Utility of ear implants: can all benefits be valued?
F BERGERON, Université Laval, Quebec City, Canada
P FERRON, Centre Hospitalier Universitaire de Québec, Quebec City, Canada
Every health system is confronted with the constantly rising cost of medical technologies and treat-
ments. Decisions regarding the adoption of these technologies are now heavily based on scientific
evidence. Economic evidence is often a key issue in accepting the new technologies and defining
indications. Thus, cost/effectiveness, and more specifically cost/utility analysis, constitutes a growing
approach in valuing medical devices, including electronic ear implants, using uniform units such as
the quality-adjusted life-year or QALY. These units are extracted from health preference weights
expressed by large portions of the general population.
Researchers have used different tools for the assessment of the utility of ear implants. In the
cochlear implant field, the Health Utility Index, the Quality of Well-Being Scale or the visual
analog scale have generally been the reference instruments. The Quality of Well-Being Scale and the
Health Utility Index are generic instruments designed to assess global health status. The Quality of
Well-Being Scale focuses on the physical aspects of daily life in three dimensions, that is mobility,
physical and social activity. The Health Utility Index assesses the functional level for eight
attributes, including sensory and psycho-social ones such as vision, hearing, speech, emotion,
cognition and pain. Each attribute is quoted on a six-level scale. The hearing scale goes from level 6,
that is unable to hear at all, to level 1, defined as being able to hear without a hearing aid. Median
scores represents a pseudo-hierarchy of capacities involving the use of hearing aids in quiet or noisy
environments. Both Quality of Well-Being Scale and Health Utility Index are weighted on prefer-
ences expressed by large samples of people. The visual analog scale is simply a segmented or
non-segmented line with extreme markers at both ends on which a person specifies his estimation of
his own quality of life. Thus, this measure is not a real utility measure, as it is not weighted by prefer-
ences from the general population.
Researchers have shown that treating profoundly deaf candidates with a cochlear implant
generally gives an improvement of 20–40% in quality of life (Harris et al., 1995; Summerfield and
Marshall, 1995; Wyatt et al., 1995, 1996; Palmer et al., 1999; Fugain et al., 2000; Bichey et al., 2002;
Francis et al., 2002). Such results should not be surprising since the efficacy of contemporary devices,
which give access to open-set speech perception, is compared to preimplantation status, which is
basically defined as ‘no or limited benefit’ from conventional hearing aids. On the Health Utility
Index, this means scoring on the hearing attribute from level 6 to level 5, since level 4 implies to be
able to hear without a hearing aid. If the pseudo-hierarchy is ignored, one could quote to level 3, but
levels 2 and 1 stay unreachable. This upward change in level yields a theoretical improvement of
18–38% in the utility rating, which is in close agreement to the field-observed improvements.
Nowadays, candidates with more residual hearing are considered for, and benefit from, cochlear
implantation. Hearing aid users with scores up to 40% in the recognition of sentences are now
considered for implantation. Post-implantation scores for these candidates are often better than 80%.
Let’s say that we need to justify the selection of these candidates based on utility measures. Using the
Quality of Well-Being Scale, not much improvement will be detected as mobility and physical activity
are not involved. Scoring on the Health Utility Index will not be an easy task. Here interpretation of
terms will play a major role: What is meant by ‘being able to hear what is said’? Are we assessing
detection of speech or understanding of speech? What about partial understanding of speech such as
40% before implantation and 80% after the surgery? Anyway, the starting level will be better than 6
and the final level will never be over 3, still because of the labelling of levels 2 and 1. Consequently,
the overall improvement in quality of life will always be less than what could be theoretically reached
by profoundly hearing-impaired cochlear implant candidates. In real life, is it so?
Similar limitations are evidenced when trying to justify improvements in technology. When a
new device yields an improvement in speech perception of, let’s say, 10–20%, how can this
improvement be quoted with the standardized measures of utility?
Let’s now consider binaural implantation. Here, utility measures, and more specifically,
cost/utility figures are crucial in the acceptance of the approach. We know from published studies
that better localization and reduction of the shadow effect are expected for binaural cochlear implant
users. But no standardized measure of utility considers the value of such improved auditory capacities.
2 Cochlear Implants International, 6 (Supplement 1), 2005 ©Whurr Publishers Ltd