Cochlear implants (CI) have been used to restore hearing in individuals with severe to
profound sensorineural hearing loss. Normally, it is required that speech identification
scores are below 50% in the ear considered for implantation and that the discrimination in
the best-aided condition should be 60% or less. These criteria exclude many patients with
asymmetrical hearing, as they have speech identification above 60% in the best-aided
condition. It is necessary to investigate how patients with asymmetrical hearing can benefit
from a cochlear implant in the poorer hearing ear compared to when bilaterally fitted with
HAs. Furthermore, it is still unclear at which clinical relevant candidacy criterion the
optimal transition from HA treatment to CI treatment in the bimodal solution occurs, as
randomized studies comparing HA users and CI users do not exist. The purpose of this study is
to provide clinicians with better evidence to determine if patients who benefit
insufficiently from bilateral HA treatment and have a speech discrimination of the better
hearing ear > 50% will benefit from a CI in the poorer hearing ear. Patients intended to
include in the study will all be adults >18 years with hearing loss on both ears where
cochlear implant will be considered as a treatment for the poorest hearing ear. All patients
have used hearing aids on both ears for at least 1 year. The benefit of bimodal fittings
compared to the best possible bilateral HA treatment is evaluated. Furthermore, it is
investigated if this results in increased speech intelligibility and quality of life with a
bimodal solution where a cochlear implant is used on the poorer hearing ear compared to
either CI alone or bilateral hearing aids. 60 patients referred for cochlear implant at
Odense University Hospital will receive new HAs that are fitted for one month. Then they will
be randomized to either the intervention group with CI+HA (bimodal) or to the wait and see
control group with continuous use of HA+HA (bilateral) for another three months. Participants
will undergo stratified randomization depending on the hearing thresholds prior to CI surgery
in the poorest hearing ear. To provide better evidence to determine if patients who benefit
insufficiently from bilateral Hearing aid treatment and have a speech discrimination of the
better hearing ear > 50% will benefit from a Cochlear implant in the poorer hearing ear.
Patients randomized to the intervention group CI+HA will undergo surgery as soon as possible
after randomization. The control group that will use the hearing aids for an additional three
months, will also be offered the bimodal solution with CI to the poorer hearing ear after
total of four months with HA+HA.
Description of the cohort Inclusion criteria - Adults >18 years old. - Fluent in Danish,
including reading and writing - Willing to participate in and to comply with all requirements
of the protocol. - Post-lingual deafness and use one or two HAs. - Participants should have
aidable hearing in the ear not considered for CI implantation - Self-reported HA use of at
least eight hour per day for at least one year in both ears prior to evaluation for cochlear
implantation in order to ensure, that both ears have received auditive stimulation prior to
participation in the study. If possible, the validity of the self-reported hearing aid use
will be checked in the HA-log by the audiology assistants. - Participants should have a PTA
(0.5,1,2,4 kHz) > 40 dB HL in the ear considered for CI implantation and PTA≥40 and ≤ 70dB HL
in the ear not considered for implantation. - A speech identification score
Ethics approval for the conduct of this study was obtained from the Ethics Committee Southern
Denmark. 21st August 2020.
The trial will be conducted in compliance with this study protocol. All participants will
undergo a process of informed consent and will be aware that participation is strictly
voluntary.
Participants may withdraw from the study at any time. The project is approved by the Danish
Data Protection Agency (file no. 20/22868) in Region South Denmark which is an independent
authority that supervises compliance with the rules on protection of personal data.
("paraplyanmeldelse" in danish).
The study statistic analysis plan will be implemented as well.