Implantable Devices for Single-Sided Deafness and Conductive or Mixed Hearing Loss: A Health Technology Assessment

Single-sided deafness refers to profound sensorineural hearing loss or non-functional hearing in one ear, with normal or near-normal hearing in the other ear. Its hallmark is the inability to localize sound and hear in noisy environments. Conductive hearing loss occurs when there is a mechanical problem with the conduction of sound vibrations. Mixed hearing loss is a combination of sensorineural and conductive hearing loss. Conductive and mixed hearing loss, which frequently affect both ears, create additional challenges in learning, employment, and quality of life. Cochlear implants and bone-conduction implants may offer objective and subjective benefits of hearing for people with these conditions who are deemed inappropriate candidates for standard hearing aids and do not meet the current indication (i.e., bilateral deafness) for publicly funded cochlear implants in Canada.

We conducted a health technology assessment, which included an evaluation of clinical benefits and harms, cost-effectiveness, budget impact, and patient preferences and values related to implantable devices for single-sided deafness and conductive or mixed hearing loss. We performed a systematic literature search for systematic reviews and cost-effectiveness studies of cochlear implants and bone-conduction implants, compared to no interventions, for these conditions in adults and children. We conducted cost-utility analyses and budget impact analyses from the perspective of the Ontario Ministry of Health to examine the impact of publicly funding both types of hearing implants for the defined populations. We also interviewed 22 patients and parents of children about their experience with hearing loss and hearing implants.

We included 20 publications in the clinical evidence review. For adults and children with single-sided deafness, cochlear implantation when compared with no treatment improves speech perception in noise (% correct responses: 43% vs. 15%, P < .01; GRADE: Moderate), sound localization (localization error: 14° vs. 41°, P < .01; GRADE: Moderate), tinnitus (Visual Analog Scale, loudness: 3.5 vs. 8.5, P < .01; GRADE: Moderate), and hearing-specific quality of life (Speech Spatial and Qualities of Hearing Scale, speech: 5.8 vs. 2.6, P = .01; spatial: 5.7 vs. 2.3, P < .01; GRADE: Moderate); for children, speech and language development also improve (GRADE: Moderate). For those with single-sided deafness in whom cochlear implantation is contraindicated, bone-conduction implants when compared with no intervention provide clinically important functional gains in hearing thresholds (36-41 dB improvement in pure tone audiometry and 38-56 dB improvement in speech reception threshold, P < .05; GRADE: Moderate) and improve speech perception in noise (signal-to-noise ratio -2.0 vs. 0.6, P < .05 for active percutaneous devices; signal-to-noise ratio improved by 1.3-2.5 dB, P < .05 for active transcutaneous devices; GRADE: Moderate) and hearing-specific quality of life (Abbreviated Profile for Hearing Aid Benefit, ease of communication: 12%-53% vs. 24%-59%; background noise: 18%-48% vs. 33%-79%; listening in reverberant condition: 26%-55% vs. 41%-65%, P < .05 [active percutaneous devices]; ease of communication: 7% vs. 20%; background noise: 46% vs. 69%; listening in reverberant condition: 27% vs. 43%; P < .05 [active transcutaneous devices]; Children's Home Inventory for Listening Difficulties score 7.3 vs. 3.4; P < .05 [passive transcutaneous devices]; GRADE: Moderate). For those with conductive or mixed hearing loss, bone-conduction implants when compared with no intervention improve hearing thresholds (improved 19-45 dB [active percutaneous devices], improved 24-37 dB [active transcutaneous devices], improved 31 dB [passive transcutaneous devices], and improved 21-49 dB [active transcutaneous middle-ear implants]; GRADE: Moderate), speech perception (% correct: 77%-93% vs. < 25%; P < .05 [active transcutaneous devices], % speech recognition: 55%-98% vs. 0-72%; P < .05 [active transcutaneous middle-ear implants]; GRADE: Moderate), and hearing-specific quality of life and subjective benefits of hearing (GRADE: Moderate).In the cost-utility analyses, cochlear implants for adults and children with single-sided deafness provided greater health gains for an incremental cost, compared with no intervention. On average, the incremental cost-effectiveness ratio (ICER) was between $17,783 and $18,148 per quality-adjusted life-year (QALY). At a willingness-to-pay of $100,000 per QALY, 70% of the simulations were considered cost-effective. For the same population, bone-conduction implants were not likely to be cost-effective compared with no intervention (ICER: $402,899-$408,350/QALY). Only 38% of simulations were considered cost-effective at a willingness-to-pay of $100,000 per QALY. For adults and children with conductive or mixed hearing loss, bone-conduction implants may be cost-effective compared with no intervention (ICER: $74,155-$87,580/QALY). However, there was considerable uncertainty in the results. At a willingness-to-pay of $100,000 per QALY, only 50% to 55% of simulations were cost-effective. In sensitivity analyses, results were most sensitive to changes in health-related utilities (measured using generic quality-of-life tools), highlighting the limitations of currently published data (i.e., small sample sizes and short follow-up).For people with single-sided deafness, publicly funding cochlear implants in Ontario would result in an estimated additional cost of $2.8 million to $3.6 million in total over the next 5 years, and an additional $0.8 million would be required for bone-conduction implants for this population. For people with conductive or mixed hearing loss, publicly funding bone-conduction implants would cost an estimated additional $3.1 million to $3.3 million in total over the next 5 years.In interviews, people with single-sided deafness and conductive or mixed hearing loss reported that standard hearing aids did not meet their expectations; therefore, they chose to undergo surgery for an implantable device. Most participants with experience of a cochlear implant or bone-conduction implant spoke positively about being able to hear better and enjoy a better quality of life. People with a cochlear implant reported additional benefits: binaural hearing, better sound localization, and better hearing in noisy areas. Cost and access were barriers to receiving an implantable device.

Based on evidence of moderate quality, cochlear implantation and bone-conduction implants improve functional and patient-important outcomes in adults and children with single-sided deafness and conductive or mixed hearing loss. Qualitative results of interviews with patients are consistent with the findings of the systematic reviews we examined.Among people with single-sided deafness, cochlear implants may be cost-effective compared with no intervention, but bone-conduction implants are unlikely to be. Among people with conductive or mixed hearing loss, bone-conduction implants may be cost-effective compared with no intervention. Results and uncertainty are mainly driven by changes in health utilities associated with having a hearing implant. Hence, further research on utility values in this population is warranted with larger sample sizes and longer follow-up.The 5-year cost of publicly funding both types of hearing implant for single-sided deafness and conductive or mixed hearing loss in Ontario is estimated to be $6.7 million to $7.8 million.