Abstract
Purpose: Age-related sensorineural hearing loss (SNHL), is a progressive, usually bilateral hearing loss that occurs in elderly. It is correctable using rehabilitative hearing devices, which can vastly improve the older person’s quality of life. This study aimed to find out the prevalence and related factors of age-related sensorineural hearing loss among elderly patients in Tanzania. Methods: A total of 380 elderly patients who received Otorhinolaryngology (ORL) services at Muhimbili tertiary hospital were enrolled. Participants were screened for hearing loss and interviewed by the structured questionnaire followed by otoscopic examination and Pure tone Audiometry (PTA). Results: This study included 182(47.9%) males, and 198 (52.1%) females. The prevalence of SNHL was 27.6%, males were mostly affected 57(31.3%) p = 0.574. Bilateral SNHL was found 90 (85.7%) p = 0.026, and the severity of age-related SNHL was found to increase as age increases. Conclusion: Sensorineural hearing loss among the elderly was prevalent, mostly bilateral, and the severity increases with age. Confounding factors such as hypertension, diabetes mellitus (DM), cigarette smoking, and ototoxic medication may have contributed. Elderly should be screened for hearing loss especially on the individuals with other co-morbidities for early diagnosis and management in order to improve the quality of life of the elderly.
Keywords: Magnitude, Sensorineural Hearing loss, co-morbidities
Introduction
Hearing loss refers to a reduction in the ability to perceive sound, with a hearing threshold of 25 decibels (dB) and beyond in both ears. It can be mild, moderate, moderately-severe, severe, or profound and can affect one or both ears. It can lead to difficulty in hearing and understanding conversational speech or loud sounds [1, 2]. World Health Organization (WHO) estimates that over 5% of the world’s population, 360 million people have disabling hearing loss [3]. Approximately one-third of people over 65 years of age are affected by disabling hearing loss and the prevalence in this age group is greatest in South Asia, Asia Pacific, and Sub-Saharan Africa [3]. Sensorineural hearing loss results from diseases of the inner ear, with the cochlear having the sensory type and the nerves having the neural type (vestibulocochlear nerve) [4].
Age-related hearing loss is a progressive, usually bilateral hearing loss that occurs in older people as they age. It is a multifactorial process determined by a combination of genetic and environmental factors. It can range from bothersome to severely disabling in its effects. And in its moderate to severe cases it can cause an older person to become isolated and depressed, and may significantly worsen age-related disabilities/cognitive impairment and dementia [5].
It is eminently correctable using rehabilitative hearing devices, and its successful correction can vastly improve the older person’s quality of life. Increasing awareness of the prevalence of hearing loss in the elderly population is of utmost importance [6].
Lateralization
Individuals with UHL may have trouble localizing sounds. Localization is important when listening especially in groups of people and helps identify who is talking at any moment as well as for safety. Another effect is difficulty in understanding speech in noisy situations. Two normal hearing ears help to filter out noise to hear speech better. An individual presenting with a UHL can often hear speech from a distance, but may not always understand what is being said [7]. Age-related sensorineural hearing loss tends to occur bilaterally and symmetrically.
Pathophysiology of SNHL in Elderly
Schuknecht identified four categories of SNHL in the elderly based on clinical and histopathologic changes within the cochlea as a result of aging; loss of sensory cells and supporting cells of the organ of Corti with epithelial atrophy and neural with a reduction in the number of functioning cochlear neurons, it is estimated that with about 35,500 cochlear neurons at birth, there is approximately loss of about 2100 neurons each decade and hearing loss occurs when neuronal population loss reaches 50% or more. Vascular disorders like atherosclerosis, and hypercoagulable states which impair tissue perfusion can easily impair inner ear perfusion and cause damage to the vital structures of the organ of Corti resulting in SNHL [8].
Another mechanism is atrophy of the stria vascularis with hearing loss resulting after atrophy of about 30% or more. An age-related change in the stiffness of the basilar membrane that results in hearing loss explains cochlear conduction disorder [8].
The risk factors can range from genetics, gender, noise exposure, use of ototoxic drugs, cigarette smoking, hypertension, and diabetes mellitus [4, 8–14]. The screening tool was a Hearing Handicap Inventory for the Elderly -Screening Version (HHIE-S). The higher the HHIE-S scores the greater the handicapping effect of hearing loss [15.16].
Impact of Age-related SNHL on Elderly
The major impact of hearing loss is on the individual’s interpersonal communication with others. This can lead to social and emotional impact which culminates in feelings of loneliness, isolation, and frustration which might easily end up with depression and cognitive impairment. Another effect is the economic impact which is unemployment due to poor communication [3, 17]. In the studies done on hearing loss and cognitive decline in elderly, it was concluded that hearing loss in elderly is independently associated with accelerated cognitive decline and incident cognitive impairment [18, 19].
Methodology
A descriptive cross-sectional analytical study was done to determine the prevalence and related factors of SNHL among elderly patients receiving ORL services. The duration of the study was from 2021 to 2022. The targeted patients were those aged 50 years and above. The elderly patients with a HHIE-S score of more than 8 and who consented to the study were included.
Data Collection and Analysis
All the elderly patients were interviewed using a specially designed questionnaire. Examination of the ears was done and any encountered foreign bodies or wax impaction was removed before the hearing test and other disorders were managed accordingly. Those with a characteristic slopping graph at higher frequencies were considered as having age-related SNHL. Confidentiality was observed and an SPSS program was used to analyse the data. A Chi-square test was used and a p-value of less than 0.05 was considered statistically significant. Multivariate Regression Analysis was used to analyse the factors association with age related hearing loss.
Ethical Consideration
Ethical clearance was sought from Muhimbili University of Health and Allied Sciences (MUHAS), under the Directorate of Research and Publications.
Results
This study recruited 380 participants, of which 198 were females and 182 were males. The mean age was 66 years with a range of 50–96 years old and the standard deviation (SD) was 10.33 (Tables 1, 2, 3, 4 and 5).
Table 1.
Demographic distribution of participants. N = 380
| Gender | ||||
|---|---|---|---|---|
| Male | Female | Total | ||
| Age | 50–59 | 55 (14.5%) | 62 (16.3%) | 117 (30.8%) |
| 60–69 | 52 (13.7%) | 84 (21.8%) | 137 (35.8%) | |
| 70–79 | 47 (12.4%) | 39 (10.3%) | 86 (22.6%) | |
| 80–89 | 19 (5.0%) | 12 (3.2%) | 31 (8.2%) | |
| 90+ | 9 (2.4%) | 1 (0.3%) | 10 (2.6%) | |
| Total | 182 (47.9%) | 198 (51.8%) | 380 (100.0%) | |
Among 380 elderly patients, males were 182(47.9%) and females were 198(51.8%) and the majority were between 60 and 69 years of age, 137(35.8%)
Table 2.
Prevalence of SNHL among elderly patients by age
| Age (yrs) | SNHL | ||
|---|---|---|---|
| Yes | No | Total | |
| 50–59 | 32 (8.4%) | 85 (22.4%) | 117 (30.8%) |
| 60–69 | 33 (8.7%) | 103 (27.1%) | 136 (35.8%) |
| 70–79 | 25 (6.6%) | 61 (16.1%) | 86 (22.6%) |
| 80+ | 15 (3.9%) | 26 (6.8%) | 41 (10.8%) |
| Total | 105 (27.6%) | 275 (72.4%) | 380 (100.0%) |
Among 380 participants, SNHL was found in 27.6% (105 participants) whereas the age group 60–69 was mostly affected by 33(8.7%) (p = 0.448)
Table 3.
Prevalence of age-related SNHL by gender
| SNHL | ||||
|---|---|---|---|---|
| Age group | Yes | No | Total | |
| Male | 50–59 | 19 (10.4%) | 36 (19.8%) | 55 (30.2%) |
| 60–69 | 12 (6.6%) | 40 (22.0%) | 52 (28.6%) | |
| 70–79 | 15 (8.2%) | 32 (17.6%) | 47 (25.8%) | |
| 80+ | 11 (6.0%) | 17 (9.3%) | 28 (15.3%) | |
| Total | 57 (31.3%) | 125 (68.7%) | 182 (100.0%) | |
| Female | 50–59 | 13 (6.6%) | 49 (24.9%) | 62 (31.5%) |
| 60–69 | 21 (10.7%) | 62 (31.5%) | 83 (42.1%) | |
| 70–79 | 10 (5.1%) | 29 (14.7%) | 39 (19.8%) | |
| 80+ | 4 (2.0%) | 10 (5.1%) | 14 (7.3%) | |
| Total | 48 (24.4%) | 149 (75.6%) | 198 (100.0%) | |
Among 380 participants, SNHL of the elderly was found in 105 (27.6%), where, males were mostly affected 57 (31.3%), p = 0.574, females were 48 (24.4%) P = 0.467
Table 4.
Prevalence of SNHL in the elderly by lateralization
| Lateralization | |||||
|---|---|---|---|---|---|
| Right ear | Left ear | Bilateral | Total | ||
| Age groups | 50–59 | 0 (0.0%) | 5 (4.7%) | 26 (24.7%) | 31 (29.5%) |
| 60–69 | 4 (3.8%) | 0 (0.0%) | 27 (25.7%) | 31 (29.5%) | |
| 70–79 | 3 (2.8%) | 0 (0.0%) | 24 (22.8%) | 27 (25.7%) | |
| 80+ | 0 (0.0%) | 3 (2.8%) | 13 (12.3%) | 16 (15.2%) | |
| Total | 7 (6.7%) | 8 (7.6%) | 90 (85.7%) | 105 (100.0%) | |
Among 105 patients with SNHL, the majority had bilateral SNHL (90 (85.7%), p = 0.026. The left ear was 8(7.6%) and the right ear 7(6.7%) with age groups 50–59, 60–69 being mostly affected 31 (29.5%)
Table 5.
Risk factors associated with age-related SNHL. N = 380
| Risk factors | SNHL | No SNHL | Total | |
|---|---|---|---|---|
| Hearing loss in the first-degree relative | Yes | 50(13.2%) | 150(39.5%) | 200(52.6%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) | |
| History of noise exposure | Yes | 26(6.8%) | 82(21.6%) | 108(28.4%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) | |
| Hypertensive disorder | Yes | 29(7.6%) | 80(21.1%) | 109(28.7%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) | |
| Diabetes mellitus | Yes | 11(2.9%) | 21(5.5%) | 32(8.4%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) | |
| History of ototoxic drug use | Yes | 2(0.5%) | 1(0.3%) | 3(0.8%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) | |
| History of cigarette smoking | Yes | 39(10.3%) | 87(22.9%) | 126(33.2%) |
| Total | 105(27.6%) | 275(72.4%) | 380(100%) |
No significant association between age-related SNHL among elderly patients to all risk factors, p > 0.05
Discussion
In this study, 380 elderly participants were included. The age range was 50–96 years with a mean age of 66 years. Males were 182(47.9%) and females were 198(51.8%).
Among 380 elderly participants, 105(27.6%) had age-related SNHL, whereas the age group 60–69 years was mostly affected, 33(8.7%) (p = 0.448). Males had higher prevalence 57(31.3%) p = 0.574, as compared to females 48(24.4%) p = 0.467.
The prevalence was lower (27.6%) as compared to most of the studies done in America and Europe, like the study by Cruickshanks et al. (45.9%), Moscicki et al. (83%), and Lin et al. (63.1%). Different methodologies could have contributed to the discrepancy in the prevalence rate. This study’s result is similar to the study done in Benin which had a prevalence of 24.94%. It also showed a higher prevalence in males as compared to females which corresponds to the studies done in Europe, America as well as sub-Saharan African countries [6, 11, 18–22].
In this study, among the 105 elderly participants, the majority had bilateral SNHL (90 (85.7%), which is statistically significant (p = 0.026), left ear lateralization was 8(7.6%) and right ear lateralization 7(6.7%) with age groups 50–59, 60–69 years being mostly affected 31 (29.5%).
In another study, 94.8% experienced bilateral hearing loss, which is almost similar to the findings of this study [22, 23]. A bilateral type of hearing loss has a higher social impact on an individual as unilateral hearing loss is frequently compensated to the normal hearing ear.
Literature suggests an increase in the severity of hearing loss with age, which is quite similar to the findings in this study, where the findings indicate the severity of age-related SNHL in the elderly tends to increase with age. In a study of presbycusis among older Chinese people in Taipei, the study cohort showed pure-tone thresholds worsening, especially at frequencies > 2 kHz, with increasing age [24–29].
In this study, 50(13.2%) of the participants had a history of hearing loss in the first-degree relative p = 0.227. This study also found no statistical significance on noise exposure to age-related SNHL in the elderly (p = 0.328) which is contrary to the findings of other studies. History of noise exposure has been shown by the Beaver Dam, Wisconsin employment in noisy occupations and hearing loss are consistent with the damaging effects of exposure to loud noise, but they also may be markers of less healthy lifestyle factors [22].
The history of hypertensive disorders was found to have no statistical significance in this study (p = 0.777), which corresponds to other studies. This might be attributed to the effect of the use of antihypertensive medications which might reduce its effect on blood vessels including the labyrinthine artery, and the duration of the illness in an individual [30–32, 36].
In the Blue Mountains study, a non-significant association between hypertension and any other hearing loss was observed but was marginal as increasing hearing loss severity [23].
In other studies, it was found that there were non-significant associations with the variables: consumption of alcohol, smoking, a family history of dyslipidemia, systemic arterial hypertension, use of hormones, use of medication continuously, and other diseases. Eleven 11(2.9%) of participants had diabetes mellitus among the 105 with age-related SNHL, (p = 0.373) which differs from the findings of other studies [33–40].
This study found 2(0.5%) among 105 participants with age-related SNHL reporting a history of using ototoxic medication p = 0.129. Other studies revealed a significant association between exposure to loud noise and ototoxic medications, p = 0.016 [11]. In this study, among 105 participants 39(10.3%) were found to have a history of cigarette smoking, p = 0.308. The effect of cigarette smoking on age-related SNHL in the elderly has been revealed by several studies which was noted to be more in smokers and in males. This was similar to the study done in the United States which observed no significant associations of hearing loss with other cardiovascular risk factors [18, 33–40].
Conclusion
Age-related SNHL in the elderly is a complex disease and is prevalent in the community. In these group of participants, various comorbidities exist which might worsen the condition and negatively affects the quality of life. Furthermore, the health care providers need to keep in mind the co-existence of age-related SNHL in these groups of patients and manage them accordingly including hearing screening.
Acknowledgements
Not applicable.
Authors’ Contributions
ERM and JSR conceived, designed and drafted the manuscript, while ERM provided critical revision of the article. The authors read and approved the final manuscript.
Funding
The Authors declare no financial support to this study.
Data Availability
All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.
Declarations
Ethics Approval and Consent to Participate
Informed written consents were obtained from the participants. Ethical approval was obtained from Muhimbili University of Health and Allied Sciences (Institutional Review Board) IRB.
Consent for Publication
Not applicable.
Competing Interests
The authors declare that they have no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
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Data Availability Statement
All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.