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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 24  |  Issue : 1  |  Page : 42-46

Targeted screening for hearing impairment in neonates: A prospective observational study


Department of Paediatrics, Kurji Holy Family Hospital, Patna, Bihar, India

Date of Web Publication24-May-2018

Correspondence Address:
Dr Jehangir Allam Bhat
Department of Paediatrics, Kurji Holy Family Hospital, Patna, Bihar
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_10_18

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  Abstract 


Background: The aim of this study is to estimate the incidence and determine the risk factors predictive of hearing impairment in newborn by targeted hearing screening. Methods: This was a prospective, observational study conducted over a period of 1 year. We screened high-risk neonates for hearing impairment admitted to the Neonatal Intensive Care Unit using evoked otoacoustic emissions (EOAEs) and brainstem auditory evoked response (BAER). Babies who tested refer on EOAE were subjected to BAER urgently. Babies having an abnormality on BAER where confirmed as hearing impaired for this study. Results: A total of 195 high-risk babies comprising males (95 = 48.7%) and females (100 = 51.3%) were screened. Fifteen neonates (7.69%) tested refer in the initial screening procedure, i.e., EOAE, who then underwent BAER and out of these 15 (7.69%) neonates, 12 (6.15%) had abnormal BAER, i.e., hearing impairment. The significant individual risk factors in neonates with hearing impairment were stigmata and/syndrome associated with hearing loss, craniofacial anomalies, and hyperbilirubinemia and Apgar score <4 at 1 min and <6 at 5 min. Hearing impairment increased from 0.917% for one risk factor, 6.66% for two risk factors, 10.52% with three risk factors, 28.57% with four risk factors, and 25% with five risk factors. Conclusions: In this study, the incidence of hearing impairment was 7.69%. Stigmata and/syndrome associated with hearing loss, craniofacial anomalies, and hyperbilirubinemia and Apgar score <4 at 1 min and <6 at 5 min are significant risk factors for hearing loss, hearing loss increased as risk factors increase.

Keywords: Evoked otoacoustic emissions, hearing impairment, high-risk screening, newborn screening, risk infants, universal screening


How to cite this article:
Bhat JA, Kurmi R, Kumar S, Ara R, Mittal AK. Targeted screening for hearing impairment in neonates: A prospective observational study. Indian J Otol 2018;24:42-6

How to cite this URL:
Bhat JA, Kurmi R, Kumar S, Ara R, Mittal AK. Targeted screening for hearing impairment in neonates: A prospective observational study. Indian J Otol [serial online] 2018 [cited 2019 Sep 21];24:42-6. Available from: http://www.indianjotol.org/text.asp?2018/24/1/42/233118




  Introduction Top


Screening is one of the most important methods of early diagnosis of treatable diseases in children and hearing loss is an important treatable disease of childhood.[1] The prevalence of bilateral hearing loss is substantial, particularly in neonates admitted to the Neonatal Intensive Care Unit (NICU) who frequently present with risk factors for hearing loss. The prevalence of significant bilateral hearing loss in this group is 1%–3%, which is 10 times higher than that in the well-baby nursery population.[2] Furthermore, early intervention in hearing-impaired children (aged 6 months or earlier) improved their language and speech outcomes as well as their socioemotional development.[3],[4],[5] The congenital hearing loss has been recognized for decades as a serious disability for affected children, with a delay in diagnosis of 2 years or more being the rule rather than the exception.[6] In 1993, the National Institutes of Health recommended that every newborn infant have a hearing test performed in the first few months of life.[7] Yoshinaga-Itano et al.[8] revealed the significantly improved outcomes for children who have congenital hearing loss and received early intervention when compared to a cohort of similar children who did not receive the benefit of early screening and detection. Similarly, independent of specific screening protocols and measures of screening follow-up success, affected infants who were born in a hospital with an established screening program had significantly improved outcomes when compared to those who were born in hospitals that did not screen.[9]

Hearing screening can be done by two ways

Targeted (high risk) – In targeted hearing screening high-risk newborns are screened. High-risk newborn criteria are defined by the Joint committee on infant hearing, year 2007 statement.[10]

Universal newborn hearing screening : All newborn are screened for hearing impairment.

Techniques used to assess hearing of infants should be capable of detecting hearing loss of this degree in infants by the age of 3 months and younger. Of the various approaches to newborn hearing assessment currently available, two physiologic measures (brainstem auditory evoked response [BAER] and evoked otoacoustic emissions [EOAEs]) show good promise for achieving this goal.

BAER has been recommended for newborn hearing assessment for almost 15 years and has been successfully implemented in both risk register and universal newborn hearing screening programs, follow-up studies of infants screened by this technique demonstrate acceptable identification of infants with hearing loss.

EOAEs have been introduced for risk register and the assessment of newborn hearing. Follow-up studies of infants screened by this technique are limited but suggest that EOAEs can identify infants with hearing loss of approximately 30 dB HL and greater. Hearing loss of 30 dB HL and greater in the frequency region important for speech recognition (approximately 500 through 4000 Hz) will interfere with the normal development of speech and language.[11]


  Methods Top


A hospital-based prospective, observational study was conducted in the Department of Pediatrics, Kurji Holy Family Hospital Patna, Bihar which is a tertiary care referral hospital for children from June 2015 to May 2016. All neonates who were delivered in this hospital or outside who came to this hospital for further management who had below mentioned any risk factors as defined by the Joint committee on infant hearing. Year 2007 statement as follows.[10]

  1. The family history of hereditary childhood sensorineural hearing loss
  2. Intrauterine infections (TORCH)
  3. Craniofacial anomalies, including those with morphologic abnormalities of the pinna and ear canal
  4. Birth weight <1500 g
  5. Hyperbilirubinemia at a serum level requiring exchange transfusion
  6. Ototoxic medications, including but not limited to the aminoglycosides, used for more than 5 days or multiple courses or in combination with the loop diuretics
  7. Bacterial meningitis
  8. Apgar scores of <4 at 1 min or <6 at 5th min
  9. Needing mechanical ventilation for more than 5 days
  10. Stigmata or other findings associated with a syndrome known to include sensorineural and/or conductive hearing loss.


Ethical committee clearance was given by the Hospital Ethical Committee. Informed consent was obtained from the parents and the guardians after explaining to them the purpose of this study.

Exclusion criteria

  1. Consent not obtained
  2. Active ear infections
  3. Severe multiple anomalies are incompatible with life.


Neonates with one or more of the above risk factors were screened for hearing impairment before the age of 3 months using a two-stage screening protocol which consisted of a preliminary screening with EOAE. Participants who were referred during the first screening with EOAE were subjected to further screening with BAER to confirm the presence of hearing loss.


  Results Top


A total of 195 high-risk babies comprising (95 = 48.7%) males and (100 = 51.3%) females were screened. Twelve hearing impairment cases were found. Out of them 4 (33%) and 8 (67%) were female. Hearing impairment had no significant statistical relationship with gender (P = 0.199) [Table 1].
Table 1: Gender distribution of study neonates with hearing loss (n=12)

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Occurrence of risk factors in increasing order of frequency was ototoxic medications (65.1%), birth weight <2500 mg (48.2%), and Apgar scores of <4 at 1 min or <6 at 5th min (22.6%). These three were major risk factors. The percentage of other risk factors was as follows: bacterial meningitis (14.4%), hyperbilirubinemia requiring exchange transfusion (13.6%), TORCH infection (3.6%), craniofacial anomalies including those with morphologic abnormalities of the pinna and ear canal (2.1%), and stigmata or other findings associated with a syndrome known to include sensorineural and/or conductive hearing loss (2.1%) [Table 2].
Table 2: Distribution of risk factors in neonates with normal hearing after EOAE followed by brainstem evoked response audiometry and hearing loss after evoked otoacoustic emissions followed by brainstem auditory evoked response

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Fifteen (7.69%) neonates tested refer in the initial screening procedure i.e. EOAE who then underwent BAER and out of these 15 (7.69%) neonates, 12 (6.15%) had abnormal BAER, i.e., hearing impairment.

The significant individual risk factors in neonates with hearing impairment were stigmata and/syndrome associated with hearing loss (P = 0.02), craniofacial anomalies (P = 0.02), hyperbilirubinemia (P = 0.012), and Apgar score <4 at 1 min and <6 at 5 min (P = 0.006). Since newborn screened were having multiple risk factors, confounding of risk factors might have occurred, to overcome the confounding all statistically significant risk factors were analyzed using multivariate logistic regression as shown in [Table 3] which proved craniofacial anomalies, hyperbilirubinemia, Apgar score <4 at 1 min and <6 at 5 min, and stigmata and/or syndrome associated with hearing loss as independent risk factors.
Table 3: Multivariate logistic regression analysis of significant risk factors for hearing loss

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Hearing impairment increased from 0.917% for one risk factor, 6.66% to two risk factors, 10.52% with three risk factors, 28.57% with four risk factors, and 25% with five risk factors. As the number of risk factors per neonate increased, the probability of being hearing impaired also increased as shown in [Table 4].
Table 4: Hearing loss (evoked otoacoustic emissions abnormal cases who undergone brainstem auditory evoked response) in relation to the number of risk factors present (n=195)

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  Discussion Top


The prevalence of bilateral hearing loss is substantial, particularly in neonates admitted to the NICU who frequently present with risk factors for hearing loss. The prevalence of significant bilateral hearing loss in this group is 1%–3%, which is 10 times higher than that in the well-baby nursery population. Furthermore, early intervention in hearing-impaired children (aged 6 months or earlier) improved their language and speech outcomes as well as their socioemotional development. It seems reasonable to include hearing screening into routine programs. Thus, screening in a population at risk as performed in the present study can only be regarded to be the first step toward a universal screening.

In this study, 195 at risk neonates were screened for hearing impairment using EOAE and who fail the EOAE test were screened by BAER. Fifteen neonates tested refer to the initial screening procedure, i.e., EOAE who then underwent BAER and out of these 15 (7.69%) neonates, 12 (6.15%) had abnormal BAER, i.e., hearing impairment. This implies a 50-fold increase in hearing impairment in high-risk neonates. Similar results have been obtained in the studies done by Zamani et al.[1] (8%) and Maisoun and Zakzouk [12] (13.5%).

In this study, there was not much statistically significant difference among male and female neonates regarding hearing (P = 0.199) [Table 1] impairment which is consistent with most of the prior studies such as Al-Meqbel and Al-Baghli [13] Maqbool et al.[14]

In this study, use of ototoxic medications, birth weight <2500 g, Apgar scores of <4 at 1 min or <6 at 5th min, and hyperbilirubinemia were the major risk factors occurring in 65.1%, 48.2%, and 22.6% at 33.3% risk neonates, respectively which is consistent with the study conducted by Zamani et al.[1] and Meyer et al.[15] In the study by Christiane Meyer et al., 12 ototoxic medication and birth weight <1500 g were the major risk factors. A higher percentage of hyperbilirubinemia requiring exchange transfusion in the study is due to poor follow-up of neonates with blood group incompatibilities and a higher percentage of home deliveries and poor accessibility to pediatricians.

Apgar score <4 at 1 min and <6 at 5 min (P = 0.006), stigmata and/or syndrome associated with hearing loss (P = 0.020), craniofacial anomalies (P = 0.020), and hyperbilirubinemia (P = 0.012) were significant independent clinical risk factors for predicting hearing impairment in high-risk neonates [Table 2] and [Table 3]. Al-Meqbel and Al-Baghli [13] found premature birth (gestational age ≤34 weeks), positive family history of hearing loss, hyperbilirubinemia, severe perinatal asphyxia, ototoxic medication, and syndromes associated with hearing loss as a significant risk factors for hearing impairment. Meyer et al.[15] have reported craniofacial anomalies, familial hearing disorders, and bacterial meningitis as significant factors associated with pathologic BAER. Kumar et al.[16] have reported major risk factors are NICU admission, LBW, hypoxia, and jaundice. Gouri et al.[17] found low Apgar Score and family history of SNHL as an independent risk factor. Similar findings were reported by Maisoun and Zakzouk [12] and Chan et al.[18]

In this study, four neonates had a family history of hearing loss, none had hearing impairment [Table 2]. This may be due to smaller sample size and lack of proper hearing impairment evaluation of neuro-handicapped children in our set up.

In this study, two out of the four neonates who had craniofacial anomalies had EOAE refer and another two were EOAE PASS. On BAER testing, of these refer neonates, both have abnormal BAER, i.e., hearing loss. On univariate regression analysis and Chi-squared testing (Fisher's exact test), a value of P = 0.002 was derived which is statistically significant [Table 2] and [Table 3]. Similar findings have been reported by Srisuparp et al.[19]

In this study, EOAE response was recorded in five out of 26 neonates with hyperbilirubinemia as risk factor. On BAER testing, all neonates had an abnormal response (Hearing loss). On Chi-squared (Fisher's exact test), a value of P = 0.012 was derived which proved hyperbilirubinemia as a statistically significant independent risk factor for hearing impairment [Table 2] and [Table 3]. In this study conducted by Zamani et al.,[1] hyperbilirubinemia was the main cause of hearing loss.

In this study, as shown in [Table 2], eight neonates out of 44, who had low Apgar score as the risk factor had referred EOAE response initially, but one neonate had normal BAER and seven had an abnormal response, i.e., hearing impairment which is in accordance with an earlier study conducted by Gouri et al.[17]

Another risk factor which has statistical significance as an independent risk factor in the study is stigmata and/or syndrome. Two out of the four neonates who had stigmata and/or syndrome EOAE refer and another two were EOAE PASS as shown in [Table 2] and [Table 3]. On BAER testing, of these refer neonates, both have abnormal BAER, i.e., hearing impairment. On univariate regression analysis and Chi-squared testing (Fisher's exact test), a value of P = 0.02 was derived which is statistically significant.

In this study, aminoglycosides were used for more than 5 days in 127 neonates making up 65% of the total study infants. This high percentage could be attributed to the high risk of sepsis in our NICU. Of these 127 neonates, aminoglycoside use was the only risk factor in 51 neonates, and one showed EOAE RERER response which also had BAER abnormality so had hearing loss. Of 76 cases who had other risk factors present besides aminoglycosides, 12 had EOAE refer response. On BAER testing, of these 12 cases, 10 had hearing loss confirmed as shown in [Table 2]. In spite of being risk factor present in majority of cases who had hearing loss 11 out of 12, it is not an independent significant risk factor for hearing impairment (P = 0.06). It could be due to a higher percentage of cases (65%) having aminoglycoside as a risk factor and the use of aminoglycosides in appropriate dosages given at proper intervals such that the drug concentration in blood remained below the toxic level. Similar findings have been reported by Meyer et al.[15]

In this study, risk factor such as meningitis (P = 0.385), intrauterine infection (TORCH) (P = 0.364), birth weight <1500, (P = 0.987), and mechanical ventilation (P = 0.257) were not statistically significant risk factors for hearing impairment [Table 2].

Hearing impairment increased from 0.917% for one risk factor, 6.66% for two risk factors, 10.52% with three risk factors, 28.57% with four risk factors, and 25% with five risk factors [Table 4]. As the number of risk factors per neonate increased, the probability of being hearing impaired also increased which is in accordance with the study conducted by Srisuparp et al.[19] and Zamani et al.,[1] and Maqbool et al.[14]


  Conclusions Top


The study data indicate a high incidence of hearing impairment in NICU graduates and a change in the pattern of risk factors for neonatal hearing loss. Apgar score <4 at 1 min and <6 at 5 min, stigmata and/or syndrome associated with hearing loss, craniofacial anomalies, and hyperbilirubinemia were significant independent clinical risk factors for predicting hearing impairment in high-risk neonates. This study was the first step toward implementing the hearing screening program in our hospital and could help in meta-analysis of the studies on hearing screen; hence, that hearing screening could be implemented throughout the country.

Acknowledgment

The authors are highly thankful to the hospital administration, the paramedical staff of the pediatric department, hospital statistician, and computer operators for helping in conducting this research.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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2.
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Al-Meqbel A, Al-Baghli H. The prevalence of hearing impairment in high-risk infants in Kuwait. Aud Vest Res 2015;24:11-6.  Back to cited text no. 13
    
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Maqbool M, Najar BA, Gattoo I, Chowdhary J. Screening for hearing impairment in high risk neonates: A Hospital based study. J Clin Diagn Res 2015;9:SC18-21.  Back to cited text no. 14
    
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Meyer C, Witte J, Hildmann A, Hennecke KH, Schunck KU, Maul K, et al. Neonatal screening for hearing disorders in infants at risk: Incidence, risk factors, and follow-up. Pediatrics 1999;104:900-4.  Back to cited text no. 15
    
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Gouri ZU, Sharma D, Berwal PK, Pandita A, Pawar S. Hearing impairment and its risk factors by newborn screening in North-Western India. Matern Health Neonatol Perinatol 2015;1:17.  Back to cited text no. 17
    
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19.
Srisuparp P, Gleebbur R, Ngerncham S, Chonpracha J, Singkampong J. High-risk neonatal hearing screening program using automated screening device performed by trained nursing personnel at Siriraj hospital: Yield and feasibility. J Med Assoc Thai 2005;88 Suppl 8:S176-82.  Back to cited text no. 19
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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