Post-market Clinical Follow-up of a Magnetic Bone Conduction Implant (Cochlear Baha Attract System)

The rationale behind this post-market clinical follow-up investigation is to collect data regarding the usability and clinical performance of the Baha Attract System in subjects with hearing impairment that are candidates for Baha surgery: to evaluate the efficacy of the Baha Attract System in terms of hearing performance compared to the unaided situation and compared to a pre-operative test situation using the sound processor on a Baha Softband; to evaluate the mid- and long-term safety of the Baha Attract System.

This investigation was designed to collect data regarding the usability and clinical performance of the Baha Attract System in subjects with hearing impairment that were candidates for Baha surgery. The investigation was performed in an open design since it was not possible to perform the investigation in a blinded fashion. The main evaluations of the investigation, i.e. free-field hearing tests, are standard audiological procedures that are routinely used in daily clinical practice at hospitals worldwide for evaluation of hearing performance in hearing impaired patients. The primary efficacy evaluation, audiometric thresholds, renders comparable results across different sites and countries as it is not a language-specific test. Language-specific audiological tests were performed as secondary efficacy evaluations; to enable comparison of data across sites, validated word lists were used at all sites and equivalent speaker configurations (speech from front, noise from behind) and test procedures (same noise and adaptive speech levels, etc) were used. For the primary evaluation in the investigation, the Baha Attract System was compared to the pre-operative unaided situation, as the intended use of the system is to improve hearing performance in patients with conductive or mixed hearing loss or single-sided sensorineural deafness. Audiological test results with the Baha Attract System were also compared against results obtained with the same Sound Processor on a Baha Softband. Use of the Sound Processor on a Softband is a standard procedure that is routinely used as a pre-operative test prior to bone conduction hearing implant surgery. The Softband test allows the patient to pre-operatively experience hearing through the Sound Processor to get an indication of the post-operative hearing outcome and to choose a suitable Sound Processor. The generic and hearing-specific quality of life questionnaires used in the investigation (HUI3, APHAB, SSQ) are validated scales that have been frequently used and reported in the literature.

This transcutaneous solution is based on a magnet coupling using magnets on both side of the skin; One implant magnet One external magnet on which a sound processor is attached, i.e. the Sound Processor magnet (SP magnet)

The Cochlear Baha Attract System incorporates both implantable and external parts. The implantable parts include the BI300 Implant and the BIM400 Implant Magnet, which is intended to be fixated to the BI300 Implant. The external parts include the Sound Processor Magnet (SP Magnet), which, together with the Implant Magnet, constitute the transcutaneous coupling. The SP Magnet incorporates a soft material (Soft pad) at the tissue facing surface that is designed to distribute the pressure over the skin. The Baha Sound Processor attaches to the SP Magnet via a snap coupling.

The change of hearing performance with the Baha Attract System (aided) at 6, 12 and 24 months from the unaided hearing performance before surgery; measured as free-field hearing tests: Threshold audiometry PTA4 (mean of 500, 1000, 2000 and 4000 Hz). The units reported for PTA4 are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

The change of hearing performance with the Baha Attract System (aided) from the unaided hearing performance before surgery; measured as free-field hearing tests: Threshold audiometry PTA4 (mean of 500, 1000, 2000 and 4000 Hz). The units reported for PTA4 are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

The change of hearing performance with the Baha Attract System (aided) from the unaided hearing performance before surgery; measured as free-field hearing tests: Threshold audiometry at frequencies of 250, 500, 1000, 2000, 3000, 4000 and 6000 Hz). The units reported for threshold audiometry are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

The change of hearing performance with the Baha Attract System (aided) from the unaided hearing performance before surgery; measured as free-field hearing tests: Threshold audiometry at individual frequencies 250, 500, 1000, 2000, 3000, 4000 and 6000 Hz. The units reported for threshold audiometry are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

The change of hearing performance with the Baha Attract System compared to the pre-operative unaided situation; Adaptive speech recognition in noise measured as signal to noise ratio The adaptive speech test in noise was conducted using validated lists of phonetically balanced sentences, with speech presented from the front (0 degrees azimuth) and noise from the back (180 degrees azimuth). The noise was kept constant at 65 dB SPL, and the speech was adapted in 2 dB steps to establish the speech-to-noise ratio (SNR) providing a 50% level of understanding. A ratio of 1 reflects the ability to correctly hear sentences at 65 dB, in the presence of 65 dB background noise. A lower ratio than 1 reflects the ability to correctly hear sentences below 65 dB. A ratio higher than 1 reflects the ability to correctly hear sentences presented above 65 dB. Manchester and Birmingham are excluded from this analysis due to incorrect set up.

The change of hearing performance with the Baha Attract System at 6, 12 and 24 months compared to the pre-operative unaided situation; Speech in quiet at 50, 65 and 80dB. Speech in Quiet is a measure of percentage of correct words. A higher score reflects a higher percentage of correct words.

The change of hearing performance with the Baha Attract System (aided) from the aided hearing performance, sound processor on a softband, before surgery; measured as free-field hearing tests: Threshold audiometry PTA4 (mean of 500, 1000, 2000 and 4000 Hz) The units reported for PTA4 are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

Hearing Performance: Threshold Audiometry Individual Frequencies: Baha Attract Versus Sound Processor on Softband

The change of hearing performance with the Baha Attract System (aided) from the aided hearing performance with Sound processor on a Softband before surgery; measured as free-field hearing tests: Threshold audiometry at individual frequencies 250, 500, 1000, 2000, 3000, 4000, 6000 Hz. The units reported for threshold audiometry are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

Hearing Performance: Threshold Audiometry Individual Frequencies: Baha Attract Versus Sound Processor on Softband

The change of hearing performance with the Baha Attract System (aided) from the aided hearing performance with Sound processor on a Softband before surgery; measured as free-field hearing tests: Threshold audiometry at individual frequencies: 250, 500, 1000, 2000, 3000, 4000, 6000 Hz. The units reported for threshold audiometry are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

Hearing Performance: Threshold Audiometry Individual Frequencies: Baha Attract Versus Sound Processor on Softband

The change of hearing performance with the Baha Attract System (aided) from the aided hearing performance with Sound processor on a Softband before surgery; measured as free-field hearing tests: Threshold audiometry at individual frequencies: 250, 500, 1000, 2000, 3000, 4000, 6000 Hz. The units reported for threshold audiometry are decibels (dB). As such, a lower or more negative score is more desirable and reflects the ability to hear softer sounds.

The change of hearing performance with the Baha Attract System compared to the pre-operative aided situation with Sound Processor on a softband; Adaptive Speech recognition in Noise measured as signal to noise ratio. A ratio of 1 reflects the ability to correctly hear sentences at 65 dB, in the presence of 65 dB background noise. A lower ratio than 1 reflects the ability to correctly hear sentences below 65 dB. A ratio higher than 1 reflects the ability to correctly hear sentences presented above 65 dB.

The change of hearing performance with the Baha Attract System at 6 months compared to the pre-operative aided situation with the Sound Processor on a softband; Speech in quiet at 50, 65 and 80dB. Speech in Quiet is a measure of percentage of correct words. A higher score reflects a higher percentage of correct words.

Change of health status and health related quality of life using the generic quality of life scale Health Utilities Index (HUI3) when wearing Baha Attract System compared to the pre-operative unaided situation. A health utility value of 1.00 indicates perfect health while a score of 0.00 indicates death. The change from unaided to aided hearing is presented. A positive value indicates an improved quality of life, a negative value indicates impaired quality of life. HUI score of 1 (maximum) describes a state of perfect health. HUI score of 0 describes a state of dead. A negative score of Comprehensive Health State describes a state worse than dead.

Measuring change of Ease of communication, Reverberation, Background noise, Aversiveness and a Global score with the Baha Attract System from the pre-operative unaided situation. The absolute APHAB scale is between 0 and 100%, where 0% indicates no problems and 100% indicates always problem. The change from unaided to aided hearing is presented. A positive value indicates an improvement, a negative value an impairment.

Measuring change of speech, spatial and hearing experiences with the Baha Attract System from the pre-operative unaided situation. A scale from 0 to 10, where 0 represents "can not hear at all", and 10 "hear perfectly". The change from unaided to aided hearing is presented. A positive value indicates improved hearing, a negative value indicates impaired hearing.

To investigate if the magnetic force required for sound processor magnet retention will change over time

To investigate how sound processor magnet choice will change over time. Six different magnetic strength could be chosen; SPM 1 had the lowest strength and SPM 6 the the highest.

Inclusion Criteria: Adult subject, i.e. ≥ 18 years of age Conductive or mixed hearing loss in the ear to be implanted: Bone conduction thresholds with a pure tone average PTA4 of < 30 dB hearing level (mean of 500, 1000, 2000 and 4000 Hz). OR Single-sided sensorineural deafness (SSD): European sites: Bone conduction thresholds with a pure tone average PTA4 of < 30dB hearing level (mean of 500, 1000, 2000 and 4000 Hz) in the good ear. US sites: Air conduction thresholds with a pure tone average PTA4 of 20 dB hearing level (mean of 500, 1000, 2000 and 3000 Hz) in the good ear OR Subject is indicated for an AC CROS but-for some reason-cannot or will not use an AC CROS. No previous bone conduction implant on the side of the skull to be implanted. Signed informed consent. Exclusion Criteria: Subjects that are scheduled for simultaneous bilateral implant surgery. The investigation is limited to subjects with unilateral use of the Baha Attract System (however, bilateral hearing loss is not an exclusion criterion). Suitable implant position for the BI300 Implant (4 mm or 3 mm) not found during surgery due to insufficient bone quality and/or bone thickness. Less than 3 mm soft tissue thickness at the planned implant site. Subjects that have received radiation therapy at the same side of the skull where the Baha Attract System will be positioned. Condition that could jeopardise osseointegration and/or wound healing as judged by the investigator (e.g. osteoporosis, psoriasis, use of corticosteroids). Uncontrolled diabetes as judged by the investigator. Condition that may have an impact on the outcome of the investigation as judged by the investigator. Unable to follow investigational procedures (e.g. to complete quality of life scales). Participation in another investigation with pharmaceuticals and/or medical device.