Changes in quality of life and the cost-utility associated with cochlear implantation in patients with large vestibular aqueduct syndrome.

Abstract

A group of 20 patients with large vestibular aqueduct syndrome was identified at the Indiana University School of Medicine. The major objective of this study was to explore the improvements in quality of life associated with cochlear implantation in patients with large vestibular aqueduct syndrome, as well as the cost-utility of cochlear implantation in this group. A total of 70 patients were identified with large vestibular aqueduct syndrome through analysis of thin-section computed tomography of the temporal bone over the past 6 years at this medical center. Data collected from the medical records for each patient included demographic data, hearing-related statistics, implantation data, and audiometric data. Sixteen children and adults with large vestibular aqueduct syndrome had undergone cochlear implantation before the beginning of this study, and the remaining 54 children and adults were identified as undergoing treatment of progressive or fluctuant sensorineural hearing loss. Health utility indexes used in this analysis were taken through the use of the Ontario Health Utility Index, Mark III. The range of costs used for cost-utility analysis was derived from the costs of cochlear implantation at this medical center, as well as from costs associated with implantation published in the medical literature. Participants were selected from the total population of patients with large vestibular aqueduct syndrome at this center who were postlingually deafened and who currently had severe hearing loss. Two groups were formed. These groups comprised either cochlear implant patients with large vestibular aqueduct syndrome or patients with large vestibular aqueduct syndrome currently using hearing aids. Ten of the 16 cochlear implant patients and 10 of the remaining 54 patients with large vestibular aqueduct syndrome met these criteria. Mark III health utility indexes were distributed to patients in each group and scored. Those health utility indexes not completed by the patients were scored by proxy, using the audiologist at this center who was the most familiar with the patient. Changes in quality of life associated with cochlear implantation were derived by comparison of the health utility index results of the two groups. Cost-utility measures were then made using discounted costs per quality-of-life years (QALYs) (5%), and a sensitivity analysis was performed that evaluated changes in scoring done by proxy. The cost-utility results were then compared with the cost-utilities derived from similar studies and associated with other disease states. Although both groups of patients had significant hearing loss, the hearing aid group had a better mean pure-tone average. The mean pure-tone average for the hearing aid group was 70.8 dB (SD 24.4), and the mean pure-tone average for the cochlear implant group was 107.0 dB (SD 21.7). Seven of the 20 health utility indexes were scored by proxy. Results from the base case indicate a 0.20 gain in health utility from cochlear implantation (hearing aid = 0.62, cochlear implant = 0.82, p = 0.037), resulting in a discounted cost per QALY of $12,774. Sensitivity analysis of the proxy scoring indicated that decreasing the hearing score one level on the health utility index resulted in a gain in health utility with cochlear implantation of 0.15, resulting in a discounted cost per QALY of $17,832. A decrease of the hearing score by two levels on the health utility survey resulted in no significant gain in quality of life with cochlear implantation. This study found an improvement in quality of life associated with cochlear implantation in postlingually deafened patients with large vestibular aqueduct syndrome. By weighing this improvement in quality of life against the significant difference noted between the pure-tone averages of each group, further strength can be given to this conclusion. This gain in quality of life, as well as the results derived for the cost-utility of cochlear implantation, was similar to that in previous published studies of cochlear implantation in all types of patients. These results also indicate a favorable cost-utility when compared with published data about other disease states. As patients with large vestibular aqueduct syndrome progress to profound levels of hearing loss, these results indicate that cochlear implantation can be offered as a beneficial, life-improving therapy.