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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 21  |  Issue : 2  |  Page : 29-32

Universal neonatal hearing screening in a tertiary care center in South India


1 Department of Otorhinolaryngology and Head and Neck Surgery, Jahra Hospital, Al Jahra, Kuwait
2 Department of ENT, Al Azhar Medical College and Super Specialty Hospital, Idukki, Kerala, India
3 Department of Otorhinolaryngology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth University, Puducherry, India

Date of Submission05-Feb-2019
Date of Decision20-Mar-2019
Date of Acceptance16-Apr-2019
Date of Web Publication22-Oct-2019

Correspondence Address:
Dr. Davis Thomas Pulimoottil
Department of ENT, Al Azhar Medical College and Super Specialty Hospital, Ezhalloor, Thodupuzha, Idukki - 685 608, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/SJOH.SJOH_6_19

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  Abstract 


Objective: The aim of the study is to determine the prevalence of hearing loss among newborn infants and to assess the effectiveness and utility of otoacoustic emission (OAE) as a screening tool to detect hearing impairment in newborns and the relationship between selected risk factors and hearing loss. Study Design: This study involved 3121 newborns delivered in a tertiary care center over a 3-year period, who were subjected to distortion product OAE (DPOAE) within 24–72 h of life; failed candidates underwent repeat DPOAE after 30 days. Infants failed the second DPOAE test and then underwent DPOAE and brain stem-evoked response audiometry (BERA) at 3 months of life. Results: 20.95% newborns failed the first screening test, 11.77% failed the second test, and 61.91% of these infants failed the third OAE test. Of the 26 infants who failed the third test, 15 had abnormal results on BERA. Overall, the prevalence of hearing loss was 0.48%. Conclusion: Implementation of a national universal newborn hearing screening program in India is the need of the hour, as early detection of hearing loss will aid early rehabilitation and better outcomes.

Keywords: Auditory brainstem evoked response, hearing loss, neonatal hearing screening, newborn, otoacoustic emission


How to cite this article:
Kaipuzha RR, Pulimoottil DT, Karthikeyan P. Universal neonatal hearing screening in a tertiary care center in South India. Saudi J Otorhinolaryngol Head Neck Surg 2019;21:29-32

How to cite this URL:
Kaipuzha RR, Pulimoottil DT, Karthikeyan P. Universal neonatal hearing screening in a tertiary care center in South India. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2019 [cited 2019 Dec 12];21:29-32. Available from: http://www.sjohns.org/text.asp?2019/21/2/29/269713




  Introduction Top


Neonatal screening is done for early detection of infants with hearing loss. Normal hearing, during very early life, is of utmost importance for laying the basis for speech and language development.[1] Hearing impairment leads to sensory deprivation with failure to develop communication skills which in turn leads to learning problems.[2] The prevalence of mild-to-profound hearing loss is reported to be between 1.1 and 6/1000 live births.[3],[4],[5],[6],[7] There are two neonatal hearing screening techniques that are widely used, namely, the automated auditory brainstem response (AABR) and otoacoustic emissions (OAEs).[8]

OAEs describe the response the cochlea emits in the form of acoustic energy, determined by the contractile activity of the external ciliated cells and the mechanical and structural features of the basilar membrane, and are used as objective indicators of cochlear pathology.[9],[10] OAEs may be either spontaneous OAEs or induced by acoustic stimulation (evoked OAEs [EOAEs]).[10] OAE as a screening tool for neonates is a fast and easy test, does not require highly trained personnel to operate, and the test can be conducted without any sedation given to the newborn.[11],[12],[13],[14],[15]

This study aimed to determine the prevalence of hearing loss among newborn infants and to assess the effectiveness and utility of OAE as a screening tool to detect hearing impairment in newborns and the relationship between selected risk factors and hearing loss.


  Materials and Methods Top


All newborns delivered in a rural tertiary care center in South India over a period of 3 years were included in the study after obtaining informed and written consent from the parents. Using a pretested questionnaire, potential risk factors were extracted from the patient records, and the cases were grouped as normal or high risk. Both the normal and high-risk neonates underwent screening for hearing loss within 24–72 h of life using distortion product OAE (DPOAE) as the screening tool.

Neonates who failed the initial screening were subjected to repeat testing with DPOAE after 30 days. Those who failed the second screening were then subjected to a third DPOAE testing at 3 months. At this screening, neonates who failed the test were then finally subjected to brain stem-evoked response audiometry (BERA) testing. This automated OAE (Smart DPOAE, Intelligent Hearing Systems Distortion Product Otoacoustic Emission System version 4.X) is a complete DPOAE acquisition and analysis system that gives a “pass” or “refer” result. The absence of emissions using repeat DPOAE was tested with OAE and BERA after 3 months of life. The automated BERA (Smart Screener Automated ABR Hearing Screening System Version Plus 2) gives a statistical measure of waveform reliability and also provides with “pass” or “refer” outcome. Screening was done by an experienced audiologist specialized in pediatric audiometry. Infants who failed rescreening by BERA were scheduled for further intervention [Figure 1].
Figure 1: Algorithm for universal newborn hearing screening

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  Results Top


The total number of newborns included in the study was 3121. All newborns underwent DPOAE. Six hundred and fifty-four (20.95%) newborns failed the first screening test. Among the 654, only 528 (80.7%) came for the second-stage screening test. Four hundred and fifty-one of them passed the repeat OAE and 77 infants failed at this stage. One hundred and twenty-six (19.27%) newborns/infants defaulted follow-up. During the third-stage follow-up at 3 months of age, only 42 (54%) infants turned up and 35 (45%) defaulted appointment. Among these 42 infants, 16 passed and 26 failed the OAE test. However, when these infants underwent BERA, 11 had normal and 15 had abnormal results. All 15 infants were still under follow-up with plans to have hearing aids fitted after behavioral testing. Overall, the prevalence of hearing loss in this study was found to be 0.48% (15/3121) [Table 1]. In BERA testing, nine children were found with mild hearing loss, four with moderate hearing loss, and two with severe-to-profound hearing loss.
Table 1: Results of otoacoustic screening test during each visit

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Out of 468 infants who were termed as “at risk,” 5 infants were found to have hearing impairment as compared to 10 out of 2653 “not at-risk” infants. This translates to an incidence of hearing impairment per 1000 screened of 10.68 and 3.77, respectively. This difference was found to be statistically very significant [Table 2]. Among the “at-risk” infants, the most common risk factors encountered were respiratory distress, birth asphyxia, severe hyperbilirubinemia, and postnatal septicemia. The most common infection seen during the study period was postnatal septicemia. The most common maternal infection seen was maternal retrovirus [Figure 2].
Table 2: Incidence of hearing impairment in a cohort of at risk and not at risk infants

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Figure 2: Distribution of risk factors for at-risk infants screened for hearing loss

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  Discussion Top


The incidence of hearing impairment in this cohort was found to be 4.81/1000 screened in a population consisting of 15% at-risk and 85% not at-risk neonates. A community-based study done under the Indian Council of Medical Research support detected the incidence of congenital hearing loss as 10/1000 and 20/1000 in rural and urban population of India, respectively.[15],[16] Another study done in rural Karnataka showed that 8 children/1000 had congenital hearing loss.[17]

In this study, the prevalence of hearing loss was 0.48% which, in view of the unacceptably high default rates, might not be accurate. Although we were able to cover 100% newborns in this study initially, achieving the guideline of the Joint Committee on Infant Hearing 2000 to get >95% coverage, the number of infants who defaulted further follow-ups was very high.

After the initial OAE screening, 654 newborns were found to have failed the first stage, only 528 (80.7%) came for the second stage at 2 months of age to repeat OAE. At this second stage, 85.41% (451/528) who “refer” OAE during the first stage “pass” the second stage. This gave the impression that there were a lot of false positives during the first stage. We postulate that we have a high failure rate (false positive) during the first stage due to the test being conducted too early (<24 h). In newborns <24 h old, they are more likely to have debris in the external auditory canal (EAC) that interferes with OAE testing. OAE has been reported to have a high false-positive rate (about 15% at the first screen on day 1 and then reduces by about 50% with each retest). Screening using AABR technique is associated with a much lower false-positive rate (about 5% on day 1 and reduces to about 1% by the second retest).[18] Gabbard et al. showed that a significant difference in the age-related effect was identified during the OAE screen test and that young neonates were less likely to pass the transitory EOAE screen test than older neonates.[19]

Vohr et al. also reported that the age of the patients might affect the OAE result.[20] Waiting as long as possible prior to discharge before screening the baby provides more opportunity for debris in the EAC to clear naturally. This was confirmed by data from the Rhode Island Hearing Assessment Project (RIHAP) in neonates tested before 24 h of age. When the examiners waited until the infants were at least 24 h of age, the “pass” rate for a sample of over 4000 infants at RIHAP increased from 70% to 82%. This might be because the vernix and amniotic fluid have a chance to clear from the ear canal during the 1st day of life.[20]

Joseph reported that since 2002, when transient OAE screen tests were complemented with an early AABR in Singapore, their reference rate for the diagnostic evaluation of hearing loss was reduced to <1%.[18] The availability of objective and simple-to-use age-appropriate screening tests makes the introduction of newborn hearing screening program essential for encouraging optimal auditory-verbal intervention, preferred by parents. The benefits of such a program outweigh the cost of implementation.

While testing with OAE is cheaper in terms of capital equipment cost, it may be necessary for a larger program involving all live births, to use automated ABR in conjunction with OAE as the system of choice. The use of automated ABR technology has the advantages of reduced false-positive rate with testing in the first few days of a baby's life which reduces parental anxiety and the ability to detect the small population of children with auditory neuropathy. Finally, it must be remembered that the identification of mild hearing loss in the neonatal period is not straightforward, that no screening test performs perfectly, and that the screening program will never identify late-onset hearing loss. Therefore, regardless of the results of the infant hearing screening, the parents, medical and nursing personnel, and all other professionals who have opportunity to observe the child should pay attention to risk factors and the behavioral signs of a possible change in the child's hearing status or language development. Although the use of OAE gives satisfying results, since it is reliable and easy to use, we must remain attentive that it does not identify retrocochlear hearing losses in this “at-risk” population.


  Conclusion Top


A high incidence of hearing impairment of 4.81/1000 in a standardized neonatal population of at-risk and not at-risk warrants the urgent implementation of universal hearing screening of all neonates in India. Screening only at-risk neonates can miss a large proportion of all the neonates with hearing disability in a typical tertiary care hospital. It is crucial that India takes a national approach to the development of a universal newborn hearing screening program. Pilot projects will help in determining suitable and culturally acceptable hearing screening models in the country. The major weakness of existing programs remains the number of infants lost to follow-up, which may partly be related to poor utilization of electronic data management systems. One of the most important issues in a universal screening program is to reduce the “false-positive” rate that can generate anxiety in the infant's family, and this may be assured by utilizing combined OAE and BERA screening technique for all infants. Newborn hearing screening should be considered the standard of care for neonates.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Stoel-Gammon C, Otomo K. Babbling development of hearing-impaired and normally hearing subjects. J Speech Hear Disord 1986;51:33-41.  Back to cited text no. 1
    
2.
Elliott LL, Armbruster VB. Some possible effects of the delay of early treatment of deafness. J Speech Hear Res 1967;10:209-24.  Back to cited text no. 2
    
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Johnsen NJ, Bagi P, Elberling C. Evoked acoustic emissions from the human ear. III. Findings in neonates. Scand Audiol 1983;12:17-24.  Back to cited text no. 3
    
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Schulma GC, Galambas R. Brainstem evoked response audiometry in newborn hearing screening. Arch Otol 1979;1:86-90.  Back to cited text no. 4
    
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Watkin PM, Baldwin M, McEnery G. Neonatal at-risk screening and the identification of deafness. Arch Dis Child 1991;66:1130-5.  Back to cited text no. 5
    
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Collet L, Levy V, Vevillet E, Morgan TA. Click-evoked otoacoustic emissions and hearing threshold in sensorineural hearing loss. J Pediatr 1993;14:141-9.  Back to cited text no. 6
    
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Davis A, Bamford J, Wilson I, Ramkalawan T, Forshaw M, Wright S, et al. Acritical review of the role of neonatal hearing screening in the detection of congenital hearing impairment. Health Technol Assess 1997;1:i-iv, 1-176.  Back to cited text no. 7
    
8.
Finitzo T. Experiences of a long-established universal newborn hearing screening program. Hear J 2000;53:11-48.  Back to cited text no. 8
    
9.
Probst R, Lonsbury-Martin BL, Martin GK. A review of otoacoustic emissions. J Acoust Soc Am 1991;89:2027-67.  Back to cited text no. 9
    
10.
Gill AW, Gosling D, Kelly C, Walker P, Wooderson S. Predischarge screening of very low birthweight infants byclick-evoked otoacoustic emissions. J Paediatr Child Health 1998;34:456-9.  Back to cited text no. 10
    
11.
Rasmussen AN, Osterhammel PA, Johannesen PT, Borgkvist B. Neonatal hearing screening using otoacoustic emissions elicited by maximum length sequences. Br J Audiol 1998;32:355-66.  Back to cited text no. 11
    
12.
Ochi A, Yasuhara A, Kobayashi Y. Comparison of distortion product otoacoustic emissions with auditory brain-stem response for clinical use in neonatal intensive care unit. Electroencephalogr Clin Neurophysiol 1998;108:577-83.  Back to cited text no. 12
    
13.
Luppari R, Orzan E, Arslan E. Acoustic distortion products otoacoustic emissions (DPOAE) in neonatal screening. Acta Otorhinolaryngol Ital 1999;19:57-63.  Back to cited text no. 13
    
14.
Rhodes MC, Margolis RH, Hirsch JE, Napp AP. Hearing screening in the newborn intensive care nursery: Comparison of methods. Otolaryngol Head Neck Surg 1999;120:799-808.  Back to cited text no. 14
    
15.
ICMR and Department of Science. Report of the Collaborative Study on Prevalence and Etiology of Hearing Impairment. New Delhi: ICMR and department of Science; 1983. p. 16.  Back to cited text no. 15
    
16.
Kicker SK. The scope of pediatric audiology in India. In: Deka RC, Kacker SK. Vijayalakshmi B, editors. Pediatric Audiology in India. 1st ed. New Delhi: Otorhinolaryngological Research Society of AIIMS; 1907. p. 20.  Back to cited text no. 16
    
17.
Chary G. Analysis and Final Report of Project on Prevalence Causes and Prevention of Hearing Impairment in Rural Karnataka, Bangalore; 2002. p. 13.  Back to cited text no. 17
    
18.
Joseph R. Mass newborn screening in Singapore – Position and projections. Ann Acad Med Singapore 2003;32:318-23.  Back to cited text no. 18
    
19.
Gabbard SA, Northern JR, Yoshinaga-Itano C. Hearing screening in newborns under 24 hours of age. Semin Hear 1999;20:291-305.  Back to cited text no. 19
    
20.
Vohr BR, White KR, Maxon AB, Johnson MJ. Factors affecting the interpretation of transient evoked otoacoustic emission result inneonatal hearing screening. Semin Hear 1993;14:57-72.  Back to cited text no. 20
    


    Figures

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    Tables

  [Table 1], [Table 2]



 

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