The primary aim of this study was to describe older adults ‘adherence to hearing aids use in the first year after fitting.
69.8% (n = 60) of the 86 participants in the study continued to use one or two HA one years after the first fitting. Only 6 subjects were non-user (7%) while the remainder were dead or did not answer to the interview.
The observed percentage of non-use is considerably lower compared to data reported in the recent literatures. Kim et al showed that 19.5% of the subjects were no longer users of the hearing aids. The authors illustrated that non use correlated with listening difficulties in noise and with the uncomfortable devices [16]. Also, in a study of Solheim and colleagues is reported a percentage of non user equal to 15.5%. The authors reported that the issues most strongly associated with HA non-use were correlated to “no perceived need”, handling difficulties and not optimal sound quality whereas they did not found any correlation with cosmetic concerns [17].
The divergences between the studies are partly related to different samples, time of follow-up and methodological approaches used (e.g. survey, interviews or personal letter-form). The population recruited in our study in fact has moderate to severe average hearing loss with average levels higher than those reported in other studies. Therefore it seems reasonable to assume that it expresses a population with greater rehabilitation needs.
In addition, most of the literature is based on retrospective studies whereas our study is prospective. It is important to note that 10 patients did not answer to the telephonic interview and it is not possible to know if there are some HA user in this sample.
For better understanding which aspects are correlated with the use of the hearing aids in elderly, we analyzed different factors. We found that age, hearing threshold, cognitive status and quality of life perception influence the use of the hearing aids over time.
In particular we found that age at the first HA fitting is 6 years lower, on average, in user group compared to non users. Literatures do not agree regarding relationship between age and HA use. Humes reports absence of correlation between age and HA adhererence [18] whereas Kim et al., who evaluated the HA satisfaction, reported a correlation between lower age and higher HA satisfaction similar to our data [16]. These last authors described, in fact, a decrease of 0.3 point of HA satisfaction every one year of age increased.
It is well known that elderly people can present with many comorbidities [19] including difficulties in movements. This can result in frequent appointments miss after the initial fitting, fundamental for a proper HA assistance. In accordance with the literature, we found that both user and non-user subjects presented at least one comorbidity but these are not statistically associated with the adherence to devices use. Also 6 of the 86 subjects had disorders like mild cognitive impairment, dementia or depression that could correlate with less HAs use. In addition, the number of comorbidies was not correlated with the mean use of the HA. Probably, for these reasons our sample showed greater adherence to the device use. In contrast to our data, Solheim et al reported that the presence of at least one comorbidity is correlated with an average lower use of 3.3 h/day compared to participants who reported no issues: in particular subjects with health related problems used their hearing aids 3 hours less per day compared to healthy people [17].
In the present study, impact of the hearing loss in elderly subjects are correlated also with the unaided hearing threshold. In fact, the mean hearing threshold is lower in user compared to non-user recipients. Some studies report that subjects with identical audiograms had different perceived hearing difficulties [18] whereas others reported that there is a correlation between hearing loss degree and usage of hearing devices [17]. Both studies of Solheim and Humes reported that non user subjects had a better hearing threshold compared to user [17; 18]. On the contrary, here we found better hearing threshold in the user group. This difference is probably associated with sampling criteria: in fact, were recruited subjects with moderate to profound HL, whereas other studies include less severe HL. Also from the analysis of the auditory performances with HAs, we found a significant correlation between unaided and aided tonal audiometry and SRT. All subjects showed an improvement of the auditory threshold with their HAs both in quiet and in noise. It is possible that the audiological benefit, correlated with the HAs use, is a cause of the adherence to devices use over time.
We found that another factor that influence the HAs use is the cognitive status. Despite a lower score of all subjects compared to the general population, a weakly significant correlation between greater MOCA score and HA user status was apparent. We also found that there is not a deterioration of the cognitive capacities after one year of HA use as the MOCA score has not changed. Our data agree with the recent literatures. In the last years the scientific community has paid great attention to cognitive disorder. It is reported that untreated or not well treated hearing loss results not only in reduced speech audibility, but also in social isolation, depression and cause negative impact on cognitive function [18]. The Lancet Commission for dementia prevention, intervention, and care, described the risk and modifiable factors correlated to dementia. This commission identified that hearing loss is the largest potentially modifiable risk factor for this disease. Therefore by treating hearing loss it is possible to delay the onset of dementia by 1 year and decrease the global prevalence of dementia by 10% [20].
Comorbidities, alteration of the cognitive status, difficulties in speech perception, isolation are just some of the factors that affect elderly people with hearing loss. Consequently also the quality of life of these patients can be impaired. Literatures agree that elderly with hearing loss have a worse quality of life [21, 22]. In our study patients in the user group have a trend of better perceived quality of life than non users although differences are not statistically significant No differences were observed in the sense subscale of the questionnaire in user and non user subjects. It is important to note that the same user subjects, had a worsening quality of life perception one year after the first fitting but at the same time had a little improvement in the sense subscale. Tsimpida and coworkers showed that quality of life in elderly subjects that use HA was correlated with different factors, especially socioeconomic position and depressive state [23]. In our sample hearing aids improved the hearing status of subjects but other aspects have worsened according with ageing. Consequently we observed a reduction of the global score of the quality of life questionnaire and, on the contrary, the sense subscale (correlated with the hearing status) improves over time.
We did not find any statistical correlation between hearing aids use and HHIE score but a significant reduction of the score after one year of HA use was apparent (22.51 vs 15.79). In agreement with us, Uchida et al. found a reduction of the HHIE score from 30.8 points before to 18 points after the 6 months of HA use [24]. Also in a study of Zorzetto Carnil et al. is reported a correlation between use of hearing aids and HHIE score in elderly [21]. It is possible to conclude that the use of HA favored emotional and social adjustment in everyday life.
In accordance with this data, also IOI-HA, that illustrate the satisfaction of hearing aid users and the impact of the devices on life, showed scores similar to that of other studies.. Wu et al report a IOI-HA score of 24.97 point 3 months after use of hearing aid whereas in our study we found a similar score of 27.9 [25].
For better understanding the parameters that affect the HA use one year after the first fitting, we evaluated the advantages of binaural amplification. Bilateral users had higher HA benefit in speech audiometry in quiet but not in speech audiometry in noise compared to monolateral users. The greater improvement in OLSA test in the monolateral group must be related to a worse score at pre evaluation.
The bilateral use of HA after one year produces significant improvements in different questionnaires like in sense subscale of the AQoL, in HHIE and in IOI-HA questionnaires. On the contrary, both monolateral and bilateral users showed worsening total scores in AQoL questionnaire probably because of more general issues related to ageing.
No significant differences were found in MOCA score between bilateral and monolateral users but a trend of slight worsening in monolateral group and a stabilization in bilateral patients was apparent.
The improvement in IOI-HA score in bilateral users is not reported in the studies of Wu et al and Brännström et al that showed no differences in satisfaction of HA use in monolateral compared to bilateral patients [25, 26]. On the contrary, in agreement with our data, Arlinger et al reported that bilateral users had higher score, or rather higher satisfaction [27].
In general our study population shows good performances with bilateral HA. Cox et al also reported a preference of bilateral devices but there were not predictive factors concerning monolateral or bilateral preference [28]. Also, in a recent study Kim et al was reported a preference of bilateral HA use in elderly subjects [16].