Listening with Unilateral versus bilateral Cochlear Implants in Adults (LUCIA): A randomised controlled trial comparing simultaneous bilateral versus unilateral cochlear implantation in adults with post-lingual severe-profound hearing loss
Adults with severe hearing loss will be randomly assigned to receive a cochlear implant in one ear or both ears, in a trial to settle a long-running debate about which approach works better. Why this matters: UK health guidance currently recommends bilateral implants for children but only unilateral for most adults, despite limited evidence from randomised trials. Without this study, adults may be missing out on the benefits of 3D hearing—the ability to locate sounds, follow conversations in noisy rooms, and reduce listening fatigue—or may be exposed to unnecessary surgical risks and costs for no added gain. Potential impact: If bilateral implantation proves clinically and cost-effective, NICE guidance could shift, giving thousands of adults access to implants in both ears. That would change everyday life: easier conversations in pubs, restaurants, or family gatherings, and less mental strain from straining to hear. If bilateral shows no meaningful advantage, the NHS avoids spending on a more expensive procedure that does not improve outcomes. Either way, the trial provides the evidence needed to make that decision. The study runs at 14 UK centres, recruiting 254 adults, with results expected by 2030.
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Research question Are the benefits of simultaneous bilateral over unilateral cochlear implantation in adults both clinically relevant and cost-effective? Background Compared to unilateral cochlear implantation, bilateral implantation may provide 3-dimensional hearing (spatial hearing), helping to: a) identify where a sound or speaker is located; b) improve ability to communicate in noisy places; c) reduce the effort required and fatigue to follow a conversation; and d) may improve social engagement and quality of life. However, it may be associated with greater risks and cost. In the UK, NICE guidance recommends that children receive bilateral cochlear implants, whereas most adults should be unilaterally implanted. The guidance recommends that a randomised control trial (RCT) should be conducted to compare benefits of bilateral versus unilateral cochlear implants in adults. Aims & objectives The aim of this trial is to establish the clinical- and cost-effectiveness of bilateral versus unilateral cochlear implantation in adults. Objectives are to compare bilateral and unilateral adult cochlear implant groups in terms of a difference in: hearing-related quality of life (using the York Binaural Hearing-Related Quality-of-Life (YBHRQL) and HUI-3 patient-reported tools; functional hearing benefits; adverse effects; and cost-effectiveness. Methods A multicentre RCT will run at 14 UK cochlear implant centres. 254 cochlear implant candidates who meet current NICE criteria, aged 18 years or older with post-lingually acquired severe-profound deafness will be invited to participate. Following formal consent and baseline data collection, participants will be randomised 1:1 to bilateral, or unilateral cochlear implantation (standard care). Implants will be switched on around 4 weeks after surgery, with outcome data collected at 1,3,6 and 12 months after this, either at routine clinic visits or with remote data capture. The primary outcome will be the YBHRQL, analysed a) as area under the curve from baseline to 12 months after device activation and b) as the difference between group scores at 12 months after device activation. Secondary outcome measures include: functional tests of spatial speech in noise perception; listening effort and fatigue; adverse effects (to include tinnitus and vertigo); and other quality of life measures and health service and resource use. A within-trial and lifetime cost-utility analysis will be conducted. An integrated qualitative study incorporating peer-to-peer interviews in 30-40 participants at baseline prior to allocation, and after 12-month follow up will explore participant experiences of the interventions, and a process evaluation to understand experiences of taking part and informing an intervention plan for future implementation in the NHS. Timelines for delivery RCT setup commences January 2026. Recruitment opens August 2026 and runs for 21 months. Last patient, last visit will be month 48, with the funded study ending 6 months later in June 2030. Anticipated impact & dissemination The study aims to generate evidence to inform future NICE guidance for cochlear implantation in adults. Dissemination will target professionals and policy makers via conference talks, journal publications and professional societies. Plain English written and video material will be co-created with patients and provided in translated and other accessible formats to reach participants, patients and the public.
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