Prevalence of permanent childhood hearing impairment

1
Prevalence of permanent childhood hearing
impairment

• Heather FortnumB Med Sci, BM BS, DM
• MRC Institute of Hearing Research, Nottingham, UK

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• Heather Fortnum
• is an epidemiologist working in Health Services
  Research for UK Medical Research Council
• ...has always been interested in the impact of
  permanent hearing impairment on children
• ...is excited by the current findings and their
  implications for Universal Newborn Hearing
  Screening

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Impact on children

• Communication skills
• Educational attainment
• Quality of life

4
Early intervention leads to improved outcomes1
5
Previous studies

• Relatively small
• No assessment of under-ascertainment

6
Capture-recapture

• No change in population
• Cases from different sources can be matched
• Same chance of being included in each data source
• Independent data sources

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(No Transcript)
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Formulae
N
(m1)(n1)(m-c)(n-c)
Var
(N)
(c1)
2
(c2)

?
95 c.i.
1.96

Var
(N)
Sources are independent if
p
x p
p
1
2
12
9
National Ascertainment Study

• Data source N of children
• Health professionals 11577
• Education professionals 12107
• Both 6524
• Either 17160

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Observed prevalence (95 confidence intervals)
11
Adjusted prevalence (95 confidence intervals)
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Prevalence by age
Prevalence(per 1000 live births)
2.5
gt40dB
2.0
1.5
1.0
0.5
0.0
0
2
4
6
8
10
12
14
16
18
Age (years)
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• Increase with age?
• Decrease with time?

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• Cohorts age in Prevalence per years 1000 live
  births
• Trent Ascertainment2
• 1985-1990 5-10 1.33 (95 ci 1.22-1.45)
• National Ascertainment3
• 1985-1990 8-13 1.63 (95 ci 1.59-1.67)
• 1988-1993 5-10 1.44 (95 ci 1.41-1.48)

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Conclusion

• The prevalence of permanent childhood hearing
  impairment continues to rise after birth over a
  wider age range than had previously been reported
  and reaches a higher plateau.

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1. Acquired impairments

• Usually due to bacterial meningitis or trauma
• Can occur at any age
• Contributes 7 of overall prevalence

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2. Delayed confirmation
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3. Late onset and/or progressive

• Many dominant genes for deafness in animal models
  are associated with late-onset progressive
  impairment.
• Van Camp G, Smith RJH. Hereditary Hearing Loss
  Homepage. WorldWide Web URL http//dnalab-www.ui
  a.ac.be/dnalab/hhh
• Steel KP. New interventions in hearing
  impairment. Brit Med J 2000320622-625.

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• Conclusions
• The prevalence of confirmed permanent childhood
  hearing impairment (gt40 dB HL) in the UK has
  risen with age to at least 1.65/1000 live births
  (and may be as high as 2.05/1000 live births)
  among children 9-years of age and older.
• If the current yield from Universal Neonatal
  Hearing Screening is sustained, then an
  additional 50-90 of children will remain to be
  detected in the post-natal years.

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Reading list 1 - epidemiology

• Davis AC, Parving A. Towards appropriate
  epidemiological data on childhood hearing
  disability a comparative European study of birth
  cohorts. J Audiol Med 1993335-47.
• Karikoski JO, Martilla TI. Prevalence of
  childhood hearing impairment in Southern Finland.
  Scand Audiol 199524237-241.
• Mäki-Torkko EM, Lindholm PK, Väyrynen MRH, Leisti
  JT, Sorri MJ. Epidemiology of moderate to
  profound childhood hearing impairments in
  Northern Finland. Any changes in ten years? Scand
  Audiol 19982795-103
• Van Naarden K, Decouflé P, Caldwell K. Prevalence
  and characteristics of children with serious
  hearing impairment in Metropolitan Atlanta.
  Pediatrics 1999103570-575.

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Reading list 2 - epidemiology

• Uus K, Davis A. Epidemiology of permanent
  childhood hearing impairment in Estonia,
  1985-1990. Audiology 200039192-197.
• Hadjikakou K, Bamford J. Prevalence and age of
  identification of permanent childhood hearing
  impairment in Cyprus. Audiology 200039198-201.
• Mencher G, Madriz JJ. Prevalence of sensorineural
  hearing loss in children in Costa Rica. Audiology
  200039278-283.
• Mencher G. Challenge of epidemiological research
  in the developing world overview. Audiology
  200039178-183.
• Streppel M, Richling F, Walger M, von Wedel H,
  Eckel H. Epidemiology of hereditary hearing
  disorder in childhood. Scand Audiol 2000293-9.

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Reading list 3 - UNHS

• Watkin PM, Baldwin M. Confirmation of deafness in
  infancy. Arch Dis Child 199981380-389.
• Kennedy CR. Controlled trial of universal
  neonatal screening for early identification of
  permanent childhood hearing impairment coverage,
  positive predictive value, effect on mothers and
  incremental yield. Wessex Universal Neonatal
  Screening Trial Group. Acta Paediatr Suppl
  19998873-75.

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Reading list 4 - capture-recapture

• LaPorte RE, McCarty DJ, Tull ES, Tajima N.
  Counting birds, bees, and NCDs. Lancet
  1992339494-495.
• International Working Group for Disease
  Monitoring and Forecasting. Capture-recapture and
  multiple-record systems estimation I History and
  theoretical development. Am J Epidemiol
  19951421047-1058.
• Cormack RM. Problems with using capture-recapture
  in epidemiology An example of a measles
  epidemic. J Clin Epidemiol 199952909-914.
• Bloor M, Wood F, Palmer S. Use of mark-recapture
  techniques to estimate the size of hard-to-reach
  populations. J Health Serv Res Pol 2000589-95