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Bonebridge® – ZA Application Nov 2012 Príloha 2: Klinický prínos používania zdravotníckej pomôcky Summary of conditions the Bonebridge is to be used for Under the current indications, the Bonebridge is used to treat adult patients (18 years of age or older), with conductive or mixed hearing loss (C/MHL). It is indicated for use in persons, who have a mild-tomoderate hearing loss indicated by bone conduction thresholds up to 45 dB HL. Additionally, patients with single-sided sensorineural deafness (SSD), which is a severe-to-profound sensorineural hearing loss (SNHL) in one ear while the other ear has normal hearing, can be treated effectively. Hearing impairment can have a significant negative impact on individuals and on society. Seen from the cultural perspective, two models are commonly used to socially situate people with hearing loss: Medical-disability model. The vast majority of people with hearing loss acquire a mild to moderate hearing loss in adult life, while a small number of people acquire deafness during childhood. People with acquired hearing loss commonly understand hearing loss as a sensory deficit within the body. For them, hearing loss can be appropriately described as a disability for which aids, devices and therapies can be indicated for. The most common reported consequence of hearing loss in this group is a loss of social participation, such as being unable to follow conversations in noisy social settings. This group often finds hearing loss stigmatizing and therefore may be less ready to take up the services on offer or to utilize commonly recommended communication strategies. For this group, hearing loss can be appropriately described as a burden within the context of the disease model. Cultural-linguistic model. By contrast, people who are born with a severe to profound hearing loss may grow up in or later join the Deaf Community. Within the Deaf Community deafness is understood as a cultural-linguistic experience. Rather than being a source of stigma, deafness is a source of pride and cultural identity. This group would define the social consequences of hearing loss in terms of reduced social participation in the broader community, and encounter the impacts of deafness in terms of socio-economic loss and reduced social interactions rather than perceiving it as a burdensome disease. Irrespective of differing cultural constructions underpinning perceptions of deafness, people who experience deafness in any form encounter communication difficulties in specific social settings. Such difficulties can result in personal, health and social consequences as well as educational and occupational progress and stability, therefore social integration. Hearing impairment does not necessarily equate to ‘disability’, ‘burden’ or ‘handicap’. Noble (1991) pointed out that an assessment of the existence of a hearing loss in itself yields little information about the exact nature of the disability or social limitation experienced by the affected individual. A person's perception of the level of difficulty caused by their hearing loss (what used to be called their hearing handicap, but now is defined in terms of social participation) may vary from individual to individual. For example, a lecturer with mild hearing loss may experience severe hearing handicap simply trying to interact with students in a lecture theatre – hearing loss reduces their capacity to work and relate effectively. Stressors are associated with this experience. By contrast, a metal worker with advanced Document1 -1- Bonebridge® – ZA Application Nov 2012 hearing loss living alone may experience little hearing handicap if he has few difficult communicative interactions. Lutman et al. (1987) observed that as the level of measured impairment increased, the likelihood of communication difficulties increased too. Cruickshanks et al. (1998) reported that the percentage of people reporting a hearing handicap increased with severity of loss: – 5.5 %, 19.7 %, 47.5 % and 71.4 % for none, mild, moderate and severe losses respectively (p for trend < .001). As such, people may choose to restrict their social, recreational or professional activities because of their hearing loss. The degree of handicap or participation restriction is usually assessed using a self-report scale. Noble (1991) states that: "(W)ithout direct inquiry into the lives and circumstances of the people who manifest signs of impairment on these tests, little useful knowledge is gained about the disabilities (functional hearing incapacities in the everyday world) and none whatever about the handicaps (the disadvantages for everyday living) experienced as a consequence of the impairment". Other authors (Hawthorne and Hogan, 2002; Dillon, 2001) have shown that measures of hearing social participation are strongly associated with health related quality of life and also observed that hearing loss is associated with a cascade of negative events: “Hearing impairment decreases a person’s ability to communicate. Decreased communication with others can lead to a range of negative emotions such as depression, loneliness, anxiety, paranoia, exhaustion, insecurity, loss of group affiliation, loss of intimacy and anger” (Dillon, 2001). Hearing loss can differ from one ear to the other (asymmetrical hearing loss). As a result of this, prevalence rates can be reported for either the better or the worse ear in terms of the level of hearing loss. Asymmetrical hearing loss results in problems with for instance the spatial identification of sound (not being able to tell where a speaker’s voice is coming from) and auditory discrimination (picking up foreground sounds from background sounds), resulting in practical problems like not being able to function in meetings or social settings especially when people are on the side of their ‘worse ear’. Having better hearing in one ear than the other impacts on the ability to communicate and may lessen the overall effect of the impairment in the worse ear. Given this outcome, disability has been defined on measures of the better ear in epidemiological hearing studies (Davis, 1989; Wilson et al, 1998), and this approach has also been adopted in this study. Differences in hearing difficulties rather than hearing loss are not expressed by an audiogram, although the level of hearing handicap may be "more highly correlated with measures of impairment in the worse ear than in the better ear" (Lutman et al, 1987). Document1 -2- Bonebridge® – ZA Application Nov 2012 HEARING LOSS AND COMORBIDITIES Hearing loss has been described as an under-estimated health problem (Wilson et al, 1992). Adult hearing loss in general is associated with an increased risk for a variety of health conditions including: diabetes (Wilson et al, 1992; Mitchell, 2002); stroke (Mitchell, 2002); elevated blood pressure (Wilson et al, 1992); heart attack, particularly for those rating their hearing as poor (Hogan et al., 2002); psychiatric disorder, particularly for those rating their hearing as poor (Hogan et al., 2001); affective mood disorders (Ihara, 1993; Mulrow et al, 1990); poor social relations (Mulrow et al, 1990); higher sickness impact profiles, physical and psycho-social (Bess et al, 1989); reduced health related quality of life, particularly for those with more severe hearing loss (Wilson, 1999). While hearing loss has been associated with a number of conditions that are life threatening (e.g. diabetes) and with social isolation that may also lead to premature mortality, no direct causality has been found between hearing loss and increased mortality or injury rates. However, apart from the greater use of medication and, for people with severe hearing loss only, an elevated utilization of GP services, health system service utilization was not significantly greater for people with hearing loss. Nevertheless, the need for help was significantly greater for all levels of hearing loss. On average, people with hearing loss delay seeking help for their disability by six years after realizing they are experiencing difficulties. There are two key factors that motivate a person to seek help for their hearing loss. First, their hearing problems become so unmanageable that they can no longer deny they have a hearing problem; and secondly, family members, tired of communication difficulties, bring pressure to bear on them to do something about their hearing problem. (Kochkin, 1999). Early intervention in hearing loss may serve to avert these difficulties or minimize their impact. Adult-onset hearing loss is ranked second as a leading cause of years lived with a disability (YLAD) and fifteenth as a leading cause of the global burden of disease. The World Health Organization has identified hearing loss as a strategic target and is introducing programs aimed at eliminating 50 % of the burden of avoidable hearing loss. Nevertheless, it remains very difficult to correlate hearing loss with direct or indirect costs for the society. A recent study by Hjalte et al. (2012) came to the conclusion that international studies with a societal perspective were limited to specific patient populations, and in most cases used different costing methods. Hearing disorders impact the social welfare system more than the medical care system. Indirect costs account for the major part and direct medical costs account for a minor part of the total costs of hearing disorders. Document1 -3- Bonebridge® – ZA Application Nov 2012 Summary of Evidence As the Bonebridge is brand-new to the market, the evidence for the device in terms of economic issues as well as adverse events is limited. Evidence for Conductive and mixed HL For safety and efficacy, data will presented in the following chapters from a study that is already submitted (Sprinzl et al, submitted in 2013). Study design The purpose of this study is to establish the safety and efficacy of the transcutaneous bone conduction implant for the treatment of conductive and mixed hearing losses with an up to moderate inner ear impairment. The device was implanted and evaluated in human subjects, with a three-month follow-up period. The study was a prospective, single-subject repeated-measures design, in which each subject served as his/her own control. Performance on audiometric tests pre-operatively was compared to the aided three-month’s post-operative condition using the Bonebridge. This type of design has been applied frequently to the evaluation of implantable hearing devices in multi-centre clinical trials (Baumgartner et al, 2010; Mylanus et al, 1994b; Chen et al, 2004). It minimizes the effect of variability inherent to the population to the evaluation of treatment outcomes. Standardized evaluation methods were used, to assure the reliability of the data across different investigational centres. Subjects Twelve German-speaking adults for whom an improvement of hearing either by otologic surgeries or by conventional hearing aid fitting was not possible or not successfulwere enrolled at four otorhinolaryngology departments in Austria (University Clinic Innsbruck) and Germany (Unfallkrankenhaus Berlin, Hannover Medical School and University Clinic Würzburg). Subject demographics and medical factors are provided in Table 1. Document1 -4- Bonebridge® – ZA Application Table 1: Nov 2012 Demographic data and medical parameter disease factors of the twelve study participants. Demographics Subject Age at number surgery Disease factors and medical history Sex Study site Implanted No. prior Duration of Type of ear ear surgeries HL (yrs) HL Aetiology PTA4 BC PTA4 AC implanted ear implanted ear (dB (dB HL) HL) 1 69 m Berlin R 2 60 CHL cholesteatoma 5 45 2 69 f Berlin R 4 60 CHL cholesteatoma 19 46 3 44 f Berlin R 2 9 mixed otosclerosis 35 50 4 28 m Hannover R 2 15 CHL COM 6 30 5 65 f Hannover R 1 2 CHL glomus tumour 6 66 6 65 f Hannover L 1 1 mixed chronic mastoiditis 14 53 7 63 f Hannover L 3 22 mixed COM 18 67 8 35 m Würzburg R 5 35 CHL cholesteatoma 8 49 9 20 f Innsbruck L 2 20 CHL atresia auris 11 73 10 19 f Innsbruck R 2 19 mixed cholesteatoma 21 61 11 28 f Innsbruck R 0 28 mixed atresia auris 25 93 12 27 f Innsbruck R 1 27 CHL atresia auris 15 73 Document1 -5- Bonebridge® – ZA Application Nov 2012 Data Collection and Statistics Audiometric testing was carried out in an audiometric sound-attenuated room, using calibrated signals and equipment. Subjects were tested unaided pre-operatively, and one and three month postimplantation in the aided condition with the Bonebridge. Speech perception in quiet was tested using the Freiburger Monosyllable Test (word recognition score presented at 65 dB SPL, Hahlbrock, 1970) and the German OldenburgerSatztest (OLSA, speech reception threshold for 50 % word intelligibility in sentences, Wagener et al, 1999). Sound field thresholds (warble tones) were tested at 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz, and 8 kHz, respectively, with the subject sitting one meter in front of (0° azimuth) and level with the loudspeaker. The contralateral ear was plugged and covered and narrow-band masking noise was applied if necessary. Audiometric pure tone thresholds were determined for air conduction at 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz, and 8 kHz, respectively, signals were delivered to the subjects under headphones. Bone conduction thresholds were determined at 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, using a calibrated bone conduction vibrator. Repeated-measure Analysis of Variance (ANOVA) was performed for all speech tests. The specific hypotheses for effectiveness were: that the word recognition score would improve through the treatment, that the SRT50 % would decrease as a result of the treatment, and that post-implantation aided sound field thresholds would improve when compared to those obtained unaided pre-operatively. The specific hypothesis for safety was that residual hearing, as measured by bone conduction thresholds (pure tones), would not decrease significantly in subjects as a result of the treatment. As device installation takes place apart from inner or middle ear structures, there was expected to be little or no risk to residual hearing in these patients.A decrease of 5 dB HL or less at a particular frequency would be within test-retest reliability and would not be considered clinically significant (Stuart et al, 1991). Subjective Device Satisfaction was tested by means of the Hearing Device Satisfaction Scale (HDSS) questionnaire. This self-assessment questionnaire was repeatedly used in other studies on implantable hearing devices and evaluates the user’s general satisfaction with the hearing device (Luetje et al, 2002; Baumgartner et al, 2010). The answer categories were transformed into a percentage score from 100 % (very satisfied) to 0 % (not satisfied) based on the answers given. Statistical analyses were performed using IBM SPSS Statistics 19 (IBM, Armonik, New York). One-way repeated measure ANOVAs with time as factor were performed (significance was accepted at p ≤ 0.05) and followed by post-hoc pairwise comparisons to examine significant differences between the single test intervals. For each ANOVA Mauchly`s test of sphericity was applied. If sphericity could not be assumed, a Greenhouse-Geisser correction was used as part to the ANOVA. P-values of the pairwise comparisons were adjusted with the Holm-Sidak method. Box-Whisker Plots represent the whole data set. Whiskers extend to the maximum value within 1.5 times the interquartile range (IQR) above the third quartile or the minimum value within 1.5 times the IQR below the first quartile. Values outside of this range are considered to be outliers, depicted as individual dots. Tukey box-whisker plots were generated using GraphPad Prism 5 (http://www.graphpad.com). Document1 -6- Bonebridge® – ZA Application Nov 2012 Results Mean unaided word recognition scores (Figure 1) averaged 14.2 % (SD ± 18.1) pre-operatively, compared to 82.9 % (SD ± 12.5) one month post-implantation and 92.9 % (SD ± 6.9) three months post-implantation. Repeated-measure ANOVA indicated a significant change with respect to time (F(2, 22) = 195.07, p < 0.001). Post-hoc pairwise comparisons confirmed that scores improved significantly between pre-operative testing and one month after implantation (p < 0.001), between pre-operative testing and three months after implantation, and from one to three months (p = 0.010). Figure 1: Word recognition scores in quiet (Freiburger monosyllables) for the implanted ear: pre-operative, one month post-operative and three month post-operative. Both postoperative scores are significantly improved from pre-operative scores (p < 0.001) and from each other (p = 0.010), n = 12. Prior to implantation the mean OLSA SRT 50 % thresholds (Figure 2) averaged 61.9 dB (SD ± 8.6), compared to 42.0 dB (SD ± 8.9) one month, and 36.6 dB (SD ± 8.8) three months post-implantation. Repeated-measure ANOVA indicated a significant change over time (F(2, 20) = 41.282, p < 0.001). Posthoc pairwise comparisons indicated significant improve-ments from pre-operative to one month testing (p < 0.001), pre-operative to three month testing (p < 0.001) and between one and three month testing (p = 0.035). Document1 -7- Bonebridge® – ZA Application Nov 2012 Figure 2: Speech Reception Threshold (SRT 50 %) in quiet for the implanted ear: pre-operative, one month post-operative and three month post-operative. Both post-operative scores are significantly improved from pre-operative scores (p < 0.001) and from each other (p = 0.035), n = 12. Audiometric thresholds for air conduction (Figure 3) and bone conduction (Figure 4) showed no significant change with respect to time, at the 5 % significance level, for any of the tested frequencies. Conversely, sound field testing (Figure 5) showed a significant improvement over time at the 5 % significance level for warble tones at all tested frequencies, and at the 0.1 % significance level for frequencies from 500 Hz to 6 kHz. Document1 -8- Bonebridge® – ZA Application Nov 2012 Figure 3: Mean air conduction thresholds for the implanted ear: pre-operative unaided testing compared to three-month postoperative aided tests. Error bars represent ± 1 SD (n = 12). Figure 4: Mean BC thresholds for the implanted ear: pre-operative unaided testing compared to three-month postoperative aided tests. Error bars represent ± 1 SD (n = 12). Document1 -9- Bonebridge® – ZA Application Nov 2012 Figure 5: Mean sound field thresholds (warble tones) for the implanted ear: pre-operative unaided testing compared to three-month postoperative aided tests. Error bars represent ± 1 SD (n = 12). Subjective hearing device satisfaction ranged from 49 % to 99 % with a mean of 79 % (Figure 6). Figure 6: Hearing Device Satisfaction Scale (HDSS): Individual and mean scores across all subjects (n=12). F-statistics and p-values obtained from repeated-measure ANOVAs for the three different audiometric tests at seven frequencies are presented in Table 2. Document1 - 10 - Bonebridge® – ZA Application Table 2: Nov 2012 F statistics and p values from ANOVA analysis of audiometric tests (pre-operative, one month post-operative and three month postoperative; n=12). 500 Hz 1 kHz 2 kHz 3 kHz 4 kHz 6 kHz 8 kHz F(2,22) p F(2,22) p F(2,22) p F(2,22) p F(2,22) p F(2,22) p F(2,22) p Air conduction (Figure 3) 0.394 0.68 0.555 0.58 0.681 0.52 0.723 0.50 1.00 0.38 0.726 0.50 0.032 0.97 Bone conduction (Figure 4) 0.919 0.41 1.00 0.38 1.16 0.33 1.61 0.22 1.46 0.25 – – – – Sound field (Figure 5) 14.7 <0.001 48.1 <0.001 24.3 <0.001 64.8 <0.001 61.8 <0.001 28.7 <0.001 5.00 0.036 Document1 - 11 - Bonebridge® – ZA Application Nov 2012 These results indicate the effectiveness of the Bonebridge, the first transcutaneous bone conduction implant system. Subjects’ word recognition scores increased to a level comparable with and in excess of studies carried out with other successful implanted hearing devices (Håkansson et al, 1994; Baumgartner et al, 2010). Improvements to subjects’ speech recognition thresholds, from 61.9 dB pre-operatively to 36.6 dB after three months, were also comparable to published results from bone conduction and BAHA studies (Håkansson et al, 1994; Mylanus, 1994c). Subjects’ word recognition and speech recognition results improved from one month to three month post-implantation, suggesting that during this period of acclimatization auditory comprehension with the device continued to improve. The secondary hypotheses that audiometric sound field thresholds will improve upon treatment can also be confirmed. Mean aided sound field thresholds (warble tones) improved after treatment by more than 10 dB across all tested frequencies. The maximum output force level (OFL dB re 1 µN) reachable with the system at full-on gain setting for input levels of 65 dB SPL is typically around 114 dB µN. In the present study, the mean output force level across study subjects for input levels of 65 dB SPL is 89.9 dB µN (range 83 – 99 dB µN). Consequently, the system provides an additional gain reserve. It could be utilized for patients with poorer bone conduction thresholds than the ones evaluated within the present cohort. Additionally, the audio processor makes use of wide dynamic range compression. The mean compression ratio across all study subjects and over all frequencies is 1:1.48, with a mean compression knee point set to 42.2 dB SPL. The fitting software allows compression ratios up to 1:4, showing that higher compression ratios can be applied to subjects with a more narrow dynamic range. Mean air conduction and bone conduction thresholds did not change by more than 5 dB at any tested frequency. This confirms that, as expected, the treatment did not degrade the subjects’ residual unaided hearing capabilities and therefore indicates a good level of safety. Document1 - 12 - Bonebridge® – ZA Application Nov 2012 Evidence for SSD indication The main objective of this literature review for SSD Indication is to identify clinical data to establish the efficacy of bone conduction devices in patients with single sided deafness. The literature review aims to provide evidence for audiological benefit in terms of speech perception in noise in patients implanted with the BAHA by augmenting the hearing and providing a degree of usable hearing. It also has the goal to establish subjective benefit experienced by the patients implanted with the BAHA. Inclusion criteria The author’s conclusions are substantiated by available data (provide evidence and rationalisation for any claims). The work reflects current medical practice. Information presented in the literature follows scientific principles (in structure, methodology, and analysis in order to avoid or minimize any possible bias). Clinical trials in humans. Exclusion criteria Not a clinical trial in humans - See inclusion criteria. Random experience – Individual case stories, editorials, letters will be excluded from the literature review as they are limited in the information contained to undertake an objective assessment. Unsubstantiated claims and opinions – As discussed above all claims must be statistically justified to support any claims made otherwise literature will be excluded from the review. Repeated Hits – Repeat literature obtained from search engines will be excluded accordingly. Reports lacking sufficient detail to permit scientific evaluation – Literature must contain adequate detail to enable a firm evaluation of the procedures employed and results obtained hence absence of this will exclude the literature from this review. Publications that do not follow scientific principles – (as explained in the inclusion criteria). Material not pertinent to the topic – Unrelated literature is excluded from the literature review. Age of literature: Literature older than 24/02/2003 are excluded from the literature review as single sided deafness is a more recently investigated topic with relevance to this literature review hence older literature is deemed out of date for this topic. Document1 - 13 - Bonebridge® – ZA Application Nov 2012 Sample Size – The sample size must consist for 15 patients or above to represent an adequate population. Date of search Two PubMed searches were conducted on 24 Mar 2010 and 18 Aug 2011. An additional hand-search was done to cover articles published in 2012. Sources searched The following sources were used to conduct a systematic search for appropriate documents and data: Published literature was taken from recognized scientific publications including favourable as well as unfavourable data. PubMed (http://www.ncbi.nlm.nih.gov/sites/entrez?db=PubMed) The key words which were utilized for the searches included the following (Table 3): Single Sided Deafness Unilateral Hearing Loss + BAHA Single Sided Hearing Loss + BAHA Table 3: Strategies for information retrieval Criteria Search Terms Number of Articles 1 Single Sided Deafness 22 resp. 22 (total 44) 2 Unilateral Hearing Loss + BAHA 40 resp. 27 (total 67) 3 Single Sided Hearing Loss + BAHA 13 resp. 16 (total 29) Following the exclusion criteria mentioned above and the removal of duplicates, 28 resp. 39 (total 67) publications were primarily identified. The literature reviewed focuses on the primary issue of SSD and the use of BAHA to assist in reducing the handicap caused by it. The literature reviewed embarks upon the aims stated above by demonstrating the ability of the BAHA to augment the hearing in an SSD individual as well as supporting the subjective benefits experienced. Document1 - 14 - Bonebridge® – ZA Application Nov 2012 Does BAHA provide sufficient hearing improvement to facilitate speech understanding in noise for individuals with SSD? It is well documented that the BAHA provides significant useable hearing for an individual with SSD. This is especially supported when hearing in noise as this is one of the greatest difficulties reported by monoaural listeners. The literature reviewed clearly emphasised that the BAHA is able to overcome this deficit by directly stimulating the functioning cochlea and allowing the individual to benefit from the improved speech recognition in noise. This is demonstrated with assessments unaided and aided with the BAHA [Annex 1, Lit. 5, 7, 14, 15, 19, 21, 25, 31, 32, 33, 34, 35, 37, 40]. One study focusing on paediatric patients concluded that the BAHA is a viable treatment option for children with unilateral profound sensorineural hearing loss and a noticeable improvement can be observed when hearing in noise and difficult listening situations. Hearing in noise is a crucial element of binaural hearing by combining the sound and articulation by the speaker one can comprehend what is being said depending on the level of background noise present [Annex 1, Lit. 1]. Yuen et al, 2009 [Annex 1, Lit. 5]investigated the management of SSD with the BAHA and concluded that speech reception thresholds in the presence of noise were improved due to the overcoming of the head shadow effect hence expanding the sound field. Linstrom et al, 2009[Annex 1, Lit. 8]found that the BAHA yielded 39.8 % gain in speech intelligibility whilst the directional BAHA yielded 31.6 % gain in speech intelligibility under the lateralised speech to the bad ear condition. Hence stating that the findings substantiated the BAHA’s efficacy in lifting the head shadow effect and enhancing communication ability in difficult listening situations for an SSD individual. Snapp et al, 2010 [Annex 1, Lit. 31]made an assessment, which was comprised of four questions specific to deficits experienced by patients with SSD. Two questions deal with speech discrimination and the last two questions are related to difficulties due to head-shadow effect and sound localization. The results support the use of speech-in-noise measures as an accurate predictor of overall benefit in patients with SSD prior to implantation. Hearing in noise is a complication experienced by an individual with SSD and this can have detrimental effects upon their quality of life which include but are not limited to social and psychological implications. Withdrawal and embarrassment may be common in such people due to their disability and typically not being able to interact with others adequately may lead to such isolation and reduced quality of life and low self-esteem. Does BAHA improve the sound localisation for individuals with SSD? Sound localisation is a vital cue in determining the source of an incoming sound. The use of binaural hearing enables one to judge better the direction of such a sound. However when binaural hearing is not possible and one must rely on monaural hearing then this may hamper one’s ability to distinguish the direction of a sound. Such difficulties are experienced by SSD individuals. The literature reviewed was sceptical at times regarding the benefits of sound localisation in SSD individuals. Some of the studies reported of no deterioration in sound localisation using the BAHA however benefit was also related to chance, not significant or no difference [Annex 1, Lit. 7, 13, 21, 17, 29, 32, 33]. For example according to Document1 - 15 - Bonebridge® – ZA Application Nov 2012 Kompis et al, 2011 [Annex 1, Lit. 29]the smallest benefit was reported for sound localization. Saliba et al, 2009 [Annex 1, Lit. 8] investigated that BAHA prosthesis in SSD patients cannot restore sound localizationeven after 6 months of use. However on the contrary Barbara et al, 2009 [Annex 1, Lit. 15]reported of an improvement in directional speech perception and sound localisation for SSD patients in their study. It was also claimed that sound localisation was greatly improved after BAHA implantation in comparison to the pre-operative condition. Sound localisation was found to significantly improve in the patients with an average improvement of 25° at 500 Hz and 19° at 3000 Hz. Snapp et al, 2010 [Annex 1, Lit. 31] (as mentioned above regarding hearing-in-noise) made an assessment, which was comprised of four questions specific to deficits experienced by patients with SSD. Two questions deal with speech discrimination and the last two questions are related to difficulties due to head-shadow effect and sound localization. They found improvement in sound localization. Does the BAHA provide significant subjective benefit to an individual with SSD? Patient outcome assessments post medical interventions have become increasingly popular in combination with audiometric assessments [Annex 1, Lit. 13]. This recognises that the aim of the intervention is that there is a benefit to the patient or the patient perceives a benefit. Dumper et al, 2009[Annex 1, Lit. 7]in their study found limited audiological benefit in the SSD subjects however a subjective benefit was reported, hence demonstrating the importance of subjective outcomes in collaboration with audiological outcomes. Lin et al, 2006 [Annex 1, Lit. 21] compared the audiological and subjective outcomes in patients by comparing the BAHA to the CROS aid. Subjects reported of greater benefit from the BAHA than the CROS aid and generally a poor acceptance of the CROS aid was reported. Similar outcomes were reported by Wazen et al, 2003 [Annex 1, Lit. 14] when comparing the BAHA to the CROS aid with patients reporting of a significant improvement in speech intelligibility in noise and greater benefit from the BAHA in comparison to the CROS aid. However Hol et al, 2004 [Annex 1, Lit. 25]investigated the BAHA CROS combination and reported of positive outcomes with speech in noise demonstrating the ability of the BAHA CROS to overcome the head shadow effect. This was supported by opinions measured using the APHAB questionnaire. The literature reviewed provided strong emphasis on subjective outcome measures for the BAHA. The subjective questionnaires used studies reported of clear positive outcomes reported by the patients [Annex 1, Lit. 1, 5, 7, 8, 14, 15, 19, 21, 27, 32, 33, 34, 35, 38]. This provides crucial evidence that there is a benefit for the end user hence supporting the need for patients with such hearing impairments to be able to benefit from the available hearing augmentation devices to help improve their quality of life. Christensen et al, 2010[Annex 1, Lit. 1]investigated the BAHA in paediatric patients and further supported the positive subjective response to the use of BAHA by claiming that the patient satisfaction improved and remained high for at least 1 year after fitting. Yuen et al, 2009 [Annex 1, Lit. 5]in their study supported the satisfaction by reporting the average daily use of the BAHA to be 5.6 day a week for an estimated mean duration of 11.4 hours per day in 16 patients. House et al, 2010 [Annex 1, Lit. 38] investigated that the Document1 - 16 - Bonebridge® – ZA Application Nov 2012 Speech, Spatial, and Qualities of Hearing Questionnaire (SSQ) demonstrated specific situations where the BAHA is most useful. The BAHA improves speech understanding in most environments (including environments with excessive background noise). Most improvement with the BAHA was seen in the Background noise subscale, with a 17.7 % improvement. Ease of Communication and Reverberation subscales also demonstrated an 11.6 % and 13.2 % benefit, respectively. Patients with a BAHA demonstrated better scores in the SSQ Speech subscale when compared to unilaterally deaf patients who did not have a BAHA, although this difference was not significant. However in literature there are also comments were the effort of BAHA in SSD is less successful. For example according to Martin et al, 2010 [Annex 1, Lit. 33]Bone-anchored hearing aid rehabilitation for single sided deafness isless successful than for other indications. There was also no significant difference between control and bone-anchored hearing aid users in the Speech and Spatial Qualities of Hearing Questionnaire. Patients with a longer duration of deafness report greater subjective benefit than those more recently deafened, perhaps due to differing expectations. All in all BAHA showed in almost all investigations audiometric benefit [Annex 1, Lit. 1, 4, 5, 8, 11, 13, 14, 15, 19, 21, 25, 27, 31, 32, 33, 34, 35, 36, 37, 38, 40]. According to Gluth et al, 2010[Annex 1, Lit. 35] BAHA implantation seems to provide a high level of short-and long-term perceived benefit and satisfaction in subjects with PUSHL (profound unilateral sensorineural hearing loss) and high rate of long-term device usage. In conclusion, the benefits of the BAHA in cases of SSD are well documented with favourable subjective outcomes strongly supporting the application. The BAHA as explained above has very similar applications to the Bonebridge. However, there are key differentiations which may favour the application of the Bonebridge. The main differentiation is that the BAHA has percutaneous coupling which in essence is the needle punching through the skin leaving the patient with an open wound which must be managed daily with a good level of hygiene as the wound is prone to infection. These issues with percutaneous coupling have been well documented and are a key factor when comparing the BAHA against the Bonebridge which is a transcutaneous system. As discussed earlier the benefits to individual with SSD are expected to be very similar to those experienced with the BAHA however a lower risk of complications is expected with the Bonebridge as oppose to the BAHA. These risk factors are appropriate in any otologic surgery so do not apply exclusively to vulnerability in the device but elements associated to the surgery and preparation. The literature reviewed demonstrates a clear advantage to subjects in terms of subjective benefit patients [Annex 1, Lit. 1, 5, 7, 8, 14, 15, 19, 21, 27, 31, 32, 33, 34, 35, 36, 37, 38, 40] which is crucial for such individuals in terms of enhancing their quality of life and being able to offer them with a rehabilitation method that benefits them. It can also be deduced that patients implanted with bone conduction implants experience better speech perception in noise [Annex 1, Lit. 5, 7, 14, 15, 19, 21, 25, 31, 32, 34, 38, 40]. Hence demonstrating the audiological benefit experienced by bone conduction devices and these outcomes are also expected with the Bonebridge. Overall taking into account all of the factors discussed during the course of this review it can be concluded that the Bonebridge is clinically Document1 - 17 - Bonebridge® – ZA Application Nov 2012 equivalent to the BAHA (an already approved device for SSD in adults and children) with potentially lower risk of complications. The literature reviewed substantially supports the aims of this review in terms of subjective benefit and audiological benefit as stated in the aims. Document1 - 18 -