al. 2008a; Hesser et al. 2012). The concept of acceptance is gaining increasing attention within clinical psychology. It has been suggested to be part of a new emerging trend within behavioral and cognitive psychotherapies (Hayes et al. 2011). Acceptance and commitment therapy (ACT) is one of the most researched of these new treatment approaches (Hayes et al. 2011). ACT is designed to treat a broad
Design: In a cross-sectional study, 362 participants with tinnitus attending an ENT clinic in Sweden completed a standard set of psychometrically examined measures of acceptance of tinnitus, tinnitus severity, and anxiety and depression symptoms. Participants also completed a background form on which they provided information about the experience of tinnitus (loudness, localization, sound characteristics), other auditory-related problems (hearing problems and sound sensitivity), and personal characteristics. Results: Correlational analyses showed that acceptance was strongly and inversely related to tinnitus severity and anxiety and depression symptoms. Multivariate regression analysis, in which relevant patient characteristics were controlled, revealed that acceptance accounted for unique variance beyond anxiety and depression symptoms. Acceptance accounted for more of the variance than anxiety and depression symptoms combined. In addition, mediation analysis revealed that acceptance of tinnitus mediated the direct association between self-rated loudness and tinnitus severity, even after anxiety and depression symptoms were taken into account. Conclusions: Findings add to the growing body of work, supporting the unique and important role of acceptance in tinnitus severity. The utility of the concept is discussed in relation to the development of new psychological models and interventions for tinnitus severity. Key words: Acceptance, Anxiety, Avoidance, Depression, Tinnitus disability. (Ear & Hearing 2015;36;e176–e182)
INTRODUCTION Tinnitus is the experience of sounds in the ears without a recognized external source and is a highly prevalent condition, affecting between 10% and 15% of the adult population (Baguley et al. 2013). The condition can be a serious health concern, and for a substantial proportion of individuals (approximately 2% to 3% of the general population), sleep, mood, and the ability to perform everyday tasks are affected to a significant degree (Henry et al. 2005). There is also growing evidence that the negative consequences of disabling tinnitus can be observed at the level of society. For example, a recent nationwide cohort study in Sweden showed that sick leave due to tinnitus was associated with increased risk of disability pension compared with sick leave due to nonaudiological diagnoses (Friberg et al. 2012). Department of Behavioural Sciences and Learning, Linköping University, Linköping, Sweden; and 2Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm, Sweden.
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array of problems and is based on a contextual model of human suffering and health. Although part of the behavioral and cognitive psychotherapy tradition (i.e., cognitive behavioral therapy [CBT]), ACT differs from traditional forms of CBT in a significant way (Hayes et al. 2013). Rather than focusing on altering the form or frequency of maladaptive cognitions and emotions as done in CBT, ACT seeks to alter the function of thoughts and feelings by changing the relationship with these experiences. Context is hence emphasized over content or form. Hayes et al. (1999) expressed the difference in the following way: “the relevant question is no longer how do we change undesirable thoughts and feelings but what context produces the most useful thought-behavior or emotion-behavior relationship?” (p. 34). In ACT, individuals are instructed to approach inner experiences (bodily sensations, thoughts, feelings) openly without defense, to be able to respond effectively in stressful situations without getting caught in unhelpful emotional reactions and judgments. An individual’s willingness to stay in contact with difficult internal (or subjective) experiences can free resources. By doing so, an individual may make life choices and accomplish goals that are meaningful. Moreover, psychological acceptance is proposed to counteract the negative long-term effects associated with avoidance of internal experiences, so-called experiential avoidance (Hayes et al. 1996). That is, avoidance of internal experiences may, in certain circumstances, exacerbate the very sensation one is trying to avoid (e.g., Wegner 2009) and acceptance of the sensation may be one way to eliminate or reduce such negative effects. This psychological approach has been found to be particularly helpful for chronic medical conditions, such as chronic pain (e.g., McCracken & Vowles 2008; McCracken 2010), and there are emerging data to support ACT as efficacious for anxiety and depression disorders (e.g., Forman et al. 2007; Arch et al. 2012). Given the similarities between tinnitus and chronic pain and the fact that anxiety and depression often accompany distressing tinnitus (Henry et al. 2005), the concept of acceptance may have utility in psychological models of adjustment to tinnitus. There is now a growing body of work that supports acceptance of tinnitus as inversely related to tinnitus severity. Crosssectional and longitudinal studies have shown that scores on measures of acceptance—or its theoretical opposite, experiential avoidance (Hayes et al. 1996)—are correlated with scores on measures of severity due to tinnitus (Davis & Morgan 2008; Westin et al. 2008a; Hesser & Andersson 2009; Kleinstäuber et al. 2013; Weise et al. 2013). A few experimental studies have also found support for the utility of the concept of acceptance in tinnitus (Westin et al. 2008b; Hesser et al. 2009a, 2013). Furthermore, studies have shown that ACT can be effective in alleviating tinnitus severity (Westin et al. 2011; Hesser et al. 2012) and that these effects can, at least in part, be explained by changes in acceptance processes (Hesser et al. 2009b, 2014). The purpose of the present study was to extend previous findings from the investigations of the role of psychological acceptance—as defined earlier and used in the underlying ACT model of health and functioning—in relation to tinnitus severity. Despite the evidence supporting the potential important role of this form of acceptance in tinnitus, to our knowledge no study to date has examined whether acceptance is uniquely associated with tinnitus severity beyond depression and anxiety symptoms in a clinical sample of individuals with tinnitus. Thus, the first
e177
aim of this study was to examine the relative contribution of acceptance of tinnitus in explaining variation in tinnitus severity when anxiety and depression symptoms were taken into account. We hypothesized that acceptance of tinnitus would explain unique variance in tinnitus severity beyond depression and anxiety symptoms. The second aim was to investigate a previously observed pattern of associations in which acceptance of tinnitus would mediate the direct association between selfrated loudness of the sounds and tinnitus severity (see Fig. 1; Weise et al. 2013). Here, we predicted that loudness would be negatively associated with acceptance (a-path), which in turn would be inversely related to tinnitus severity (b-path), and that the mediated pathway (ab-path) would be significantly different from zero, even when anxiety and depression symptoms would be statistically taken into account.
MATERIALS AND METHODS Participants Data were collected retrospectively from an ENT clinic at a university hospital. The clinic uses a stepped-care approach to the management of tinnitus. All patients who are referred to the clinic for tinnitus receive information about tinnitus in group-format, but depending on their needs, patients also receive additional medical and psychological treatments. The following inclusion criteria were used: patients had to have a confirmed diagnosis of tinnitus as attested by the medical files (International Classification of Diseases, Tenth Revision, code H 93.1), be at least 18 years old, and have sought treatment and/ or further information about tinnitus at the clinic between the years 2004 and 2012. No other inclusion/exclusion criteria were applied. All patients fulfilling these criteria were mailed the survey at home (n = 634) and were asked to complete and return it by e-mail. The postal survey contained a set of psychometrically validated self-report measures (see Measures). In addition to these measures, the survey included a background form on which participants provided information about their tinnitus experience and other auditory-related problems, as well as information about their personal characteristics (e.g., age, work status, and sex). A letter containing information about the purpose of the research and how data were going to be used accompanied the survey. Patients were asked to sign and return a written informed consent along with the postal survey by e-mail. A reminder was sent to patients after 3 weeks. The study followed the ethical principles as outlined in the Declaration of Helsinki, and the regional ethics committee at Linköping University, Linköping, Sweden, approved the study protocol.
Fig. 1. A schematic diagram of the mediator model explored in the study. The mediated effect is the product of the regression coefficients associated with the a-path and b-path in the model. TAQ, Tinnitus Acceptance Questionnaire; THI, Tinnitus Handicap Inventory.
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Measures Acceptance of tinnitus was measured with the 12-item Tinnitus Acceptance Questionnaire (TAQ; Westin et al. 2008a). It includes two factors, activity engagement (i.e., ability to engage in value-based activities despite presence of tinnitus) and suppression (i.e., cognitive avoidance strategies to avoid tinnitusrelated thoughts and emotions; scale is reversed in scoring), but it is generally recommended to combine scores from both scales to provide a single measure of psychological acceptance. All items are rated on a 0 (never true) to 6 (always true) scale and are summed to calculate the total score of a maximum of 72 points. Higher scores on the instruments reflect greater acceptance. The TAQ has demonstrated satisfactory psychometric properties, including good internal consistency, temporal stability, and factor structure (Westin et al. 2008a; Weise et al. 2013). Tinnitus Handicap Inventory (THI; Newman et al. 1996) was used to assess global tinnitus severity. The THI is one of the more widely used instruments to assess severity and handicap due to tinnitus and consists of 25 items; each rated on a threepoint graded response categorical scale. Scores on the instrument are summed to create an index of global tinnitus severity. The instrument has repeatedly demonstrated satisfactory internal consistency, temporal stability, concurrent validity, and a unidimensional factor structure (Newman et al. 1998; Baguley et al. 2000; Hesser & Andersson 2014). The 14-item Hospital Anxiety and Depression Scale (HADS; Zigmond & Snaith 1983) was used to assess anxiety and depression symptoms. The HADS is commonly used to assess depression and anxiety symptoms among patients with somatic illness (Herrmann 1997). The two-factor solution has been confirmed, and adequate reliability, sensitivity, and specificity have been demonstrated (Herrmann 1997). The satisfactory psychometric properties of the HADS have also been established in samples of individuals with tinnitus (Andersson et al. 2003; Svedlund et al. 2003).
Data Analytic Approach We first present descriptive statistics in the form of means, standard deviations, Cronbach’s alpha, and unadjusted bivariate correlations (zero-order correlations) for primary study variables (TAQ, HADS, THI). Multiple ordinary least square regression analysis was used to address the primary aims of the study. To examine the relative contribution of acceptance of tinnitus in explaining variation in tinnitus severity beyond anxiety and depression symptoms, we conducted two hierarchical regression analyses. All independent variables included in the regression model were grand mean centered (i.e., the variable mean was subtracted from each individual score to create a deviation score) to avoid problems with multicollinearity. In the first step of the first analysis, we added demographic and audiological characteristics that had a significant zero-order correlation with THI (p < 0.05). In the second step, both HADS subscales were entered into the regression model. In the final step, we entered TAQ in the model. Thus, this first regression analysis allowed us to test the independent contribution of acceptance to the criterion variable after all other variables in the model were taken into account. In the second analysis, the order of entry for the HADS subscales and TAQ was reversed, that is, TAQ was entered in the second step and the HADS subscales were entered in the third and final step. This procedure allowed us to
test the independent contribution of TAQ in explaining variation in THI scores relative to HADS. To examine whether acceptance mediated the association between self-rated loudness of tinnitus and tinnitus severity (see Fig. 1), mediation analysis using regression was performed and the indirect effect was formally tested with a bootstrapped extension of the Sobel test (see for further details, Preacher & Hayes 2004, 2008). The Sobel test examines whether the crossproduct of a and b paths (ab-product; see Fig. 1) in mediation analysis is significantly different from zero by dividing the point estimate of the product with its standard error. As the product of two random variables are only normally distributed in rare cases and given that the traditional Sobel test relies on normal theory assumptions, resampling methods (i.e., bootstrapping) are often recommended to test whether the ab-product is significantly different from zero in finite samples (Preacher & Hayes 2004, 2008). In the current bootstrap extension of the Sobel test, the point estimate of the ab-product is the mean of the ab-estimates calculated in each of 5000 random samples, and the empirical distribution of estimates are used to calculate a standard error and a bias-corrected confidence interval (CI) for hypothesis testing of the point estimate. If the upper limit (UL) and lower limit (LL) of the bootstrapped bias-corrected CI (95%) does not contain zero, the indirect effect is significantly different from zero at the specified alpha level (i.e., 0.05).
RESULTS Descriptive Statistics The sample included in the present study consisted of 362 participants, of which 52% were men. Mean age was 59.6 years (SD = 11.6). About half of the participants were employed, 49.6%, or retired, 42% (long-term sick leave, 3.9%, student/ other, 4.5%). Average length of time with tinnitus was 12.5 years (SD = 9.4). About half of the participants reported hearing tinnitus in both ears/head, 45.4% (left, 33.8%, right, 20.8%). A significant proportion reported that tinnitus changed in pitch, location, and character (fluctuating tinnitus: “Does your tinnitus change in terms of pitch, level and/or character?”), 91.3%, that they were sensitive to everyday sounds (noise sensitivity: “Are you sensitive to everyday sounds?”), 83.5%, and that they had hearing problems, 78.9% (hearing problems: “Do you have any hearing difficulties?”). Average self-rated loudness of tinnitus, as rated on a Likert-like scale from 0 to 100, was 54.7 (SD = 22.5). About half experienced more than one tinnitus sound, 43.9%, and reported problems with dizziness, 51.5%. Some participants had missing data at the item level on the psychometrically examined self-report measurements (TAQ, HADS, and THI). We calculated a score on these measures if the missing items did not exceed 20% of the items in the scale. Missing items were in these cases replaced with the mean of the item responses from the individual on that scale. Results from correlation analyses of scores on measures of acceptance of tinnitus (TAQ), depression, anxiety symptoms (HADS), and tinnitus severity (THI) and descriptive statistics for these variables are shown in Table 1. All primary study variables were significantly correlated in the expected directions. The TAQ displayed the strongest zero-order correlation with tinnitus severity (r = −0.74). Greater acceptance was associated with less tinnitus severity, as well as less severe anxiety and depression symptoms.
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TABLE 1. Descriptive statistics and intercorrelations for primary study variables Variable
N*
M
SD
Cronbach’s Alpha†
1.
2.
3.
4.
1. Tinnitus Handicap Inventory 2. Tinnitus Acceptance Questionnaire 3. Hospital Anxiety and Depression Scale–depression 4. Hospital Anxiety and Depression Scale–anxiety
361 356 360 361
39.15 42.76 4.42 5.58
22.20 11.96 3.97 4.25
0.93 0.88 0.86 0.88
— −0.74‡ 0.60‡ 0.59‡
— −0.59‡ −0.54‡
— 0.72‡
—
*Number of individuals who completed a sufficient number of items on the scale to calculate a total score. We calculated a score on a scale if the missing responses did not exceeded more than 20% of the items in the scale. Missing items were in these cases replaced with the mean of the responses from the individual on that scale. †Alpha is based on participants who completed all items on the scale/questionnaire. ‡p < 0.001.
Acceptance As an Independent Correlate of Tinnitus Severity Table 2 shows the results of the first regression analysis in which the TAQ was entered in the third and final step. In the first step, age of participant and audiological characteristics (i.e., subjective report of sound sensitivity, tinnitus loudness, and complex tinnitus sound, which all had significant zeroorder correlations with the criterion) accounted for 31% of the total variation in tinnitus severity, and all predictors in this first step had a significant independent contribution to the regression model. Self-rated tinnitus loudness was the strongest predictor in the first step. In the second step, both HADS subscales had an independent contribution and together they explained more than 25% of the variance in THI after demographic and audiological characteristics of participants were taken into account. In the final step, TAQ had a significant contribution, explaining almost 13% of the variance beyond depression and anxiety symptoms as measured with the HADS subscales. In the second regression analysis in which the order of entry was reversed, TAQ accounted for 34% of the variance in
THI after demographic and audiological variables were taken into account, F(1, 310) = 300.25, p < 0.001. The HADS subscales also had a significant contribution in the final step, F(2, 308) = 21.73, p < 0.001, but accounted for only 4% of the variance beyond the variance explained by TAQ. Thus, the relative contribution of acceptance of tinnitus was larger than the combined contribution of anxiety and depression symptoms.
Acceptance As a Mediator Between Loudness of Sounds and Tinnitus Severity In the mediation analysis (see Fig. 1), self-rated loudness of tinnitus had a significant negative association with TAQ (a-path), b = −0.21 (SE = 0.03), p < 0.001, and TAQ was significantly and negatively correlated with THI after the direct effect of self-rated loudness was taken into account (b-path), b = −1.27 (SE = 0.07), p < 0.001. The cross-product of these estimates (ab = 0.27) was significantly different from zero as evaluated with the normal theory test of the Sobel, z = 7.10, p < 0.001, as well as with the biascorrected CI method (i.e., bootstrapping), 95% CI LL = 0.20, UL = 0.35. This inference was not altered when anxiety and
TABLE 2. Hierarchical regression analysis predicting scores on the Tinnitus Handicap Inventory Unstandardized Coefficients Step
Predictor
B
SE
Standardized Coefficients β
p
1 Age Complex sound Tinnitus loudness Sound sensitivity
−0.27 6.95 0.48 7.96
0.09 2.17 0.05 2.95
−0.14 0.16 0.49 0.13
0.004 0.001
