A systematic review of the effectiveness and cost-effectiveness of bilateral multichannel cochlear implants in adults with severe-to-profound hearing loss

Background: In the UK, approximately 10 000 people have cochlear implants, more than 99% with a unilateral implant. Evidence shows that adults implanted bilaterally may benefit from binaural advantages; however, systematic review evidence is limited. Objectives of the review: To conduct a systematic review to discover the evidence for effectiveness and cost-effectiveness of using bilateral cochlear implants in adults with severe-to-profound hearing loss by comparing their effectiveness with unilateral cochlear implantation or unilateral cochlear implantation and acoustic hearing aid in the contralateral ear. Type of review: Systematic review. Search strategy: This examined 16 electronic databases, plus bibliographies and references for published and unpublished studies. Evaluation method: Abstracts were independently assessed against inclusion criteria by two researchers, and disagreements were resolved. Selected papers were then retrieved and further independently assessed in a similar way. Included studies had their data extracted by one reviewer and checked by another. Results: Searches yielded 2892 abstracts producing 19 includable studies. Heterogeneity between studies precluded meta-analysis. However, all studies reported that bilateral cochlear implants improved hearing and speech perception: one randomised controlled trial found a significant binaural benefit over the first ear alone for speech and noise from the front (12.6 +/- 5.4%, P < 0.001) and when noise was ipsilateral to the first ear (21 +/- 6%, P < 0.001); and another found a significant benefit for spatial hearing at 3 and 9 months post-implantation compared with pre-implantation [mean difference (sd) scores: 3 months = 1.46 (0.83-2.09), P < 0.01].Quality of life results varied, showing bilateral implantation may improve quality of life in the absence of worsening tinnitus. Limited cost-effectiveness evidence showed that bilateral implantation is probably only cost-effective at a willingness-to-pay threshold above 62 pound 000 per quality adjusted life year. Conclusions: Despite inconsistency in the quality of available evidence, the robustness of systematic review methods gives weight to the positive findings of included studies demonstrating that bilateral implantation is clinically effective in adults but unlikely to be cost-effective.