Clinical and Health Economic Evaluation With a New Baha® Abutment Combined With a Minimally Invasive Surgical Technique

Clinical and Health Economic Evaluation With a New Baha® Abutment Combined With a Minimally Invasive Surgical Technique

Clinical and Health Economic Evaluation of a New Baha® Abutment, With a Minimally Invasive Surgical Technique. An International Multicentre, Open, Randomised, Comparative, Parallel Group, Investigation. 1y Investigation, 2y Follow-up

To demonstrate that the minimally invasive surgical procedure in combination with the use of the Cochlear Baha BA400 abutment is associated with a reduction of inflammation/infection, overgrowth, pain and numbness at the site of implantation compared to the traditional surgical procedure in combination with the use of the standard Baha abutment (Cochlear Baha BA300 Abutment). To demonstrate that the minimally invasive surgical procedure in combination with the use of the Cochlear Baha BA400 abutment is associated with a reduction in direct medical costs, due to shorter surgical procedures, faster wound healing and less complications compared to the traditional surgical procedure in combination with the use of the standard Baha abutment (Cochlear Baha BA300 Abutment).

Despite extensive soft tissue reduction, the most common complications associated with Baha implants are related to adverse skin reactions around the abutment. The reduction of the skin also adds complexity to the surgical procedure that is otherwise a routine type of skin incision. A less invasive surgical technique avoiding reducing the thickness of the skin would render a simpler and shorter procedure and would be aesthetically appealing to the patients, as permanent hair removal in the area around the abutment would not be required. Faster healing and less numbness (sensory loss/ paraesthesia) at the implant site may also be expected if the soft tissue thickness is left intact. The Cochlea Baha BA300 Abutment together with a surgical procedure that includes soft tissue reduction was CE marked in April 2010. The test abutment, Cochlear Baha BA400, together with a surgical procedure that does not require soft tissue reduction was CE marked in June 2012. The rationale behind this investigation was to make a 'head-to-head' comparison between the BA300 and BA400 Abutment and the associated surgical techniques in order to collect information regarding complications (inflammation/infection, numbness and pain), aesthetic outcome and utilisation of direct medical cost associated with surgery.

Bone anchored hearing aid, Bone anchored implant, Abbreviated Profile of Hearing Aid Benefit (APHAB), Health Utility Index (HUI), Holgers Index, Implant stability

The Cochlear Baha BA400 Abutment has been designed with a concave shape at the lower aspect of the abutment. The abutment is made of commercially pure titanium and is coated with a hydroxyapatite layer on the entire soft tissue-contacting surface of the abutment up to 3 mm below the top surface (2 mm below the top surface on 6 mm abutments).

The BA300 abutment is made of commercially pure titanium and is available in two different lengths (6 mm and 9 mm).

Combined endpoint of infection/inflammation, overgrowth, pain and numbness will be evaluated, as the sum of the following four events: Holgers Index >=2 any time between 3 weeks to 1 year Any overgrowth any time between 3 weeks to 1 year Pain (scar/neuropathic) according to POSAS >=3 any time between 3 weeks to 1 year Any numbness any time between 3 weeks to 1 year Each medical event is counted only once per subject resulting in a score of 0 to 4 for every subject.

Combined endpoint of infection/inflammation, overgrowth, pain and numbness will be evaluated, as the sum of the following four events: Holgers Index >=2 any time between 3 weeks to 1 year Any overgrowth any time between 3 weeks to 1 year Pain (scar/neuropathic) according to POSAS >=3 any time between 3 weeks to 1 year Any numbness any time between 3 weeks to 1 year Each medical event is counted only once per subject resulting in a score of 0 to 4 for every subject.

Max of Holgers index from day 10 to month 12, and to month 36 was recorded, using the Holgers scale from 0 - 4, where 0 = no inflammation and 4 = removal of abutment/implant necessary due to infection. 0. No irritation Slight redness. Local temporary treatment, if needed Red and slightly moist tissue. No granulation formation, local treatment and extra controls as indicated* Reddish and moist; sometimes granulations tissue, revision surgery is indicated* R. Removal of the abutment / implant necessary due to infection* R Removal of implant for reasons not related to skin problems*

Infection and inflammation were evaluated by the holgers index at visits 3-10 (Day 10, Weeks 3, 6, 12, 24, months 12, 24 and 36) and the following scale was used: 0. No irritation. Epidermal debris removed, if present Slight redness. Local temporary treatment, if needed Red and slightly moist tissue. No granulation formation, local treatment and extra controls as indicated* Reddish and moist; sometimes granulations tissue, revision surgery is indicated* Removal of the abutment / implant necessary due to infection* R. Removal of implant for reasons not related to skin problems*

Subjects were asked if they experience any numbness around the abutment at each visit. The maximum numbness each subject experienced is summarized in this analysis. The following scale will be used: No numbness Numbness within 2 cm from the abutment Numbness within and beyond 2 cm from the abutment

The subject rated the following questions 'has the scar been painful the past few weeks' and 'have you had any neuropathic pain during the past weeks' on the 1-10 scale were 1 = no, not at all and 10 = yes, very much.

The maximum neuropathic pain and the maximum scar pain experienced at any time throughout the study up until and including 12 months.

The maximum neuropathic pain and the maximum scar pain experienced at any time throughout the study up until and including 36 months.

The subject rated the following questions 'has the scar been painful the past few weeks' and 'have you had any neuropathic pain during the past weeks' on the 1-10 scale were 1 = no, not at all and 10 = yes, very much. Pain scale was categorised as 1='no pain', 2-3='mild pain', 4-6='moderate pain', 7-10='severe pain'.

The investigator rated the implant site in regards to soft tissue thickening/overgrowth at visits 3-10 according to the following scale: 0. No soft tissue thickening or overgrowth Slight soft tissue thickening or overgrowth Moderate soft tissue thickening or overgrowth. Local treatment and extra controls as indicated* Marked/distinct soft tissue thickening or overgrowth. Revision surgery is indicated.* Should also be reported on the AE page in the CRF

The investigator measured the visible abutment length at each visit. The length of BA400 test abutments initially placed were longer than BA300 control abutments places. A direct comparison between the groups is not relevant. In some cases of increased soft tissue thickening or overgrowth, the abutment was exchanged for a longer abutment. The results presented here are only for patients with no change of abutment

The Aesthetic Outcome of Surgery, the 'Patient and Observer Scar Assessment Scale' Consisted of Two Parts - a Patient and an Observer Scale, Week 12, Month 12 and 36.

The patient scale contains six items (pain, itching, color, stiffness, thickness and irregularity) scored 1-10. The observer scale contains six items (vascularity, pigmentation, thickness, relief, pliability and surface area) scored 1-10. Besides the 10-step scale, category boxes are available to score nominal parameters (e.g. type of color). Both patient and observer should also score the overall opinion of the scar on the 1-10 scale. For all above scales 1=normal skin, 10 worst scar imaginable. Total score is the sum of the variables pain, itching, color, stiffness, thickness and irregularity (patient) and vascularity, pigmentation, thickness, relief, pliability and surface area (observer). The scale ranges from 6 to 60 (6 normal, 60 worst scar imaginable). The "pain not with in the scar" variable ranges from 1 to 10. 1 being no pain at all and 10 being very much pain

Health Utilities Index (HUI) is a generic preference-based system for measuring comprehensive health status and health-related quality of life. Each index provides descriptive evidence on multiple dimensions of life quality. HUI3: Comprehensive Health State, Vision, Hearing, Speech, Ambulation, Emotion, Cognition, Pain. HUI2: Comprehensive Health State, Sensation, Mobility, Emotion, Cognition, Self Care, Pain. Subjects completed HUI2/3 questionnaires at visit 1 (baseline), 7 (week 24), 8 (month 12) and 10 (month 36). 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.

The Abbreviated Profile of Hearing Aid Benefit (APHAB) is a 24-item self-assessment, disability-based inventory that can be used to document the outcome of a hearing aid fitting, to compare several fittings, or to evaluate the same fitting over time. The subjects will complete the APHAB at pre-surgery, week 24, month 12 and 36. Questions assess 'Ease of Communication', 'Background Noise', 'Reverberation', 'Aversiveness', and 'Global' in the aided and unaided situations. The aided situation was compared to the unaided situation at baseline (pre-surgery). For each subscale, a score of 99 indicates that there is 'always' difficulty, and a score of 1 indicated that there is 'never' difficulty for that particular subscale.

Use of the sound processor can be seen as a reflection of patient satisfaction and treatment compliance. Patients were asked to record how many hours per week they used the sound processor after Baha loading at week 3.

ISQ is a well-established method to measure stability of osseointegrated implants and has been used for several years both for bone conduction implants and for dental implants. Measurements were performed using resonance frequency analysis at the abutment level. The highest and lowest ISQ value out of two perpendicular measurements obtained at each time point was recorded, ISQ High and ISQ Low. The ISQ values ranges from 1 to 100. Overall, the length of test abutments (BA400) were longer than control abutments (BA300) and there is an inverse correlation between abutment length and stability. A direct comparison between the groups is not relevant. Implant Stability Quotient (ISQ) was recorded at surgery as a baseline value and at visit 2-10.

Nicotine use and smoking habits were recorded for patients. Does not smoke Less than 10 cigarettes/day (Low consumption) Between 11 and 20 cigarettes/day (Medium consumption) Between 21 and 40 cigarettes/day (High consumption) More than 40 cigarettes/day (Very high consumption) In Sweden a large proportion of adults use another form of tobacco, wet snuff. In Sweden the patients were asked if they used wet snuff.

'Loss of Implant' refers to the loss of the implant for reasons including failure of implant to osseointegrate, or an implant that was loose form surgery. It does not include elected removal of the device.

Count of subjects who had their abutment removed for reasons of health and safety, such as infection, inflammation or pain.

Inclusion Criteria: Eligible for the Baha system Signed informed consent Exclusion Criteria: Patient scheduled for simultaneously bilateral implant surgery Uncontrolled diabetes as judged by the investigator Condition that could jeopardize osseointegration and/or wound healing, e.g. osteoporosis, psoriasis and use of corticosteroids Unable to follow the cleaning instruction Unable to follow investigational procedures, e.g. to complete quality of life scales Participation in another investigation with pharmaceuticals and/or device Condition that may have an impact on the outcome of the investigation as judged by the investigator Suitable implant position for the 4 mm implant not found during surgery due to insufficient bone quality and/or bone thickness

van Hoof M, Wigren S, Ivarsson Blechert J, Molin M, Andersson H, Mateijsen DJM, Bom SJH, Calmels MN, van der Rijt AJM, Flynn MC, van Tongeren J, Hof JR, Brunings JW, Anteunis LJC, Marco Algarra J, Stokroos RJ, Joore MA. A Multinational Cost-Consequence Analysis of a Bone Conduction Hearing Implant System-A Randomized Trial of a Conventional vs. a Less Invasive Treatment With New Abutment Technology. Front Neurol. 2020 Mar 13;11:106. doi: 10.3389/fneur.2020.00106. eCollection 2020.