Adult-onset Hearing Loss Research Articles

Mutation of Foxo3 causes adult onset auditory neuropathy and alters cochlear synapse architecture in mice.

Auditory neuropathy is a form of hearing loss in which cochlear inner hair cells fail to correctly encode or transmit acoustic information to the brain. Few genes have been implicated in the adult-onset form of this disease. Here we show that mice lacking the transcription factor Foxo3 have adult onset hearing loss with the hallmark characteristics of auditory neuropathy, namely, elevated auditory thresholds combined with normal outer hair cell function. Using histological techniques, we demonstrate that Foxo3-dependent hearing loss is not due to a loss of cochlear hair cells or spiral ganglion neurons, both of which normally express Foxo3. Moreover, Foxo3-knock-out (KO) inner hair cells do not display reductions in numbers of synapses. Instead, we find that there are subtle structural changes in and surrounding inner hair cells. Confocal microscopy in conjunction with 3D modeling and quantitative analysis show that synaptic localization is altered in Foxo3-KO mice and Myo7a immunoreactivity is reduced. TEM demonstrates apparent afferent degeneration. Strikingly, acoustic stimulation promotes Foxo3 nuclear localization in vivo, implying a connection between cochlear activity and synaptic function maintenance. Together, these findings support a new role for the canonical damage response factor Foxo3 in contributing to the maintenance of auditory synaptic transmission.

P166 When English isn’t your first language: supporting deaf people in end of life care

Identified as a significant public health issue, hearing loss affects more than 10 million people in the UK. This figure is expected to rise to 14.5 million by 2031 [1]...

The Need for Improved Detection and Management of Adult-Onset Hearing Loss in Australia

Adult-onset hearing loss is insidious and typically diagnosed and managed several years after onset. Often, this is after the loss having led to multiple negative consequences including effects on employment, depressive symptoms, and increased risk of mortality. In contrast, the use of hearing aids is associated with reduced depression, longer life expectancy, and retention in the workplace. Despite this, several studies indicate high levels of unmet need for hearing health services in older adults and poor use of prescribed hearing aids, often leading to their abandonment. In Australia, the largest component of financial cost of hearing loss (excluding the loss of well-being) is due to lost workplace productivity. Nonetheless, the Australian public health system does not have an effective and sustainable hearing screening strategy to tackle the problem of poor detection of adult-onset hearing loss. Given the increasing prevalence and disease burden of hearing impairment in adults, two key areas are not adequately met in the Australian healthcare system: (1) early identification of persons with chronic hearing impairment; (2) appropriate and targeted referral of these patients to hearing health service providers. This paper reviews the current literature, including population-based data from the Blue Mountains Hearing Study, and suggests different models for early detection of adult-onset hearing loss.

Variation in Genes Related to Cochlear Biology Is Strongly Associated with Adult-Onset Deafness in Border Collies

Domestic dogs can suffer from hearing losses that can have profound impacts on working ability and quality of life. We have identified a type of adult-onset hearing loss in Border Collies that appears to have a genetic cause, with an earlier age of onset (3–5 years) than typically expected for aging dogs (8–10 years). Studying this complex trait within pure breeds of dog may greatly increase our ability to identify genomic regions associated with risk of hearing impairment in dogs and in humans. We performed a genome-wide association study (GWAS) to detect loci underlying adult-onset deafness in a sample of 20 affected and 28 control Border Collies. We identified a region on canine chromosome 6 that demonstrates extended support for association surrounding SNP Chr6.25819273 (p-value = 1.09×10−13). To further localize disease-associated variants, targeted next-generation sequencing (NGS) of one affected and two unaffected dogs was performed. Through additional validation based on targeted genotyping of additional cases (n = 23 total) and controls (n = 101 total) and an independent replication cohort of 16 cases and 265 controls, we identified variants in USP31 that were strongly associated with adult-onset deafness in Border Collies, suggesting the involvement of the NF-κB pathway. We found additional support for involvement of RBBP6, which is critical for cochlear development. These findings highlight the utility of GWAS–guided fine-mapping of genetic loci using targeted NGS to study hereditary disorders of the domestic dog that may be analogous to human disorders.

Factors that influence disclosure of hearing loss in the workplace

Objective: The objective of the study was to identify factors that lead individuals to conceal or disclose their hearing loss in the workplace. Design: A qualitative research paradigm called qualitative description was selected to address this issue. Study sample: Twelve people who had an adult onset hearing loss, and were gainfully employed, participated in audio-recorded semi-structured interviews designed to probe issues related to disclosure of hearing loss. A photo elicitation interview technique was employed during the interviews. Content analyses were used to extract pertinent information from verbatim transcripts. Results: Five recurring themes emerged as important considerations in relation to this topic: (1) perceived importance of the situation; (2) perceived sense of control; (3) community affiliation; (4) burden of communication; and (5) coexisting issues related to hearing loss. Conclusions: The findings are discussed in relation to other concealable stigmatizing traits, stigma-theory, and social-cognitive theory. The clinical implications of these findings are discussed, with particular emphasis placed on worker self-efficacy.SumarioObjetivo: El objetivo de este estudio fue identificar los factores que llevan a los individuos a ocultar o revelar su pérdida auditiva en el lugar de trabajo. Diseño: Se escogió un paradigma cualitativo de investigación llamado descripción cualitativa para enfrentar el asunto. Muestra del Estudio: Doce sujetos con una hipoacusia adquirida en la edad adulta con empleos bien remunerados participaron en una entrevista semi-estructurada grabado en audio, diseñada para evaluar asuntos relacionados con la revelación de su problema auditivo. Se empleó una técnica de entrevista por provocación fotográfica durante la misma entrevista. Se usó un análisis de contenidos para extraer la información pertinente de las transcripciones literales. Resultados: Cinco temas recurrentes emergieron como consideraciones importantes en relación con este tópico: 1. Percepción de la importancia de la situación; 2. Percepción del sentido de control; 3. Afiliación a la comunidad; 4. Carga en la comunicación; y 5. Asuntos coexistentes relacionados con la hipoacusia. Conclusiones: Los hallazgos se discuten en relación con otros rasgos estigmatizantes ocultables, con la teoría del estigma y con la teoría social-cognitiva. Las implicaciones clínicas de estos hallazgos se discuten, con un énfasis particular puesto en la auto-eficacia del trabajador.

Group Audiologic Rehabilitation for Adults and Their Communication Partners

Group Audiologic Rehabilitation for Adults and Their Communication Partners

Noise-induced hearing loss in Asia

The aim of this manuscript is to summarize the current scenarios encompassing noise exposure in the workplace and the risk of noise-induced hearing loss (NIHL) in Asia. NIHL is the most prevalent and preventable occupational disease in most Asian countries. Sources of noise in these countries include manufacturing and agriculture industries, exploitation of natural resources, and urban traffic. The highest attributable fraction of adult-onset hearing loss resulting from noise exposure in the world comes from Asian countries. NIHL is a serious health problem in Asia, not only because of the number of affected labourers, but also because the majority of Asian countries are still developing economies where access to health services and preventive programmes are limited. Lack of awareness about NIHL among employers, employees, and health care professionals is one of the main barriers for the prevention of NIHL in Asia. In this paper, the sources of noise, NIHL prevalence in different industries, local legislation, and research publications on NIHL from Asia are discussed.SumarioEl propósito de este manuscrito es resumir los escenarios actuales relacionados con la exposición a ruido en el lugar de trabajo y el riesgo de hipoacusia inducida por ruido (NIHL) en Asia. La NIHL es la enfermedad ocupacional más prevalente y prevenible en la mayoría de los países asiáticos. Las fuentes de ruido en estos países incluyen las industrias de manufactura y agricultura, la explotación de los recursos naturales y el tráfico urbano. La fracción más alta en el mundo atribuible de la hipoacusia de inicio en la edad adulta proveniente de la exposición a ruido, viene de los países asiáticos. La NIHL es un serio problema de salud en Asia, no sólo por el número de trabajadores afectados, sino porque la mayoría de los países asiáticos aún son economías en desarrollo, donde el acceso a los servicios de salud y a los programas preventivos es limitado. La falta de conciencia sobre la NIHL entre los empleadores, los empleados y los profesionales en salud, es una de las principales barreras para la prevención de la NIHL en Asia. En este trabajo, se discuten las fuentes de ruido, la prevalencia de NIHL en las diferentes industrias, la legislación local y las publicaciones de investigación sobre NIHL.

Carotid dissection in mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a rare, genetic etiology of stroke in young individuals. The most commonly associated genetic mutation is an adenine to guanine transition at nucleotide 3243 in the mitochondrial genome [1]. The pathogenesis of stroke-like episodes is not fully understood, but is believed to be due to mitochondrial angiopathy, metabolic defects, or neuronal hyperexcitability [2]. Mitochondrial angiopathy has largely been attributed to small vessel disease. In this report, we describe a patient with MELAS who presented with multiple strokes and was also found to have bilateral pseudoaneurysm formation of the internal carotid arteries with accompanying dissection. A 47-year-old female originally presented to an outside hospital with a two day history of word finding difficulties, headache, and right upper extremity weakness. Imaging confirmed a left middle cerebral artery (MCA) stroke. Her past medical history is significant for an episode of eclampsia complicated by bilateral visual and hearing loss. Her vision gradually improved but her hearing loss became progressively worse with time. Her family medical history includes adult onset hearing loss and diabetes in her mother. Initial stroke evaluation included magnetic resonance angiography (MRA) of the head and neck that demonstrated minimal atherosclerotic changes in the left middle cerebral artery with otherwise normal vessels, a normal transesophageal echocardiogram, and a normal cerebrospinal fluid profile. She had mildly elevated cholesterol and heterozygous inheritance of the prothrombin gene mutation. She initially recovered partially, but one week later, she had progressive decline in her mental status and subsequently decreased oral intake, prompting transfer to our facility for further evaluation. At presentation, she was found to be encephalopathic with infrequent, non-sensical speech. Initial labs were significant for a bicarbonate of 19 mmol/L with an anion gap of 13 mmol/L, hemoglobin A1c of 6.1%, and normal serum lactate (Table 1). A head CT showed bilateral basal ganglia and thalamic calcifications in addition to her stroke, and an EEG revealed bilateral slowing. Her vessels were re-examined with a CT angiogram of the head and neck that revealed a right internal carotid artery dissection with pseudoaneurysm and evidence of chronic dissection on the left carotid artery (Fig. 1a). The outside hospital MRA was reviewed and did not reveal any dissections. A lumbar puncture was performed and revealed an elevated lactic acid of 5.4 mmol/L. Repeat MRI/MRA with spectroscopy revealed a normal lactate peak and extension of the left MCA stroke involving the full MCA territory, new left PCA stroke, and a new right hemisphere infarct consistent with a right embolic phenomenon, possibly to the anterior choroidal artery, or an atypical lipohyalinosis of the lenticulostriates from the right MCA (Fig. 1b). A muscle biopsy was performed showing ragged red fibers. MELAS genetic testing was ordered and was positive for the mtA3243G mitochondrial mutation. In the setting of bilateral carotid dissections, genetic test for Ehlers–Danlos Syndrome Type IV was also ordered and was negative. No history of head or neck trauma was elicited. CT angiogram of the chest, abdomen and pelvis did not reveal any other R. C. C. Ryther Department of Child Neurology, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA, USA

Genomic Duplication and Overexpression of TJP2/ZO-2 Leads to Altered Expression of Apoptosis Genes in Progressive Nonsyndromic Hearing Loss DFNA51

Age-related hearing loss is due to death over time, primarily by apoptosis, of hair cells in the inner ear. Studies of mutant genes responsible for inherited progressive hearing loss have suggested possible mechanisms for hair cell death, but critical connections between these mutations and the causes of progressive hearing loss have been elusive. In an Israeli kindred, dominant, adult-onset, progressive nonsyndromic hearing loss DFNA51 is due to a tandem inverted genomic duplication of 270 kb that includes the entire wild-type gene encoding the tight junction protein TJP2 (ZO-2). In the mammalian inner ear, TJP2 is expressed mainly in tight junctions, and also in the cytoplasm and nuclei. TJP2 expression normally decreases with age from embryonic development to adulthood. In cells of affected family members, TJP2 transcript and protein are overexpressed, leading to decreased phosphorylation of GSK-3beta and to altered expression of genes that regulate apoptosis. These results suggest that TJP2- and GSK-3beta-mediated increased susceptibility to apoptosis of cells of the inner ear is the mechanism for adult-onset hearing loss in this kindred and may serve as one model for age-related hearing loss in the general population.

Short-term hearing aid benefit in a large group.

Short-term benefit in a very large group (N = 4,584) following hearing aid treatment was estimated using a revised version of the Self-Assessment of Communication (SAC-Hx). A total of 4,584 veterans with adult-onset hearing loss and mean audiometric findings consistent with a mild to severe, sloping, symmetrical, sensorineural hearing impairment were fitted with hearing aids. Responses to the SAC-Hx were gathered prior to and then 6 weeks following hearing aid fitting. Benefit was defined as the difference between the baseline and the posttreatment SAC-Hx scores. Hearing aid treatment resulted in robust and statistically significant benefit in each category of self-perceived communication consequences. Prior experience influenced benefit: New hearing aid users demonstrated the greatest magnitude of benefit, but even previously satisfied and dissatisfied users obtained significant benefit after new hearing aid fitting. Duration of experience did not have a remarkable effect on the magnitude of benefit: All groups with various durations of experience obtained comparable benefit. Severity of the baseline scores paralleled degree of hearing impairment when impairment was defined using a better ear pure tone average at 1,000, 2,000, 3,000, and 4,000 Hz. Also, severity of perceived communication consequences paralleled poorer monosyllabic word recognition. Hearing aid treatment provided a functional, robust, and statistically significant benefit to individuals in all categories of hearing impairment (normal, mild, moderate, severe, and profound). This report demonstrates the feasibility of the SAC-Hx as a tool to efficiently assess outcome domains in hearing aid fitting.

Effects of sex, gonadal hormones, and augmented acoustic environments on sensorineural hearing loss and the central auditory system: Insights from research on C57BL/6J mice

Mice of the C57BL/6J (B6) inbred strain exhibit genetic progressive sensorineural hearing loss and have been widely used as a model of adult-onset hearing loss and presbycusis. Males and females exhibit similar degrees of hearing loss until about 3 months of age, after which, the loss accelerates in females. This paper reviews research on how the B6 auditory system is affected by sex, gonadectomy (i.e., a reduction of gonadal hormone levels), and nightly exposure to moderately intense augmented acoustic environments (AAEs) – a low-frequency noise band (LAAE) or high-frequency band (HAAE). Several findings indicate a negative effect of ovarian hormones on the female B6 auditory system. Whereas the sex difference in high-frequency hearing loss was not significantly affected by gondadectomies, the female disadvantage in ABR thresholds at lower frequencies was erased by ovariectomy. Moreover, exposure to the LAAE or HAAE caused losses of hair cells that were more severe in intact females than in ovariectomized females or in males. Finally, intact females had more severe loss of neurons in the low-frequency region of the anterior ventral cochlear nucleus (AVCN) than other groups. In contrast, the presence of androgens had beneficial effects. Loss of hair cells and AVCN neurons after AAE exposure were more severe in orchidectomized males than in intact males. Ideas, hypotheses, and potential mechanisms concerning the findings are discussed.

Sudden Sensorineural Hearing Loss: Otolaryngologic and Audiologic Options

Sudden Sensorineural Hearing Loss: Otolaryngologic and Audiologic Options

Intrachromosomal partial triplication of chromosome 13 secondary to a paternal duplication with mild phenotypic effect

Intrachromosomal triplications are rare and can be mistaken for duplications. The majority of triplications reported are de novo, mostly involving chromosome 15q, and have a middle inverted repeat. We report on the clinical, cytogenetic, and molecular analyses of a patient with a novel triplication 13q21.1-q21.33 secondary to a familial duplication 13q21.1-q21.33 with mild phenotypic effect in three generations. The propositus was an 8-year-old boy referred because of language delay and mild mental retardation. His weight, height and OFC were above the 97th centile. He had delayed tooth eruption and subtle dysmorphic features. Chromosome analysis (550 band stage) showed extra material in 13q21. Family history was unremarkable except for adult-onset sensorineural hearing loss in the father and paternal grandfather. Their karyotypes and those of both brothers of the propositus also showed an abnormal chromosome 13 but with less extra genetic material. FISH analysis with several BAC clones showed a triplication in the propositus between 204N9 and 184B18 (which mapped to 13q21.1 and 13q21.33, respectively) and a direct duplication for the same fragment (around 12 Mb) in the rest of the family members with the abnormal chromosome 13. The FISH signals did not show a middle inverted repeat. We describe the first intrachromosomal triplication 13q21.1-q21.33 derived from a paternal duplication. Meiotic instability in the transmission of a duplication has not been previously observed. Phenotypic variability may be explained by chromosomal non-penetrance or dosage critical loci located in the triplicate/duplicate segment.

Perceptual coherence in listeners having longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing

Perceptual coherence, the process by which the individual elements of complex sounds are bound together, was examined in adult listeners with longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing. It was hypothesized that perceptual coherence would vary in strength between the groups due to their substantial differences in hearing history. Bisyllabic words produced by three talkers as well as comodulated three-tone complexes served as stimuli. In the first task, the second formant of each word was isolated and presented for recognition. In the second task, an isolated formant was paired with an intact word and listeners indicated whether or not the isolated second formant was a component of the intact word. In the third task, the middle component of the three-tone complex was presented in the same manner. For the speech stimuli, results indicate normal perceptual coherence in the listeners with adult-onset hearing loss but significantly weaker coherence in the listeners with childhood hearing losses. No differences were observed across groups for the nonspeech stimuli. These results suggest that perceptual coherence is relatively unaffected by hearing loss acquired during adulthood but appears to be impaired when hearing loss is present in early childhood.

Hearing problems at working age: Audiometric features and the aetiology of hearing impairment

Sixty patients, 37 women and 23 men, aged 30−65 years, were included in the study. All had adult-onset hearing loss to an extent that necessitated hearing-aid fitting. The objective was to describe the audiometric features and extent of hearing loss, and to determine the aetiology of hearing impairments in hard-of-hearing patients in working life. The extent of hearing loss varied considerably; about one-third of the patients had moderate to severe hearing loss in both ears, about one-third had bilateral, mild hearing loss, and somewhat less than one-third had unilateral or asymmetrical hearing loss, with mild loss or even normal hearing in one ear. In 77% of the cases a diagnosis, verified or tentative, could be established. Middle ear disease with conductive or mixed hearing loss was found in 20% of the cases. Noise-induced hearing loss was diagnosed in 10% of the cases. The most common, but highly tentative, diagnosis was hereditary hearing loss. Including cases of otosclerosis, genetic hearing loss wa...

An Advocate for Self-Assessment: Barbara Weinstein

An Advocate for Self-Assessment: Barbara Weinstein

Identification and functional analysis of common sequence variants in the DFNA15 gene, Brn-3c

A rare mutation in Brn-3c ( Brn3.1, POU4F3) underlies adult onset hearing loss (DFNA15) and targeted deletion of this gene in mice leads to complete deafness due to loss of sensory hair cells from the cochlea. Therefore the aim of our study was to identify and characterise common functional variation in the Brn-3c gene, which could potentially be a genetic risk for more common forms of adult onset hearing loss. We identified seven sequence variants at the Brn-3c locus. One of these, a novel, common variant at position − 3432 was extremely complex consisting of a variable guanine repeat that also exhibited single nucleotide substitutions within the poly-guanine repeat: − 3432 poly-G polymorphism. In-vitro studies show that this polymorphism modifies binding affinity for the SP1 transcription factor. Furthermore, reporter constructs of the Brn-3c 5′-flanking region containing different − 3432 poly-G alleles show altered transcriptional activity when endogenous SP1 levels are reduced using a dominant negative approach. Results also indicate that this effect is influenced by the length of a novel polymorphic (GT) n repeat at position − 566 in the Brn-3c 5′-flanking region. In summary, our data show there are common sequence variants in the Brn-3c 5′-flanking region that affect transcriptional regulation in vitro; these variants are candidates for large-scale population based association analysis as they could potentially affect the genetic risk for more common types of adult onset hearing loss.

Audiologic/Aural Rehabilitation is Valued and Necessary

You have accessThe ASHA LeaderFeature1 Jun 2007Audiologic/Aural Rehabilitation is Valued and Necessary Joseph MontanoEdD, CCC-A Joseph Montano Google Scholar More articles by this author , EdD, CCC-A https://doi.org/10.1044/leader.FTR2.12082007.5 SectionsAbout ToolsAdd to favorites ShareFacebookTwitterLinked In John O’Neill is the subject of the second article contributed by Special Interest Division 7, Aural Rehabilitation and Its Instrumentation, highlighting the work of master clinicians in audiologic/aural rehabilitation (AR). While in his doctoral program at Ohio State University, O’Neill worked in an AR program under the direction of staff that included three individuals from the Army and another from the Navy AR programs. The intensive residential program included hearing aid evaluation and dispensing, individual and group speechreading, and auditory training along with psychological counseling. He served on the Ohio State faculty and then joined the faculty at the University of Illinois, where currently he is professor emeritus. O’Neill became one of the founders of the Academy of Rehabilitative Audiology (ARA), and has served as its president. He was ASHA president in 1969. You have published and presented extensively on the complementary nature of vision and audition. What do you think is the historical impact of speechreading on the professions of audiology and speech-language pathology? Speechreading along with auditory training was one of the approaches to working individually with people who have hearing impairments that enabled audiology to separate from education of the deaf. Once audiology began to work with people who are hard of hearing, it utilized a therapeutic model that gave some emphasis to the need for speech training. Thus audiology and speech-language pathology needed to interact with each other. Some of our colleagues believe that traditional adult AR therapeutic intervention approaches such as auditory training and speechreading are no longer crucial components of the treatment of hearing loss. What is your opinion? I believe that a traditional-based AR therapeutic approach is still needed. Some individuals who receive hearing aids feel they do not help as much as desired. Other individuals who are hearing impaired cannot or choose not to utilize amplification because of slight or mild hearing loss or perhaps moderate or severe hearing loss with poor speech recognition. Both groups need help in developing emphasis on visual and auditory cues as well as developing coping mechanisms. As the population ages, these approaches along with the determination of previous communication skills will become necessary. How do you feel about the recent technological advances that have made services like speechreading and auditory training available for use as home-based interactive self-study? Home-based interactive services for speechreading and auditory training have a place for those individuals who have transportation and mobility problems. Such programs will need initial interaction with a clinician before the start of the programs. Further, there will be a need for a monitoring source. A continuing problem with any type of treatment program is the lack of an objective measure of significant improvement. What are your views on the current state of AR and what changes do you foresee in the future? I feel AR is quite neglected today with the clinical and research emphasis on the characteristics of the hearing aid and the function of the inner ear. In my experience, some recent AuD graduates tend to think in terms of fitting an ear rather than fitting an individual with a hearing loss. Until AR proves to be economically feasible, it will not be recommended often. Ongoing research is encouraging on the effects of individual speech elements on success in speechreading and aural reception in quiet and noise. Such approaches will give some objectivity to AR. The increase in the number of cochlear implants reveals the need for audiologic/aural rehabilitation or habilitation as a necessary part of success with some procedures. Increased attention should be paid to the individual needs and long-term performance of individuals who have received a hearing aid. Training of AuD candidates should include more of an emphasis on the value of and need for AR. Author Notes Joseph Montano, AdD, CCC-A, is director of audiology and speech-language pathology at New York Presbyterian Hospital-Weill Cornell Medical Center. Montano’s clinical expertise is audiologic rehabilitation with a particular interest in adjustment to adult-onset hearing loss, hearing assistive technology systems, and hearing aids. Contact him at [email protected]. Advertising Disclaimer | Advertise With Us Advertising Disclaimer | Advertise With Us Additional Resources FiguresSourcesRelatedDetails Volume 12Issue 8June 2007 Get Permissions Add to your Mendeley library History Published in print: Jun 1, 2007 Metrics Current downloads: 171 Topicsasha-topicsleader_do_tagasha-article-typesleader-topicsCopyright & Permissions© 2007 American Speech-Language-Hearing AssociationLoading ...

The global burden of occupational noise‐induced hearing loss

Excessive noise is a global occupational health hazard with considerable social and physiological impacts, including noise-induced hearing loss (NIHL). This paper describes the worldwide morbidity of occupational NIHL in the year 2000. The proportion of the population exposed to occupational noise was estimated using noise exposure data from the US National Institute for Occupational Safety and Health (NIOSH), adjusted by data on the distribution of the work force by occupational category and economic sector, and economic activity rates in each WHO subregion. These values for the exposed population and risk measures for NIHL were used to develop estimates of the attributable fraction (AF) of adult-onset hearing loss resulting from occupational noise exposure. The AFs were applied to WHO estimates of total disability-adjusted life years (DALYs) from adult-onset hearing loss to estimate the DALYs due to occupational noise. Worldwide, 16% of the disabling hearing loss in adults (over 4 million DALYs) is attributed to occupational noise, ranging from 7% to 21% in the various subregions. The effects of the exposure to occupational noise are larger for males than females in all subregions and higher in the developing regions. Occupational noise is a significant cause of adult-onset hearing loss. The majority of this NIHL burden can be minimized by the use of engineering controls to reduce the generation of noise at its source.

The WHO-DAS II: Psychometric Properties in the Measurement of Functional Health Status in Adults With Acquired Hearing Loss

The World Health Organization's (WHO) Disability Assessment Scale II (WHO-DAS II) is a generic health-status instrument firmly grounded in the WHO's International Classification of Functioning, Disability and Health (WHO-ICF). As such, it assesses functioning for six domains: communication, mobility, self-care, interpersonal, life activities, and participation. Domain scores aggregate to a total score. Because the WHO-DAS II contains questions relevant to hearing and communication, it has good face validity for use as an outcome measure for audiologic intervention. The purpose of the present study was to determine the psychometric properties of the WHO-DAS II on a sample of individuals with adult-onset hearing loss, including convergent validity, internal consistency, and test-retest stability. Convergent validity was established by examining correlations between the WHO-DAS II (domain and total scores) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Hearing Aid Handicap for the Elderly (HHIE), two disease-specific measures, as well as with the Short Form-36 for veterans (SF-36V), a second generic measure. Data on all four measures were collected from 380 older individuals with adult-onset hearing loss who were not hearing aid users. The results of the convergent validity analysis revealed that the WHODAS II communication domain score was moderately and significantly correlated with scores on the APHAB and the HHIE. WHO-DAS II interpersonal and participation domain scores and the total scores were also moderately and significantly correlated with HHIE scores. These findings support the validity of using the WHO-DAS II for assessing activity limitations and participation restrictions of adult-onset hearing loss. Several WHO-DAS II domain scores and the total score were also significantly and moderately-markedly correlated with scores from the SF-36V. These findings support the validity of the WHO-DAS II as a generic health-status instrument. Internal consistency reliability for all the domain scores was adequate for all but the interpersonal domain. Test-retest stability for all the domain scores was adequate. Critical difference values were calculated for use in clinical application of the WHO-DAS II. From these findings, we concluded that the WHO-DAS II communication, participation, and total scores can be used to examine the effects of adult-onset hearing loss on functional health status. Further work examining the utility of the WHO-DAS II as an outcome measure for hearing aid intervention is warranted.