Objectives: Objectives were, first, to estimate the additional number of quality-adjusted life years (QALYs) gained by deaf children from bilateral compared with unilateral implantation (DeltaQ); second, to estimate the additional cost to the healthcare system in the United Kingdom for providing bilateral compared with unilateral implantation (DeltaC); and, third, to compare the values of incremental net benefit (INB), rDeltaQ - DeltaC, with criteria used by policy makers in deciding whether to adopt health technologies. In England and Wales, the healthcare policy-making body must be satisfied that the INB is positive for a maximum value of r of pound30,000 (the "net-benefit" criterion). Policy makers may also require the likelihood that the technology is cost-effective to exceed 0.8 (the "likelihood" criterion).
Design: An opportunity sample of 180 informants, composed of clinicians/researchers, students, and parents, valued the quality of life of a hypothetical child born profoundly deaf. The child was described in written vignettes as achieving typical outcomes with no implant, a unilateral implant, a unilateral implant with benefit from a contralateral acoustic hearing aid, or bilateral implants. Valuations were made using the time trade-off (TTO) and a visual analog scale (VAS). A decision model was constructed to describe events related to implantation that could occur over a child's lifetime after the decision to implant. A cost and a probability were associated with each event. Monte Carlo simulations modeled the management of cohorts of 3000 children and estimated a value of DeltaC for each child. An increment in quality of life was sampled with replacement from the appropriate distribution of informants' valuations to estimate a value of DeltaQ for each child. The minimum value of r for which the average INB was positive was calculated to test the net-benefit criterion. The proportion of simulations for which the INB was positive when r was pound30,000 was calculated to test the likelihood criterion.
Results: Estimates of the cost-effectiveness of unilateral implantation aligned closely with published estimates, giving credibility to analyses of bilateral implantation. Based on TTO data (VAS data in parentheses), bilateral implantation was associated with an increment in quality of life of +0.063 (+0.076), yielding 1.57 (1.87) additional QALYs at a cost of pound34,000. Net benefit was positive, provided that pound21,768 ( pound18,173) could be spent to gain a QALY. If pound30,000 could be spent, the probability that bilateral implantation is cost-effective was 0.480 (0.539). Thus, the net-benefit criterion, but not the likelihood criterion, was met in both analyses. The net-benefit criterion was also met in analyses based on data from the three groups of informants individually.
Conclusions: Groups of adults varying widely in age and life experience perceived sufficient additional quality of life from giving children two implants rather than one to mean that bilateral cochlear implantation is possibly a cost-effective use of healthcare resources in the UK. Wide variation in valuations within the groups of informants means that considerable uncertainty surrounds that conclusion. Further data on the costs and benefits of bilateral implantation are needed to resolve the uncertainty.