8.2.3. Hearing loss
8.2.3.1.
Introduction
Hearing impairment is the most frequent
sensory deficit in humans. It affects more than 250 million people in the
world. Consequences of hearing impairment include inability to interpret speech
sounds, often producing a reduced ability to communicate, delay in language
acquisition, economic and educational disadvantage, social isolation and
stigmatisation. It may be worsened by some medical conditions such as
hypothyroidism, diabetes, and possibly hyperlipidemia, among others.
8.2.3.2. Data
Sources
Studies of hearing loss occurrence have been
carried out in relatively few Countries in the world (see a list of studies
with their basic features in Mathers et al, 2003). In Europe, surveys have been
carried out in representative population samples of Denmark, Finland, Italy,
Sweden and United Kingdom (Davis, 1989; Fortnum and Davis, 1997; Johansson and
Arlinger, 2003; Karlsmose et al, 1999; Quaranta et al, 1996; Uimonen et al,
1999). Self-reported data on hearing problems have been also collected in
several EU Member States by means of EU Labour Force Survey (LFS) carried out
in 2002 and the EU SILC carried out in 2004. The results obtained with these
two surveys have been analysed in a Report published in 2007 (APPLICA et al,
2007).
Definitions
There is a diversity of definitions of
hearing impairment, thus, comparison among studies is difficult. WHO has
classified hearing impairment according to the hearing threshold average of
pure tones of four frequencies: 0.5, 1, 2, and 4 kHz (WHO, 1997). The different
grades of hearing impairment and their impact in performance are presented in
Table 8.4. Available data have been elaborated by WHO to obtain comparable
estimates of hearing loss. While the prevalence of slight impairment
(26-40dBHL) has been estimated, it has been assumed to result in negligible
disability and it has not been considered in the estimation of the burden of
disability for hearing loss due
to ageing or noise exposure, which excludes hearing loss due to congenital
causes, infectious diseases, other diseases or injury (adult-onset hearing loss, ICD-10 codes H90-H91) (WHO, 2002).
Table 8.4.
WHO grades of hearing impairment
8.2.3.3. Data
description
Prevalence of congenital permanent childhood hearing loss (≥ 40
dB hearing loss in the better ear) has been estimated as 0.1% in a study
carried out in the Trent Region (UK) during the years 1985-1993 on a population
sample ob about 553000 children aged 0-9 years (Fortnum and Davis, 1997).
Data available from the other surveys in EU
Member States were interpolated to obtain comparable estimates according to the
WHO definitions of severity (Mathers et al, 2003). The results obtained are
shown in Table 8.5. An additional study carried out in 590 randomly selected
Swedish subjects aged from 20 to 80 years (Johansson and Arlinger, 2003) showed
that 16.9% subjects showed no hearing impairment (≥25 dB HL), 7.7% showed
≥35 dB HL, 3.3% showed ≥45 dB HL, and 0.2% showed ≥65 dB HL.
Hearing loss appeared generally similarly distributed between genders in United
Kingdom, Italy and Sweden (Odds Ratios males/females in the range 0.9-1.2),
with some evidence of increased prevalence in Italian men associated with
manual occupations with greater noise exposure. In Denmark and Finland, the
prevalence of slight to moderate hearing loss was more marked in men (Odd
Ratios males/females in the range 1.5-2.3). Prevalence of adult onset hearing
loss of at least moderate severity in the age group 15-19 year has been
estimated to be 0.1 to 0.2%.
Table 8.5.
Estimated prevalence of adult onset hearing loss for adults aged 15 years and
over
The leading causes of adult-onset hearing
loss are presbycusis (age related hearing loss) followed by
noise-induced hearing loss.
From these data, age-standardized prevalence
and hearing loss was estimated to be 3.3% (males) and 2.8% (females) in the WHO
EUR-A epidemiological region (where most population is from 18 EU Member
States, Croatia and EFTA Countries) as well as in the WHO EUR-B1 epidemiological
region (to which Bulgaria, Poland, Romania, Slovakia and Turkey belong)
(Mathers et al, 2003).
The burden of disability due to hearing loss
has been estimated to amount, in 2001, to 4.6 YLD/1000 (males) and 4.3 YLD/1000
(females) in the WHO EURO A and to 3.3 YLD/1000 (males and females) in the WHO
EURO B1 (WHO, 2002).
8.2.3.4. References
Davis AC (1989): The prevalence of hearing impairment and reported
hearing disability among adults in Great Britain. International J Epidemiology.
1989;18:911-91
European Union Statistics on Income and
Living Conditions (EU-SILC) (2004): Database available at: http://circa.europa.eu/Public/irc/dsis/eusilc/library
European Union Statistics on Income and
Living Conditions (EU-SILC) (2007): Men and women with disabilities in the eu:
statistical analysis of the LFS ad hoc module and the EU-SILC. On line
publication available at: http://ec.europa.eu/employment_social/index/lfs_silc_analysis_on_disabilities_en.pdf
Fortnum H, Davis A (1997): Epidemiology of
permanent childhood hearing impairment in Trent
Region, 1985-1993. British Journal of
Audiology 31(6):409-46.
Johansson MSK, Arlinger SD (2003):
Prevalence of hearing impairment in a population in Sweden. International J Audiology. 2003;42:18-28
Karlsmose B, Lauritzen T, Parving A (1999):
Prevalence of hearing impairment and subjective hearing problems in a rural
Danish population aged 31-50 years. British Journal of Audiology
33(6):395-402.
Mathers C, Smith A, Concha M (2003): Global
burden of hearing loss in the year 2000 (on-line publication available at: http://www.who.int/healthinfo/statistics/bod_hearingloss.pdf)
UK Office of National Statistics (ONS)
dataset available online at: http://www.statistics.gov.uk/StatBase/xsdataset.asp?vlnk=1381&Pos=2&ColRank=1&Rank=272
Quaranta A, Assennato G, Sallustio V (1996):
Epidemiology of hearing
problems among adults in Italy. Scandinavian Audiology 1996;Supplement
42:9-13
Uimonen S, Huttunen K, Jounio-Ervasti K,
Sorri M (1999): Do we know the real need for hearing rehabilitation at the
population level? Hearing impairments in the 5- to 75-year-old crosssectional
Finnish population. British Journal of Audiology 33(1):53-9.
WHO (1997): Report on the First Informal
Consultation on Future Programme Developments for the Prevention of Deafness
and Hearing Impairment. (WHO/PDH/97.3.) Geneva: WHO
WHO (2002): The World Health Report (on-line
publication available at http://www.who.int/whr/2002/en/whr2002_annex3.pdf)
8.2.3.5. Acronyms
