A Systematic Review of Hearing Loss and Its Associated Factors Among Workers in the Metal Industry

Teens at Risk: “We’re on the Edge of an Epidemic”

To systematically assess the data on the prevalence and causes of hearing impairment in Africa. Systematic review on the prevalence and causes of hearing loss in Africa. We undertook a literature search of seven electronic databases (EMBASE, PubMed, Medline, Global Health, Web of Knowledge, Academic Search Complete and Africa Wide Information) and manually searched bibliographies of included articles. The search was restricted to population-based studies on hearing impairment in Africa. Data were extracted using a standard protocol. We identified 232 articles and included 28 articles in the final analysis. The most common cut-offs used for hearing impairment were 25 and 30 dB HL, but this ranged between 15 and 40 dB HL. For a cut-off of 25 dB, the median was 7.7% for the children- or school-based studies and 17% for population-based studies. For a cut-off of 30 dB HL, the median was 6.6% for the children or school-based studies and 31% for population-based studies. In schools for the deaf, the most common cause of hearing impairment was cryptogenic deafness (50%) followed by infectious causes (43%). In mainstream schools and general population, the most common cause of hearing impairment was middle ear disease (36%), followed by undetermined causes (35%) and cerumen impaction (24%). There are very few population-based studies available to estimate the prevalence of hearing impairment in Africa. Those studies that are available use different cut-offs, making comparison difficult. However, the evidence suggests that the prevalence of hearing impairment is high and that much of it is avoidable or treatable.

Occupational noise is a common cause of hearing loss in low-income countries. Unfortunately, screening for hearing loss is rarely done due to technical and logistical challenges associated with pure tone audiometry. Wulira app is a valid and potentially cost-effective alternative to pure tone audiometry in screening for occupational hearing loss. We aimed to determine the prevalence of occupational hearing loss among workers in a metal industry company in Kampala district. We recruited 354 participants conveniently from a steel and iron manufacturing industry in Kampala. All eligible participants answered a pretested and validated questionnaire and were assessed for noise induced hearing loss in a quiet office room approximately 500 meters from the heavy machinery area using the Wulira app. Descriptive statistics such as proportions were used to describe the study population while inferential statistics were used to determine associations. Of the 354 participants sampled, 333 (94.1%) were male, and the median age was 27, IQR (25-30). Regarding the risk factors of hearing loss, fourteen (3.9%) had history of smoking and more than half (65.5%) had worked in the industry for more than 2 years. The overall prevalence of hearing loss among industrial workers was 11.3% (40/354). 16.2% and 9% had mild hearing loss in the right and left ear respectively. Bilateral audiometric notch was present where fourteen (4%) of the participants had notch in their right ear while seven (2%) had notch in their left ear. Residing outside Kampala district was associated with hearing loss (OR, 95% CI, 0.213 (0.063-0.725), p = 0.013). One in 10 workers in a metal manufacturing industry in Kampala had occupational hearing loss. Industrial workers residing outside Kampala were likely to develop hearing loss. Periodic screening should be done for early detection and intervention to prevent progression of hearing loss in this population.

Objectives:Childhood hearing loss has well-known lifelong consequences. Certain rural populations are at higher risk for infection-related hearing loss. For Alaska Native children, historical data on hearing loss prevalence suggest a higher burden of infection-related hearing loss, but updated prevalence data are urgently needed in this high-risk population.Design:Hearing data were collected as part of two school-based cluster-randomized trials in 15 communities in rural northwest Alaska over two academic years (2017–2019). All enrolled children from preschool to 12th grade were eligible. Pure-tone thresholds were obtained using standard audiometry and conditioned play when indicated. The analysis included the first available audiometric assessment for each child (n = 1634 participants, 3 to 21 years), except for the high-frequency analysis, which was limited to year 2 when higher frequencies were collected. Multiple imputation was used to quantify the prevalence of hearing loss in younger children, where missing data were more frequent due to the need for behavioral responses. Hearing loss in either ear was evaluated using both the former World Health Organization (WHO) definition (pure-tone average [PTA] > 25 dB) and the new WHO definition (PTA ≥ 20 dB), which was published after the study. Analyses with the new definition were limited to children 7 years and older due to incomplete data obtained on younger children at lower thresholds.Results:The overall prevalence of hearing loss (PTA > 25 dB; 0.5, 1, 2, 4 kHz) was 10.5% (95% confidence interval [CI], 8.9 to 12.1). Hearing loss was predominately mild (PTA >25 to 40 dB; 8.9%, 95% CI, 7.4 to 10.5). The prevalence of unilateral hearing loss was 7.7% (95% CI, 6.3 to 9.0). Conductive hearing loss (air-bone gap of ≥ 10 dB) was the most common hearing loss type (9.1%, 95% CI, 7.6 to 10.7). Stratified by age, hearing loss (PTA >25 dB) was more common in children 3 to 6 years (14.9%, 95% CI, 11.4 to 18.5) compared to children 7 years and older (8.7%, 95% CI, 7.1 to 10.4). In children 7 years and older, the new WHO definition increased the prevalence of hearing loss to 23.4% (95% CI, 21.0 to 25.8) compared to the former definition (8.7%, 95% CI, 7.1 to 10.4). Middle ear disease prevalence was 17.6% (95% CI, 15.7 to 19.4) and was higher in younger children (23.6%, 95% CI, 19.7 to 27.6) compared to older children (15.2%, 95% CI, 13.2 to 17.3). High-frequency hearing loss (4, 6, 8kHz) was present in 20.5% (95% CI, 18.4 to 22.7 [PTA >25 dB]) of all children and 22.8% (95% CI, 20.3 to 25.3 [PTA >25 dB]) and 29.7% (95% CI, 27.0 to 32.4 [PTA ≥ 20 dB]) of children 7 years and older (limited to year 2).Conclusions:This analysis represents the first prevalence study on childhood hearing loss in Alaska in over 60 years and is the largest cohort with hearing data ever collected in rural Alaska. Our results highlight that hearing loss continues to be common in rural Alaska Native children, with middle ear disease more prevalent in younger children and high-frequency hearing loss more prevalent with increasing age. Prevention efforts may benefit from managing hearing loss type by age. Lastly, continued research is needed on the impact of the new WHO definition of hearing loss on field studies.

To summarize the literature on the prevalence of pediatric hearing loss in low- and middle-income countries (LMICs). A systematic review initially identified 2833 studies, of which 122 met the criteria for inclusion. Eighty-six of those studies included diagnoses and were included in a meta-analysis. The meta-analysis indicated a 1% (95% confidence interval=0.8-2.0) prevalence of childhood hearing loss across LMICs. There was significant heterogeneity between studies and evidence of publication bias. The prevalence of mild and moderate cases of hearing loss was higher than more severe cases and there were fewer cases of mixed hearing loss compared to conductive or sensorineural hearing loss. No differences were identified between the prevalence of unilateral versus bilateral hearing loss or hearing loss according to sex. The quality of the studies, age of participants, and location of data collection may have influenced the results. High variability in the reporting of etiology made the causes of hearing loss unclear. The literature indicates that 1% of children in LMICs have hearing losses. However, most studies missed children with acquired hearing loss, which may lead to under-reporting of global prevalence. This systematic review is an initial step toward developing and implementing population-appropriate treatment and prevention programs for childhood hearing loss in LMICs. The prevalence of childhood hearing loss in low- and middle-income countries is 1%. Reporting of hearing loss etiology was highly variable.

The objective of this study was to determine the prevalence of hearing loss in children attending primary schools in urban and rural Ethiopia. A cross-sectional study was performed to determine the prevalence of hearing loss in children aged 7 to 14 years. A total of 384 children had complete examinations and were included in the study. The prevalence of hearing loss of all types in the urban school was 6.2% using a cut-off of 40 dB Fletcher index (500-2000 Hz). The prevalence increased to 10.2 % in the same population if a cut-off of 25 dB HL FI was used. In the rural school with a cut-off of 30 dB HL the hearing prevalence was 5.9%. The proportion of conductive hearing loss was lower in the urban school and constituted 16% of all hearing losses. We estimated the proportion of conductive hearing loss in the rural school to be at least 50%. In the urban school the prevalence of sensorineural hearing loss was 5.8% while it was much lower at 1.3% and exclusively unilateral in the rural school. The degree of hearing loss according to WHO criteria was calculated only for the urban population. A prevalence of bilateral severe hearing loss (≥61 dB HL) of 0.5% and of moderate hearing loss (> 41 dB and ≤60dB HL) of 1% was found using WHO criteria.The prevalence of chronic suppurative otitis media and of dry perforations were similar between schools (2.5 to 2.7%). Otitis media was rare in this study likely due to seasonal influences and exclusion of very young children. These results are compared to similar school studies in Sub-Saharan Africa. The prevalence of hearing loss in these two Ethiopian cohorts (rural and urban) is in agreement with the data published by WHO for Sub-Saharan Africa. While some of the variation between urban and rural populations may have been real, some of the discrepancy may have resulted from differences in acoustic testing environments. We describe these challenges in hopes of improving universal screening procedures.

Hearing loss: a global health issue

Prevalence and clinical aspects of hearing loss among the South Korean adolescent: Data from a population-based study

To estimate prevalence of severe-profound hearing loss (HL) in South Korea, and analyse a 10-year trend of HL according to age, sex, and region by using a nationwide population-based database. Retrospective review from Korean National Health Insurance Service from 2006 to 2015. The degree of severe-profound HL was classified into six grades, based mostly on HL worse than 60 dB HL for both ears. Absolute number of HL was the highest in 2011 (0.25 million; males, 0.14 million; females, 0.11 million); it decreased gradually until 2015. Total HL prevalence was the highest in 2010 (0.5%; 251,954), and decreased annually to 2015 (0.46%; 237,272). The trend of HL prevalence showed a gradual decrease from 2010 to 2015. Prevalence of severe-profound HL was always higher in the male population (1.19 times higher than female in 2015). Prevalence of HL was higher in rural areas than in urban areas (1.4 times higher in 2015). Number of severe-profound HL in South Korea decreased gradually in all age groups annually, even though some older age groups had the highest peak in 2010–2011. Prevalence of severe-profound HL decreases gradually in all age groups annually in South Korea, although the absolute number of HL cases increases rapidly among those aged over 80 years.

Objective: To investigation the situation of occupational noise exposure and hearing loss among workers in automobile manufacturing enterprise during 2017-2019 in Wuhan. Methods: Workers in automobile manufacturing who underwent physical examination in Wuhan Hospital for the Prevention and Treatment of Occupational Diseases from 2017 to 2019 were included as subjects in the cross-sectional survey. Questionnaire survey, noise detection and pure tone threshold test were used. Excluding individuals with working time less than 3 years and information deficiency, 3 948 individuals were finally included in the study. Results: Among 3 948 workers, 128 workers had hearing loss and the rate of hearing loss was 3.24%, among which 101 workers had high-frequency hearing loss and 27 workers were diagnosed as occupational noise deafness. The prevalence of hearing loss among workers previously exposed to noise was significantly higher than that without prior exposure (12.10%, 0.96%, P<0.05) . The prevalence of hearing loss among workers with occupational noise exposure <80 dB (A) , 80~<85 dB (A) and ≥85 dB (A) was 1.83%, 2.69% and 5.09%, respectively. The prevalence of high frequency hearing loss was 1.60%, 2.05% and 3.71%, respectively. The prevalence of occupational noise deafness was 0.23%, 0.64% and 1.38%, respectively. The prevalence of hearing loss and high frequency hearing loss among workers exposed to different occupational noise was statistically significant (P<0.05) , while the prevalence of occupational noise deafness was not statistically significant (P>0.05) . There were statistically significant differences in the prevalence of hearing loss (2.88%, 4.45%) and occupational noise deafness (0.46%, 1.41%) between those who used protective equipment and those who did not (P<0.05) . Compared with workers exposed to occupational noise <80 dB (A) , workers exposed to occupational noise ≥85 dB (A) had A 3.16-fold increased risk of hearing loss (OR=3.16, 95%CI: 1.44~6.95, P<0.05) . Compared to workers using hearing protective equipment, the risk of hearing loss (OR=1.96, 95%CI: 1.25~3.06, P<0.05) and occupational noise deafness (OR=3.46, 95%CI: 1.51-7.96, P<0.05) significantly increased among those without using hearing protective equipment. Conclusion: The risk of hearing loss in automobile manufacturing workers is significantly associated with occupational noise exposure and the use of hearing protective equipment. Good hearing protection may reduce the risk of occupational noise-induced hearing loss and occupational noise deafness.

A better understanding of how the prevalence of hearing loss and its associated factors change over time could help in developing an appropriate program to prevent the development of hearing loss. Population-representative cross-sectional data from the United States National Health and Nutrition Examination Survey (NHANES) were used to estimate the trends in the prevalence of hearing loss among adults in the USA over the period 1999-2018. A total of 15,498 adult participants aged 20years or older had complete audiometric examination data. Logistic regression was employed to evaluate the trend in hearing loss; weighted Rao-Scott χ2 tests and univariate logistic regression analyses were used to examine the association between hearing loss and relevant factors. The overall hearing loss prevalence in 1999-2018 was 19.1% 19.1 (95% CI, 18.0-20.2%). The prevalence of hearing loss decreased in cycles (P for trend < 0.001). For participants aged 20-69years, the prevalence decreased from 15.6% (95% CI, 12.9-18.4%) in 1999-2000 to 14.9% (95% CI, 13.2- 16.6%) in 2015-2016; for participants aged > 70years the prevalence decreased from 79.9% (95% CI, 76.1-83.8%) in 2005-2006 to 64.5% (95% CI, 58.8-70.2%) in 2017-2018. Participants with hearing loss were likely to be older, male, non-Hispanic white, and to have not completed high school. Mild hearing loss was more prevalent among those aged 20-79years; in those aged over 80years the prevalence of moderate hearing loss exceeded that of mild loss. Among all otologically normal participants, hearing thresholds increased with age across the entire frequency range. The prevalence of hearing loss in USA adults changed over the period 1999-2018. The trends observed provide valuable insight for making public health plans and allocating resources to hearing care. Further investigation is necessary to monitor hearing loss and its potential risk factors.

Cancer survivors are at a higher risk of developing hearing loss (HL) due to older age, chemotherapy, and radiotherapy. However, the prevalence of HL among US cancer survivors remains unknown. Additionally, there is a lack of uniform HL screening guidelines for this enlarging population. To estimate the prevalence of subjective HL and objective HL by audiometry test among cancer survivors and compare them with the general population as well as to assess the performance of subjective HL questions in detecting true (ie, audiometry-confirmed) HL. In a cross-sectional design, adults between ages 20 and 80 years who had audiometry testing and responded to a hearing questionnaire from the National Health and Nutrition Examination Survey (2011-2012, 2015-2016, and 2017 to March 2020 prepandemic survey cycles) were selected. Data analysis was conducted from August 13, 2022, to July 26, 2023. The weighted prevalence of subjective HL (troublesome hearing and tinnitus) and objective HL (speech-frequency HL and high-frequency HL) by audiometry were calculated. Analyses with χ2 testing and multiadjusted logistic regression models were used to compare HL between cancer survivors and the general population. To evaluate the performance of subjective HL questions as a tool to screen for objective HL by audiometry, areas under the curve were estimated using age- and gender-adjusted logistic regression. Among the total 9337 participants (weighted n = 90 098 441; 51.2% women), 10.3% were cancer survivors. Compared with the general population, cancer survivors had a higher prevalence of troublesome hearing (adjusted odds ratio [AOR], 1.43; 95% CI, 1.11-1.84), tinnitus (AOR, 1.28; 95% CI, 0.94-1.74), speech-frequency HL (AOR, 1.43; 95% CI, 1.11-1.85), and high-frequency HL (AOR, 1.74; 95% CI, 1.29-2.34). When using the subjective HL tool and questioning regarding whether the participants were having troublesome hearing and/or tinnitus in screening for HL, the age- and gender-adjusted area under the curve was 0.88 in detecting speech-frequency HL and 0.90 in detecting high-frequency HL. The findings of this study suggest that cancer survivors have a significantly higher prevalence of HL than the general population. Two subjective HL questions could potentially accurately identify those who have true HL and provide a simple and efficient screening tool for health care professionals. Cancer survivors and their families should be educated and encouraged to discuss hearing concerns, and health care professionals should facilitate raising awareness and provide early screening and timely referral when HL is identified.

Sjögren syndrome (SS) is a multisystem autoimmune disease, primarily targeting salivary and lacrimal glands; skin, nasal and vaginal dryness, along with musculoskeletal pain and fatigue are the most commonly reported symptoms. Hearing loss is hypothesized to be frequent as well. The purpose of this systematic review was to estimate the prevalence of Hearing loss and its different subtypes in patients with Sjögren syndrome. PRISMA guidelines were followed to ensure highest quality for our systematic review. A random effects model meta-analysis and meta-regression was conducted using I2 as heterogeneity indicator. Eleven observational studies were included in this systematic review. Ten of them were cross-sectional, while one study was case-control. Studies were assessed for risk of bias: all were rated to a moderate level, except for two rated to a low level. Pooled prevalence of any type of hearing loss was 52.2%. After excluding studies rated to moderate bias, the pooled prevalence of hearing loss was 36.7%. We also conducted a subgroup analysis depending on type of hearing loss. Pooled prevalence of sensorineural hearing loss was 42.6%., while pooled prevalence of conductive hearing loss and mixed hearing loss were 5% and 2.3%, respectively. Meta-regression was conducted in an effort to identify possible variables capable to explain high heterogeneity between studies. Sample size and year of study were separately found to account for a portion of heterogeneity between studies of sensorineural hearing loss. Year of study was also found to account for a portion of heterogeneity between studies of conductive hearing loss. In conclusion, sensorineural hearing loss, is highly prevalent in patients with Sjögren syndrome. On this basis, early screening and follow-up of patients with Sjögren syndrome by pure tone audiometry is important.

In Australian remote communities, First Nations children with otitis media (OM)-related hearing loss are disproportionately at risk of developmental delay and poor school performance, compared to those with normal hearing. Our objective was to compare OM-related hearing loss in children randomised to one of 2 pneumococcal conjugate vaccine (PCV) formulations. In 2 sequential parallel, open-label, randomised controlled trials (the PREVIX trials), eligible infants were first allocated 1:1:1 at age 28 to 38 days to standard or mixed PCV schedules, then at age 12 months to PCV13 (13-valent pneumococcal conjugate vaccine, +P) or PHiD-CV10 (10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine, +S) (1:1). Here, we report prevalence and level of hearing loss outcomes in the +P and +S groups at 6-monthly scheduled assessments from age 12 to 36 months. From March 2013 to September 2018, 261 infants were enrolled and 461 hearing assessments were performed. Prevalence of hearing loss was 78% (25/32) in the +P group and 71% (20/28) in the +S group at baseline, declining to 52% (28/54) in the +P groups and 56% (33/59) in the +S group at age 36 months. At primary endpoint age 18 months, prevalence of moderate (disabling) hearing loss was 21% (9/42) in the +P group and 41% (20/49) in the +S group (difference -19%; (95% confidence interval (CI) [-38, -1], p = 0.07) and prevalence of no hearing loss was 36% (15/42) in the +P group and 16% (8/49) in the +S group (difference 19%; (95% CI [2, 37], p = 0.05). At subsequent time points, prevalence of moderate hearing loss remained lower in the +P group: differences -3%; (95% CI [-23, 18], p = 1.00 at age 24 months), -12%; (95% CI [-30, 6], p = 0.29 at age 30 months), and -9%; (95% CI [-23, 5], p = 0.25 at age 36 months). A major limitation was the small sample size, hence low power to reach statistical significance, thereby reducing confidence in the effect size. In this study, we observed a high prevalence and persistence of moderate (disabling) hearing loss throughout early childhood. We found a lower prevalence of moderate hearing loss and correspondingly higher prevalence of no hearing loss in the +P group, which may have substantial benefits for high-risk children, their families, and society, but warrant further investigation. ClinicalTrials.gov NCT01735084 and NCT01174849.

We aimed to estimate the prevalence of hearing loss and influencing factors among workers in automobile manufacturing industry in Wuhan, China. We conducted cross-sectional analyses of 2017 through 2019 data from survey of the key occupational diseases on 17,176 workers in automobile manufacturing industry, Wuhan, China. Hearing loss was defined as a pure tone mean of 25 dB or higher in either ear at 0.5, 1, and 2 kHz for speech frequency and at 3, 4, and 6 kHz for high frequency. Among the 17,176 workers, more than a quarter of participants had high frequency hearing loss, and 6.41% had speech frequency hearing loss. The prevalence of hearing loss was higher among participants with diabetes mellitus and current smoking, temporary tinnitus, and sudden change in hearing. Compared with the controls, age (OR = 1.08, 95% CI = 1.08-1.09), male (OR = 1.40, 95% CI = 1.21-1.63), occupational noise exposure (OR = 1.19, 95% CI = 1.08-1.30), having temporary tinnitus (OR = 1.20, 95% CI = 1.08-1.33), and having sudden change in hearing (OR = 1.58, 95% CI = 1.20-2.08) were associated with higher prevalence of high frequency hearing loss; meanwhile, age (OR = 1.09, 95% CI = 1.08-1.09), male (OR = 1.38, 95% CI = 1.11-1.71), having family history of hearing loss (OR = 2.84, 95% CI = 1.35-5.97), and having sudden change in hearing (OR = 2.58, 95% CI = 1.80-3.70) were associated with higher prevalence of speech frequency hearing loss. No additive and multiplicative interaction was found between occupational noise and these factors for hearing loss. Hearing loss directly affects 25% of workers in automobile manufacturing industry in Wuhan. Measures should be implemented for the control of occupational noise and other factors simultaneously in the workplace.