Risk factors for childhood sensorineural hearing loss in the Oxford region

Hearing Loss in Children: Clinical-Epidemiological Data from Two Different Provinces of the Same Region

BACKGROUND

In many countries, neonatal hearing screening programs (NHS) have been available for many years; however, because of the presence of hearing loss at late onset, early hearing detection programs (EHDP) have been implemented. The aim of this study was to evaluate all cases of infantile hearing loss under the care of two different provinces of a regional health service since the introduction of NHS.

METHODS

Clinical data (the presence of audiological risk factors, age at which children are placed under the care of health service, entity of hearing loss, treatment, and exposure to bilingualism) were retrospectively collected during the period from 1 January 2012 to 31 December 2018, starting from the IT management system used in all of the regional neuropsychiatric services.

RESULTS

In total, 124 children were included-116 cases failed the screening, 1 case had an untraceable result, and 7 cases (5.6%) had hearing screening that passed. Most of the children were placed under the care of a neuropsychiatric infantile and adolescence (NPIA) service within the first year of life. The main differences across the two provinces concerned the percentages of audiological risk factors and the number of unilateral hearing loss cases.

CONCLUSION

In order to plan and manage hearing rehabilitation programs for children in the best way, it is very important to know the local clinical-epidemiological features of the population.

Effect of audiological testing on programmable ventriculoperitoneal shunts

OBJECTIVE

This study aimed at measuring the magnetic field strength of commonly used types of audiological testing equipment and determine their effects on the three most commonly used programmable ventriculoperitoneal (VP) shunts to try and quantify the risk of a VP shunt being reprogrammed during audiological testing.

DESIGN

In this in vitro study, magnetic field strength was measured for TDH 39 supra-aural earphones, B71 bone vibrator, ALGO 3i probe, Bio-logic Nav Pro probe, Otodynamics otoport insert earphone and Madsen Zodiac tympanometry probe.

STUDY SAMPLE

Magnetic field strength associated with transducers placed on a model of a skulls having implanted Miethke ProGAV 2.0, Medtronic Strata II and Codman Hakim programmable VP shunts was measured.

RESULTS

The supra-aural earphones had a magnetic field strength of 14 mT at 0 mm, which dropped to 0 mT at 10 mm away from the transducer. All other equipment had a magnetic field strength of 3.5 mT or less at 0 mm. There was no instance of reprogramming of the shunts by the transducers.

CONCLUSIONS

The findings suggest that the risk of inadvertent valve-reprogramming by the transducers is extremely small. However, care should be taken to avoid placing any of the transducers directly over the shunt.

Prevalence of permanent childhood hearing loss detected at the universal newborn hearing screen: Systematic review and meta-analysis

CONTEXT

Permanent childhood hearing loss (PCHL) can affect speech, language, and wider outcomes. Adverse effects are mitigated through universal newborn hearing screening (UNHS) and early intervention.

OBJECTIVE

We undertook a systematic review and meta-analysis to estimate prevalence of UNHS-detected PCHL (bilateral loss ≥26 dB HL) and its variation by admission to neonatal intensive care unit (NICU). A secondary objective was to report UNHS programme performance (PROSPERO: CRD42016051267).

DATA SOURCES

Multiple electronic databases were interrogated in January 2017, with further reports identified from article citations and unpublished literature (November 2017).

STUDY SELECTION

UNHS reports from very highly-developed (VHD) countries with relevant prevalence and performance data; no language or date restrictions.

DATA EXTRACTION

Three reviewers independently extracted data and assessed quality.

RESULTS

We identified 41 eligible reports from 32 study populations (1799863 screened infants) in 6195 non-duplicate references. Pooled UNHS-detected PCHL prevalence was 1.1 per 1000 screened children (95% confidence interval [CI]: 0.9, 1.3; I2 = 89.2%). This was 6.9 times (95% CI: 3.8, 12.5) higher among those admitted to NICU. Smaller studies were significantly associated with higher prevalences (Egger's test: p = 0.02). Sensitivity and specificity ranged from 89-100% and 92-100% respectively, positive predictive values from 2-84%, with all negative predictive values 100%.

LIMITATIONS

Results are generalisable to VHD countries only. Estimates and inferences were limited by available data.

CONCLUSIONS

In VHD countries, 1 per 1000 screened newborns require referral to clinical services for PCHL. Prevalence is higher in those admitted to NICU. Improved reporting would support further examination of screen performance and child demographics.

Hearing loss in Korean adolescents: The prevalence thereof and its association with leisure noise exposure

The increasing use of personal listening devices (PLDs) has been accompanied by a rise in the prevalence of hearing loss (HL) in younger age groups. However, there have been few reports on the relationship between HL and leisure noise exposure (LNE) in adolescents. The purpose of our study was to investigate the prevalence of HL in students attending general middle and high schools and to identify factors affecting HL prevalence. A total of 2,879 nationally representative adolescents in the first years of middle and high school underwent audiometric testing and otological examinations, and completed questionnaires, from June to December 2016. A speech-frequency hearing loss (SFHL) was considered present when the pure tone averages (PTAs) at 0.5, 1, and 2 kHz were ≥ 15 dB and a high-frequency hearing loss (HFHL) was considered present when the PTAs at 3, 4, 6, and 8 kHz were ≥ 15 dB. About 17% of Korean adolescents exhibited at least slight HL. The prevalence rates of SFHL and HFHL in the poorer ear were 11.6% and 10.3%, respectively, among Korean adolescents. The use of local area network (LAN) gaming centers and an experience of being asked by others to lower earphone volume were associated with both SFHL and HFHL. It is important to avoid excessive LNE to prevent adolescent HL. Additionally, SFHL or HFHL in the poorer ear was associated with lower academic performance.

Prenatal Alcohol Exposure and Suspected Hearing Impairment Among Children: A Population-based Retrospective Cohort Study

Aims

This study aimed to examine the association between prenatal alcohol exposure and hearing impairment among Japanese children using early childhood health check-up data.

Methods

This retrospective cohort study used population-based health check-up data for children who were born between April 2000 and March 2013 in Hofu city, Japan. Logistic regression models were used to evaluate the association between prenatal alcohol exposure and hearing impairment among children at the age of 36 months. The models were adjusted for mother's age, smoking habit, child sex, birth weight, birth order, history of otitis media and familial history of hearing impairment.

Results

Among the 16,211 registered children, 10,680 children had maternal gestational information and underwent a health check-up at the age of 36 months. A total of 10,562 children were included in the analyses, which revealed that 640 children required a re-examination for hearing impairment, 157 children required a detailed examination for hearing impairment and 83 children were receiving treatment for hearing impairment at 36 months. Prenatal alcohol exposure was independently associated with suspected hearing impairment among children after adjusting for potential confounders.

Conclusions

Our findings suggest that prenatal alcohol exposure may adversely affect the auditory system of children.

Short Summary

Prenatal alcohol exposure was associated with suspected hearing impairment among children at 36 months, based on the findings of a population-based retrospective cohort study that used health check-up data from 10,562 Japanese children.

Association of nuclear and mitochondrial genes with audiological examinations in Iranian patients with nonaminoglycoside antibiotics-induced hearing loss

Mitochondrial DNA mutations play an important role in causing sensorineural hearing loss. The purpose of this study was to determine the association of the mitochondrial genes RNR1, MT-TL1, and ND1 as well as the nuclear genes GJB2 and GJB6 with audiological examinations in nonfamilial Iranians with cochlear implants, using polymerase chain reaction, DNA sequencing, and RNA secondary structure analysis. We found that there were no novel mutations in the mitochondrial gene 12S rRNA (MT-RNR1) in patients with and without GJB2 mutation (GJB2⁺ and GJB2⁻, respectively), but a total of six polymorphisms were found. No mutations were observed in tRNA^Leu(UUR) (MT-TL1). Furthermore, eight polymorphisms were found in the mitochondrial ND1 gene. Additionally, no mutations were observed in the nuclear GJB6 gene in patients in the GJB2⁻ and GJB2⁺ groups. The speech intelligibility rating and category of auditory perception tests were statistically assessed in patients in the GJB2⁻ and GJB2⁺ groups. The results indicated that there was a significant difference (P<0.05) between the categories of auditory perception score in the GJB2⁻ group compared to that in the GJB2⁺ group. Successful cochlear implantation was observed among individuals with GJB2 mutations (GJB2⁺) and mitochondrial polymorphisms compared to those without GJB2 mutations (GJB2⁻). In conclusion, the outcome of this study suggests that variation in the mitochondrial and nuclear genes may influence the penetrance of deafness. Therefore, further genetic and functional studies are required to help patients in making the best choice for cochlear implants.

Disabling chronic conditions in childhood and socioeconomic disadvantage: a systematic review and meta-analyses of observational studies

OBJECTIVE

To determine the association of socioeconomic disadvantage with the prevalence of childhood disabling chronic conditions in high-income countries.

STUDY DESIGN

Systematic review and meta-analyses.

DATA SOURCES

6 electronic databases, relevant websites, reference lists and experts in the field.

STUDY SELECTION

160 observational studies conducted in high-income countries with data on socioeconomic status and disabling chronic conditions in childhood, published between 1 January 1991 and 31 December 2013.

DATA EXTRACTION AND SYNTHESIS

Abstracts were reviewed, full papers obtained, and papers identified for inclusion by 2 independent reviewers. Inclusion decisions were checked by a third reviewer. Where reported, ORs were extracted for low versus high socioeconomic status. For studies reporting raw data but not ORs, ORs were calculated. Narrative analysis was undertaken for studies without data suitable for meta-analysis.

RESULTS

126 studies had data suitable for meta-analysis. ORs for risk estimates were: all-cause disabling chronic conditions 1.72 (95% CI 1.48 to 2.01); psychological disorders 1.88 (95% CI 1.68 to 2.10); intellectual disability 2.41 (95% CI 2.03 to 2.86); activity-limiting asthma 2.20 (95% CI 1.87 to 2.85); cerebral palsy 1.42 (95% CI 1.26 to 1.61); congenital abnormalities 1.41 (95% CI 1.24 to 1.61); epilepsy 1.38 (95% CI 1.20 to 1.59); sensory impairment 1.70 (95% CI 1.39 to 2.07). Heterogeneity was high across most estimates (I(2)>75%). Of the 34 studies without data suitable for meta-analysis, 26 reported results consistent with increased risk associated with low socioeconomic status.

CONCLUSIONS

The findings indicate that, in high-income countries, childhood disabling chronic conditions are associated with social disadvantage. Although evidence of an association is consistent across different countries, the review provides limited evidence to explain the association; future research, using longitudinal data, will be required to distinguish low socioeconomic status as the cause or consequence of childhood disabling chronic conditions and the aetiological pathways and mechanisms.

The validity of family history as a risk factor in pediatric hearing loss

OBJECTIVES

A family history of permanent childhood hearing loss is considered a risk factor for pediatric hearing loss, although its validity has been sparsely examined. This study aimed to: (1) investigate the prevalence and yield of this risk factor for congenital and postnatal hearing losses, (2) define the audiometric characteristics of hearing loss in children with positive family histories, and (3) assess the nature of the familial relationships.

METHOD

A retrospective cohort study including all children born in Queensland, Australia between September 2004 and December 2011 who had completed Healthy Hearing's newborn hearing screen (n=380,895).

RESULTS

(1) Prevalence of the risk factor was 1.09% (4138/380,895). Prevalence of the risk factor in congenital cases was 7.29% and in postnatal cases was 36.84%. A low yield was identified for both congenital and postnatal groups (1.43% and 1.7%, respectively). (2) The degree of loss in congenital cases was highly varied, whereas the predominant degree in postnatal cases was mild. The most frequent type of loss for congenital cases was sensorineural, whereas for postnatal cases it was conductive. (3) Maternal or sibling relationships were most commonly reported for congenital losses, and maternal or paternal relationships for postnatal losses.

CONCLUSIONS

Children with a family history of pediatric hearing loss should have their hearing screened at birth and be monitored throughout early childhood. However, more efficient surveillance methods should be considered in view of the high prevalence with low yield.

Societal-level Risk Factors Associated with Pediatric Hearing Loss: A Systematic Review

OBJECTIVE

To determine if the current body of evidence describes specific threshold values of concern for modifiable societal-level risk factors for pediatric hearing loss, with the overarching goal of providing actionable guidance for the prevention and screening of audiological deficits in children.

DATA SOURCES

Three related systematic reviews were performed. Computerized PubMed, Embase, and Cochrane Library searches were performed from inception through October 2013 and were supplemented with manual searches.

REVIEW METHODS

Inclusion/exclusion criteria were designed to determine specific threshold values of societal-level risk factors on hearing loss in the pediatric population. Searches and data extraction were performed by independent reviewers.

RESULTS

There were 20 criterion-meeting studies with 29,128 participants. Infants less than 2 standard deviations below standardized weight, length, or body mass index were at increased risk. Specific nutritional deficiencies related to iodine and thiamine may also increase risk, although data are limited and threshold values of concern have not been quantified. Blood lead levels above 10 µg/dL were significantly associated with pediatric sensorineural loss, and mixed findings were noted for other heavy metals. Hearing loss was also more prevalent among children of socioeconomically disadvantaged families, as measured by a poverty income ratio less than 0.3 to 1, higher deprivation category status, and head of household employment as a manual laborer.

CONCLUSIONS

Increasing our understanding of specific thresholds of risk associated with causative factors forms the foundation for preventive and targeted screening programs as well as future research endeavors.

Hearing difficulties in children with special health care needs

OBJECTIVE

To determine characteristics of children with special health care needs (CSHCN) with hearing difficulties including patterns of hearing aid use, comorbidity, and social and communication function.

METHODS

Bivariate and multivariable analysis of cross-sectional data on 40,723 children aged from birth to 17 years from the 2005-2006 National Survey of Children with Special Health Care Needs, including 1,982 (5%) with parent-reported hearing difficulties.

RESULTS

Among CSHCN, 383 (1%) used hearing aids, representing 20% of those with reported hearing difficulties. Odds of hearing aid use increased with age, primary language other than English, and lower income. More than half (58%) of the aided children reported hearing difficulties even with their aid. Among CSHCN with cerebral palsy, 13% had reported hearing difficulties and 3% used hearing aids. Equivalent figures for children with Down syndrome were 24% and 4%, mental retardation/developmental delay 12% and 5%, and autism spectrum disorder 9% and 2%. Overall, two-thirds of CSHCN with hearing difficulties had one or more sensory/developmental comorbidities; CSHCN with both hearing difficulties and a sensory/developmental comorbidity had highest odds of learning difficulties, speaking/communication difficulties, feeling anxious/depressed, acting out/bullying, and difficulty making friends. CSHCN with hearing difficulties alone, or sensory/developmental conditions alone had intermediate odds, after socio-demographic adjustment.

CONCLUSIONS

Sensory/developmental comorbidities are common among CSHCN with hearing difficulties, and they are associated with higher odds of poorer social, communication, and educational function. Services for CSHCN must be equipped to address a range of hearing difficulties as well as sensory/developmental comorbidities and to improve social/emotional functioning as well as learning and communication.

Childhood infections, but not early life growth, influence hearing in the Newcastle thousand families birth cohort at age 14 years

Background

While current research priorities include investigations of age-related hearing loss, there are concerns regarding effects on childhood hearing, for example through increased personal headphone use. By utilising historical data, it is possible to assess what factors may have increased hearing problems in children in the past, and this may be used to inform current public health policies to protect children against hearing loss and in turn reduce the long-term burden on individuals and services that may possible evolve. The aim of this study was to investigate which factors in early life significantly impacted on hearing level in childhood using existing data from the Newcastle Thousand Families Study, a 1947 birth cohort.

Methods

Data on early life factors, including growth, socio-economic status and illness, and hearing at age 14 years were collated for a representative subset of individuals from the cohort (n = 147). Factors were assessed using linear regression analysis to identify associations with hearing thresholds.

Results

Males were found to have lower hearing thresholds at 250 Hz, 500 Hz and 1 kHz. Main analyses showed no associations between hearing thresholds and early life growth or socio-economic indicators. An increasing number of ear infections from birth to age 13 years was associated with hearing thresholds at 250Hz (p = 0.04) and 500Hz (p = 0.03), which remained true for females (p = 0.050), but not males (p = 0.213) in sex-specific analysis. Scarlet fever and bronchitis were associated with hearing thresholds at 8 kHz. After adjustment for all significant predictors at each frequency, results remained unchanged.

Conclusions

We found no associations between childhood hearing thresholds and early life growth and socio-economic status. Consistent with other studies, we found associations between childhood infections and hearing thresholds. Current public health strategies aimed at reducing childhood infections may also have a beneficial effect upon childhood hearing.

Prelingual sensorineural hearing loss and infants at risk: Western Sicily report

OBJECTIVE

To evaluate independent etiologic factor associated with sensorineural hearing loss (SNHL) in newborn at risk; to study the role of their interaction especially in NICU infants who present often multiple risk factors for SNHL.

METHODS

The main risk factors for SNHL reported by JCIH 2007 were evaluated on 508 infant at risk ranging from 4 to 20 weeks of life, transferred to the Audiology Department of Palermo from the main births centers of Western Sicily. After a global audiological assessment, performed with TEOAE, tympanometry and ABR, the prevalence and the effect of risk factors was statistically studied through univariate and multivariate analysis on the total population (normal and deaf subjects).

RESULTS

Fifty-one infants (10.03%) were diagnosed with SNHL (45 bilateral and 6 monolateral) with a mean hearing threshold of 87.39 ± 28.25 dB HL; from logistic regression analysis family history of hearing impairment (HI) and TORCH infections resulted independent significant risk factors (P<0.00001 and P=0.024 respectively). High SNHL percentages were evidenced also in NICU babies, due to the various pathologies and risk factors presented by these infants, and among newborns who suffered from hyperbilirubinemia requiring exchange transfusion (11.97% and 9.52% respectively). Craniofacial abnormalities (CFA) and syndromes associated to HI showed an important relationship (P<0.00001) with conductive hearing loss (CHL). Multiple regression analysis of the variation in SNHL among NICU infants evidenced an increased risk for SNHL of 21.24% and of 19.33% respectively in preterm infants and in case of hyperbilirubinemia if respiratory distress is concomitant with these risk factors. It was also observed an higher risk of SNHL (99.66%) in case of coexistence of prematurity and hyperbilirubinemia. Finally among infants with very low birth weight (VLBW) it was evidenced a statistically difference between the mean weight of SNHL infants respect to NHL newborns (P=0.048).

CONCLUSION

The high SNHL prevalence (10.03%) in our cohort underlines how infants at risk are more susceptible to suffer from SNHL; in particular NICU newborns have a 33% greater chance of developing SNHL, because of the presence of multiple risk factors (or=1.33) and their interaction. As the number of coexisting risk factors increases, the prevalence of SNHL also increases (r(2)=0.93).

An epidemiological study on children with syndromic hearing loss

OBJECTIVES

To study the epidemiological factors in children with syndromic hearing loss.

STUDY DESIGN

Interview based prospective study.

SETTINGS

Govt. ENT Hospital, AYJNIHH, NIMH-SEC, and Schools for the Deaf-in Hyderabad and SecunderabadPatients: Children aged below 14 years, with hearing loss, their parents/guardians.

INTERVENTION(S)

The study revealed type and degree of hearing impairment. In high risk groups genetic counseling was offered.

RESULTS

Epidemiological studies were carried out in 743 children below 14 years with hearing impairment and 138 (18.57%) were found to have syndromic deafness. Majority of the children with hearing loss have an association of ocular abnormality (22.46%, n=31) followed by skeletal anomalies 14.49% (n=20) and dental anomalies (10.86%). We observed 24 cases (3.21%) with genetically well recognized syndromes.

CONCLUSION

Data is generated on epidemiological and etiology of Hearing Impairment. Hearing Impairment is due to both environmental and genetic causes. Environmental factors in 17 (13.77%), genetically inherited 21 cases (15.22%) and the cause is not known in the remaining cases. Such a data is required in order to offer genetic counseling to reduce the genetic burden.

Audiologic profile of infants at risk: experience of a Western Sicily tertiary care centre

OBJECTIVE

To identify the incidence of sensorineural hearing loss (SNHL) on infant at risk and to classify the degree and type of hearing loss describing the main causes associated in Western Sicily. To compare single TEOAE and combined TEOAE/ABR techniques studying the referral rate, the false-positive and false-negative rates through concordance test (κ coefficient), sensitivity (TPR) and specificity (TNR) for each protocol.

METHODS

From January 2010 to June 2011, 412 infants at risk, ranging from 4 to 20 weeks of life, transferred to Audiology Department of Palermo from the births centers of Western Sicily, underwent to audiological assessment with TEOAE, tympanometry and ABR. The following risk factors were studied: family history of SNHL, consanguinity, low birth weight, prematurity, cranio-facial abnormality and syndromes associated to SNHL, respiratory distress, intensive care in excess of 5 days (NICU), pregnant maternal diseases, perinatal sepsis or meningitis, hyperbilirubinemia, ototoxic drugs administration.

RESULTS

Forty-seven infants (11.41%) were diagnosed with SNHL; median corrected age at final audiological diagnosis was 12 weeks. SNHL resulted moderate in 44.68%, severe in 10.64% and profound in 21 cases with a significant difference in family history and NICU infants (p<0.0001). As the number of coexisting risk factors increases, the percentage value of SNHL in infants (χ(2)=12.31, p=0.01, r(2)=0.98) and the degree of hearing loss (χ(2)=13.40, p=0.0095, r=0.92) also increase. The study of single TEOAE and combined TEOAE/ABR showed a statistical difference (χ(2)=14.89, p<0.001) with a low concordance value (κ=0.87) confirming the importance of combined techniques for NICU group (κ=0.86) where four cases (0.97%) of auditory neuropathy were diagnosed.

CONCLUSION

This study demonstrates the necessity to implement a neonatal hearing screening program in Western Sicily because of the high percentage of SNHL in infants at risk. Family history of HL is an independent significant risk factor for SNHL easily diagnosed through single TEOAE technique. Combined TEOAE/ABR is the gold standard for NICU babies which are at risk for auditory neuropathy. Coexisting risk factors are an additional risk factor for HL.

Risk indicators for hearing loss in infants treated in different neonatal intensive care units

AIM

To assess which infants' characteristics and specialized procedures are risk indicators for unilateral or bilateral hearing loss (HL) and to evaluate whether these risk indicators are associated with variation in prevalence of HL between Neonatal Intensive Care Units (NICUs).

METHODS

For 2002-2005, data from the NICU hearing screening database in the Netherlands were matched with the national neonatology database in which all NICU infants with their patient characteristics and specialized procedures are registered. Multivariate logistic regression analyses were performed to assess risk indicators for HL and to explain differences in prevalence rates between NICUs.

RESULTS

A total of 10 830 infants were available for analyses. The prevalence of HL was 1.8% and ranged from 0.7 to 3.7% between NICUs. Infants' characteristics that significantly increased the risk of HL were the presence of craniofacial anomalies, chomosomal/syndromal anomalies, central nervous system conditions, circulatory system conditions and intra-uterine infections. The specialized procedures involving > or =12 days of intensive care and high frequency oxygenation ventilation were independent risk indicators for HL. Approximately 20% of the variance can be explained by the studied risk indicators. Differences in prevalence rates between NICUs were slightly reduced after adjustment for these risk indicators. NICUs with the highest prevalence rates of HL were situated in the largest cities in the Netherlands with a mixed population because of immigration. Therefore, ethnicity may be a risk indicator.

CONCLUSIONS

Several independent risk indicators for HL were found, but they could not explain all differences in prevalence rates of HL between NICUs.

Smoking and height as risk factors for prevalence and 5-year incidence of hearing loss. A questionnaire-based follow-up study of employees in Denmark aged 18–59 years exposed and unexposed to noise

This paper investigated whether smoking and short stature in adulthood were independent risk factors for hearing loss. We reanalyzed data from the Danish Work Environment Cohort Study (an existing cohort study), on prevalence of self-reported hearing loss among 7,221 employees and on five-year incidence among 4,610 employees. We found that smoking predicted hearing loss incidence and prevalence. Smoking did not predict incidence at noise exposure during half or more of a worker's hours. Very short stature predicted prevalence in the total adult population only weakly, but strongly among employees born before 1951. These prospective findings indicate that smoking is an independent risk factor for incidence of hearing loss. Very short stature predicted prevalence of hearing loss only in a subpopulation.

Epidemiology of congenital hearing loss in Victoria, Australia: Epidemiología de la hipoacusia congénita en Victoria, Australia

The aim of this study was to report the incidence, prevalence and clinical characteristics of congenital hearing loss sufficient to require hearing aid fitting in the first 6 years of life for the 1993 birth cohort of the state of Victoria (population 4.4 million), Australia. In 1993, 64,116 infants born in the state of Victoria survived the neonatal period. Subjects included all children with congenital hearing loss for which hearing aids were fitted, at any time up to and including 31 December 1999, when the youngest member of the cohort reached 6 years of age. Data on the degree, type and etiology of hearing loss were available from the Australian Hearing database for all subjects. Sociodemographic and health data were available from the Victorian Infant Hearing Screening Program (VIHSP) and parent questionnaires. The known prevalence of identified congenital hearing loss increased as the cohort aged. By the time the youngest member had reached the age of 6 years, 134 children (78 boys, 56 girls) had been fitted with hearing aids for permanent congenital hearing loss of any degree (2.09/1000). Fifty-four (40%) of these had known mild losses (20-40 dB HL). The prevalence of known moderate or greater loss (> 40 dB HL) was 1.12/1000; the data suggest that over 90% could have been detectable by neonatal hearing screening. A further seven children from the birth cohort were fitted with hearing aids due to acquired forms of hearing loss (0.11/1000). The etiology was known in only 57 (43%) congenital cases, with known non-syndromal genetic causes accounting for 21 (37%) of these. This study reports on the prevalence of congenital hearing loss requiring hearing aid fitting for an entire birth cohort. These data indicate the possible yield from neonatal screening, and hence the likely benefit of such screening. For a large proportion of cases, the etiology remains unknown. These data have implications for health service delivery and illustrate the usefulness of a population database in monitoring the prevalence of congenital hearing loss.

Birthweight and the risk of childhood sensorineural hearing loss

The aim of this study was to estimate the impact of birthweight on the risk of sensorineural hearing loss in children. The study was a nested case-control study. Cases (n = 327) were identified through the Norwegian county registers of children with hearing loss, and controls (n = 391 992) were all children without hearing loss born in the same counties, identified through the Norwegian Medical Birth Registry of Norway. Case definition was mean sensorineural hearing loss (MHL) > or =35 decibel (dB) hearing level (HL) in the better-hearing ear averaged over the pure-tone hearing thresholds at 500, 1000 and 2000 Hz, diagnosed before the age of 5 years. Birthweight <1500 g, as compared with 3500-3999 g, gave an adjusted odds ratio for sensorineural hearing loss of 6.3 [95% CI 2.4, 16.4], controlled for gestational age, gender, parity, maternal age and concurrent birth defects. The risk of hearing loss decreased with increasing birthweights, with adjusted odds ratios of 4.4, 3.8, 1.7 and 1.4 for the birthweights 1500-1999, 2000-2499, 2500-2999 and 3000-3499 g respectively. The risk of both mild to moderate (MHL 35-70 dBHL) and severe/profound hearing losses (MHL >70 dBHL) were influenced by birthweight.

Newborn hearing screening project using transient evoked otoacoustic emissions: Western Sicily experience

OBJECTIVE

To study the incidence of congenital sensorineural hearing loss in all newborns introducing a screen test with a protocol no expensive, with a good "screen sensitivity" that could let an earlier identification of hearing impairment beginning early intervention by 2 months of age and increasing the probability of having language development within the normal range of development.

METHODS

The study was conducted in Sciacca hospital from the beginning of 2003 to our days and was carried out with transient evoked otoacoustic emission using the criteria for PASS or RETEST and considering eventual prenatal and perinatal risk factors. All the newborns were divided into four groups each one with its personal secondary step program.

RESULTS

In the years 2003-2004 the number of the newborns in Sciacca hospital was: 538 for 2003, 653 for 2004 with a total of 1191; all these infants were divided in three groups: resident in Sciacca, resident in the Sciacca borderlands and resident out of the district of Sciacca. The coverage (percentage of the target population who undergo the screen) was of 90% in the 2003 (483 newborns) and of 90% in the 2004 (585 newborns) with two cases of congenital sensorineural hearing loss identified. The incidence of sensorineural hearing loss, in the District of Sciacca, was estimated to be 2.07/1000 in 2003 and 1.70/1000 in 2004.

CONCLUSIONS

The higher incidence of sensorineural hearing loss in our study is due to a high prevalence of consanguineous marriage in Sicily that was shown to be linked with hearing impairment. The "sensitivity value" was 95% at the first step but became 99% after the second step with a few number of false positive (0.74%). All the infants with a diagnosis of sensorineural hearing loss began a rehabilitation program before the age of 5 months and they have a good speech development and speech intelligibility.

An exploration of demographic bias in a questionnaire survey of hearing-impaired children: implications for comparisons of children with and without cochlear implants

OBJECTIVES

Responders to questionnaire surveys, who are self-selecting, are generally accepted to be unrepresentative of the total available population, at least in demographic terms. Since demographic and other variables are known to be predictive of outcome, it is important to understand the extent of that unrepresentativeness when using survey data to report comparisons of outcome. This paper aims (i) to evaluate the extent to which a sample of hearing-impaired children surveyed by postal questionnaire was representative of the population of hearing-impaired children in the United Kingdom (UK), and (ii) to identify demographic differences between children with and without cochlear implants.

METHODS

Data from a previously reported total ascertainment of hearing-impaired children in the UK which identified 17,160 with permanent bilateral hearing impairment >40 dB HL were compared with data collected by postal questionnaire for a sample of 3224 children, including 527 with cochlear implants.

RESULTS

The sampled children were similar to the ascertained population in gender, age at onset of hearing impairment, and number of additional disabilities, but came from more recent birth cohorts and from more affluent families. Compared with profoundly impaired non-implanted children, implanted children had greater degrees of hearing loss, fewer additional disabilities, a later age of onset, were younger, came from more affluent families, were more likely to use spoken language at home, and to be taught using spoken language only.

CONCLUSIONS

Comparisons of outcomes and generalisation of results require adjustment for relevant variables to avoid confounding estimates of the effectiveness of interventions including cochlear implantation.

Trends in the Prevalence of Hearing Loss Among Young Adults Entering An Industrial Workforce 1985 to 2004

OBJECTIVES

Studies have suggested that hearing loss due to recreational noise exposure may be on the rise among adolescents and young adults. This study examines whether the hearing status of young US adults entering an industrial workforce has worsened over the past 20 yr.

DESIGN

The baseline audiograms of 2526 individuals ages 17 to 25 beginning employment at a multisite US corporation between 1985 and 2004 were analyzed to determine the yearly prevalence of hearing loss.

RESULTS

Approximately 16% of the young adults in the sample had high frequency hearing loss (defined as hearing thresholds greater than 15 dB in either ear at 3,4, or 6 kHz). In a linear regression model, this prevalence decreased over the 20-yr period (odds ratio (OR) = 0.96, 95% confidence interval (CI): 0.94, 0.99). Almost 20% of subjects had audiometric "notches" consistent with noise exposure; this rate remained constant over the 20 yr, as did the prevalence (5%) of low frequency hearing loss.

CONCLUSIONS

These results indicate that despite concern about widespread recreational noise exposures, the prevalence of hearing loss among a group of young US adults has not significantly increased over the past two decades.

The association between short stature and sensorineural hearing loss

In order to test the Thrifty Phenotype Hypothesis on hearing, data from two cross-sectional studies on hearing were re-evaluated. The data sets comprised 500 18-year-old conscripts, and 483 noise-exposed male employees. Sensorineural hearing loss (SNHL) was over-represented among conscripts with a short stature (odds ratio=2.2) or hearing loss in the family (odds ration=4.2), but not among noise-exposed conscripts (odds ratio=0.9-1.3). Among noise-exposed short employees, hypertension and age exhibited a negative impact on high frequency hearing thresholds, while among tall employees hypertension had no effect on hearing and the influence of age was less pronounced (p<0.01 for body height; p<0.02 for age, hypertension and the interaction between body height and hypertension; p<0.05 for the interaction between body height and age). This suggests that mechanisms linked to fetal programming and growth retardation and/or insulin-like growth factor 1 levels during fetal life, such as a delayed cell cycle during the time window when the cochlea develops, may cause SNHL in adulthood.

Sensorineural hearing loss in children

During the past three to four decades, the incidence of acquired sensorineural hearing loss (SNHL) in children living in more developed countries has fallen, as a result of improved neonatal care and the widespread implementation of immunisation programmes. The overall decrease has been accompanied by a relative increase in the proportion of inherited forms of SNHL. The contribution made by one gene in particular, GJB2, to the genetic load of SNHL has strongly affected the assessment and care of children with hearing loss. These changes in the incidence of SNHL have not been seen in children living in less developed countries, where the prevalence of consanguinity is high in many areas, and both genetic and acquired forms of SNHL are more common, particularly among children who live in poverty. Focused genetic counselling and health education might lead to a decrease in the prevalence of inherited SNHL in these countries. Establishment of vaccination programmes for several vaccine-preventable infectious diseases would reduce rates of acquired SNHL. Although the primary purpose of such programmes is the prevention of serious and in many cases fatal infections, a secondary benefit would be a reduction in disease-related complications such as SNHL that cause permanent disability in survivors.

Is deafness a disease of poverty? The association between socio-economic deprivation and congenital hearing impairment

An association between congenital hearing impairment and deprivation has been suggested, but evidence is limited. We studied children born in Greater Glasgow, 1985-94, with bilateral congenital hearing impairment. The children were divided into seven deprivation categories using the Carstairs Deprivation Index. One hundred and twenty-four hearing-impaired children were born over the study period, an incidence of 1.18/1000 live births. There was a clear association between deprivation category and incidence, ranging from 0.47/1000 to 1.72/1000. An association with deprivation was seen for children with a family history and perinatal problems (such as prematurity and low birth weight). No association was found for other aetiological groups such as craniofacial syndromes or early postnatal infection. Deprivation had no effect on age of diagnosis or hearing aid provision. Deprivation is associated with congenital hearing impairment, due to more prematurity and low birth weight in deprived families, and the fact that families with many hearing-impaired members are economically disadvantaged. There should be a strong emphasis on the needs of the socio-economically disadvantaged when planning services for hearing-impaired children.

Birth weight and hearing impairment in norwegians born from 1967 to 1993

OBJECTIVES

To estimate the association between birth weight and hearing impairment among Norwegians born between 1967 and 1993, taking other pregnancy-related conditions into consideration.

METHODS

A cohort study was conducted of all Norwegian live births from 1967 to 1993 (n = 1 548 429) linking information of the Medical Birth Registry of Norway and the register for the National Insurance Administration, which covers all Norwegians. The Medical Birth Registry of Norway has recorded information on birth weight and other pregnancy-related conditions as well as diseases of the mother before and during pregnancy. The register of the National Insurance Administration contains information on all Norwegians who have received cash benefits for a disease/disability, including hearing impairment. Data up to 1997 are included; thus, the follow-up period varies between 29 and 3 years.

RESULTS

The occurrence of hearing impairment was 11 per 10 000, decreasing from 60 per 10 000 for birth weights <1500 g to 6 per 10 000 for birth weights >4499 g. Compared with birth weights between 3000 g and 3499 g, the adjusted rate ratio of hearing impairment was 7.55 (95% confidence interval: 4.81-11.87) for birth weights <1500 g and 0.50 (95% confidence interval: 0.34-0.73) for birth weights >4499 g. The association did not change substantially with adjustment for other pregnancy-related conditions. Restricting the analyses to term born, the association between hearing impairment and low birth weight became stronger.

CONCLUSIONS

Birth weight was a strong predictor of hearing impairment in the Norwegian population. Children who were born at term with a low birth weight seemed to be a particularly vulnerable group.

Medical evaluation of pediatric hearing loss. Laboratory, radiographic, and genetic testing

Specific investigations of pediatric hearing loss are based on the history, physical examination, and age of the patient. The radiographic investigation of choice is high-resolution CT of the temporal bone. Patients with a dilated vestibular aqueduct need to be investigated further for Pendred syndrome. Screening for mutations in connexin 26 has become increasingly available in many centers and should be performed in all cases of nonsyndromic hearing loss. It is important to understand the implications and pitfalls of genetic testing. Genetic counseling is necessary.

Impact of family health insurance and other environmental factors on universal hearing screen program effectiveness

OBJECTIVE

The study objective was to evaluate the relationship among health insurance type, other demographic factors, and newborn hearing screen compliance and outcomes.

STUDY DESIGN

The cohort consisted of 39,153 infants screened in Rhode Island between July 1, 1995 and June 30, 1998. Multivariate analyses were completed to evaluate relationships between health insurance type and completion of the in-hospital hearing screen and the rescreen, if indicated.

RESULTS

Successful newborn screen rates ranged from 98.1% to 99.8%. Infants with traditional Medicaid insurance were more likely to not be screened (p<0.0001) and to not return for a rescreen (p<0.0001). Infants in families with managed care Medicaid had screen compliance similar to infants with commercial health insurance. Multivariate analyses revealed that Medicaid insurance, no insurance, neonatal intensive care unit status, and out-of-state address predicted no initial screen (p<0.001) and no rescreen (p<0.0001).

CONCLUSION

In population-based health services, it is important that the effects of socioeconomic and demographic variables on outcomes be evaluated.

Genetics of hearing impairment

Our understanding of the genetics of hearing impairment (HI) has advanced rapidly during the last decade. In this review, we focus on HI due to single gene abnormalities, highlighting some of the more common causes of syndromic HI. We also outline the current state of knowledge of the genetics of non-syndromic HI. The most significant clinical advance has been the finding that mutations in GJB2 cause half of moderate-to-profound congenital hereditary deafness in many world populations. The implications of this finding for screening and genetic counseling are discussed.

Adverse perinatal conditions and the inner ear

Epidemiological studies in a number of Western countries have attributed 6-14% of sensorineural hearing impairment from birth or early childhood to problems relating to the birth process [1-4]. In spite of this association it is not always clear in individual instances whether adverse perinatal conditions identified subsequently have been causative of a hearing loss or not. It is possible that the hearing impairment was the consequence of an earlier intrauterine insult or is a coincidental finding. Infants carrying genetic mutations for hearing loss may coincidentally experience perinatal stress. It is therefore important to investigate the cause of a hearing loss discovered in infancy irrespective of the history of the infant having experienced adverse conditions surrounding the time of birth.

Identification of neonatal hearing impairment: characteristics of infants in the neonatal intensive care unit and well-baby nursery

OBJECTIVE

The objective of this study was to describe the demographic data, medical status, and incidence of risk factors for hearing impairment in the neonatal intensive care unit (NICU) and well-baby populations in a multicenter prospective study designed to assess neonatal hearing impairment and to evaluate factors that might affect neonatal hearing test performance.

DESIGN

This was a prospective multicenter study funded by the National Institutes of Health-National Institute on Deafness and Other Communication Disorders to evaluate the effectiveness of auditory brain stem response, transient evoked otoacoustic emissions, and distortion product otoacoustic emissions for newborn hearing screening. Research staff at each site obtained informed consent and detailed demographic and medical data, including information on established risk factors for hearing loss on 4478 high-risk infants cared for in the NICU, 2348 infants from the well-baby nurseries with no risk factor, and 353 infants from the well-baby nurseries with risk factors. For follow-up purposes the sample was divided further to include a subgroup called selects. Selects were either infants from the well-baby nursery who had an established risk factor for hearing impairment (N = 353) or did not pass the neonatal hearing screen protocol (N = 80). In this study, we focus on the distribution of infants by nursery and risk factors only. Particular effort was made to enroll infants with risk factors for hearing loss in both the NICU and well-baby nurseries. Descriptive analyses are used to describe characteristics of this sample.

RESULTS

All 10 of the risk factors established by the Joint Committee on Infant Hearing in 1994 were identified in the NICU population. The four most common were ototoxic medications (44.4%), very low birth weight (17.8%), assisted ventilation > 5 days (16.4%), and low Apgar scores at 1 or 5 min (13.9%). In contrast, only six risk factors were present in the well-baby nurseries: family history (6.6%), craniofacial abnormalities (3.4%), low Apgar scores (2.8%), syndromes (0.5%), ototoxic medications (0.2%), and congenital infection (0.1%).

CONCLUSION

These descriptive risk factor data reflect both the newborn populations at the study sites and the bias for enrolling infants at risk for hearing loss. The high-risk NICU sample reflects the characteristics typically found in graduates of the NICU. The data summarized in this study will be used to assess the relationships between risk factor and hearing test outcome.

Neonatal hearing screening using the auditory brainstem response

A targeted screen of babies at risk of having a sensorineural hearing loss (SNHL) using the auditory brainstem response has been in place since 1987 in Bradford and Airedale. The aims of this paper were to ascertain what proportion of a 4-year cohort of children with SNHL should have been identified by the programme; was identified by the programme; and the reasons for failing when children were missed. The cohort of 49 children had moderate to profound SNHL (> 50 dB) and were born between 1 April 1991 and 31 March 1995. Although 92% had at risk factors (higher than in other series), 80% was the maximum that could have been prospectively detected by the programme and only 37% were actually diagnosed as a result of the screening programme. Apart from a generalised under-recruitment, children with risk factors arising because of in utero, perinatal and postnatal events (as opposed to family history, craniofacial abnormalities and syndromes) tended to be missed (P < 0.01). The overall yield of the screening programme was 0.5/1000/year. While the yield of a universal neonatal screening programme based on otoacoustic emissions should be double this, a targeted infant distraction test later in infancy will be an essential backup. Improved liaison with paediatricians in particular as well as simplification of the referral criteria should improve targeting children at risk.

Unilateral sensorineural hearing loss and its aetiology in childhood: the contribution of computerised tomography in aetiological diagnosis and management

OBJECTIVES

The objective of this study was to identify factors correlated with the CT outcome and to examine the contribution of the CT scan in the aetiological diagnosis and management of unilateral sensorineural hearing loss in childhood.

METHODS

The records of 35 consecutively investigated patients by the Audiology Department of Great Ormond Street Hospital between January 1996 and June 1998 were reviewed. The CT results, population sample characteristics, initiation of further investigations after the CT results and management decisions based on the CT results were tabulated and analysed.

RESULTS

In a series of 35 consecutively investigated children with unilateral sensorineural hearing loss, 11 CT scans were identified as abnormal. The CT findings were: labyrinthitis ossificans (3), unilaterally dilated vestibular aqueduct (2), bilaterally dilated vestibular aqueduct (2), unilateral deformity of the cochlea ('Mondini') (1), unilateral severe labyrinthine dysplasia (1), unilateral markedly narrow internal acoustic meatus (1), bilaterally dilated lateral semicircular canals (1). The presence of progressive hearing loss was a significant predictor of abnormal CT outcome, while the severity of hearing loss was not. The CT scans offered valuable information regarding the aetiological diagnosis in all cases and, in addition, prompted the appropriate vestibular rehabilitation in three cases, further investigations in four (with dilated vestibular aqueduct) and hearing preservation counselling in two (bilateral DVA) (seven out of 35 = 20%).

CONCLUSION

All children with unilateral sensorineural hearing loss should have a CT scan of the petrous pyramids/IAMs performed at some stage, as not only aetiology but also prognosis and management of these cases may be significantly influenced by the CT outcome.

The need for universal neonatal hearing screening--some aspects of epidemiology and identification

The devastating consequences of a congenital/early-acquired hearing disability on the speech language and social development of a child and the estimated prevalence rates of at least 1-1.5/1000 live births of congenital permanent hearing impairment are important health problems. Universal neonatal hearing screening programs have provided the opportunity to detect neonates with permanent congenital hearing loss, and thus initiate auditory rehabilitation before the age of 3 mo. Universal neonatal hearing screening represents secondary prevention of hearing impairment/deafness, and the world-wide documented delayed identification of children with congenital/early-acquired hearing impairment will no doubt be improved with the implementation of universal neonatal hearing screening programs.

Neonatal screening for hearing disorders in infants at risk: incidence, risk factors, and follow-up

OBJECTIVE

To determine the incidence and risk factors for hearing disorders in a selected group of neonates and the feasibility of selective hearing screening.

SETTINGS

Multicenter prospective trial at five centers in Germany.

METHODS

Enrollment criteria: in addition to previously defined risk factors by the Joint Committee on Infant Hearing (family history of hearing loss, in utero infections, craniofacial anomalies, birth weight <1500 g, critical hyperbilirubinemia, ototoxic medications, bacterial meningitis, postnatal asphyxia, mechanical ventilation >5 days, stigmata, or syndromes associated with hearing loss), the impact of maternal drug abuse, birth weight <10th percentile, persistent pulmonary hypertension, and intracranial hemorrhage more than or equal to grade III or periventricular leukomalacia on infant hearing were evaluated. The screening procedure was performed by automated auditory brainstem response (A-ABR; ALGO 1-plus; Natus Med Inc, San Carlos, CA).

STATISTICS

univariate analyses of risk factors versus A-ABR results and a multivariate regression analysis were used; additionally, the total test time was recorded.

RESULTS

Seven hundred seventy recordings from 777 infants enrolled consecutively constitute the basis of this analysis. Mean gestational age was 33.8 +/- 4.3 weeks, birth weight 2141 +/- 968 g; 431 infants being male and 339 female; 41 (5.3%) infants exhibited pathologic A-ABR results (16 bilateral and 25 unilateral). Meningitis or sepsis, craniofacial malformations, and familial hearing loss were independent significant risk factors. Median total test time was 25 minutes. Follow-up examinations in 31 infants revealed persistent hearing loss in 18 infants (13 infants sensorineural, 5 from mixed disorders), 7 requiring amplification.

CONCLUSION

Hearing screening in high-risk neonates revealed a total of 5% of infants with pathologic A-ABR (bilateral 2%). Significant risk factors were familial hearing loss, bacterial infections, and craniofacial abnormalities. Other perinatal complications did not significantly influence screening results indicating improved perinatal handling in a neonatal population at risk for hearing disorders.

Epidemiology of moderate to profound childhood hearing impairments in northern Finland. Any changes in ten years?

The epidemiology of childhood hearing impairments was studied in a clinical series of the birth cohorts for 1973-82 and 1983-92 from a geographically well-defined area. The overall prevalence of hearing impairments with PTA0.5-4 kHz > or = 40 dB was 1.2/1000 live births. Even in the later cohort, the median age ascertainment was 2.6 years for the congenital or early acquired group and 3.0 years for all impairments. Risk indicators for hearing impairment were present in half of the children, and those referred for the risk were ascertained at the median age of 1.1 years. The delay from suspicion to ascertainment was over a year in about one fifth of cases, while the median time from referral to ascertainment was only 1.8 months. The planning and implementation of neonatal hearing screening are suggested, and general information is given on paedoaudiology for both parents and professionals. A database could be beneficial in increasing the systemacy of the diagnostic process.

Epidemiology of permanent childhood hearing impairment in Trent Region, 1985-1993

This retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in children born between 1985 and 1993 and resident in Trent Health Region, achieved an ascertainment of 92.9% of that expected from previous studies and 100% for the subset of children born between 1985 and 1990. The prevalence rate of all permanent hearing impairment > or = 40 dB HL for the birth cohort 1985-90 is 133 (95% confidence interval, (ci) 122-145) per 100,000 live births (1 in 750). Sixteen per cent of PCHI were postnatally acquired, late-onset or progressive impairments. Excluding these, the prevalence rate for congenital impairments is 112 (ci 101-123) per 100,000 (1 in 900). The rate for profound impairments > or = 95 dB HL is 24 (ci 20-30) per 100,000 live births (1 in 4150). Prevalence was increased sixfold for children with a history of neonatal intensive care and 14-fold for children with a family history, compared with children with no risk factors. A more than two-fold increase in prevalence was seen in Asian children. For the congenitally-impaired children born between 1985 and 1990, 29% had a stay in neonatal intensive care > or = 48 hours, 30% had a family history of permanent childhood hearing impairment, and 12% had a cranio-facial abnormality (CFA). Over 59% were potentially detectable by a targeted neonatal screening programme using these three high-risk factors. For 1985-1993, the overall yield of the targeted neonatal screening programmes available in three of the 11 health districts was 15% but increased over time. The overall yield from the Health Visitor distraction test was 30% but lower in districts with neonatal screening programmes. Only 59% of children had a stated aetiology, classified by time of onset into genetic, including syndromes and CFA (41%), pre- or peri-natal (10%), post-natally acquired (6%), and uncertain onset (2%). Just under 40% of the children were said to have another clinical or developmental problem, about half of whom had at least two additional problems. The median age at referral, confirmation of the impairment, prescription of the hearing aid and fitting of the hearing aid were, respectively, 10.4 months, 18.1 months, 24.4 months and 26.3 months. A more severe impairment was associated with earlier age. Small improvements in the median age of hearing aid prescription and fitting were seen over time. Twenty-five per cent of children were referred for genetic counselling, the proportion increasing systematically with the severity of the impairment. Based on evidence of the yield from hearing screens we suggest a wider implementation of neonatal screening and further consideration of the role of the health visitor distraction test in the identification of children with PCHI. To facilitate further assessment of services for hearing-impaired children we suggest implementation of a co-ordinated shared list of children with permanent hearing impairment on a region-wide basis to provide adequate numbers for comparison over time, and the routine collection of a minimum set of data for each child.