Discussion
Baseline scores placed the majority of the sample in the severe disability category of HUI3 multi-attribute score (Figure 1, left) levels i.e. where at least one attribute is at a reduced level of function that cannot be corrected and prevents many activities (Feng et al., 2009). This is typical for a cohort of hearing-impaired individuals with sensorineural hearing loss (Summerfield et al., 2019; Swan et al., 2012; Barton et al 2012). After implantation, there was a significant gain in HUI3 scores at one year which was maintained at 2 and 3 years. At least 50% of the subjects had moved into the moderate disability category (Figure 1, left), where at least one attribute is at a reduced level of function that cannot be corrected and/or prevents some activities. However, we see that most subjects reached level 3 on the hearing attribute scale. This level describes functional hearing with the use of a “hearing aid” (in this case a CI).
Of the factors considered in the logistic regression analysis telephone use and the speech and emotion attributes on HUI3 were significant. Those who did not use the telephone at baseline were 1.5 times more likely to get a clinically meaningful gain on the HUI3 from implantation. As expected, subjects in the poor hearing category at baseline, (hearing attribute levels 4, 5 or 6) were also more likely not to use the telephone (OR 1.52). Thus, telephone use is an easy parameter to use for the screening of potential adult CI candidates presenting to the audiology clinic. With poor access to adult hearing screening in many countries, the capability to use the telephone use would provide a simple criterion for urgent referral for cochlear implant assessment. Those who reported that strangers were unable to understand them, or even poorer verbal communication, also had a higher chance of clinically significant gain in health utility. Improved overall verbal communication due to better hearing and other rehabilitation following CI may have contributed to this effect. Those who were unhappy prior to implant were also more likely to show a meaningful gain in the HUI3, probably due to the implant and rehabilitation process improving their communication and thus emotional state.
The Fisher’s exact test showed that there was also a non-random association between a meaningful gain on the HUI3 and the hearing single attribute. Not surprisingly, those subjects with poor baseline hearing were more likely to gain more than 0.1 points. The SSQ was still sensitive to changes in hearing brought about by CI, even in the group with no clinically important gain in HUI3. For that group the mean improvement of 2.43 on the SSQ scale was highly clinically significant.