ISSN 1174-44170
New Zealand Deafness Notification Data
January – December 2005
Report prepared by Greville Consulting for
National Audiology Centre
Auckland District Health Board
March 2007
PO Box 26 506, Epsom, Auckland 1344, New Zealand
Phone: 0800 87 11 00; +64 27 281 3072; greville@ihug.co.nz ; www.grevilleconsulting.co.nz
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NZ Deafness Notification Data
CONTENTS
Summary ................................................................................................................................ 3
Introduction ......................................................................................................................... 4
Notification and Reporting Criteria ........................................................................... 5
Age of identification .......................................................................................................... 7
Degree of Hearing Loss ................................................................................................... 10
Other Disabilities ..............................................................................................................11
Cause of Hearing Loss ...................................................................................................... 12
Confirmation of Hearing loss .......................................................................................... 13
Risk Factors ........................................................................................................................ 16
Ethnicity .............................................................................................................................. 17
Location ............................................................................................................................... 21
Unilateral Hearing Loss .................................................................................................. 26
REFERENCES ......................................................................................................................... 27
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NZ Deafness Notification Data
Summary
This report presents deafness notification data differently from past years.
Efforts have been made to remove duplicate entries from the database, and to
ensure that numbers quoted refer only to children meeting the notification
criteria.
The average age of identification of a moderate or greater degree of hearing
loss for children notified during 2005 was 33 months – 10 months on average
after hearing loss was first suspected. The average age of confirmation is
considerably better than in 2004 when it was 45 months. Analysis of the
degree of hearing loss showed that the improvement was due to improved
identification of children with moderate hearing loss. However, the
internationally recommended age of identification of a hearing loss is three
months, with intervention commencing by six months (Joint Committee on
Infant Hearing, 2000).
Only 10% of children with bilateral prelingual hearing loss had hearing loss
severe or profound in degree. Most children (82%) had no handicaps apart
from hearing loss.
58% of children had no risk factors. However, a family history of hearing loss
was present in 32% of notifications. Children with risk factors present were
identified earlier on average for children with mild and moderate hearing loss.
Parents were most likely to suspect hearing loss (41%) followed by Vision and
Hearing Technicians (19%).
Maori children continue to be over-represented in the data. They made up
43% of 2005 notifications with Census data (2001) showing this group making
up 23% of the population. The proportion of Maori children is highest amongst
those with mild hearing loss. Maori children also tended to be identified later
than European and Asian children, although Pacific Island children were the
last to be identified.
The area with the highest prevalence of prelingual hearing loss notifications is
Northland, followed by Bay of Plenty and East Coast. These are areas with
particularly high proportions of Maori children with prelingual hearing loss.
The average age of identification varies widely across regions.
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NZ Deafness Notification Data
Introduction
When a child is confirmed with a hearing loss, the person confirming the loss,
usually an audiologist, notifies the national deafness database.
New Zealand’s national policy is to use the high-risk register for infants born
with risk factors for permanent hearing loss. These risk factors are:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Family history of hearing loss
Jaundice requiring exchange transfusion
Craniofacial abnormalities
Ototoxic drugs
Mechanical ventilation lasting five or more days
Low Apgar scores (0 to 4 one minute or 0 to 6 at five minutes)
Birth weight less than 1500 grams
Bacterial meningitis
Infection such as rubella, herpes and toxoplasmosis and those associated
with hearing loss
In some areas, a tenth factor is also used:
10. Stigmata or other findings associated with a syndrome known to include
sensorineural hearing loss (eg Waardenburg, Usher's syndromes, etc.)
Hearing loss in infants referred for being high risk is usually confirmed using
Auditory Brainstem Response (ABR) audiometry, often in conjunction with
Otoacoustic Emissions and/or behavioural assessment. Behavioural techniques
are the primary tools for assessing older children.
The data presented here are the notification data for the year i.e. those
children notified to the database in a calendar year, rather than those who are
identified in this year. In the case of hearing loss the incidence of permanent
prelingual hearing loss would be the number of children born with hearing loss
in any one year. This is difficult to estimate because of delays in identification
of hearing loss in many children, particularly those with milder degrees of
hearing loss.
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NZ Deafness Notification Data
Notification and Reporting Criteria
In the year 2005, 209 children were reported to the Deafness Detection
Database.
Of the 209 notifications, 135 met the audiometric criteria for inclusion.
The notification criteria are:
“Children under 18 years with congenital hearing losses or any hearing loss not
remediable by medical or surgical means, and who require hearing aids and/or surgical
intervention. They must have an average bilateral hearing loss (over four audiometric
frequencies 500-4000Hz), greater than 26dBHL in the better ear (Northern and
Downs classification 1984).”
Those children who were excluded on audiometric criteria were:
 23 with slight hearing losses (<26dBHL in the better ear)
 51 with unilateral losses
In addition, those excluded for non-audiometric reasons were:
 19 with acquired hearing losses
 24 who were born overseas
The total number meeting all criteria and used in the following analysis was
therefore 93.
There was a slight decrease in the level of notifications in 2005 following
higher levels experienced during the years 1998 – 2003 (see Figure 1). Note
that these numbers are lower than in previous reports. The database has now
been cleansed of duplicate entries, and notifications not within the referral
criteria have been excluded.
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NZ Deafness Notification Data
Numbers notified each year
160
140
120
y = 20.9Ln(x) + 55
100
80
60
40
20
0
1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 1: The number of children meeting referral criteria notified to the Deafness Database
from 1983 to 2005
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NZ Deafness Notification Data
Age of identification
Figure 2 shows the degree of hearing loss for the 93 children notified in 2005,
by birth year. The large numbers of children detected in 1999 corresponds to
the years when 5 and 6 year olds were born and reflects the contribution to
identification of children with predominantly mild hearing loss of the Vision
and Hearing Screening Programme. The trend shown is very similar to that in
previous years. Children with a severe or profound hearing loss were born no
earlier than 1999.
20
18
16
14
12
Prof
Sev
Mod
Mild
10
8
6
4
2
0
1988
1990
1991
1992
1993
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Birth year
Figure 2: Degree of hearing loss for children notified in 2005 as a function of birth year
(n=93).
Figure 3 below shows the average age of identification of hearing loss (for
children with hearing loss at least moderate in degree) over the last 15 years.
This shows an improvement of 12 months to an average age of 33 months for
2005 compared with 2004.
Figure 4 details the age of confirmation by degree of hearing loss over the
same period. From this graph, it is evident that the improvement in 2005 was
due to earlier identification of children with moderate hearing losses, the age
of confirmation of children with other categories of hearing loss having
remained relatively static.
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NZ Deafness Notification Data
Age confirmed
50
45
40
Age (months)
35
30
25
20
15
10
5
0
1991
1992
1995
1994
1993
1996
1997
1998
1999
2000
2002
2001
2003
2004
2005
Figure 3: Average age of identification for children with hearing loss at least moderate in
degree over 15 years
Age of confirmation of hearing loss by degree
90
80
70
Age (months)
60
Mild
Mod
Sev
Prof
50
40
30
20
10
0
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Figure 4: Average age of identification by degree of hearing loss over 15 years
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NZ Deafness Notification Data
Figure 5 shows the cumulative percentage identified by each year of age for
the last six years. In this method of presenting the data as well, 2005
emerged as a better year compared with performance in recent years.
100%
90%
80%
70%
60%
2001
2002
2003
2004
2005
50%
40%
30%
20%
10%
0%
0
1
2
3
4
5
>5
Cumulative age at confirmation (years)
Figure 5: Cumulative percentage of children with hearing loss at least moderate in the better
ear notified from 2001 to 2005 in yearly age groups
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NZ Deafness Notification Data
Degree of Hearing Loss
The classification for the degree of hearing loss used in this report is based
on the Northern and Downs classification (1984). The degree of hearing loss is
based on the better hearing ear, and is an average of the pure-tone thresholds
at 500, 1000, 2000 and 4000 Hz.
The divisions for the degrees of hearing loss are:
 Mild
26-40 dB HL
 Moderate
41-65 dB HL
 Severe
66-95 dB HL
 Profound
96+ dB HL
Figure 6 shows the distribution of each degree of hearing loss for children
notified during 2005, including the degree of hearing loss in the worse ear.
Degree of Hearing loss
Sev-sev
4%
Prof-prof
6%
Mod-sev
4%
Mild-mild
34%
Mod-mod
39%
Mild-mod
11%
Mild-sev
2%
Figure 6: Distribution of degree of hearing loss (better ear - worse ear), n=93
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NZ Deafness Notification Data
Other Disabilities
Most children (82%) had no other disability apart from hearing loss. 5% of
children notified had syndromes other than Downs. 4% had intellectual
disability (including those with Downs syndrome), and only 1% had multiple
disabilities.
Other Disabilities
1%
1%
1%
1%
2%
2%
5%
5%
None
Syndromes
Other
IHC
Downs Syndrome
OME
Multiple
Heart problems
Blindness
82%
Figure 7: Other disabilities (apart from hearing loss) for the children notified in 2005 (n=93).
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NZ Deafness Notification Data
Cause of Hearing Loss
This year the primary cause of prelingual hearing loss continues to be classed
as unknown (58%).
Cause of Hearing loss
1%
1%
2%
1%
2%
3%
Unknown
Family history
Facial malformation
Ototoxic drugs
Other
32%
58%
Multiple
Congenital infection
Asphyxia
Figure 8: Causes of hearing loss identified for the children with prelingual hearing loss
notified during 2005 (n=93).
A family history of hearing loss continues to be the strongest predictor of
prelingual hearing loss (32%).
There appears to be a strong link between causation and ethnicity. Of the 40
Maori children notified with a hearing loss, 17 (or 43%) have a family history
of prelingual hearing loss. This is significantly higher than for non-Maori
children where for 13 of 52 children (25%) a family history was reported.
In addition to the 93 children with prelingual hearing loss, 16 children with
acquired hearing loss were notified. Ten of these had the sequelae of OME,
two had meningitis, and four had unidentified acquired hearing loss. 6 of these
children were born overseas.
Of the 16 children born overseas with prelingual hearing loss, ten had no known
risk factors, four had a family history, and two had facial malformation.
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NZ Deafness Notification Data
Confirmation of Hearing loss
Figure 9 shows the mean ages of suspicion and confirmation of children with at
least a moderate hearing loss over the past six years.
In 2005 the average age when a hearing loss was first suspected was 23
months, with average confirmation age of 33 months. This shows it takes 10
months on average to confirm a hearing loss. This is shorter than for any year
over the last 6 years – the range over this period being from 10 to 15 months.
Age suspected and confirmed
50
45
40
Age (months)
35
30
Age suspected
Age confirmed
25
20
15
10
5
0
2000
2001
2002
2003
2004
2005
Figure 9: Mean age (months) of suspicion and confirmation of a moderate or greater hearing
loss for years 2000-2005.
As usual, parents were most likely to suspect a hearing loss in their children
(see Figure 10). The second key group of people were Vision Hearing
Technicians.
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NZ Deafness Notification Data
Who suspected hearing loss
Ear nurse
1%
Other family member
2%
Teacher ENT
PHN
1%
2%
2%
Tech
3%
Plunket
3%
Speech path
1%
Unknown
4%
Parent
41%
GP
4%
Aud
4%
Other
5%
Paed
8%
VHT
19%
Figure 10: Role of person who suspected hearing loss for children notified in 2005 (n=93).
In 96% of cases notified during 2005, an audiologist confirmed the hearing
loss.
A significant delay between suspecting and confirming a hearing loss is longer
than six months. Figure 11 shows that, for the year 2005, 55% had no delay in
confirming this loss. In 17% of cases, the reason for any delay was unknown.
Parents emerged as the largest identified category with 9%. The presence of a
conductive overlay was the next most common reason cited.
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NZ Deafness Notification Data
Cause of delay
Untestable Slight HL
1%
1%
Referral pathway
2%
Child ill
1%
ENT
1%
Combination
4%
Waiting list
4%
Conductive overlay
5%
Parents
9%
None
55%
Unknown
17%
Figure 11: Reasons for any delay in confirming hearing losses in 2005 (n=93).
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NZ Deafness Notification Data
Risk Factors
The average age of identification varies greatly with the degree of hearing
loss and this can be seen below in Figure 12 and earlier in Figure 4. Not
surprisingly, the less the degree of hearing loss in the better ear, the later
the hearing loss tends to be confirmed. Amongst children notified during 2005
the average age for detecting a mild loss was 76 months, moderate 36 months,
severe 34 months and profound 13 months.
Figure 12 also shows the age of identification related to the presence of risk
factors for hearing loss. These risk factors are noted in the introduction (see
Page x). For all degrees of hearing loss apart from severe (with only four
children represented), there was a slight average advantage for children with
risk factors. Those children with mild and moderate hearing losses were
identified on average 13 months earlier if they had risk factors present. In
children with profound losses there was a risk advantage of 3 months.
Risk factors & age of identification
90
80
70
Age (months)
60
50
No risk factors
Risk factors
40
30
20
10
0
Mild
Mod
Sev
Prof
Figure 12: Age of identification for mild (26-40dBHL), moderate (41-65dBHL), severe (6695dBHL) and profound (>95dBHL) degrees of hearing loss according to risk factors.
This year’s report shows, contrary to earlier years, some advantage in the use
of the risk register in assisting with the detection of hearing loss in children.
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NZ Deafness Notification Data
Ethnicity
Figure 13 shows the ethnicity of the children reported to the database during
2005.
This graph shows that Maori children make up 43% of the notifications and
European children comprised 48%. The proportion of Pacific Island children
notified is lower than usual at 4%, compared to 16% last year.
The 2001 Census population statistics for children (aged up to 19 years)
showed percentages of European, Maori, Pacific Island and Asian and peoples
to be 61%, 23%, 8% and 7% respectively. Maori children continue to be
significantly over-represented in the notifications.
.
Ethnicity (2005 notifications)
Pacific Id
4%
Asian Other
1%
4%
European
48%
European
Maori
Pacific Id
Asian
Other
Maori
43%
Figure 13: Ethnic origin of children identified in 2005 with bilateral hearing loss (n=93).
The ethnic makeup of the database showing children born since 1990 (when
ethnicity data were first collected) is shown in Figure 14. It is clear from this
that Maori children are consistently over-represented.
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NZ Deafness Notification Data
Ethnicity by year of birth
160
140
120
100
U/K
Other
Asian
Pacific Id
Maori
European
80
60
40
20
0
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Figure 14: Ethnic origin of children born since 1990 with bilateral hearing loss (n=1354).
Maori children notified are more likely to have mild hearing losses than any
other ethnic grouping. The degree of hearing loss as a function of ethnicity is
shown in Figures 15 (2005 notifications) and 16 (data since 1990).
Degree of HL & ethnicity
2005 notifications
50
45
40
35
30
Other
Asian
Pacific Id
Maori
European
25
20
15
10
5
0
Mild
Mod
Sev
Prof
Figure 15: Ethnic origin of children identified in 2005 with bilateral hearing loss of various
degrees (n=93).
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NZ Deafness Notification Data
Degree of HL & ethnicity
1990-2005
700
600
500
Other
Asian
Pacific Id
Maori
European
400
300
200
100
0
Mild
Mod
Sev
Prof
Figure 16: Ethnic origin of children born since 1990 with bilateral hearing loss of various
degrees (n=1354)
Figure 17 shows the cumulative percentage of children identified in each year
of age with hearing loss at least moderate in degree as a function of ethnicity
in the year 2005. European children tend to be identified earlier than other
ethnic groups – the 50% point for European children is around 18 months,
compared with 2 years for Asian children, and just under 4 years for Maori
children. There was only one Pacific Island child who was identified late, so the
data for this group are distorted.
For the database as a whole, the picture is a little different (see Figure 18).
Overall Asian children tended to be identified earlier (the 50% point being
around 18 months), followed by European (just under 2 years) & other
groupings. Maori children came next (3½ years), followed by Pacific Island
children of whom only 50% were identified by 5 years of age.
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NZ Deafness Notification Data
100%
90%
80%
70%
60%
European
Maori
Pacific Id
Asian
50%
40%
30%
20%
10%
0%
1
2
3
4
5
>5
Cumulative age at confirmation (years)
Figure 17: Cumulative percentage of children identified during 2005 at each age for hearing
losses at least moderate in degree, by ethnicity (n=48)
100%
90%
80%
70%
60%
European
Maori
50%
Pacific Id
Asian
Other
40%
30%
20%
10%
0%
1
2
3
4
5
>5
Cumulative age at confirmation (years)
Figure 18: Cumulative percentage of children identified 1990-2005 at each age for hearing
losses at least moderate in degree, by ethnicity (n=815)
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NZ Deafness Notification Data
Location
Table 1 shows the area of residence for the children notified to the Database
in 2005, as well as numbers born in the 15 years prior to the 2001 census.
Table 1: Numbers of children with prelingual hearing loss notified during 2005, and from the
database as a whole, those born during 1987-2001, compared to population figures (2001
census). Also shown are prevalence estimates of prelingual hearing loss at 2001.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
Notified 2005
16
68
27
2
15
0
5
11
26
3
3
0
28
2
0
2
Born 19872001
144
494
140
41
117
32
48
76
100
110
42
10
149
25
38
45
Population
<15 years
35,178
269,607
77,049
24,303
42,678
12,087
24,393
34,836
50,532
91,044
26,460
6,810
86,136
11,106
32,712
22,794
Prevalence/1000
4.09
1.83
1.82
1.69
2.74
2.65
1.97
2.18
1.98
1.21
1.59
1.47
1.73
2.25
1.16
1.97
Areas with prevalence above 2/1000 are displayed in colour in the above table.
The area that showed the highest prevalence was Northland. Other areas with
rates above 2.5 are Bay of Plenty and East Coast.
Numbers notified during 2005 with acquired hearing loss, or born outside New
Zealand, or with unilateral hearing losses are shown in Table 2.
The interaction of area and ethnicity on the children with prelingual hearing
loss born between 1987 and 2001 (where known) is shown in Table 3.
Particularly high proportions of Maori children are evident in East Coast (83%),
Northland (78%), Bay of Plenty (64%), Hawkes Bay (63%) and Taranaki (61%).
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Table 2: Numbers of children notified during 2005 not meeting the notification criteria, by
geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
Bilateral loss
Born overseas
Acquired
1
1
10
11
3
2
1
2
Unilateral
6
14
3
1
2
2
1
2
5
10
2
2
10
Table 3: Proportion of children with prelingual hearing loss born during 1987-2001 of
different ethnic groupings by geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
European
20%
34%
43%
48%
32%
17%
34%
36%
38%
58%
73%
100%
83%
79%
86%
74%
Maori
78%
32%
52%
42%
64%
83%
61%
63%
53%
21%
24%
0%
8%
13%
11%
26%
Pacific Id
1%
23%
2%
6%
3%
0%
2%
1%
6%
12%
3%
0%
5%
0%
3%
0%
Asian
1%
8%
3%
3%
1%
0%
2%
0%
1%
8%
0%
0%
3%
8%
0%
0%
Other
0%
2%
1%
0%
0%
0%
0%
0%
2%
1%
0%
0%
1%
0%
0%
0%
There were also geographical differences in degree of hearing loss (see Table
4). Areas with the highest proportions of mild hearing loss were West Coast
(70%), Taranaki (63%), Northland and Nelson/Marlborough (57%), Bay of
Plenty (56%).
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NZ Deafness Notification Data
Areas with the highest proportions of children with severe or profound
hearing loss were Canterbury (26%), East Coast (25%), Otago (24%),
Southland (22%) and Lakes (20%).
Corresponding numbers of children with each degree of hearing loss are
presented in Table 5.
Table 4: Proportion of children with prelingual hearing loss born during 1987-2001 with
different degrees of hearing loss for each geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
Mild
57%
49%
54%
46%
56%
34%
63%
51%
52%
45%
57%
70%
29%
48%
37%
53%
Moderate
31%
34%
31%
34%
37%
41%
23%
36%
33%
38%
33%
20%
46%
36%
39%
24%
Severe
10%
12%
13%
12%
3%
16%
10%
12%
8%
14%
5%
0%
17%
8%
21%
13%
Profound
2%
5%
2%
7%
3%
9%
4%
1%
7%
3%
5%
10%
8%
8%
3%
9%
Table 5: Numbers of children with prelingual hearing loss born during 1987-2001 with
different degrees of hearing loss for each geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
March 2007
Mild
Moderate
82
244
76
19
66
11
30
39
52
50
24
7
43
12
14
24
44
167
43
14
43
13
11
27
33
42
14
2
68
9
15
11
Severe
Profound
15
57
18
5
4
5
5
9
8
15
2
26
2
8
6
3
26
3
3
4
3
2
1
7
3
2
1
12
2
1
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The average age of confirmation of hearing loss by area for each degree of
hearing loss is presented in Tables 6 (those notified during 2005) and 7 (those
notified 1991-2004).
Particularly concerning are those with severe or
profound hearing loss identified late – amongst those notified in 2005, mean
age of confirmation of children with severe hearing losses was particularly
poor in Auckland and Waikato. These represented only 3 children, however.
Table 6: Mean age (months) of children with different degrees of prelingual hearing loss
notified during 2005 for each geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
Mild
61
85
82
76
63
66
88
Mod
65
36
41
71
72
14
51
52
Sev
42
37
Prof
1
37
47
19
18
12
14
22
22
46
Table 7: Mean age (months) of children with different degrees of prelingual hearing loss
notified 1991- 2004 for each geographical area.
Area
Northland
Auckland
Waikato
Lakes
Bay of Plenty
East Coast
Taranaki
Hawkes Bay
Manawatu Wanganui
Wellington
Nelson Marlborough
West Coast
Canterbury
South Canterbury
Otago
Southland
March 2007
Mild
58
67
72
61
67
82
71
66
75
64
54
72
54
49
95
70
Mod
53
54
41
46
54
39
27
25
59
49
30
36
42
30
59
46
Sev
25
21
20
24
45
27
12
5
26
18
3
19
15
20
18
Prof
25
18
16
7
21
17
15
3
19
11
18
3
15
34
13
11
Greville Consulting
25
NZ Deafness Notification Data
The mean age of confirmation for children with hearing loss at least moderate
in degree over the last 15 years is presented in Figure 19.
There appears to have been an increase in the age of confirmation, compared
with the baseline years of 1991-1995, in many areas of the country –
specifically in northern areas (north of Bay of Plenty), in Manawatu to
Wellington, and, to a lesser degree, in the four most southern regions.
A further deterioration from 1996-2000 to 2001-2005 is evident in a few
areas – Lakes, Manawatu/Wanganui & Wellington. An improvement over this
period was observed in Northland, East Coast, Nelson/Marlborough, and Otago.
Mean age of confirmation by area
60
50
40
1991-1995
1996-2000
2001-2005
30
20
10
th
la
nd
go
ta
O
So
u
so
n
el
N
at
u
an
aw
M
W
el
lin
gt
on
M
ar
lb
or
ou
gh
W
es
tC
oa
st
C
an
te
So
rb
ur
ut
y
h
C
an
te
rb
ur
y
y
ga
nu
i
W
an
s
Ba
ki
ke
H
aw
st
oa
ra
na
Ta
y
Ea
st
C
of
Pl
en
t
La
ke
s
Ba
y
o
W
ai
ka
t
N
or
th
la
n
d
Au
ck
la
nd
0
Figure 19: Mean age of confirmation (in months) for children with prelingual hearing loss at
least moderate in degree by area and for each of the last 5-year periods (n=856).
March 2007
Greville Consulting
26
NZ Deafness Notification Data
Unilateral Hearing Loss
A total of 51 children with unilateral hearing loss were notified during 2005.
Of these, 28 had a mild hearing loss in the worse ear, 14 had a moderate
unilateral loss, and 9 had severe unilateral hearing loss.
Cause of Unilateral Losses
4%
3%
14%
1%
55%
14%
Acquired
Congenital infection
Family history
Mumps
OME
Other
Unknown
9%
Unilateral loss was more likely to be associated with acquired hearing loss
(20% cf 13% for children with bilateral loss). This was also true for the
database as a whole (22% cf 11% for the period 1991-2005).
March 2007
Greville Consulting
27
NZ Deafness Notification Data
REFERENCES
Northern J.L. and Downs M.P. (1984) Hearing in Children, Third Edition,
Williams and Wilkins, Baltimore
Joint Committee on Infant Hearing - Year 2000 Position Statement: Principles
and Guidelines for Early Detection and Intervention Programs
March 2007
Greville Consulting