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HANG ET AL. / EAR & HEARING, VOL. 36, NO. 1, 8–13
testing was 18.09 months (SD 24.1, range 1–131). The overall
mean age at the time of CI surgery was 26.14 months (SD
22.3, range 6–136). Since referrals to the CI team are based
on behavioral audiometry, not surprisingly the time from
behavioral testing to CI surgery for both the dABR and cABR
groups is similar, 5.87 versus 5.20 months, respectively. The
time from ABR to CI surgery is lowered for the cABR group
since many of the ABRs were performed on the day of sur-
gery to rule out ANSD and confirm behavioral audiometric
test results.
To further characterize how the CI evaluation process is
affected by the age at ABR testing, only the data from the chil-
dren with dABRs were considered for the statistical analysis.
Figure 3 shows the relationship between the various time inter-
vals between interventions and age of ABR for the dABR group.
The correlation coefficient (
r
) was graphically demonstrated
for each relationship. Although children progressed through
the CI evaluation process at varying rates, those who presented
at later ages progressed to CI faster than younger patients. As
depicted in the bottom graph of Figure 3, there is a statistically
significant negative correlation between age at ABR testing and
time to CI surgery (
r
= −0.335,
p
= 0.014). This is, of course, is
confounded by the fact that older children are able to perform
behavioral testing sooner than younger children as seen in the
top graph of Figure 3, which shows a clear negative correlation
between time of ABR testing and time to behavioral testing (
r
= −0.593,
p
= <0.001). Once confirmatory behavioral testing
is obtained and referral to the CI team is made, the amount of
time until CI surgery remains fairly constant regardless of age
at initial ABR. The middle graph of Figure 3 shows no sig-
nificant correlation between age at ABR testing and time from
behavioral testing to CI surgery (
p
= 0.713), with average time
interval of 5.87 months (SD 3.8). This suggests that delays in
progressing to CI in a timely fashion likely arise during the time
between dABR testing and reliable behavioral testing when
referral to the CI team is made.
Only 15 (34.0%) children had more than 1-year duration
between the dABR and CI surgery. Reasons for the long elapsed
time within this group included delays in behavioral testing
because of middle ear pathology (
n
= 7), need for other medical
interventions (
n
= 4), lost to follow-up or scheduling conflicts
(
n
= 7), and/or parental choice (
n
= 1). Appropriate progress
with amplification (
n
= 0) and too much residual hearing (
n
= 0)
did not account for delays in this group of children.
DISCUSSION
Universal NBHS has greatly improved early identification
of children with hearing loss. dABR testing allows clinicians
to estimate auditory thresholds for the purposes of fitting
amplification at a much earlier age than behavioral testing.
Despite the advances in early diagnosis, many congenitally
deaf children do not receive hearing aids or CIs until 2 years of
age or older. The benefits of early intervention in the form of
amplification and CI have been described in numerous studies.
91
0
3
11
0 10 20 30 40 50 60 70 80 90 100
Received CI
CI not recommended due to residual hearing
CI not recommended due to co-morbidities
Lost to follow up
Fig. 2. Clinical outcomes of all included patients.
TABLE 3. Age at ABR diagnosis and timing to behavioral audiometry testing and CI surgery
N
(%)
Age (Months) at Testing/Intervention
Time (Months) Between Testing/Interventions
ABR
Behavioral
Testing
CI Surgery
ABR to
Behavioral
Testing
Behavioral
Testing to CI
Surgery
ABR to CI
Surgery
Diagnostic ABR
(dABR)
53 (58.2)
1–36
5.40
(6.2)
6–36
10.04
(5.0)
8–41
15.98
(6.5)
0–13
4.71
(2.7)
1–28
5.87
(3.8)
3–38
10.78
(5.0)
Confirmatory ABR
(cABR)
38 (41.8)
4–131
35.79
(28.4)
5–131*
34.58
(27.9)
6–136
40.32
(28.2)
Variable†
N/A
1–18
5.20
(3.7)
0–22
4.49
(4.9)
Overall
91
1–131
18.09
(24.1)
5–131
20.29
(22.0)
6–136
26.14
(22.3)
Variable†
N/A
1–28
5.59
(3.8)
0–38
8.15
(5.8)
For each category, range as well as
average
and (SD) are shown.
*First reliable audiometric data closest to date of NR ABR.
†Audiometric data may have been obtained before or after ABR.
ABR, auditory brainsem response; CI, cochlear implantation.
160