The objective of this study was to examine variables that may predict open set speech discrimination following cochlear implantation. It consisted of a retrospective case review conducted in a tertiary referral centre with a cochlear implant programme. The patients were 117 postlingually deafened adult cochlear implant recipients. The main outcome measures were Bench, Kowal, Bamford (BKB) sentence scores recorded nine months following implant activation. The variables studied were age at the time of surgery, sex, duration of hearing loss, aetiology of hearing loss, residual hearing, implant type, speech processor strategy, number of active electrodes inserted. Variables found to have a significant effect on BKB following univariate analysis were entered into a multivariate analysis to determine independent predictors. Multivariate ordinal regression analysis gave an odds ration of 1.09 for each additional year of deafness prior to implantation (confidence interval 1.06-1.13; p < 0.001). Duration of deafness prior to implantation is an independent predictor of implant outcome. It accounted for 9% of the variability. Other factors must influence implant performance.

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Open-set speech recognition without the use of visual clues is common following multichannel cochlear implantation in adults. However, large variations exist among the observed audiological outcomes. This research sought to identify preoperative and operative predictors of postoperative implant performance.The study took the form of a retrospective case review with statistical modelling. Subjects were 117 post-lingually deafened adult recipients of multichannel cochlear implants with a mean age of 52 years (range 18-79) and a mean duration of deafness of 16 years (range 0.125-48). Outcomes were open-set Bench-Kowal-Bamford (BKB) sentence test scores achieved after nine months of device use. Factors tested for predictive ability included historical variables: duration of profound deafness, aetiology of deafness and age at implantation; preoperative audiological variables: pre-operative speech recognition scores; electrode variables: percentage of active electrode array inserted; device variables: implant type and speech-processing strategy.BKB outcome scores demonstrated significant variability and were skewed towards higher outcome scores (mean 56% words correct). A multivariate ordinal regression analysis was therefore employed to identify independent predictors of implant performance using outcomes of poor, average and good performance based on word recognition cut-offs of 0-30, 30-70 and 70%+ respectively. Multivariate ordinal regression analysis demonstrated that duration of hearing loss prior to implantation was the only independent predictor of implant performance. The effect on implant performance of each additional year of deafness was small (9% greater chance of being in a poorer outcome group). This suggests that there are other factors influencing outcome that we were unable to identify in this study.