Normal aging is a set of molecular, histological, physiological and psychological processes that accompany advancing age. In terms of hearing, this aging results in a neurosensorial damage responsible for a progressive bilateral sensorineural hearing loss called presbycusis [1]. It is the most frequent sensory deficit in the world [2] and its prevalence increases with age.

With the increase in life expectancy, it is obvious that presbycusis will increase in the coming years. Indeed, the population aged over 60 years will increase from 605 million in the year 2000 to 2 billion in 2050 [3]. In Africa, this number will increase from 56 to 215 million, almost as many as in Europe [4].

The onset of presbycusis may be accelerated by certain factors. Davanipour et al. [5] identified in their survey certain risk factors such as alcohol and tobacco consumption, high blood pressure and low socio-economic status. Studies have shown a higher prevalence in men than in women [5] [6].

Complications of presbycusis can be severe. Presbycusis can induce character disorders (anxiety, apathy, ...), mood disorders (depression), communication disorders, isolation and cognitive disorders [7] [8].

In view of all these considerations, the diagnosis of presbycusis and its management represent major public health issues in developing countries. The lack of existing data on this subject in Benin, and more specifically in Parakou town, motivated the present study, the objectives of which were: 1) to identify the factors associated with presbycusis among people of Parakou aged at least 50 years in 2021; 2) to evaluate its socio-professional impact.

This was a cross-sectional, descriptive, analytical study with prospective data collection, from February to May 2021, i.e. 04 months.

Were included in the study, people:

· aged 50 years and more;

· residing for at least six (06) months in the commune of Parakou in the course of the survey;

· who gave their consent to participate in the study.

Were not included in the study, people:

· who were absent or busy during survey team visitation;

· who objected to the performance of a pure tone audiometry;

· exposed to loud noise because of their work;

· who were ill and unable to answer questions promptly.

Were excluded from the study:

· people who had withdrawn at any time during data collection;

· people who had an abnormal otoscopic examination.

The sample was probabilistic, obtained through a four-stage cluster random sampling. In the first stage, clusters were selected from the city neighborhoods. In the 2^nd stage, concessions were selected; in the 3^rd and 4^th stages, households and individuals per household were selected (respectively). The sampling list consisted of the 42 neighborhoods of Parakou commune accompanied by their respective household counts; as presented by the 4^th General Census of Population and Housing (RGPH 4) conducted by INSAE in 2013 [9].

The Schwartz formula was used to determine the sample size (n).

n = k * Z α 2 * p * ( 1 − p ) i 2

With:

α = 0.05: first-species risk, hence Zα = 1.96;

p = 22.7% (Prevalence of presbycusis in Egypt) [10];

i = 5%: the desired precision;

n: the expected sample size;

k = 2: cluster effect;

n = 540.

The variables studied were:

· presbycusis;

· socio-demographic variables;

· functional signs;

· medical history;

· lifestyle;

· audiometry result;

· socio-professional impact.

Diagnostic criteria

Presbycusis was retained when the following criteria were met:

· an age equal or superior to 50 years;

· the presence or absence of auditory discomfort reported on questioning;

· a normal otoscopic examination;

· a sensorineural bilateral and symmetrical deafness (average hearing loss > 20 dB HL).

Symmetry was defined as a difference in perception between the two ears of less than 10 dB on the audiometric frequencies between 500 and 4000 Hz [11].

Data collection

The data collection tools were: a survey questionnaire, a HEINE Mini 3000 otoscope with 2.5× magnification, and a portable AUDIOSMART audiometer with a 3 - 4 hours measurement autonomy.

The socio-professional impact was assessed using the questionnaire “Evaluation of the impact of hearing loss in adults” [12]. The questionnaire includes four domains, “Quality of life”, “Personal life”, “Social life” and “Professional life”. Each domain consists of five questions written in a precise and short manner, in a common vocabulary and without negative wording. For each question, a visual analogue scale proposes a response from 0 to 10, allowing a quick count. The score 0 corresponds to a maximum difficulty, the score 10 to an ideal situation. The scores are averaged for each life domain. This average, for each domain, has a maximum value of 50 and a minimum value of 0. The lower the average, the greater the impact of the deafness on this area of life.

The data collection technique consisted of:

· an individual interview with each respondent;

· an otological examination of each respondent;

· a tonal audiometry.

Data processing and analysis

After collection, the data were verified, coded and then entered into EPI data 3.1.fr software. Data analysis was processed by the medium of Epi info 7.2.0.1. The qualitative variables were expressed in number and percentage and the quantitative variables in mean ± standard deviation or median with the first and third quartile depending on whether the distribution was normal or not. The comparison of proportions was performed with the Pearson Chi-square test or Fisher's exact test, as appropriate. The comparison of quantitative variables was performed with the Student’s test or the Kruskal-Wallis test, depending on whether the distribution was normal or not. A p-value of less than 0.05 allowed the recognition of statistically significant associations in univariate analysis.

Binary logistic regression was performed to adjust for associated factors. The initial multivariate analysis model included the associated variables in univariate analysis at a threshold of p < 0.2.

A total of 541 people were included in this study.

Prevalence of presbycusis

Of the 541 persons who participated in the present study, the diagnosis of presbycusis was retained in 272, for a prevalence of 50.28%.

Characteristics of the respondents

The sex ratio (male/female) was 1.23. The average age was 59.48 ± 9.80 years with extremes of 50 and 96. Most of the respondents (71.11%) were exposed to noise.

Figure 1 shows the distribution of the respondents according to the type of

hearing loss found.

As for the degree of deafness of the population studied, mild deafness was the most common. It was present in 56.56% of the respondents in the left ear and in 52.31% of the respondents in the right ear. On the right and left ears respectively, the moderate, severe and profound degrees represented 15.07% and 15.50%; 0.27% and 1.46%; 0.82% and 0.29%.

The other characteristics are shown in Table 1.

In univariate analysis, there was a significant association between presbycusis and certain socio-demographic variables (Table 1). There was also a significant association with hearing loss (p < 0.001), tinnitus (p = 0.004), vertigo (p = 0.078), osteoarthritis (p = 0.024), family history of age-related hearing loss (p = 0.009), alcoholism (p = 0.009), smoking (p = 0.004).

df = degree of freedom; HBP = high blood pressure.

From the multivariate analysis, it appears that the occurrence of presbycusis in adults in Parakou commune within 2021 is a function of age, sex, the presence of hypoacusis and the presence of a family history of age-related hearing loss (Table 2).

CI = Confidence interval.

Thus, when adjusted for other factors, people over 80 years of age were nearly 8 times more likely to develop presbycusis than those aged 50 to 60 years. Similarly, men were 1.59 times more likely than women. The risk of developing presbycusis was inversely proportional to the level of education.

The average scores obtained for different aspects of personal life among presbycusic people in Parakou are as follows: communication with relatives 6.97 ± 2.26; following a conversation without knowing the topic 7.24 ± 2.43; participation in a conversation with several people, in a quiet environment 6.76 ± 2.57; discussion in a noisy environment (family meeting, meal with television, ...) 4.39 ± 2.39; self-confidence to initiate a discussion with relatives 7.53 ± 2.84. The aspect of personal life most affected was communication in noise.

Prevalence of presbycusis

The prevalence of 50.28% found in the present study is close to those observed by Cruickshanks et al. in the United States in 2012 as well as Valero-Garcia et al. in Spain in 2018 who had reported prevalences of 42.7% and 54.87% respectively [13] [14].

It is however, lower than that reported by Lin et al. in the United States in 2011, Folorunso et al. in Nigeria in 2020 who had reported prevalences of 63% and 75% respectively [15] [16]. Similarly, lower prevalences had been found by Nash et al. in the United States in 2011 and Hannula et al. in Finland in 2011 who had reported prevalences of 6.1%, 14.1%, and 37% respectively [17] [18].

This large variability could be explained by the fact that there are very large differences in the method and diagnostic criteria used.

Indeed, the definition of deafness varied from one study to another. In the present study, we used the BIAP classification while other authors used the WHO classification [19]. Clearly, the lack of a common definition prevents the availability of comparable data on the prevalence of presbycusis.

The age ranges of the subjects surveyed differed from one study to another. There are no recommendations regarding the age limit for presbycusis. The choice of the age range of the study population was in most cases arbitrary and the reasons for this choice were not often mentioned.

It should also be noted that the size of the target populations and the type of study were very different from each other. Nash et al. [17] conducted a cohort study with more than 3000 volunteers, whereas the study by Folorunso et al. [16] was a cross-sectional study with 114 volunteers.

Factors associated with presbycusis

In the present study, age was significantly associated with presbycusis and the prevalence of presbycusis increased with age. For example, subjects over 80 years of age were at least 8 times more likely to develop presbycusis than younger subjects. This finding corroborates that of Cruickshanks et al. [14] in the United States in 2012 and Lasisi et al. [20] in Nigeria in 2010. This association of age and presbycusis found by several studies could be explained by the aging of the hearing system. Indeed, the contingent of sensory cells (less than 20,000 hair cells per cochlea) that we are endowed with at birth is limited and non-renewable. This contingent diminishes irreversibly over the years [21].

Gender was significantly associated with presbycusis. The prevalence of presbycusis was higher among male subjects. This finding has been made by many authors [8] [15] [22]. This male predominance could be explained by several factors: the protective role of female hormones [23] [24], the difference in exposure to other exogenous factors that may favor the occurrence of presbycusis. Indeed, men are more exposed to noise than women from a very young age. Even more men than women work in construction, factories, mechanics or welding. The same applies to the other factors of smoking and alcohol consumption [25].

Educational level was significantly associated with presbycusis in the present study. Indeed, illiterate subjects were up to 4 times more likely to develop presbycusis than subjects with a university education. This finding is similar to that of several authors [14] [17] [26]. Indeed, a high level of education would represent an indicator of socio-economic status which is also indicative of better access to health care, a healthier environment and less stress at work. On the other hand, a low socio-economic level would be more likely to lead to cardiovascular disease, which is a risk factor for presbycusis [18].

In the present study, only osteoarthritis was significantly associated with presbycusis. This factor was also found by Sogebi et al. [26] in Nigeria in 2013. This association could be explained by the fact that osteoarthritis is an inflammatory disease and the autoimmune mechanisms it involves, could contribute to the progressive destruction of the inner ear [27].

From the results of the study, a family history of age-related hearing loss was associated with presbycusis. These data have met the requirements of those of Bouata et al. [28] who also reported a statistically significant association between presbycusis and a family history. This could be explained by the fact that genetic factors are involved in the occurrence of presbycusis. Indeed, several studies have investigated this link and have identified a number of genetic variants with a statistical correlation that suggests that they may be involved in the development of presbycusis [29] [30].

Impact of presbycusis

In this survey,, all areas of life were impacted by presbycusis. The most impacted life domain was personal life. Several studies have shown that the first area to be affected once overt presbycusis is reached is the family area [28] [31] [32]. This could be explained by the fact that family members are the first to notice hearing difficulties. The patient, on the other hand, does not realize that he or she cannot hear well. This observation implies that the family and friends play a crucial role in the early detection of presbycusis. A diagnosis at this stage would allow an early management of presbycusis which could avoid the evolution towards complications.

In this research work, the aspect of personal life most affected was communication in noise. This finding was also presented by Espmark et al. [33] and Bouata et al. [28]. Indeed, presbycusis leads to a discomfort in noise which is characterized by a difficulty to follow a conversation in a group or in a noisy environment realizing the classic sign of the “cocktail”. The subject has the impression of hearing very well, even too well, especially motorcycles or any other violent noise. This phenomenon is explained by the fact that his painful threshold for high intensity sounds is confused, or almost, with his/her hearing threshold [34].

Strengths and weaknesses

This study has several strengths. It was conducted in a general population. Such type of study is the most relevant for determining the prevalence of a condition in the community. Method used was appropriate and the material collection was reliable. However, the study had some shortcomings: the audiometry was carried out in the respondents' homes, a setting in which the noise level was unknown, even though the examination was carried out away from any sound source. Voice audiometry was not performed. It could have provided additional data to better refine the diagnosis of presbycusis.

The prevalence of presbycusis was high among people over 50 years old in Parakou commune during 2021. Factors associated with presbycusis were: age ≥ 80 years, male gender, educational level, family history of age-related hearing loss. The associated sign was hearing loss. Presbycusis had a negative impact on all areas of life but impacted more, the personal life of the affected subjects. Controlling and addressing the associated factors could significantly contribute to reducing the prevalence of presbycusis, improving the hearing health of elderly subjects.

The authors declare no conflicts of interest regarding the publication of this paper.

Flatin, M.C., do Santos Zounon, A.A., Ametonou, C.B., Bouraima, F.A., Kimba, M.R., Hounkpatin, S.H., Adjibabi, W. and Vignikin-Yehouessi, B. (2022) Impact and Factors Associated with Presbycusis among 50 Years Old People of Parakou and Over in 2021. International Journal of Otolaryngology and Head & Neck Surgery, 11, 56-73. https://doi.org/10.4236/ijohns.2022.111007

Sheet N˚……

Date of investigation /….…./….…../….…./

Address……………… Phone………………