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Neonatal Hearing Screening in Low- and Middle-Income Countries

By Dominic McKenna

ENT SAS Surgeon based in Northern Ireland



As a core aspect of our innate human capacities, our sense of hearing is pivotal for our communication and interaction within social environments. It allows us to perceive and interpret the rich tapestry of sounds in our world, is integral to our ability to develop language and speech, and is a gateway for cultural and emotional expression.

Significant hearing loss is common, with over 5% of the global population suffering from disabling hearing loss requiring rehabilitation, including 34 million children. About 1 in 1000 children will be born with severe to profound hearing loss1

In the 2021 'World Report on Hearing,' the WHO emphasizes global strategies for preventing, identifying, and rehabilitating hearing loss, particularly in low- and middle-income countries where 80% of global hearing loss occurs.2 The report highlights that 60% of childhood hearing loss is attributable to preventable factors, including vaccine-preventable infectious diseases, ototoxic medications, ear infections, and birth-related causes. This underscores the urgent need for targeted interventions to address these avoidable risks and safeguard children's hearing health.

Unaddressed childhood hearing loss carries wide-ranging implications that can persist into adulthood. This includes not only delayed speech and language acquisition3 but also hindered cognitive development4, leading to diminished educational achievements5 and limited job prospects5. Moreover, it often results in social withdrawal and isolation, with resultant deleterious mental health impacts. 7

Hearing loss extends its impact far beyond individual challenges, exerting a substantial economic burden on society. This includes escalated healthcare and educational expenses, along with a significant loss in productivity. According to WHO data, the global cost of unaddressed hearing loss is estimated at a staggering $980 billion annually. Notably, 53% of this expense is borne by LMIC, highlighting the disproportionate economic strain on these regions.8 These figures underscore the urgent need for comprehensive hearing loss strategies, particularly in resource-limited settings, to alleviate both individual and societal costs.

Neonatal hearing screening has become a key instrument in addressing childhood hearing loss. Its widespread implementation is largely due to the development of portable, objective auditory assessment tools that can be used within the first few days following birth. Technologies like transient-evoked otoacoustic emissions (TEOAE) evaluate outer hair cell function, while automated auditory brainstem response tests (AABR) assess the integrity of the auditory neural pathway.

By identifying hearing impairments at an early stage, screening enables timely interventions, ideally before the child reaches six months of age. Such prompt action is crucial, as it aligns with the critical period of language development, allowing children with hearing impairments to develop language skills on par with their hearing peers. 9 Moreover, early intervention capitalizes on the heightened neuroplasticity of auditory brain pathways, particularly in the first year of life, which is a key window for optimizing hearing and language outcomes

Studies from various countries, including the UK, USA, China, India, Nigeria, and the Philippines, have consistently shown the cost-effectiveness of neonatal hearing screening programs. The WHO projects a significant return on investment in these initiatives, estimating that every $1 spent on newborn hearing screening in LMICs could yield a return of $1.67. This underscores the economic viability and long-term benefits of such programs in different global contexts. 2

Universal hearing screening all of neonates is the gold standard, as it captures the 40% of infants with permanent hearing loss who lack high-risk factors and would otherwise be overlooked in targeted 'at-risk' protocols. 10 Such protocols only screen children identified with significant risk factors for hearing loss, missing a substantial portion of affected newborns. While opportunistic screening based on parental concerns is another method, it should ideally serve as a stopgap measure leading to universal screening, especially in resource-limited environments where comprehensive programs may not yet be feasible.

The Joint Committee on Infant Hearing issues guidelines to optimize early hearing loss detection, endorsing universal newborn screening with differentiated protocols for healthy infants and those in intensive care. The latter group is more susceptible to auditory neuropathy, necessitating the use of AABR for accurate diagnosis. They also suggested the 1-3-6 rule: with screening before 1 month, diagnosis prior to 3 months and intervention by the age of 6 months. 11,12,13

The effectiveness of a newborn hearing screening program implemented in Israel was highlighted in a 2019 study. 98.7% of neonates were screened with a reduction in the commencement of hearing rehabilitation, from an average of 19 months to 9.4 months, taking greater advantage of the child’s neuroplasticity. 14

Similar implementation in low- and middle-income countries however faces significant barriers. Limited resources, lack of awareness, and inadequate healthcare infrastructure often hinder the establishment of widespread neonatal hearing screening programs in these regions. Government funding is often limited and strained by high mortality rate diseases such as HIV/AIDS, malaria and tuberculous.

Screening program implementation must take into account the local culture context. A newborn screening program in Côte d’ivoire for example elected to implement their hearing program in primary care centres when BCG vaccination was being delivered, as opposed to a hospital-based screening program. This was due to very short hospital stays in both the public and private sectors. Serial TEOAE allowed detection of profound hearing loss in 6 per 1000 babies in that population. 15 Similarly, implementation in countries which a high percentage of births outside conventional health facilities will need a screening program that takes this into account.

The delivery of screening and diagnostic services for hearing impairment requires a multidisciplinary team, including otolaryngologists, audiologists, speech pathologists, and teachers of the deaf. However, critical shortages in these professions pose a significant barrier to effective hearing service delivery. Therefore, raising awareness and the involvement of international advocacy groups are crucial steps in addressing these shortages. Such efforts can help increase the number of trained professionals and improve access to essential hearing services worldwide.

Public health education plays a crucial role in raising awareness about the causes, consequences, and available treatments for childhood deafness. Community midwives can have a significant role in this regard, educating and motivating expectant parents regarding available newborn screening programs. 16

While access to advanced treatments like cochlear implants may be limited, it's essential that parents are thoroughly informed about all available options. Financial constraints should not lead to prejudiced assumptions about a family's ability to secure resources. Often, the potential for community support or personal sacrifices to facilitate treatment access is underestimated. Ensuring equitable information distribution helps empower families to make informed decisions for their children's health. 17

In conclusion, neonatal hearing screening represents a crucial strategy in mitigating the impacts of childhood hearing loss, especially in LMICs. The success of such programs depends on a multifaceted approach, incorporating early detection, cost-effective intervention, and overcoming resource constraints. Collaboration among healthcare professionals, awareness campaigns, and international support are key to overcoming existing barriers. Ultimately, investing in comprehensive neonatal hearing screening not only enhances individual outcomes but also contributes to societal well-being, making it an indispensable component of global health initiatives


 

Sources


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4. Cardon G, Campbell J, Sharma A. Plasticity in the developing auditory cortex: evidence from children with sensorineural hearing loss and auditory neuropathy spectrum disorder. J Am Acad Audiol. 2012;23(6):396–411

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8. McDaid, A-La Park & Shelly Chadha. Estimating the global costs of hearing loss, International Journal of Audiology (2021), 60:3, 162-170, DOI: 10.1080/14992027.2021.1883197.

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10. Wake M, Ching TY, Wirth K, Poulakis Z, Mensah FK, Gold L, et al. Population outcomes of three approaches to detection of congenital hearing loss. Pediatrics. 2016;137(1):e20151722.

11. Joint Committe on Infant Hearing Joint committee on infant hearing 1994 position statement. American academy of pediatrics joint committee on infant hearing. Pediatrics. 1995;95:152–156. doi: 10.1542/peds.95.1.152.

12. Joint Committe on Infant Hearing Joint Committee on Infant Hearing year 2000 position statement: principles and guidelines for early hearing detection and intervention programs. Am J Audiol. 2000;9(4):9–29. doi: 10.1044/1059-0889(2000/005)

13. Joint Committe on Infant Hearing Year 2007 Position statement: principles and guidelines for early hearing detection and intervention programs. Pediatrics. 2007;120:898. doi: 10.1542/peds.2007-2333

14. Wasser J, Roth DA-E, Herzberg O, Lerner-Geva L, Rubin L. Assessing and monitoring the impact of the national newborn hearing screening program in Israel. Isr J Health Policy Res. 2019;8(1):30

15. Tanon-Anon M, Sanogo-Gone D, Kouassi K B. Newborn hearing screening in a developing country: results of a pilot study in Abidjan, Côte d'ivoire. Int J Pediatr Otorhinolaryngol. 2010 Feb;74(2):188-91. doi: 10.1016

16. Das S, Seepana R, Singh Bakshi S. Perspectives of newborn hearing screening in resource constrained settings. J Otol. 2020 Dec; 15(4): 174–177.

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