Abstract
This study aims to analyze the pattern of hearing loss among patients visiting ENT department in Nepal Police Hospital. Pure tone audiometry results of 1654 patients with a complaint of the hearing loss were analyzed and the results were expressed in number and percentage. Among 1654 patients, 294 patients had normal hearing on both ears. So, a total of 1360 patients had hearing loss. Among 1360 patients, 897 (66%) cases were male and 463 (34%) were female. Most commonly affected age group was 31–40 years followed by 21–30 years age group. Out of 1360 patients, 432 (31.76%) patients had unilateral hearing loss whereas 928 (68.24%) cases had bilateral hearing loss. Sensorineural hearing loss was the most common 1349 (49.60%), followed by conductive 683 (25.11%) and mixed 256 (9.41%) hearing losses respectively. Conductive hearing loss was more common in younger age groups whereas sensorineural hearing loss was more common in older age groups. Mild hearing loss was seen in 1079 ears (39.67%), moderate in 671 (24.67%), severe in 368 (13.52%) and profound in 170 (6.25%). The mean hearing threshold was 42.90 ± 19.26 dB on right ear and 42.60 ± 18.76 dB on left ear with no statistically significant difference (p value −0.68). Hearing loss was more common in male population with younger age group involvement. Sensorineural hearing loss was the most common type. Mild degree of hearing loss and bilateral involvement was most common.
Keywords: Conductive hearing loss, Hearing loss, Mixed hearing loss, Pure tone audiogram, Sensorineural hearing loss
Introduction
Hearing impairment is a common problem that affects people of all age groups. It affects more than 1.33 billion people globally [1]. Hearing impairment at any stage of life can compromise individual’s quality of life [2]. Hearing impairment may lead to negative consequences like poor general health, poor academic performance, higher unemployment, social isolation and an increased risk of depression [3]. The burden of hearing loss is higher in developing countries [4]. A study conducted in Nepal has shown that 16.6% of total population had hearing impairment [5].
Hearing loss can affect one or both ears. It can be classified as conductive, sensorineural or mixed type [6]. Conductive hearing loss is due to the defect in the sound conducting mechanism of the ear. Sensorineural hearing loss occurs due to the abnormality in the cochlear nerve, neural pathway, or the auditory cortex. Mixed hearing loss has components of both conductive and sensorineural hearing losses. World Health Organization (WHO) has developed the grading system to assesses the degree of hearing impairment [7].
Pure tone audiometry (PTA) is a tool used for the diagnosis of hearing loss. It is performed by the audiologists as per the recommendation from the otorhinolaryngologists [8]. PTA gives information regarding the degree, type, configuration of hearing loss and helps in further management planning [9].
Methods
This is a retrospective review of data retrieved from the record of Pure Tone Audiometry (PTA) results from ENT department of Nepal Police Hospital between 1st April 2016 to 31st May 2020. Total 1654 patients who had undergone PTA for a suspected hearing loss, were selected for the study. PTA was performed by two experienced audiologists using Amplaid 309 clinical audiometer. Pure tone average of 0.5, 1, 2 and 4 kHz frequencies was used to calculate the hearing threshold for bone and air conduction. PTA records of 1654 patients were tabulated and analyzed. The results were expressed in number and percentage. Degree of Hearing loss was measured using WHO classification [7]. Data were analyzed using Microsoft excel and SPSS 21. p value <0.05 was taken as level of significance.
Results
Total of 1654 patients with a complaint of hearing loss, who underwent PTA, were selected for the study. Among them 294 patients had normal hearing on both ears. So, a total of 1360 patients had hearing loss on either one or both ears. Among them, most commonly affected age group was 31–40 years followed by 21–30 years group (Table 1). The mean age was 43.6 ± 17.7 years (8–90 years). Among 1360 patients, 897 (66%) were male and 463 (34%) were female, and the male to female ratio was 1.94:1 (Table 1).
Table 1.
Age and sex distribution of the respondents
| Variables | Hearing loss | Normal hearing | Total |
|---|---|---|---|
| Age (Years) | |||
| 0–10 | 22 | 3 | 25 |
| 11–20 | 64 | 19 | 83 |
| 21–30 | 286 | 105 | 391 |
| 31–40 | 305 | 85 | 390 |
| 41–50 | 222 | 58 | 280 |
| 51–60 | 184 | 16 | 200 |
| 61–70 | 169 | 5 | 174 |
| 71–80 | 86 | 2 | 88 |
| 81+ | 22 | 1 | 23 |
| Gender | |||
| Male | 897 | 168 | 1065 |
| Female | 463 | 126 | 589 |
| Total | 1360 | 294 | 1654 |
Out of 1360 patients, 227 cases (16.69%) had hearing loss in right ear only, 205 (15.07%) cases had hearing loss in left ear only, whereas 928 (68.24%) cases had bilateral hearing loss (Table 2). So, total of 2288 ears had hearing loss. Total number of right ears involved was 1155(50.48%) whereas left ears was 1133 (49.52%). Sensorineural hearing loss was the most common 1349 (49.60%), followed by conductive 683 (25.11%) and mixed 256 (9.41%) hearing losses respectively (Table 3).
Table 2.
Involvement of ear in disease process (n = 1360)
| Ear involved | No. of patients | Percentage (%) |
|---|---|---|
| Only right ear | 227 | 16.69% |
| Only left ear | 205 | 15.07% |
| Both ear | 928 | 68.24% |
| Total | 1360 | 100% |
Table 3.
Type of hearing loss among the patients (n = 1360)
| Type of hearing loss | Right ear | Left ear | Total (Right + Left Ear) |
|---|---|---|---|
| No. of ears (%) | No. of ears (%) | No. of ears (%) | |
| Normal | 205 (15.07) | 227 (16.69) | 432 (15.88) |
| Conductive | 334 (24.56) | 349 (25.66) | 683 (25.11) |
| Sensorineural | 694 (51.03) | 655 (48.16) | 1349 (49.60) |
| Mixed | 127 (9.34) | 129 (9.48) | 256 (9.41) |
| Total | 1360 (100) | 1360 (100) | 2720 (100) |
On correlating the age groups with the type of hearing loss, conductive hearing loss was more common in the lower age groups while sensorineural hearing loss was more common in the higher age group of patients. Mixed hearing loss was more common in the middle-aged population (Table 4).
Table 4.
Type of hearing loss according the age group of patients (n = 1360)
| Age group | Type of hearing loss | ||
|---|---|---|---|
| Conductive | Sensorineural | Mixed | |
| 0–10 | 10 | 12 | – |
| 11–20 | 40 | 24 | – |
| 21–30 | 159 | 107 | 20 |
| 31–40 | 134 | 146 | 25 |
| 41–50 | 37 | 167 | 18 |
| 51–60 | 13 | 153 | 18 |
| 61–70 | 7 | 153 | 9 |
| 71–80 | 1 | 80 | 5 |
| 81 + | 1 | 21 | – |
On evaluating degree of hearing loss, mild hearing loss was seen in 1079 ears (39.67%), moderate in 671 (24.67%), severe in 368 (13.52%) and profound in 170 (6.25%) ears (Table 5). Mean hearing threshold was 42.90 ± 19.26 dB on the right ear and 42.60 ± 18.76 dB on the left ear. This difference was not statistically significant (p value −0.68).
Table 5.
Degree of hearing loss among the patients (n = 1360)
| Degree of hearing loss | Right ear | Left ear | Total (Right + Left Ear) |
|---|---|---|---|
| No. of ears (%) | No. of ears (%) | No. of ears (%) | |
| Normal (≤25 dB) | 205 (15.08) | 227 (16.70) | 432 (15.89) |
| Mild (26–40 dB) | 557 (40.96) | 522 (38.38) | 1079 (39.67) |
| Moderate (41–60 dB) | 330 (24.26) | 341 (25.07) | 671 (24.67) |
| Severe (61–80 dB) | 181 (13.30) | 187 (13.75) | 368 (13.52) |
| Profound (≥81 dB) | 87 (6.40) | 83 (6.10) | 170 (6.25) |
| Total | 1360 (100) | 1360 (100) | 2720 (100) |
Discussion
Hearing loss is a significant public health problem in countries like Nepal. Hearing loss has a significant financial and socioeconomic burden in low- and middle-income countries [4]. Hearing loss has a negative impact on the individual, which may result into poor general health, poor academic performance, higher risk of unemployment and depression [3]. Hearing loss also increases the financial burden to the society.
The pattern of hearing loss may vary between different geographic regions and between different hospitals. Knowledge of pattern of hearing loss can help health personnel to make the proper diagnosis and provide best treatment to the patients. Such study helps in early identification of the hearing problems and their management, ultimately helping to reduce morbidity and improve the quality of life [8].
In this study, pure tone audiograms of 1654 patients who presented to ENT outpatient department with the complaint of hearing loss were analyzed. Among 1654 patients, 294 patients had normal hearing on both ears. So, a total of 1360 patients had hearing loss on either one or both ears. In this study, hearing loss was highest in 31–40 years age group and it was 305 (27.74%). The next order was seen in age group of 21–30 and it was 286 (21.03%), followed by 41–50 years which was 222 (16.32%). Lowest incidence was seen in age group of above 80 years which was 22 (1.62%). These results are different from the study by Browning et al. [10] which showed that the hearing loss was highest in 61–80 years age group (45.3%) followed by 41–60 years age group (17.4%). This difference might be due to lack of awareness about hearing impairment and poor access to health care services especially among elderly in the developing country like Nepal.
In present study, maximum number of hearing loss was seen in 31–40 years followed by 21–30 years. This may be due to higher level exposure to risk factors among these age groups as these age groups constitute working class of people. Most of peoples in these age groups have increased awareness as well as easy access to hospital services compared to other age groups. Early visit to hospitals among these age group even after mild hearing impairment is common as slightest loss in hearing power may have negative impact on their work.
In present study, among 1360 patients with hearing loss, 897 (66%) were male and 463 (34%) were female. The male to female ratio was 1.94:1. The study performed by Uju [11] also found the higher prevalence of hearing loss in male as compared to female. Similar results have been shown by other studies [12, 13]. The higher prevalence of disease in male has been attributed to their increased exposure to the outdoor activities and other risk factors as well as early and easy access to healthcare services compared to females.
In present study bilateral hearing loss was seen in 928 (68.24%) cases and 432 (31.76%) had unilateral involvement. There was similar distribution of disease in the both ears i.e. 50.48% right ear and 49.52% left ear involvement These results are similar to the studies by Rabbani et al. [9] and Varshney et al. [14], which have shown that bilateral hearing loss more common and similar distribution of right and left ear involvement.
In present study, sensorineural hearing loss was the commonest type (49.60%) followed by conductive type (25.11%) and mixed type (9.41%). In right ear 51.03% was sensorineural, 24.56% was conductive and 9.34% was mixed. Similarly, in left ear, 48.16% was sensorineural, 25.66% was conductive and 9.48% was mixed. These results are similar to the findings of studies by Louw et al. [15], Shuaibu et al. [16] and Browning et al. [10]. In this study mild hearing loss was seen in 39.67% of ears, followed by moderate in 24.67%, severe in 13.52% and profound in 6.25%. These findings are similar to the results of other studies. [10, 13, 15, 16]
The main limitation of this study is that it is a retrospective study and correlation of the hearing loss with ear pathology was not done. Another limitation is the relatively smaller sample size. Studies with larger sample size are required to have better result.
Conclusion
This study concluded that sensorineural hearing loss was the commonest type among the patients with a complaint of the hearing loss. Most of them were adult male with bilateral mild hearing loss (26–40 dB). Audiometric assessment is an important tool that helps in early diagnosis and proper management of the hearing impairment.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Compliance with Ethical Standards
Conflicts of interest
The authors declare that they have no conflict of interests.
Research involving Human Participants and/or Animals
This article does not contain any studies with human participants performed by any of the authors.
Footnotes
Publisher's Note
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