Sound therapy (using amplification devices and/or sound generators) for tinnitus: Cochrane systematic review

Abstract

Background

Tinnitus affects 10% to 15% of the adult population, with about 20% of these experiencing symptoms that negatively affect quality of life. In England alone there are an estimated ¾ million general practice consultations every year where the primary complaint is tinnitus, equating to a major burden on healthcare services. Clinical management strategies include education and advice, relaxation therapy, tinnitus retraining therapy (TRT), cognitive behavioural therapy (CBT), sound enrichment using ear-level sound generators or hearing aids, and drug therapies to manage co-morbid symptoms such as insomnia, anxiety or depression. Hearing aids, sound generators and combination devices (amplification and sound generation within one device) are a component of many tinnitus management programmes and together with information and advice are a first line of management in audiology departments for someone who has tinnitus.

Objectives

To assess the effects of sound therapy (using amplification devices and/or sound generators) for tinnitus in adults.

Search methods

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL, via the Cochrane Register of Studies); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 23 July 2018.

Selection criteria

Randomised controlled trials (RCTs) recruiting adults with acute or chronic subjective idiopathic tinnitus. We included studies where the intervention involved hearing aids, sound generators or combination hearing aids and compared them to waiting list control, placebo or education/information only with no device. We also included studies comparing hearing aids to sound generators, combination hearing aids to hearing aids, and combination hearing aids to sound generators.

Data collection and analysis

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were tinnitus symptom severity as measured as a global score on multi-item tinnitus questionnaire and significant adverse effects as indicated by an increase in self-reported tinnitus loudness. Our secondary outcomes were depressive symptoms, symptoms of generalised anxiety, health-related quality of life and adverse effects associated with wearing the device such as pain, discomfort, tenderness or skin irritation, or ear infections. We used GRADE to assess the quality of evidence for each outcome; this is indicated in italics.

Main results

This review included eight studies (with a total of 590 participants). Seven studies investigated the effects of hearing aids, four combination hearing aids and three sound generators. Seven studies were parallel-group RCTs and one had a cross-over design. In general, risk of bias was unclear due to lack of detail about sequence generation and allocation concealment. There was also little or no use of blinding.

No data for our outcomes were available for any of our three main comparisons (comparing hearing aids, sound generators and combination devices with a waiting list control group, placebo or education/information only). Data for our additional comparisons (comparing these devices with each other) were also few, with limited potential for data pooling.

Hearing aid only versus sound generator device only

One study compared patients fitted with sound generators versus those fitted with hearing aids and found no difference between them in their effects on our primary outcome, tinnitus symptom severity measured with the Tinnitus Handicap Inventory (THI) at 3, 6 or 12 months (low-quality evidence). The use of both types of device was associated with a clinically significant reduction in tinnitus symptom severity.

Combination hearing aid versus hearing aid only

Three studies compared combination hearing aids with hearing aids and measured tinnitus symptom severity using the THI or Tinnitus Functional Index. When we pooled the data we found no difference between them (standardised mean difference -0.15, 95% confidence interval -0.52 to 0.22; three studies; 114 participants) (low-quality evidence). The use of both types of device was again associated with a clinically significant reduction in tinnitus symptom severity.

Adverse effects were not assessed in any of the included studies.

None of the studies measured the secondary outcomes of depressive symptoms or depression, anxiety symptoms or generalised anxiety, or health-related quality of life as measured by a validated instrument, nor the newly developed core outcomes tinnitus intrusiveness, ability to ignore, concentration, quality of sleep and sense of control.

Authors' conclusions

There is no evidence to support the superiority of sound therapy for tinnitus over waiting list control, placebo or education/information with no device. There is insufficient evidence to support the superiority or inferiority of any of the sound therapy options (hearing aid, sound generator or combination hearing aid) over each other. The quality of evidence for the reported outcomes, assessed using GRADE, was low. Using a combination device, hearing aid or sound generator might result in little or no difference in tinnitus symptom severity.

Future research into the effectiveness of sound therapy in patients with tinnitus should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies. We also recommend the use of validated, patient-centred outcome measures for research in the field of tinnitus.

Author(s)

Sereda Magdalena, Xia Jun, El Refaie Amr, Hall Deborah A, Hoare Derek J

Summary

Sound therapy (using amplification devices or sound generators) for tinnitus

Review question

Is sound therapy (using amplification devices, sound generators or both) effective for tinnitus in adults?

Background

Tinnitus is the awareness of a sound in the ear or head without any outside source. It affects 10% to 15% of the adult population. About 20% of people with tinnitus experience symptoms that negatively affect their quality of life including sleep disturbances, difficulties with hearing and concentration, social isolation, anxiety, depression, irritation or stress. Tinnitus can be managed through education and advice, relaxation therapy, psychological therapy, or devices that improve hearing or generate sound such as sound generators or hearing aids. Sometimes drugs are prescribed to manage problems associated with tinnitus such as sleep problems, anxiety or depression. The purpose of this review is to evaluate the evidence from high-quality clinical trials to work out the effects of sound therapy (hearing aids, sound generators and combination hearing aids) on adults with tinnitus. We particularly wanted to look at the effects of sound therapy on tinnitus severity and any side effects.

Study characteristics

Our review identified eight randomised controlled trials with 590 participants in total. Seven studies looked at the effects of hearing aids, four combination hearing aids and three sound generators. Seven studies allocated participants into parallel groups and in one study participants tried each intervention in a random order. The outcomes that we looked for were severity of tinnitus symptoms, depression, anxiety, quality of life and side effects. In general, the risk of bias in the studies was unclear. There was also little or no use of blinding.

Key results

We did not find any data for our outcomes for any of our three main comparisons (comparing hearing aids, sound generators and combination devices with a waiting list control group, placebo or education/information only). There were also few data for our additional comparisons (comparing these devices with each other) and it was difficult to pool (combine) the data.

Hearing aid only versus sound generator device only

One study compared patients fitted with sound generators with those fitted with hearing aids and found no difference between them in their effects on our primary outcome, tinnitus symptom severity, at 3, 6 or 12 months. The use of both types of device was associated with a clinically significant reduction in tinnitus symptom severity.

Combination hearing aid versus hearing aid only

Three studies compared combination hearing aids/sound generators with hearing aids alone and measured tinnitus symptom severity. When we combined the data for tinnitus symptom severity we found no difference between them. The use of both types of device was again associated with a clinically significant reduction in tinnitus symptom severity.

Adverse effects were not assessed in any of the included studies.

None of the studies measured depressive symptoms or depression, anxiety symptoms or generalised anxiety, or other important outcomes of interest in this review.

Quality of evidence

Where outcomes that we were interested in for this review were reported, we assessed the quality of the evidence available as low. Using a hearing aid, sound generator or combination device might result in little or no difference in tinnitus symptom severity.

Reviewer's Conclusions

Implications for practice

Sound therapy is the preferred mode of audiological tinnitus management in many countries, including the United Kingdom (Hall 2011). Postulated mechanisms through which sound therapy can be beneficial for tinnitus include reducing tinnitus intrusiveness, aiding habituation, distracting attention from tinnitus and triggering neuroplasticity within the brain (Hoare 2014a). However, we did not find evidence to support or refute the provision of sound therapy as the primary intervention for people with tinnitus. We did not find evidence to suggest that one type of sound therapy device (i.e. hearing aid, sound generator or combination hearing aid) is better than others. However, there were also no reports of adverse effects in the included studies.

In line with the lack of evidence for the effectiveness of sound therapy current tinnitus management guidelines do not make strong recommendations regarding its use in clinical practice and allow patients' preferences to play a significant role in the choice of this management option (Cima 2018; Tunkel 2014). The American Academy of Audiology Clinical Practice Guideline recommends that clinicians should offer a hearing aid evaluation for patients with hearing loss and persistent, bothersome tinnitus (Tunkel 2014). This recommendation was informed by findings from observational studies with a preponderance of benefit over harm and by the lack of high-quality evidence. Highlighted benefits of amplification in patients with hearing loss and tinnitus were improvement in communication function and health-related quality of life with "potential benefit for tinnitus relief". While a recent Cochrane Review found evidence of improvements in communication and general health-related quality of life in people with mild to moderate hearing loss (Ferguson 2017), the current review did not find evidence of benefit for tinnitus. More in line with the evidence presented here, the Multidisciplinary European Guideline for Tinnitus recommends hearing aids for the management of hearing loss and that they should be considered as an option for patients with tinnitus and hearing loss, but should not be offered to patients with tinnitus but without hearing loss (Cima 2018).

With regard to other sound therapy options, namely sound generators and combination hearing aids, neither Tunkel 2014 nor Cima 2018 made a recommendation because they judged the strength of evidence for effectiveness to be low. This is very much in line with the findings of this review. Tunkel 2014 stated that clinicians might recommend sound therapy to patients with persistent, bothersome tinnitus, with a significant role for the patient in deciding whether to pursue sound therapy and choosing among the available options. Cima 2018 concluded that sound therapy may be useful for the purposes of acute tinnitus relief but did not consider it to be effective over the long term.

Implications for research

Future research into the effectiveness of sound therapy in patients with tinnitus should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies (CONSORT 2010).

We also recommend the use of standardised and validated, patient-centred outcome measures for research in the field of tinnitus. Visual analogue scales have limited value in this regard because quantifying change using only a single item has inadequate measurement properties (e.g. internal consistency cannot be established and test-retest scores are at greater risk of instability). Although most recent studies included in this review used multi-item questionnaires of tinnitus symptom severity, other outcomes such as depressive symptoms or depression, anxiety symptoms or generalised anxiety and health-related quality of life were not measured. None of the studies reported adverse effects. In future trials, in addition to multi-item questionnaires of tinnitus symptom severity, validated instruments measuring depression, anxiety and health-related quality of life should also be used. Adverse effects such as increased tinnitus loudness and adverse effects associated with wearing the device such as pain, discomfort, tenderness, skin irritation or ear infections should be collected and reported.

At the time of the publication of this review, core outcome measures for adults with subjective tinnitus have only recently been identified (Hall 2018a). For sound-based interventions, these are tinnitus intrusiveness, ability to ignore, concentration, quality of sleep and sense of control. None of the trials directly reported any of the core outcome measures. Use of the core outcome set as a minimum standard for what should be assessed and reported in randomised controlled trials will facilitate comparison between studies and meta-analyses (Tunis 2016).

Given the heterogeneity of tinnitus patients, future trials should assess and report baseline characteristics so that the risk of potential confounding factors can be better understood. Examples include tinnitus duration, tinnitus symptom severity, age, hearing loss and co-morbidities since these might reasonably modify treatment success. Future trials might also consider, as a subgroup analysis, the differential effect of sound therapy on acute (i.e. less that three months duration) versus chronic (more than three months duration) subjective idiopathic tinnitus.

Currently there are no trials that consider the effectiveness of sound therapy for acute tinnitus. Only two included studies performed a sample size estimation (dos Santos 2014; Henry 2017), and even then not necessarily reaching the pre-specified targets (dos Santos 2014). Future studies should seek to recruit an adequate sample size based on an appropriate power calculation for the primary outcome.

Evidence for the effectiveness of hearing aids, combination aids and sound generators compared to no intervention, placebo intervention or education/information only is lacking and only a limited number of small-scale studies compared different sound therapy options (hearing aids, combination hearing aids and sound generators). Further research should concentrate on generating the evidence for the effectiveness of each of those management options for tinnitus, followed by trials comparing the effectiveness of different sound therapy options.

All studies included follow-up at three to six months, which was shown to be sufficient for demonstrating improvements with sound therapy (Hobson 2012). However, as the use of sound is intended to alter the tinnitus perception and/or the reactions to tinnitus, the timescale for different mechanisms of action might be different and extend beyond that limit (Hoare 2013). Future studies might consider including long-term follow-up in order to explore differences in the mechanisms of action of different sound therapy options (i.e. short- versus long-term intervention; Cima 2012) and changes in patterns of use (Sweetow 2015).

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