Research

Candidacy and Cochlear Implants

International Comparisons

There is considerable variation at the International level (Vickers et al., 2016a) with many countries with audiometric guidelines which are much less restrictive. In Australia they use 70 dB HL criteria, Germany, Italy and the USA are also less restrictive than the UK with the majority of clinics using a 75–80 dB HL cut off at frequencies greater than 1 kHz (Raine 2013; Vickers et al., 2016). Further in Germany, Italy and Australia implant teams have a greater level of clinical discretion to determine appropriate candidacy using a number of criteria that clinicians find useful (Raine 2013; Vickers et al., 2016a). In the UK however there are only limited examples of obtaining funding for special cases.

A number of recent reviews of the research suggest that lower hearing threshold criteria would be appropriate in the UK (Lamb 2016, Leal 2016, Vickers 2016b, Raine 2016).

With children who are candidates for bilateral CI’s (Lovett 2015) concludes that “Children should be candidates for bilateral cochlear implantation if their unaided 4-frequency PTA is 80 dB HL or poorer in both ears. For children who are developmentally too young to permit measurement of a 4-frequency PTA, the criterion of candidacy should be a 2-frequency PTA of 85 dB HL or poorer in both ears.” Vickers also concludes that “The candidacy criteria in the United Kingdom for bilateral CIs in children should be based on either a four-frequency (0.5, 1, 2, and 4 kHz) pure tone average poorer than or equal to 80 dBHL or a two frequency (2 and 4 kHz) pure tone average poorer than or equal to 85 dBHL.”  (Vickers 2015) Both of these recommendations are currently outside of the NICE guidelines.

Further Carlson et al. (2015) concluded, after a retrospective case study of implanted children who had less severe hearing loss than specified in the current indications and who had open-set word and/or sentence recognition scores greater than 30% for children who are able to participate in speech perception testing; that a large-scale reassessment of paediatric cochlear implant candidacy, including less severe hearing losses and higher preoperative speech recognition, should be undertaken.

Sentence Tests 

A sentence test, the BKB test, is also used to assess candidacy and this is no longer fit for purpose according to a recent review by experts in the field who concluded; “Use of this measure (the BKB test) alone to assess hearing function has become inappropriate as the assessment is not suitable for use with the diverse range of implant candidates today.” (Vickers 2016b). The current BKB sentence test set at a presentation level of 70 dBSPL in quiet does not reflect natural listening conditions of everyday life.

Clinical Changes

The ability to preserve residual hearing at low frequency thanks to improved implantation techniques and the ability to use EAS stimulation also indicates that we might need to reassess our views on candidacy as it is clear that more patients could benefit. Verschuur et al. (2016)

Improved Effectiveness of Cochlear Implants 

The effectiveness of Cochlear Implants has improved massively over the last 10 years according to Doran (2016) who found that the “average open sentence set identification averaged  less than 40% for sound processors in the 1990s compared to an average 80% correct score with modern technology, even without visual cues.”

Consensus on what needs to change

A recent consensus meeting was held by the British Cochlear Implant Group Candidacy Working Party because its members thought this was the most pressing issues faced by the sector. That meeting of over 40 experts in the sector concluded that the current guidelines are too restrictive and that performance of cochlear implant recipients are much better than in 2009 when the current candidacy rules were derived. The group agreed that the current guidelines should be changed and have developed a set of recommendations (https://www.cicandidacy.co.uk/ ).

Key recommendations from the consensus process are that;

  • Expanding candidacy to include some groups of adults and children with less profound forms of hearing loss would be appropriate because the benefits would outweigh the risks.
  • The current assessment used to determine whether someone receives sufficient benefit from their hearing aids (the BKB sentence test) does not adequately assess the difficulties with listening that adults and children experience in everyday life.
  • The process to determine whether someone receives sufficient benefit from their hearing aids should be revised to better assess real-world listening difficulties.
  • Assessment procedures should be chosen based on evidence that they are reliable and valid for determining candidacy for cochlear implantation. Different procedures may therefore need to be adopted for different sub-groups of patients who are potential candidates.

For a more detailed summary of current evidence see;

CI’s and Candidacy Evidence Base

 Cost Effectiveness and CI’s

References

Carlson, M.L., Sladen, D.P., Haynes, D.S., Driscoll, C.L., DeJong, M.D.,Erickson,H.C. et al., 2015. Evidence for the expansion of paediatric cochlear implant candidacy. Otology & Neurotology, 36(1): 965–971.

Doran, M. & Jenkinson, L. Mono-syllabic word test score as a pre-operative assessment criterion for cochlear implant candidature in adults with acquired hearing loss. Cochlear Implants International Vol. 17 , Iss. sup1,2016

Dowell R, C. (2012) Evidence about the effectiveness of Cochlear implants in adults. In: Wong L, Hickson L, editors. Evidence- Based Practice in Audiology. San Diego: Singluar Publishing; 2012.

Lamb, B. (2016) Expert opinion: Can different assessments be used to overcome current candidacy issues?, Cochlear Implants International, 17:sup1, 3-7,

Leal, C., Marriage, J., Vickers, D. 2016. Evaluating recommended audiometric changes to candidacy using the Speech Intelligibility Index. Cochlear Implants International, 17(S1).

Lovett RE, Vickers DA, Summerfield AQ. Bilateral cochlear implantation for hearing-impaired children: criterion of candidacy derived from an observational study. Ear Hear. (2015) Jan; 36(1):14-23

O’Neill, C., Lamb, B., Archbold, S. (2016) Cost implications for changing candidacy or access to service within a publicly funded healthcare system? Cochlear Implants International, 17: S1, 31-35

Raine, C. (2013) Cochlear implants in the UK: Awareness and utilisation. Cochlear Implants International Supplement 1, vol. 14: S32–S37.

Raine, C., Atkinson, H., Strachan, D, R., & Martin, J M. (2016) Access to cochlear implants: Time to reflect, Cochlear Implants International, 17: S1, 42-46.

Verschuur, C.,Hellier,W.,Teo,C.2016. An evaluation of hearing preservation outcomes in routine cochlear implant care: Implications for candidacy. Cochlear Implants International, 17(S1).

Vickers, D.  Summerfield, Q & Lovett, R. (2015) Candidacy criteria for paediatric bilateral cochlear implantation in the United Kingdom, Cochlear Implants International, 16:sup1, S48-S49

Vickers, D, De Raeve L, and Graham J . (2016a) International survey of cochlear implant candidacy Cochlear Implants International 17: S1, 36-41

Vickers, D. Kitterick, P. Verschuur, C. Leal, C. Jenkinson, L. Vickers, F.  &  Graham, J. (2016b) Issues in Cochlear Implant Candidacy. Cochlear Implants International, 17: S1, 1-2.

WHO Report for World Hearing Day. 2017. http://www.who.int/pbd/deafness/world-hearing-day/2017/en/  for their report Global cost of unaddressed hearing loss and the cost-effectiveness of interventions.