Universal Hearing Screening
P. Nagapoornima, A. Ramesh2, Srilakshmi3, Suman Rao, P.L. Patricia, Madhuri Gore1, M. Dominic and
St John’s Medical College Hospital, Bangalore and 1S.R.C. Institute of speech and hearing, Bangalore
Objective. To determine the weighted incidence of hearing impairment in a standardized population of at risk and not at risk
neonates seeking care at a tertiary level hospital in India.
Methods. A prospective study of a nonrandomized cohort of 1769 neonates (1490 : Not at risk ; 279 : At risk ) from a total of
8192 neonates (6509 : Not at risk; 1683 : At risk ) who sought care at St John’s medical College hospital from 1st September
2002 to 31st March 2006 were screened for hearing impairment using transient evoked otoacoustic emissions .Weighting was
performed using the expected value of 10 % at risk and 90 % not at risk infants in a typical tertiary care level center in India
derived from the National Neonatology and Perinatology database 2002 – 2003. Z test and 95 % confidence interval was used
to determine the external validity of the results.P less than 0.05 was considered as statistically significant.The power of the study
is 90 %.
Results. The incidence of hearing impairment in infants screened was 10 per 1769 infants screened (1490 : Not at risk ; 279
: At risk) which is 5.65 per 1000 screened. 279 at risk infants were screened and 3 were detected to have hearing impairment
which is an incidence of approximately 10.75 per 1000 screened. Of the 1490 not at risk infants screened 7 had hearing
impairment that is 4.70 per 1000 screened. If this was extrapolated to a standardized population consisting of 10 % at risk and
90 % not at risk then the incidence would be 5.60 per 1000 screened with a 95 % confidence interval of 4.13 – 7.06 . This narrow
95 % confidence interval with a p equal to 0.001 indicates that this value may be close to the caseload in a typical tertiary care
Conclusion. In this study the incidence of hearing impairment is 3 per 279 in at risk infants screened and 7 per 1490 in not at
risk infants screened. The weighted incidence in a standardized population of neonates seeking care at tertiary level center
in India is 5.60 per 1000 as per this study. This high incidence calls for all pediatricians to consider incorporating a basic hearing
screen for all the neonates using cost effective and appropriate technology. Initial screening may be performed using behavioral
observation techniques and confirmation by otoacoustic emissions. [Indian J Pediatr 2007; 74 (6) : 545-549]
E-mail : email@example.com
Key words : Neonatal; Infant hearing screening
Incidence of hearing impairment in a standardized regardless of the degree of hearing impairment.3 Most of
population of neonates at risk and not at risk to develop the neonatal facilities in the United states and European
hearing impairment ranges from 6-60 per 1000 neonates union have enforced mandatory screening of all
with an average of 4 per 1000 neonates. 1 As hearing newborns. These programs have demonstrated a definite
impairment is a hidden disability it is usually detected reduction in the age of detection of hearing impairment.
after 2 yr of age. 2 Late detection causes irreversible 4
This study has used otoacoustic emissions as the
stunting of the language development potential of the screening tool. Otoacoustic emission was used this study
child. Detection and rehabilitation of hearing impairment as it is very sensitive , noninvasive , cost and time
in infants by 6 mth of age has a proven advantage over effective making it an ideal screening method.5
those detected after 6 mth to acquire normal language
Till date there has been no large scale incidence studies
among the neonates in the Indian context. This
benchmark study intends to examine the incidence in a
Correspondence and Reprint requests : Dr. A. Ramesh, Assistant cohort of 1769 neonates who sought care at St John’s
Professor, Department of Otolaryngology Head and Neck surgery, St Medical college hospital, Bangalore over a period of 3 and
John’s Medical College Hospital, Bangalore – 560034 a half yr. This data maybe used in the formulation of
[Received July 19, 2006; Accepted December 29, 2006] proposals to policy making bodies in order to get grants
Indian Journal of Pediatrics, Volume 74—June, 2007 545
P. Nagapoornima et al
to implement a national universal neonatal hearing 4. Craniofacial anomalies including those with
screening program. Also private institutions can take the morphologic abnormalities of the pinna and ear
lead in establishing self sustaining and affordable canal.
screening programs in their facilities. 5. In-utero infections by TORCH group of organisms
6. Parental concern
7. Severe birth asphyxia requiring ventilation
MATERIALS AND METHODS 8. Hyperbilirubinemia requiring exchange transfusion
The working definitions of morbidities in the at risk
A prospective study of a nonrandomized cohort of 1769 group in this study are derived from the national
neonates (1490 : Not at risk ; 279 : At risk ) from a total of neonatology and perinatology database report 2002 –
8192 neonates ( 6509 : Not at risk ; 1683 : At risk ) who 2003 and are as follows.6 Severe birth asphyxia : Apgar
sought care at St John’s medical College hospital from 1st score of 3 or less at 1 minute of age, Hyperbilirubinemia
September 2002 to 31st March 2006 were screened for requiring exchange transfusion : serum bilirubin level >
hearing impairment using the following test protocol. 20 mg/dl, respiratory distress : presence of at least 2 of
Transient evoked Otoacoustic emissions (OAE ) were the following criteria – respiratory rate more than 60 per
used as the first level of screening by 6 weeks of age.The minute/subcostal or intercostals recessions/expiratory
failed neonates underwent a second screen within 3 grunt or groaning, meningitis and sepsis had to be
weeks of first screen. Auditory brainstem response and culture positive for CSF and blood respectively.
behavioural audiometry was used to confirm the hearing Statistical Analysis
loss if the neonates failed the second OAE screen..
Professionals from the following specialties constituted Internal validity : The otoacoustic emission analyzer and
the neonatal hearing screening team : Neonatology, auditory brain stem response equipment were calibrated
Audiology, Otorhinolaryngology, Child psychology, and the protocol driven measurement ensured internal
Neurology and Medicosocial work. validity.
Specification of the equipment and criteria for pass and External validity : The Z test was used to test the external
fail validity. As there are no large scale Indian studies on
incidence of hearing impairment the reference values
The program was initiated in September 2002 using were drawn from the American Joint Committee
automated equipment Echo screen sw-rev 6.8, fischer statement on Infant hearing screening 2000. The
zoth and an equipment hired form the S.R.C Institute of information of this cohort were used to calculate the
speech and hearing Bangalore. Till September 2004 probable incidence in other neonatal care centers by
screening was done on once a week basis for only high examining the distribution of risk factors in various
risk infants. From October 2004 , we acquired an ILO 292 centers. This data was drawn from the national
USB -1 otoacoustic emission (OAE) analyser. Since, then neonatology and perinatology database report 2002 –
screening of high risk as well as not at risk infants were 2003.6 Statistical package for social sciences (SPSS) version
done on all the working days. The criteria for passing was 10 was used to calculate these projections and obtain 95%
a signal noise ratio of 3dB in at least 3 frequencies bands. confidence intervals. P value less than 0.05 was taken as
Auditory brain stem response (ABR) and behavioral statistically significant. The power of the study is 90%.
observation audiometry (BOA) was used to confirm if the
child failed the OAE screen 2 times. Follow up was done
using Receptive expressive emergent language RESULTS
scale(REELS) and Behavioural observation audiometry
Incidence in the cohort of all infants screened
The neonates were grouped as at risk to develop
Table 1 shows the incidence of hearing impairment in
hearing impairment if one of the following was
1769 infants screened (1490 : Not at risk; 279 : At risk) was
present.These criteria were adapted from the American
10 which is 5.65 per 1000 screened. The 95 % percent
Joint Committee statement on Infant hearing screening
confidence interval was between 2.15 – 9.15 infants per
1000 screened. This finding was highly significant with p
1. An illness or condition requiring admission of 24 = 0.001.
hours or more to a NICU.
Incidence in no risk newborns
2. Stigmata or other findings associated with a
syndrome known to include a sensorineural and / or Table 1 shows that in the 1490 infants screened 7 had
conductive hearing loss. hearing impairment that is approximately 4.70 per 1000
3. Family history of permanent childhood sensorineural screened. The 95 % percent confidence interval was
hearing loss between 1.22 – 8.17 infants per 1000 screened. This
546 Indian Journal of Pediatrics, Volume 74—June, 2007
Universal Hearing Screening
TABLE 1. Incidence of Hearing Impairment in a Cohort of at Risk and not at Risk Infants (N=1769)
Infant cohort Incidence in Incidence 95% confidence p value
the cohort expressed interval in a by Z test
per 1000 population of
screened 1000 screened
All infants 10 per 1769 5.65 2.15 – 9.15 0.001
At risk infants 3 per 279 10.75 1.42 – 2.29 0.001
Not at risk infants 7 per 1490 4.70 1.22 – 8.17 0.001
Standardized population of
neonates consisting of 10 % at - 5.60 4.13 – 7.06 0.001
risk and 90 % not at risk
*p values were calculated based on American Academy of Pediatrics ,data.
finding was highly significant with p = 0.001. The median :1,pre auricular skin tags :1 ,osteogenesis imperfecta :3
weight was 2.98 kg with a skewness of 0.61. The median and hydrocephalus:1. Down’s syndrome was the most
gestation was 38 weeks with a skewness of 0.91. common syndrome seen.
Incidence in the at risk newborns Table 3 shows the distribution of infants with prenatal
and post natal infections requiring NICU admission.
279 at risk infants were screened and 3 were detected to
There was no infant in these groups detected to have
have hearing impairment which is an incidence of
hearing impairment. Retroviral infection and pneumonia
approximately 10.75 per 1000 screened. The 95% percent
were the most common prenatal and post natal infection
confidence interval was between 1.42 – 2.29 per 1000
respectively. The absence of hearing impairment even in
screened with a high statistical significance of p = 0.001.
neonates with meningitis could be due to the low number
The incidence in various groups of infants with the risk
screened or the absence of Hemophilus influenzae as the
factors is shown in Table 2. The highest incidence seen
etiological factor in any of the cases screened. The highest
was is infants with family history of childhood onset
incidence is seen in H.influenzae meningitis.5
sensorineural hearing loss. The infants with severe birth
asphyxia was the other group with an incidence of 1 per TABLE 3. Distribution of Various Prenatal and Post Natal
51 screened. None of the other groups had any infant Infections Among Infants Screened for Hearing Loss
with hearing impairment. Though low birth weight (< (N=158)
2500 gms) had not been included in the JCIH statement, Nature of infection Number of infants screened
in this cohort we found an incidence of 2 in 262 infants
screened that is 7 per 1000 screened. The weight of the 1. Congenital Reubella 3
two infants with hearing impairment was 1.1 and 1.5 Kgs. Syndrome
2. Hepatitis B (Maternal) 2
TABLE 2. Distribution of at Risk Infants (N=279) 3. Cytomegalovirus (Maternal) 2
4. Chickenpox (Maternal) 1
Risk factor No. of infants No. of infants 5. Syphilis (Maternal) 1
Screened with hearing 6. Retrovirus infection (Maternal) 4
impairment 7. Respiratory distress suggestive 96
Family history of 8. Septicemia (Postnatal) 32
childhood onset 8 2 9. Meningitis (Postnatal) 14
sensorineural loss 10. Hepatitis (Postnatal) 3
Craniofacial anomalies 24 0 Total 158
Severe birth asphyxia 51 1
Pre and post natal infections Risk comparison of at risk and not at risk neonate to
requiring NICU 158 0
have hearing impairment
Hyperbilirubinemia 38 0
requiring exchange transfusion In this study there was no statistically significant
Total 279 3
difference in the incidence of hearing impairment
between at risk and not at risk infant. (P=0.20 : Fisher’s
There were no cases detected with hearing impairment exact test) However the at risk infant has a relative risk of
in the group with craniofacial anomalies.The various 2.29 (95% confidence interval of 0.60 – 8.80) in
craniofacial anomalies seen were antimongoloid slant: 5, comparison to not at risk infant to have hearing
microcephaly: 4, cleft palate : 3, microtia : 2, dandy impairment.
Walker syndrome : 1, microtia with pre-auricular skin tag
Results of the protocol used to screen
and facial palsy: 1, pierre robin syndrome : 1, occipital
encephalocoele : 1, preauricular skin tag with facial palsy The following flow chart shows the results of various
Indian Journal of Pediatrics, Volume 74—June, 2007 547
P. Nagapoornima et al
levels of screening as per the protocol used in the implement universal hearing screening.
program. Otoacoustic emission passed first time : 1662 →
High risk or Universal screening : Where to begin ?
Otoacoustic emission failed first time and passed second
time :97 → Otoacoustic emission failed first and second This pilot study in India has shown that screening of
time and ABR failed : 10. These were evaluated using only at risk neonates can miss detection of 70 % of the
behavioural observation audiometry to confirm hearing newborns with hearing impairment. Though incidence
impairment.The referral rate for a second screen was 5.5 per 1000 is higher among at risk infants, focusing only on
% and the referral for an ABR was 0.6 %. the at risk infants may miss 50 % of the newborns with
hearing impairment . 11,12,13,14,15,16 If the resources are
limited then one could focus initially on at risk neonates
and gradually implement universal screening .
The incidence of hearing impairment in this cohort is 5.65
per 1000 screened. If this was extrapolated to a
standardized population consisting of 10 % at risk and 90
% not at risk then the incidence would be 5.60 per 1000 A high incidence of hearing impairment of 5.60 per 1000
screened with a 95% confidence interval of 4.13 – 7.06. in a standardized neonatal population of at risk and not
This narrow 95% confidence interval with a p = 0.001 at risk warrants the urgent implementation of universal
indicates that this value may be close to the caseload in a hearing screening of all the neonates in India. Screening
typical tertiary level hospital in India. The assumption of only at risk neonates can miss upto 70 % of all the
10 % to be at risk was calculated by projecting the neonates with hearing disability in a typical tertiary care
distribution from Neonatal database 2002 -2003. 6 An hospital. In this study there is no statistically significant
ICMR supported Community based disability survey has difference in the incidence of hearing impairment
detected incidence of congenital hearing loss as 10 per between at risk and not at risk infants. Cost effective and
thousand and 20 per thousand in rural and urban India appropriate behavioural methods may be used if
respectively. 7,8 Another study undertaken in rural resources are limited and use Otoacoustic emissions test
Karnataka has detected 8 children per thousand with to confirm.The final goal should be to screen all neonates
congenital hearing loss.9 using automated Otoacoustic emission technology.
This is a very high incidence in relation to other Acknowledgements
congenital defects for which cure can be provided.10 The
The authors acknowledge Dr GRK. Sarma , Dr Vijayaraman , Ms
findings of this study correlates well with most of the Eliza Perreira and the management of St John’s National Academy
large scale studies in the United states and European of Health Sciences for their unflinching support of the program.
union. So there is no significant difference in the case load Special thanks for Christoffel Blinden mission for the grant that
per 1000 seen in India in comparison to the developed aided in the purchase of OAE analyzer.
nations. The incidence may vary based on high risk
population characteristics in different set ups.
There is an urgent need to incorporate universal
neonatal hearing screening in all the neonatal health care
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