Universal newborn hearing screening programs and developmental outcomes

Current status of universal newborn hearing screening program at 26 institutions in China

OBJECTIVES

The present study aimed to determine the status of a universal newborn hearing screening (UNHS) program being conducted in parts of China, by comparing differences in the program findings between 2016 and 2017, as well as across regions in China.

METHODS

This study investigated a nationally representative sample of newborns from 26 provinces, autonomous regions, and municipalities in mainland China. A ''Newborn Hearing Screening Survey'' questionnaire was sent to 43 hearing screening institutions throughout China and the data were analyzed, with appropriate quality control throughout the study process.

RESULTS

Twenty-six questionnaires, covering 55.88% (19/34) of the provincial administrative regions in China were appropriately completed. The overall sampling frame comprised 238,795 (year 2016) and 229,185 (year 2017) newborns, respectively. We found differences between two years, the initial screening coverage in 2017 (96.10%) was higher than that in 2016 (94.96%); the referral rate at initial screening in 2017 (9.21%) was lower than that in 2016 (10.26%); and the rescreening rate in 2017 (73.50%) was higher than that in 2016 (68.44%). We found differences across three regions, the rescreening rate were highest in West China, the referral rate at rescreening and the referral rate to diagnostic audiological assessment diagnosis were both highest, while the hearing-loss rate was lowest, in the East China in two years. Overall, 61.54% (n = 16) reported using otoacoustic emissions (OAEs), while 38.46% (n = 10) reported using OAEs in combination with automated auditory brainstem response (AABR) tests, for the initial screening. For rescreening, most sites (n = 19, 73.08%) reported using OAEs in combination with AABR, followed by OAEs only (n = 4, 15.38%) and AABR only (n = 3, 11.54%). Of the twenty-six institutions, 57.69% (n = 15) were equipped with a digital information management system for UNHS program, East China had the highest rate of it (81.82%, 9/11).

CONCLUSIONS

This study indicated that implementation of a UNHS program had essentially been achieved in many regions of China under the guidance of technical specifications for newborn hearing screening. Compared with 2016, the overall quality of the UNHS program had improved in 2017 and that in East China was better than in the Midland and West China. However, national quality control of the UNHS program is still required to enhance the quality of the program and public education needs to be emphasized to improve the rescreening and reception rate.

A Longitudinal Investigation of the Home Literacy Environment and Shared Book Reading in Young Children With Hearing Loss

OBJECTIVES

The principle goal of this longitudinal study was to examine parent perceptions of home literacy environment (e.g., frequency of book reading, ease of book reading with child) and observed behaviors during shared book reading (SBR) interactions between parents and their children with hearing loss (HL) as compared with parents and their children with normal hearing (NH) across 3 time points (12, 24, and 36 months old). Relationships were also explored among home literacy environment factors and SBR behaviors and later language outcomes, across all three time points for parents of children with and without HL.

DESIGN

Participants were a group of parents and their children with HL (N = 17) and typically developing children with NH (N = 34). Parent perceptions about the home literacy environment were captured through a questionnaire. Observed parent behaviors and their use of facilitative language techniques were coded during videotaped SBR interactions. Children's oral language skills were assessed using a standardized language measure at each time point.

RESULTS

No significant differences emerged between groups of parents (HL and NH) in terms of perceived home literacy environment at 12 and 36 months. However, significant group differences were evident for parent perceived ease of reading to their child at 24 months. Group differences also emerged for parental SBR behaviors for literacy strategies and interactive reading at 12 months and for engagement and interactive reading at 36 months, with parents of children with HL scoring lower in all factors. No significant relationships emerged between early home literacy factors and SBR behaviors at 12 months and oral language skills at 36 months for parents of children with NH. However, significant positive relationships were evident between early home literacy environment factors at 12 months and oral language skills at 36 months for parents and their children with HL.

CONCLUSIONS

Although both groups of parents increased their frequency of SBR behaviors over time, parents of children with HL may need additional support to optimize SBR experiences to better guide their toddlers' and preschoolers' language skills. Early intervention efforts that focus on SBR interactions that are mutually enjoyed and incorporate specific ways to encourage parent-child conversations will be essential as children with HL acquire language.

Parental Support for Language Development During Joint Book Reading for Young Children With Hearing Loss

Parent and child joint book reading (JBR) characteristics and parent facilitative language techniques (FLTs) were investigated in two groups of parents and their young children; children with normal hearing (NH; n = 60) and children with hearing loss (HL; n = 45). Parent-child dyads were videotaped during JBR interactions, and parent and child behaviors were coded for specific JBR behaviors using a scale developed for this study. Children's oral language skills were assessed using the Preschool Language Scale-4 (PLS-4). Parents of children with HL scored higher on two of the four subscales of JBR: Literacy Strategies and Teacher Techniques. Parents of children with NH utilized higher level FLTs with their children who had higher language skills. Higher level FLTs were positively related to children's oral language abilities. Implications are discussed for professionals who work with families of very young children with HL.

Typical consonant cluster acquisition in auditory-verbal children with early-identified severe/profound hearing loss

Early-identified severe/profound hearing loss (HL) following universal newborn hearing screening (UNHS) has been associated with improved speech and language outcomes. However, speech outcome reports have typically been based on broad measures of speech intelligibility and/or singleton consonant accuracy, with little known about production of consonant clusters. Using a prospective design, the range and accuracy of consonant clusters produced by a homogenous cohort of 12 children early-identified with severe/profound HL aged 3- and 4-years were examined. All children demonstrated bilateral aided thresholds within a range of 15-25 dB HL across all frequencies, were optimally amplified with cochlear implants (11/12) or hearing aids (1/12), and attended auditory-verbal (AV) early intervention. Standardized speech and language assessments were administered. Consonant clusters were strategically sampled in single-word and conversational speech contexts. All standard scores for speech, receptive, and expressive language were within normal limits. All children produced consonant clusters commensurate with expectations for typically-developing hearing peers at 3- and 4- years-of-age. Children's production of phonetically complex morphophonemes (final consonant clusters marking grammatical morphemes) was also in keeping with developmental expectations. Factors which contributed to these encouraging outcomes require further investigation.

Assessment of the feasibility and coverage of a modified universal hearing screening protocol for use with newborn babies of migrant workers in Beijing

BACKGROUND

Although migrant workers account for the majority of newborns in Beijing, their children are less likely to undergo appropriate universal newborn hearing screening/rescreening (UNHS) than newborns of local non-migrant residents. We hypothesised that this was at least in part due to the inadequacy of the UNHS protocol currently employed for newborn babies, and therefore aimed to modify the protocol to specifically reflect the needs of the migrant population.

METHODS

A total of 10,983 healthy babies born to migrant mothers between January 2007 and December 2009 at a Beijing public hospital were investigated for hearing abnormalities according to a modified UNHS protocol. This incorporated two additional/optional otoacoustic emissions (OAE) tests at 24-48 hours and 2 months after birth. Infants not passing a screening test were referred to the next test, until any hearing loss was confirmed by the auditory brainstem response (ABR) test.

RESULTS

A total of 98.91% (10983/11104) of all newborn children underwent the initial OAE test, of which 27.22% (2990/10983) failed the test. 1712 of the failed babies underwent the second inpatient OAE test, with739 failing again; thus significantly decreasing the overall positive rate for abnormal hearing from 27.22% to 18.36% ([2990-973 /10983)]; p = 0). Overall, 1147(56.87%) babies underwent the outpatient OAE test again after1-month, of whom 228 failed and were referred for the second outpatient OAE test (i.e. 2.08% (228/10983) referral rate at 1month of age). 141 of these infants underwent the referral test, of whom 103 (73.05%) tested positive again and were referred for a final ABR test for hearing loss (i.e. final referral rate of 1.73% ([228-38/10983] at 2 months of age). Only 54 infants attended the ABR test and 35 (0.32% of the original cohort tested) were diagnosed with abnormal hearing.

CONCLUSIONS

Our study shows that it is feasible and practical to achieve high coverage rates for screening hearing loss and decrease the referral rates in newborn babies of migrant workers, using a modification of the currently employed UNHS protocol.

Cost-effectiveness analysis of a national neonatal hearing screening program in China: conditions for the scale-up

BACKGROUND

In 2009, the Chinese Ministry of Health recommended scale-up of routine neonatal hearing screening - previously performed primarily only in select urban hospitals - throughout the entire country.

METHODS

A decision analytical model for a simulated population of all live births in china was developed to compare the costs and health effects of five mutually exclusive interventions: 1) universal screening using Otoacoustic Emission (OAE) and Automated Auditory Brainstem Response (AABR); 2) universal OAE; 3) targeted OAE and AABR; 4) targeted OAE; and 5) no screening. Disability-Adjusted Life Years (DALYs) were calculated for health effects.

RESULTS AND DISCUSSION

Based on the cost-effectiveness and potential health outcomes, the optimal path for scale-up would be to start with targeted OAE and then expand to universal OAE and universal OAE plus AABR. Accessibility of screening, diagnosis, and intervention services significantly affect decision of the options.

CONCLUSION

In conclusion, to achieve cost-effectiveness and best health outcomes of the NHS program, the accessibility of screening, diagnosis, and intervention services should be expanded to reach a larger population. The results are thus expected to be of particular benefit in terms of the 'rolling out' of the national plan.

Listen up: children with early identified hearing loss achieve age-appropriate speech/language outcomes by 3 years-of-age

OBJECTIVES

Age-appropriate speech/language outcomes for children with early identified hearing loss are a possibility but not a certainty. Identification of children most likely to achieve optimal outcomes is complicated by the heterogeneity of the children involved in outcome research, who present with a range of malleable (e.g. age of identification and cochlear implantation, type of intervention, communication mode) and non-malleable (e.g. degree of hearing loss) factors. This study considered whether a homogenous cohort of early identified children (≤ 12 months), with all severities of hearing loss and no other concomitant diagnoses could not only significantly outperform a similarly homogenous cohort of children who were later identified (>12 months to <5 years), but also achieve and maintain age-appropriate speech/language outcomes by 3, 4 and 5 years of age.

METHODS

A mixed prospective/retrospective comparative study of a homogenous cohort of 45 early identified (≤ 12 months) and 49 late identified (> 12 months to < 5 years) children with hearing loss was conducted. The children all attended the same oral auditory-verbal early intervention programme. Speech/language assessments standardized on typically developing hearing children were conducted at 3, 4 and 5 years of age.

RESULTS

The early identified children significantly outperformed the late identified at all ages and for all severities of HL. By 3 years of age, 93% of all early identified participants scored within normal limits (WNL) for speech; 90% were WNL for understanding vocabulary; and 95% were WNL for receptive and expressive language. Progress was maintained and improved so that by 5 years of age, 96% were WNL for speech, with 100% WNL for language.

CONCLUSIONS

This study found that most children with all severities of hearing loss and no other concomitant diagnosed condition, who were early diagnosed; received amplification by 3 months; enrolled into AV intervention by 6 months and received a cochlear implant by 18 months if required, were able to "keep up with" rather than "catch up to" their typically hearing peers by 3 years of age on measures of speech and language, including children with profound hearing loss. By 5 years, all children achieved typical language development and 96% typical speech.

Cost-effectiveness analysis of neonatal hearing screening program in China: should universal screening be prioritized?

Background

Neonatal hearing screening (NHS) has been routinely offered as a vital component of early childhood care in developed countries, whereas such a screening program is still at the pilot or preliminary stage as regards its nationwide implementation in developing countries. To provide significant evidence for health policy making in China, this study aims to determine the cost-effectiveness of NHS program implementation in case of eight provinces of China.

Methods

A cost-effectiveness model was conducted and all neonates annually born from 2007 to 2009 in eight provinces of China were simulated in this model. The model parameters were estimated from the established databases in the general hospitals or maternal and child health hospitals of these eight provinces, supplemented from the published literature. The model estimated changes in program implementation costs, disability-adjusted life years (DALYs), average cost-effectiveness ratio (ACER), and incremental cost-effectiveness ratio (ICER) for universal screening compared to targeted screening in eight provinces.

Results and discussion

A multivariate sensitivity analysis was performed to determine uncertainty in health effect estimates and cost-effectiveness ratios using a probabilistic modeling technique. Targeted strategy trended to be cost-effective in Guangxi, Jiangxi, Henan, Guangdong, Zhejiang, Hebei, Shandong, and Beijing from the level of 9%, 9%, 8%, 4%, 3%, 7%, 5%, and 2%, respectively; while universal strategy trended to be cost-effective in those provinces from the level of 70%, 70%, 48%, 10%, 8%, 28%, 15%, 4%, respectively. This study showed although there was a huge disparity in the implementation of the NHS program in the surveyed provinces, both universal strategy and targeted strategy showed cost-effectiveness in those relatively developed provinces, while neither of the screening strategy showed cost-effectiveness in those relatively developing provinces. This study also showed that both strategies especially universal strategy achieve a good economic effect in the long term costs.

Conclusions

Universal screening might be considered as the prioritized implementation goal especially in those relatively developed provinces of China as it provides the best health and economic effects, while targeted screening might be temporarily more realistic than universal screening in those relatively developing provinces of China.

Prognostic validity of dichotic multiple frequencies auditory steady-state responses versus distortion product otoacoustic emissions in hearing screening of high risk neonates

OBJECTIVE

To determine the validity of dichotic multiple frequencies auditory steady-state responses (ASSR) as a hearing screening technique versus using distortion product otoacoustic emissions (DPOAEs) among high-risk neonates.

METHODS

A cross sectional study was performed on 118 high-risk neonates by means of dichotic multiple frequencies ASSR and DPOAE for hearing screening. DPOAE results were used as the standard for hearing screening in parallel with ASSR. Dichotic multiple frequencies ASSR results were analyzed by means of F-value of less or greater than 0.05 criteria as a pass-fail for the responses. Dichotic multiple ASSR hearing screening technique was considered in two intensity levels at 40 and 70 dB HL. The ASSRs thresholds were measured in high risk neonates with and without hearing deficits as determined by DPOAES. The results of ASSR and DPOAE were compared to be gathered by contingency table in order to obtain sensitivity, specificity and other different statistical values. Average performing times for the tests were analyzed.

RESULTS

The specificity of dichotic multiple ASSR was 92.6%, 93.8% and the sensitivity was 71.6%, 62.2% at the 70 and 40 dB hearing levels, respectively. Mean ASSR thresholds for normal-hearing infants at an average corrected age of 6 days were 32.2 ± 12.2, 29.8 ± 10.2, 26.2 ± 11.4 and 30.4 ± 10.8 dB HL for 0.5, 1, 2 and 4 kHz, respectively. The average times for performing the tests were 18.7 and 32.9 min respectively.

CONCLUSIONS

ASSR with this special paradigm is a fairly desirable method for hearing screening of high-risk neonates. There is good concordance between ASSRs and DOPAEs results among high risk neonates referred for hearing screening. The sensitivity and specificity of this test is sufficient for hearing screening in high risk neonates. This test could be valuable for rapid confirmation of normal thresholds. As long as further research have not been conducted on ASSR, great caution should be made to interpret the results of ASSR as a hearing screening technique in young infants and also additional techniques such as the tone-evoked ABRs should be used to cross-check results. It's still too soon to recommend ASSRs as a standalone electrophysiologic measure of hearing thresholds in infants.

Universal neonatal audiological screening: experience of the University Hospital of Pisa

The early identification of pre-lingual deafness is necessary to minimize the consequences of hearing impairment on the future communication skills of a baby. According to the most recent international guidelines the deafness diagnosis must occur before the age of three months and the prosthetic-rehabilitative treatment with a traditional hearing aid should start within the first six months. When a Cochlear implant becomes necessary, the treatment should start between the age of 12 months and 18 months. The only way to diagnose the problem early is the implementation of universal neonatal audiological screening programs. Transient evoked otoacoustic emissions (TEOAE) is the most adequate test because it's accurate, economic and of simple execution. Automatic auditory brainstem response (AABR) is necessary to identify patients with auditory neuropathy but it is also important to reduce the number of false-positives.The 20-30% of infant hearing impairment is represented by progressive or late-onset hearing loss (HL) so it's also necessary to establish an audiological follow up program, especially in infants at risk.From November 2005 all neonates born in the University hospital of Pisa undergo newborn hearing screening. From 2008 the screening program follows the guidelines for the execution of the audiological screening in Tuscany which have been formulated by our group according to the 2007 JCIH Position Statement and adaptated to our regional reality by a multidisciplinary effort. From November 2005 to April 2009 8113 neonates born in the Neonatal Unit of Santa Chiara Hospital (Pisa) have undergone newborn hearing screening. 7621 neonates (93.9%) without risk factors executed only the TEOAE test. 492 (6.1%) neonates had audiological risk factors and thus underwent TEOAE and AABR. 84 patients (1,04%) failed both TEOAE and AABR tests. 78 of them underwent further investigations. 44 patients resulted false positives (the 0,54% of the screened newborns). 34 neonates (4,2 ‰) had a final diagnosis of hearing impairment. 8 patients (0.99 ‰) had unilateral hearing loss (HL). 26 patients (3,2 ‰) had bilateral hearing impairment.In our screening program the percentage of false-positives was quite low (0.54%) while the incidence of bilateral HL (3.2 ‰) is a little higher than that found in literature reports. In most of our patients premature birth or neonatal suffering represent the main cause of HL.

Genetic syndromes involving hearing

OBJECTIVE

The fundamental processes involved in the mechanism of hearing seem to be controlled by hundreds of genes and hereditary hearing impairment may be caused by a large variety of genetic mutations in different genes. Approximately 150 loci for monogenic syndromic and non-syndromic hearing impairment (HI) disorders have been mapped to the human genome. The identification of these genes and functional analysis of the proteins they encode, are paving the way towards a better understanding of the physiology and pathophysiology of the auditory system. To date, approximately 50 causative genes have been identified.

METHODS

The clinical and neuroradioldical findings of syndromal hearing impairment are analysed.

RESULTS

This paper presents an updated report on genetic syndromes in which a hearing impairment is involved, with a particular attention to the ones associated with external ear and craniofacial malformations.

CONCLUSIONS

Concepts in human genetics are rapidly evolving together with technologies. The concept itself of gene is changing. A genetic diagnosis of syndromal hearing impairment has many practical consequences: it can implies specific prognosis, specific management, specific recurrence risk in relatives and, if the diagnosis is confirmed at the molecular level, possibility of a specific early prenatal diagnosis for severe syndromes. It is important to highlight the necessity that the pediatric otolaryngologist must have a close collaboration with a clinical geneticist and a neuroradiologist.

A novel service delivery model for infant hearing screening in developing countries

Newborn hearing screening is the procedure of choice for ensuring optimal outcomes for infants with hearing loss, whether in a developed or developing country. Unfortunately, apart from a small number of recent exceptions, newborn hearing screening has been a practice reserved for the developed world. Despite the prevailing challenges towards implementing hearing screening in developing countries, there are existing structures in these countries that need to be investigated as possible platforms from which programs can be actualized. Immunization clinics, constituting part of a primary healthcare approach characteristic of developing countries, offer one such a platform. A novel service delivery model, based on initial results from a pilot study, was developed for infant hearing screening at immunization clinics in South Africa as an integrated part of primary, secondary, and tertiary levels of healthcare. This type of model is a first step toward ensuring that infants with hearing loss in developing communities are afforded opportunities for optimal development and societal integration through accountable and contextually relevant early hearing detection and intervention services.

Audiology in South Africa

Audiology in South Africa is an established profession facing the challenge of serving a diverse population in predominantly developing contexts. The profession has developed over the last half century from an adjunct to speech-language pathology into a profession in its own right. Several tertiary institutions offer undergraduate training in audiology with optional postgraduate qualifications. Institutions are continually adapting to a profession characterised by rapid change--evidenced even in the very composition of the profession itself. This article aims to provide an overview of the development and current status of audiology as a profession in South Africa.

Visual input enhancement via essay coding results in deaf learners' long-term retention of improved English grammatical knowledge

This study explored the efficacy of visual input enhancement, specifically essay enhancement, for facilitating deaf college students' improvement in English grammatical knowledge. Results documented students' significant improvement immediately after a 10-week instructional intervention, a replication of recent research. Additionally, the results of delayed assessment documented students' significant retention of that improvement five and a half months beyond the instructional intervention period. Essay enhancement served to highlight, via a coding procedure, students' successful and unsuccessful production of discourse-required target grammatical structures. The procedure converted students' written communicative output into enhanced input for inducing noticing of grammatical form and, through essay revision, establishing form-meaning connections leading to acquisition. With its optimal design characteristics supported by theoretical and empirical research, essay enhancement is a highly effective methodology that can be easily implemented as primary or supplementary English instruction for deaf students. The results of this study hold great promise for facilitating deaf students' English language and literacy development and have broad implications for second-language research, teaching, and learning.

Impact of early hearing screening and treatment on language development and education level: evaluation of 6 years of universal newborn hearing screening (ALGO) in Flanders, Belgium

OBJECTIVES

Early intervention in hearing-impaired children may improve language outcomes and subsequent school and occupational performance. The objective of this study was to retrospectively analyze over 6 years the educational outcome and language development of a first cohort of children, detected by the Flemish universal newborn hearing screening (UNHS) program based on automated auditory brainstem response (AABR), with the oldest children being in primary school.

METHODS

We studied 229 hearing-impaired children from 1998 till 2003. The following variables were considered: the age during the school year 2005-2006, the degree of hearing loss, additional impairments including presence of intellectual disability, school placement and early intervention.

RESULTS

Analysis showed that 85.4% of the children with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Further detailed description was provided for the outcomes of children with uni- and bilateral cochlear implants. Overall results stress that 46% of all children with a cochlear implant obtain mainstream education. Of all cochlear implant (CI) children above 5.5 years, without additional handicaps, 78.9% of children attend primary mainstream school. Data on language development show that up to 45% of the children with unilateral cochlear implant and no additional disabilities had normal to slight delay on language development. These data are fulfilling the goals stated by the JCIH and the American Academy of Pediatrics (AAP) in 2000. The role and impact of additional handicaps is discussed. The importance of early hearing loss identification and hearing therapy for appropriate language development is highlighted. Finally our preliminary results on children with bilateral cochlear implants without additional handicaps present an improved language development in comparison to unilateral CI-children.

CONCLUSION

A vast majority of the children detected by the UNHS program, with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Additional disabilities have a major influence.

Post-natal hearing loss in universal neonatal hearing screening communities: current limitations and future directions

Universal hearing screening has dramatically improved outcomes for babies born with detectable hearing abnormalities; yet there are some infants who develop significant hearing problems after passing a neonatal screen. There is much conjecture as to the number and the characteristics of infants with post-natal hearing losses; yet evidence suggests that many children may be affected, and that a large proportion have no discoverable cause. Currently, screening programmes use lists of risk factors to enroll babies into surveillance programmes. This practice is problematic because audiological follow-ups are expensive and under-utilised, and parental disclosure is often inaccurate. The large databases from universal neonatal programmes could inform the development of effective, evidence-based practice and policy for the detection and intervention of children who develop post-natal hearing losses.

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.

Infant hearing screening at immunization clinics in South Africa

OBJECTIVE

Benefits of early identification and subsequent intervention for hearing loss are not accessible to infants in developing countries like South Africa. There are no systematic screening programs and traditional platforms for newborn hearing screening, such as well-baby and intensive care nurseries, do not provide sufficient coverage due to the high incidence of births at home or in primary healthcare facilities. Primary healthcare structures, in the form of immunization clinics, have been proposed as an alternative screening platform. The current study, therefore, investigates a hearing screening program implemented at two immunization clinics in a representative South African community.

METHODS

The two clinics in the current study were selected by a convenience sampling method in a community representative of large sections of the population. The hearing screening program was conducted over a 5-month period, and enrolled 510 infants (0-12 months of age). The screening protocol included Distortion Product Oto-Acoustic Emissions (DPOAE) and a high frequency probe tone (1000 Hz) tympanogram. Referral was based on one or both ears referring the DPOAE screen. Follow-up screening and diagnostic evaluations were scheduled for referred subjects.

RESULTS

Coverage with DPOAE amounted to 95% of the sample ears (93% of sample subjects) compared to tympanogram coverage amounting to 94% (93% of sample subjects). OAE pass rates were 93% for the sample ears with neonatal ears indicating a higher pass rate of 95% compared to 92% for infant ears (5-52 weeks of age). Eighty-seven percent of the sample ears indicated peaked tympanograms indicative of normal middle-ear functioning and neonatal ears presented with an increased incidence of peaked tympanograms (92%). A highly significant association between the DPOAE and high frequency tympanometric result was found. Follow-up screening appointments were scheduled for 68 subjects (14% of screened sample). Only 40% returned for the second follow-up and 44% for the third follow-up.

CONCLUSIONS

Immunization clinics indicate promise as infant hearing screening platforms, but identification of only bilateral hearing losses may be warranted initially to keep referral rates acceptably low. In addition to this efficient tracking systems are necessary to ensure acceptably high follow-up return rates are reached over time.

Longitudinal study of hearing impairment in children

The aim of this study is to evaluate the frequency of progression in permanent childhood hearing impairment (PHI) and to relate potential specific factors to the eventual progression. A description is made of the true longitudinal hearing thresholds in four groups of children according to different observation periods and being part of a prospective pediatric audiological registry-based study established in 1989. At the time of data collection the registry included 1373 children born after 1/1-1970 with a PHI > 20 dB in either the right or the left ear at any pure tone frequency. The children were subdivided according to the following observation periods: 1-3 years (N=266), >3-5 years (N=148), >5-10 years (N=212) and >10 years (N=62). The differences from the first to the most recent audiometric thresholds were analysed for the right and left ears separately, at the pure tone frequencies 250, 500, 1000, 2000, 4000 and 8000 Hz, for the average of 500, 1000, 2000 and 4000 Hz, for the average of 2000 and 4000 Hz and for the average of 4000 and 8000 Hz. Those showing a progression >15 dB for the average across 500-4000 Hz were analysed for age at onset and aetiology of hearing impairment, showing that genetic factors are predominant in progressive PHI. It was also found that progression in PHI is most frequent in early childhood but found only in 5.7% after the age of 4 years.