The early hearing detection and intervention programmes for children in Hong Kong: how well are we doing?

Iris HY Ng 伍凱怡，Michael CF Tong 唐志輝，Kathy YS Lee 李月裳

HK Pract 2021;43:58-63

Summary

Early hearing detection and intervention for children has been advocated worldwide since the early 90s. Our Hong Kong family doctors / medical practitioners may have been aware of the universal newborn hearing screening services provided by the Hospital Authority as well as the Department of Health. However, it may not be apparent to some of our doctors how beneficial this early detection is to our local children, as the follow-up and intervention services are provided in various settings.

This educational update article will try to summarise the latest information regarding the early hearing detection and intervention programmes, delineate the referral pathways, and thus provide a brief information and quick overview for our local primary care practitioners.

摘要

自上世紀90年代初起，早期聽力檢測及治療受廣泛推 廣。本港醫生相信已熟悉由衛生署及醫院管理局推行的新 生嬰兒聽力篩查服務。但在聽力篩查以後，本地兒童接受 聽力診斷及復康的途徑牽涉多個不同範疇，則未必為醫療 界所熟知。本文期望提供一個有關本地兒童現時接受聽力 篩查、診斷及復康的綜合簡介，包括一些最新資訊，以便 參閱。

Introduction

It has been 50 years since the Joint Committee on Infant Hearing (JCIH) published its first position statement in 1971, encouraging ongoing research and acknowledging the need to detect hearing loss early in life. Over the past 50 years, the JCIH has continuously reviewed the latest technology and recommended the preferred practice in early identification and appropriate intervention of hearing loss among children. Since 1994, the JCIH has recommended universal detection of hearing loss in newborns prior to their hospital discharge, and that all infants with hearing loss should be identified before their 3 months of age, and be provided with intervention by their 6 months of age. This indeed sets the milestone for many early hearing detection and intervention programmes for children around the world.

In their latest position statement published in 2019¹ , JCIH reiterated the importance of Early Hearing Detection and Intervention (EHDI), which facilitates language development, and makes communication and linguistic competence achievable, when optimal audiologic and early intervention services are timely accessible. Studies consistently revealed that hearing abilities, improved by the provision of hearing devices, are associated with better speech and language development in children. The duration of hearing device experience does interact with the aided hearing to influence outcomes, suggesting that early provision of well-fitted hearing devices is beneficial to children with hearing loss.²

Early detection of hearing loss

It has been well-established that, the prevalence of permanent significant bilateral hearing loss is approximately 1.33 per 1,000 live births in developed countries with universal newborn hearing screening implemented for almost 30 years, such as the UK³ . Hearing loss is thus regarded as one of the most common congenital birth defects, more prevalent than many other routinely screened newborn conditions such as congenital hypothyroidism. Considering the cumulative addition of patients with progressive, acquired or lateonset hearing loss, the prevalence is estimated to be 2.83 per 1,000 children at their primary school age^4,5, and a further increase to 3.5 per 1,000 in adolescents.³

At the Hospital Authority

The first pilot study of a hospital-based universal newborn hearing screening programme in Hong Kong was performed in Tsan Yuk Hospital in 1999, for assessing the feasibility, parent understanding as well as parental acceptability of newborn hearing screening programme.⁶ Soon after that, the Hospital Authority set up a multidisciplinary working group, including paediatricians, otolaryngologists and audiologists, to establish a universal newborn hearing screening programme in Hong Kong.

Another pilot study was conducted in 2001 to evaluate various screening protocols with different screening devices. Eventually, it was suggested that a well-coordinated hospital-based screening programme, with a two-stage automated auditory brainstem response (AABR) screening protocol, could achieve a high coverage rate of over 95% and a low referral rate, indicating a low false positive rate. ⁶ AABR is a simplified electroencephalography measurement, which involves more expensive consumables including disposable adhesive coupler earphones and electrodes. With its low referral rate and the implementation being done by well-trained dedicated technicians, the screening programme can be conducted at a reasonable cost.

Ten years later, comparison was made again between two different universal newborn hearing screening protocols implemented in a Hospital Authority birthing hospital and a private hospital in Hong Kong in 2010. Results suggested that both the two-stage AABR screening protocol implemented in the Hospital Authority birthing hospital and the two-stage combined distortion product otoacoustic emissions (DPOAE) and AABR screening protocol implemented in the private hospital yielded similar final referral rates.⁷ The research team commented that the two-stage combined DPOAE and AABR screening protocol was implemented about 2.5 times cheaper and almost 3 times faster than the two-stage AABR protocol.⁷

According to a systematic review published in 2015, the pooled sensitivity and specificity of the OAE test used for universal newborn hearing screening were 0.77 and 0.93 respectively. On the other hand, the meta-analysis revealed that the pooled sensitivity and specificity of the AABR test were 0.93 and 0.97 respectively. ⁸ These indeed echoed with the local findings that, there was no big difference between the two screening tests commonly used in universal newborn hearing screening in detecting infants with typical hearing. The difference in sensitivity between the two tests however suggested a difference in their abilities to detect infants with hearing loss. Considering the ultimate goal of early detection of hearing loss, it seems that AABR is the more preferable option as a newborn hearing screening protocol.

To this day, the universal newborn hearing screening programme implemented in local birthing hospitals under the Hospital Authority is adopting the two-stage AABR screening protocol. Neonates are screened with AABR before their hospital discharge, usually within the first 2 to 3 days of life. For those referred from the AABR test in one or both ears in the first attempt, the AABR measurement is conducted once again before their hospital discharge. Neonates referred from the two-stage AABR screening protocol are scheduled with a follow-up visit to the hospital for re-screening, usually before their 1 month birthday. Infants referred from this hearing re-screening are referred to ENT specialists for medical consultation, as well as audiologists for diagnostic assessment of their hearing status. Any presence of hearing loss among these infants, in one or both ears, is confirmed by 3 months of age. All infants with hearing loss are then referred immediately to receive targeted and appropriate intervention services.

At the Department of Health

On the other hand, universal newborn hearing screening is not being implemented in all private birthing hospitals in Hong Kong yet. For the neonates who are born in private hospitals with no arrangement of universal newborn hearing screening, or those who missed the screening or the follow-up appointment in other birthing hospitals, the hearing screening is provided through the integrated child health and development programme implemented in the Maternal & Child Health Centres.⁹ The screening is implemented with a two-stage DPOAE protocol for neonates and infants between their 2 weeks and 4 months of age, though a screening appointment by the neonates’ one month of age is encouraged. Infants referred from this twostage hearing screening are referred to Child Assessment Service for medical consultation, as well as diagnostic audiological assessment of their hearing status.¹⁰ All infants with hearing loss are then referred immediately to receive targeted and appropriate intervention services.

Apart from the newborn hearing screening, the Department of Health also offers hearing screening for school-age children through the Student Health Service Centres. Enrolled students are given an annual appointment for health assessment at the Student Health Service Centres. Hearing screening is included as part of the health assessment programme for children in their primary one as well as secondary two years.¹¹ Additional hearing screening can also be arranged in other years if indicated, or if requested by the family of the student. Students referred from the hearing screening are referred to the Special Assessment Centres of the Student Health Services, or ENT specialists, for medical consultation and diagnostic assessment of their hearing status. Students with hearing loss are then referred to receive appropriate intervention services.

Medical practitioners from all specialty backgrounds, in particular family physicians who may identify infants and children with suspected hearing loss during their consultations, can contribute to this early hearing detection by encouraging the families to obtain routine hearing screening services from the Maternal & Child Health Centres, or the Student Health Service Centres. Checklists like “Hints for Parents – Can your baby hear you?” and “Does your child hear normally?” have been published online by the Family Health Service and the Student Health Service respectively, which may be used for simple screening of childhood hearing loss. Referral for ENT specialist consultation, either to hospitals or private practices, can help ensure the timely detection of childhood hearing loss as well. The unfortunate events of missing the golden opportunity in detecting and managing early childhood hearing loss can be minimised with the collaborative efforts of all medical practitioners.

In view of the EHDI goals of physiological hearing screening with objective determination of outcomes by 1 month of age, and confirmation of hearing status with appropriate audiologic evaluation by 3 months of age, we are meeting the goals of early detection of hearing loss in general in Hong Kong.

Early intervention for hearing loss

Research over the past couple of decades has shown that the earlier the hearing loss is identified, and the earlier the intervention begins, the less impact on the development of the child will result.¹² Delayed detection and intervention of hearing loss may give rise to negative impacts on the social, emotional, cognitive and academic development, and, subsequently, their vocational and economic potential as they grow up.^13,14

The successful implementation of EHDI relies on the collaborative efforts of all the stakeholders involved in the process, including birthing hospitals, parents, medical practitioners, nurses, audiologists, speech therapists, educators, and community organisations. The goals of early detection of hearing loss and the provision of appropriate intervention services in a timely manner for very young children can only be met with the full participation of each stakeholder. A seamless transition from screening to diagnosis, to a habilitation plan leading from early intervention, to preschool and school, is only possible with effective collaboration among the medical, healthcare, educational, and social sectors.¹⁵

(1)   Medical and surgical aspects

When infants and children are referred from hearing screening for medical consultation by ENT specialists, aetiology of the hearing loss, as well as any additional conditions, will be investigated. Some infants could be diagnosed with bilateral severe to profound hearing loss by 3 months of age with the universal newborn hearing screening programme. They are referred for hearing aid fitting and evaluation immediately. With the use of hearing aids, their responses to sound, early phonetic repertoire and interactions between caretakers and the children are closely observed for at least 3 months. If limited benefits from the hearing aid amplification are observed, the children will be assessed for cochlear implant candidacy. For those who meet the cochlear implant candidacy criteria, the cochlear implantation surgery will usually take place at around 12 months of age, as previously approved by the U.S. Food and Drug Administration (FDA). In March 2020, the FDA granted approval to lower the age for cochlear implantation, from a certain manufacturer, from the age of 12 months to 9 months for children with bilateral profound sensorineural hearing loss. It is thus expected that infants with bilateral severe to profound hearing loss in Hong Kong will be able to receive their cochlear implantation earlier, at around 9 months of age.

Some other children, apart from the hearing loss, are born with congenital craniofacial anomalies, such as microtia or atresia. This may include a wide array of abnormal appearances of the pinna, and additional structural anomalies such as external auditory canal, tympanic membrane, middle ear ossicles, or any combination of the above. The severity ranges from very mild (microtia) to a complete absence of the pinna (anotia) or an absence of an opening to the external ear canal (atresia), which is usually accompanied with conductive hearing loss. These children are referred for hearing aid fitting immediately. As their pinna and ear canal deformity make conventional hearing aid amplification difficult or even impossible, many of those who have bilateral microtia or atresia, eventually have to receive bone-anchored hearing aid (BAHA) implantation. As FDA only approves surgical implantation of BAHA for children over the age of five years, these children need other amplification options before the implantation, such as wearing the device externally with a headband, before the surgery and implantation.

Besides, as mentioned above, there are children who have progressive, acquired, or late-onset hearing loss, who are able to use conventional hearing aid amplification at a younger age, but need the transition to cochlear implantation when they grow older. They are referred for cochlear implant candidacy assessment by ENT specialists, audiologists and the cochlear implant professional team as well.

All these cases are currently being routinely followed up at several dedicated Audiology Centres under Hospital Authority in Hong Kong for both their externally used hearing devices as well as their implantable devices as commissioned by the Education Bureau since early 2020.

(2)   Educational aspects

In the local context, the Education Bureau (EDB) is basically serving as the single coordinated point of entry into the intervention system for children identified through the EHDI programmes in Hong Kong. Newborns, infants, children, and students referred from any hearing screening programme described above, are referred to the EDB for intervention services, in particular hearing aid fitting. For newborns and infants with hearing loss confirmed by 3 months of age, the majority of them are referred to the EDB for intervention services by 6 months of age. The EDB provides hearing aid related services for children with hearing loss at all age till they leave their secondary school education. From 2005 to 2019, the hearing aid related services were outsourced from the EDB to the commercial sector. However, since early 2019, no commercial service provider could provide such services, the EDB has therefore taken up the related services.¹⁶ Currently, all the hearing aid fitting services for local preschool, primary school, and secondary school children are provided by the EDB, except those who are under candidacy assessment of implantable devices and those who have already received any implantable device. For these children who are receiving the hearing device fitting services at the Audiology Centres of the Hospital Authority as described above, the EDB is the coordinator of their intervention services.

The primary purpose of hearing aid fitting, is obviously to ensure that speech sounds that are inaudible due to hearing loss, are made audible through the amplification. The hearing aid fitting, which is usually done by a qualified audiologist or a member of the register of audiologists accredited by Department of Health, includes initially obtaining an accurate measurement of the hearing loss followed by making an impression (a cast) of the child’s ear canal. A custommade earmould is produced from the impression, to couple with the hearing aid and transmit sounds into the ear canal. Then the hearing aids are prescribed, which means they are digitally programmed to provide sufficient intensities of sounds at different frequencies according to the specific hearing loss, based on a paediatric-focused and validated prescriptive formula considering the developmental and auditory needs of children.¹⁷ The audiologist then uses a technique called real-ear measurement to take into account the specific child’s ear canal resonance, and to verify the amplification and output of the hearing aids measured at the position of the specific child’s tympanic membrane.¹⁸ This measurement may account for the unique acoustic properties of each individual ear, and the ever-changing ear canal resonance of the specific ears between the ages of 3 and 9 years of a child. This hearing aid verification procedure can be performed on all persons aged over 3 years old. ¹⁹ For older children who have sufficient spoken language abilities, the hearing aids are often validated with standardised age-appropriate speech materials in local language, to determine speech audibility as well.,^20,21 The hearing aid fitting appointment usually ends with education on use and care of the hearing aids, as well as counselling for parents and caretakers on how to encourage consistent use of the hearing aids by the children and how to observe the outcomes and the benefits of the devices.

Besides hearing aid fitting and related services, the EDB also coordinates other intervention services in the local educational sector for these children with hearing loss. The EDB has all along been promoting integrated education for students with special education needs, including those with hearing loss. For public sector ordinary schools which take in students with special educational needs, additional resources, professional support, and teacher training are provided by the EDB. The EDB has also been providing school-based speech therapy services in the public sector ordinary schools since the 2019/20 school year, which may help students with hearing loss to develop their communication, speech and language abilities.¹⁶ For students who have further learning and communication problems despite receiving school-based support, the EDB refers them to receive the Enhanced Support Service for Students with Hearing Impairment, such as to receive after-school support for mastering learning strategies, improving language skills and enhancing communication skills. The EDB also refers students who cannot construct knowledge because of inadequate speech abilities, such as those who need to use sign language in communication and learning, to special schools for children with hearing loss to receive intensive support services.²²

For children with hearing loss at their preschool age, on-site pre-school rehabilitation services are provided by the Labour and Welfare Bureau to kindergartens and kindergarten-cum-child care centres, with the support from multi-disciplinary service teams including social workers, speech therapists, clinical psychologists / educational psychologists, and special child care workers. Children with hearing loss or other special needs are provided with rehabilitation services and training, while professional advices are given to kindergarten teachers, and support is provided for parents.

On the other hand, there are also early educational training centres and special child care centres under the Social Welfare Department of Hong Kong, providing habilitation services for children with hearing loss from birth. They provide intensive speech and communication skills training to infants and toddlers with hearing loss, as well as their parents.

Medical practitioners, especially family physicians, can motivate families with infants and children who have been diagnosed with different degrees of hearing loss to grasp the golden opportunity to receive early intervention. Families may feel ambivalent in obtaining intervention for their children with hearing loss, in particular those who perceive the loss as not too serious. It has, however, been well established that, even a mild hearing loss would result in language difficulty, thus resulting in possible academic difficulties and behavioural problems. Medical practitioners can encourage families to obtain intervention devices and services from the education sector or hospitals.

In summary, inview of the EHDI goals of immediate referral of infants with hearing loss by their 6 months of age, to early intervention in order to receive targeted and appropriate services, and a simplified, coordinated point of entry into an intervention system appropriate for the child, we are generally meeting the goals of early intervention in Hong Kong.

Discussion

The apparent implementation of EHDI programmes and meeting the EHDI 1-3-6 goals have been successful in Hong Kong. In the latest JCIH position statement, it is encouraged that EHDI programmes meeting current targets might consider setting a new target of 1-2-3 months (screening completed by 1 month of age, audiologic diagnosis completed by 2 months of age, and early intervention initiated no later than 3 months of age). This not only facilitates infants with hearing loss to receive earlier intervention for auditory access to language, but also practically allows objective audiologic diagnostic testing to be completed without sedation during the natural sleep that occurs when newborn / infants are young enough to sleep for prolonged periods of time.

This is, however, only possible with the collaborative efforts of all the involved parties, including medical practitioners from all specialty background, in particular family physicians who may be the point of first contact of the family with a newborn or infant with suspected hearing loss. Regardless of the results from the newborn hearing screening, events such as culture-positive infections associated with sensorineural hearing loss, significant head trauma especially basal skull / temporal bone fractures, or caretaker concern regarding hearing, speech, language, developmental delay and / or developmental regression, are formally regarded as risk factors for early childhood hearing loss.¹ Referral for ENT specialist consultation, as well as audiological assessment, are necessary. With the concerted efforts across the medical, healthcare, education and social sectors, a normal developmental trajectory for young children with hearing loss can be achieved through the local EHDI programmes.

Conclusion

In this educational update article, the focus has primarily been on how early childhood hearing loss is detected and intervened in Hong Kong. We believe that, when hearing loss is diagnosed in early childhood, and hearing technologies are fitted soon thereafter, children with hearing loss and their parents can begin intervention that facilitates language development. The early hearing detection and intervention programmes allow children with hearing loss to grow up in this hearing world, hopefully with minimal negative impact on their social, emotional, cognitive, and academic development, with the collaborative support from various sectors.