The role of socioeconomic factors and third-party support in language development for children with cochlear implants

Abstract

It has been reported that the higher the parents’ education level and income, the better language performance after cochlear implant (CI). We investigate whether socioeconomic factors (household income, parental education level, type of family, and location of residence) affect the language performance after CI even when all financial support for examination, hospitalization, surgery, and language rehabilitation program after CI was provided by a third-party. Of the 892 pediatric patients who underwent CI between 2007 and 2020 at our institution, data from 109 patients who received full financial support were analyzed retrospectively. Categories of Auditory Performance (CAP) and K-Ling test (reading and speech) scores (preoperative and 3, 6 and 12 months postoperative) were analyzed according to socioeconomic factors. With third-party support, there was no significant difference in language performance based on the household income and location of residence. However, there were significant differences in K-ling-reading (phoneme) according to father’s and mother’s education level, K-ling-speech (phoneme, phonology) according to mother’s education level and CAP score according to type of family (single-parent family or not). Additionally, when the mother’s education level was less than a university degree, the mean age at the time of CI surgery was 3.1 years old, higher than 2.7 years old for mothers with a university degree or more (p < 0.001). Parental education level and family type significantly affected language performance following CI, even when financial support was fully provided. Additionally, children underwent CI earlier when the maternal education level was high.

Full text

The role of socioeconomic factors
and third-party support in language
development for children with
cochlear implants
ChangHee Lee1, Se-Eun Son1, Il Joon Moon1, Won-Ho Chung1, Yang-Sun Cho1,
Sung Hwa Hong2 & Young Sang Cho1
It has been reported that the higher the parents’ education level and income, the better language
performance after cochlear implant (CI). We investigate whether socioeconomic factors (household
income, parental education level, type of family, and location of residence) aect the language
performance after CI even when all nancial support for examination, hospitalization, surgery, and
language rehabilitation program after CI was provided by a third-party. Of the 892 pediatric patients
who underwent CI between 2007 and 2020 at our institution, data from 109 patients who received full
nancial support were analyzed retrospectively. Categories of Auditory Performance (CAP) and K-Ling
test (reading and speech) scores (preoperative and 3, 6 and 12 months postoperative) were analyzed
according to socioeconomic factors. With third-party support, there was no signicant dierence in
language performance based on the household income and location of residence. However, there were
signicant dierences in K-ling-reading (phoneme) according to father’s and mother’s education level,
K-ling-speech (phoneme, phonology) according to mother’s education level and CAP score according
to type of family (single-parent family or not). Additionally, when the mother’s education level was
less than a university degree, the mean age at the time of CI surgery was 3.1 years old, higher than 2.7
years old for mothers with a university degree or more (p < 0.001). Parental education level and family
type signicantly aected language performance following CI, even when nancial support was fully
provided. Additionally, children underwent CI earlier when the maternal education level was high.
Keywords Cochlear implants, Language development, Socioeconomic factors, Rehabilitation of speech and
language disorders, ird-party support
Cochlear implant (CI) can be recommended for children with congenital severe to profound hearing loss, oering
them a better chance of acquiring speech perception and production1. As children with severe to profound
hearing loss are more likely to have language developmental delays, detecting hearing loss and initiating eective
auditory rehabilitation early are critical to preventing developmental delays2. Several studies have found that
children with early CI surgery show greater reading ability comparable to their normal-hearing peers. is
eective language development allows children with congenital hearing loss to accomplish mainstream
education3. However, the outcome of language development aer CI varies greatly4. erefore, many studies
have been conducted to identify prognostic factors that aect pediatric CI performance. e factors can be
classied into three categories. First, patient characteristic factors include the patient’s age at the time of CI
surgery5, the duration of hearing loss6, degree of residual hearing7, and anatomical abnormalities4. Second,
postoperative factors should be considered, including the daily use time of the CI following surgery8 and the
degree of language rehabilitation program aer CI9. Finally, socioeconomic factors include parental education
level10, parental occupation, the family’s annual income and wealth11, location of the residence12, the type of
family (dual-income or single-parent family), and family involvement13,14.
In terms of socioeconomic factors, it has been reported that the higher the parents’ education level and family
income, the better speech and language performance aer CI10–12,15–18. However, since most households with
high socioeconomic status actively participate in excellent language rehabilitation programs aer surgery, it is
1Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University
School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Republic of Korea. 2Soree Ear Clinic, Seoul, Republic of
Korea. email: Ys83.cho@samsung.com
OPEN
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diculty to verify whether socioeconomic factors actually aect the prognosis of performance aer CI surgery,
except for the eect of language rehabilitation aer CI. e purpose of this study was to investigate whether
socioeconomic factors (household income, parental education level, type of family, and location of residence)
aect the outcome aer CI surgery even when nancial support for examination, hospitalization, surgery, and
continued language rehabilitation program was provided by a third-party.
Methods
Participants
is retrospective study was approved by the institutional review board of the authors’ hospital (Approval No.
2022-07-091). e requirement of informed consent was waived, and all methods were carried out in accordance
with relevant guidelines and regulations. is study retrospectively identied children with congenital bilateral
deafness (N = 892) who underwent CI between 2007 and 2020 at the authors’ hospital. Among them, 333
patients received support from the CIDP (Cochlear Implant Donation Program), which supports all expenses
related to CI through a third-party. Patients with signicant abnormalities that could interfere with language
development (including cognitive disorders and brain parenchymal lesions), patients who did not provide their
socioeconomic information, or patients who did not regularly engage in language rehabilitation program and
evaluation were excluded (attendance is less than 50%). Finally, data from 109 pediatric patients were analyzed.
Financial support
All patients who were included in this study were supported by the CIDP that nancially supports hearing-
impaired children from families who are not economically wealthy (below median income). is program
was started in February 2007 in the authors’ institution. Patients for assistance were chosen from among low-
income hearing-impaired children under the age of 18 whose families’ property and income were below a
certain threshold. e property and income criteria were developed using annual household data from the area
in which the families lived. All expenses relevant to CI surgery including examinations, outpatient clinic visits,
hospitalization, surgery, and four-year language rehabilitation program up to 5,000,000 Korean won (3,600 US$)
per year were supported. For pediatric patients who could benet from bilateral CI surgery, the full cost of
bilateral surgery was covered.
e language rehabilitation program was available in conjunction with a language rehabilitation institution
close to patients’ residences. It is a signicant distinction from other support programs that do not cover the costs
of language rehabilitation program. Integrated language rehabilitation program could be continued through
continuous and systematic linkage with various institutions and periodic evaluations.
Data collection
We investigated the baseline characteristics of pediatric CI users and their families. Patient information included
age when the child received their rst CI surgery, sex, and hearing aid modality aer CI. Family information
included information on socioeconomic factors including the economic level (monthly household income and
property status including real estate), parental education level, type of family (dual-income or single-parent
family) and location of family residence (rural or urban).
For assessment of speech and language perception, we used the categories of auditory performance (CAP)
scale and K-Ling test (reading and speech). CAP scale evaluates auditory and speech perception abilities,
specically focusing on how individuals use their hearing in real-world situations. It does not directly assess
overall language development but emphasizes the auditory foundation necessary for language acquisition with
a scoring system from 0 to 7, where higher scores represent more advanced auditory and speech perception
skills. K-Ling test is a Korean adaptation of Ling’s speech development model, designed to evaluate phonetic
and phonologic development in children with cochlear implants. e scoring range typically spans from 0 to 7
for both the phonetic level and the phonologic level, corresponding to Ling’s seven stages of speech acquisition.
It allows longitudinal assessment of speech progress, regardless of age, and focuses on seven stages of speech
acquisition, from basic sound production to meaningful speech19. Language evaluation of pediatric CI patients
was assessed routinely before CI and 3, 6 and 12 months aer CI and analyzed according to socioeconomic
factors.
Statistical analyses
ANOVA or two-sample t tests were used to compare age at the time of rst CI surgery according to socioeconomic
factors, parental education level, family monthly income and location of residence.
A linear mixed model with an unstructured covariance matrix was used to determine whether there was a
dierence in the change in language development over time according to socioeconomic factors. When the p value
for group by time was less than 0.05, the interaction was considered signicant; and post hoc analysis was carried
out to determine dierences in the language evaluation results at each time point according to socioeconomic
factors. To ascertain whether there was a signicant dierence in the level of language development over time
according to socioeconomic factors, language evaluation results were adjusted for age at the time of rst CI
surgery and hearing aid modality aer CI surgery. is was done because age at the time of rst CI surgery and
hearing aid modality are factors that had a signicant eect on postoperative language outcome in previous
studies. Statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC, USA).
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Results
Characteristics of pediatric CI users and their families
Characteristics of pediatric CI users and their families are listed in Table1. A total of 109 children had a
comparable sex ratio of 50.5:49.5 and those with less than a university graduate education exceeded those with
a university graduate or higher in terms of parental education (for fathers, 60.8% versus 39.2%, respectively
and for mothers, 58.4% versus 41.6%, respectively). When monthly household income was divided into four
subgroups and evaluated, 47.6% belonged to households with a monthly income of less than two million Korean
won. 32.1% of households live in around the capital (Seoul and Gyeonggi-do more urban than the other 6
areas), while 20.2% live in one of the other six metropolitan areas in South Korea (Busan, Daegu, Incheon,
Gwangju, Daejeon and Ulsan). In 22% of households, one spouse worked full-time; and the other worked at
least part-time (dual-income family). e remaining 77.9% were single-income earners and the second spouse
was responsible for childcare. Among all patients, single-parent families accounted for 9.1%; and seven out of
ten single parents were working at least part-time. Only three single-parent families were dedicated entirely
to childcare. Table2 summarizes age at the time of rst CI surgery, hearing aid modality aer CI surgery and
overall language evaluation results by time. e average age of the rst CI was 2.71 years old and pediatric
patients under two years of age accounted for 38.5%. e most common hearing aid modality following CI
surgery was sequential bilateral CI (47.7%), followed by bimodal and simultaneous bilateral CI (32.1% and
11.0%, respectively). e language evaluation scores all showed a tendency to rise progressively over time aer
CI surgery. When comparing preoperative and one-year postoperative scores, the CAP score increased from 1.1
to 4.1, K-Ling-reading (phoneme) increased from 1.5 to 4.1, K-Ling-reading (phonology) increased from 1.6 to
4.5, K-Ling-speech (phoneme) increased from 0.7 to 3.1 and K-Ling-speech (phonology) increased from 0.8 to
3.3.
Correlation between socioeconomic factors and age at the time of rst CI surgery
e correlation between socioeconomic factors and the age at which a patient underwent CI surgery is analyzed
in Table3. As for the parents’ educational background, only 7% had less than a high school diploma, so we
divided educational background into two groups: less than university graduate and more than university
graduate. When the mother’s education level was less than a university degree, the age at which CI surgery was
conducted was 3.1 years (mean SD 1.89) but was 2.1 years (mean SD 1.01) for those with a university degree or
more. e dierence was statistically signicant (p < 0.001). ere was no signicant dierence in age at the time
of rst CI surgery according to father’s education level, monthly household income and location of residence.
Correlation between socioeconomic factors and speech and language performance
after CI
e correlation between socioeconomic factors and language evaluation outcomes is analyzed in Table 4.
A linear mixed model with an unstructured covariance matrix was used to determine whether there was a
dierence in the change in language evaluation outcomes over time based on socioeconomic factors. ere
was a signicant dierence in the outcome change of K-ling-reading (phoneme) over time according to the
Variables N (%)
Sex Male 55 (50.5)
Female 54 (49.5))
Education level (father) Less than high school graduation 7 (6.9)
Less than university graduation 55 (53.9)
University graduation 40 (39.2)
Higher than university graduation 0 (0)
Education level (mother) Less than high school graduation 7 (6.5)
Less than university graduation 56 (51.9)
University graduation 39 (36.1)
Higher than university graduation 6 (5.5)
Monthly household income (Korean won) 0–1,000,000 15 (13.7)
1,000,000–2,000,000 37 (33.9)
2,000,000–3,000,000 39 (35.9)
> 3,000,000 18 (16.5)
Location of residence Capital city or near capital city 35 (32.1)
6 metropolitans 22 (20.2)
Other cities 52 (47.7)
Number of incomes Dual-income family 24 (22.0)
Single-income family 85 (77.9)
Number of parents in household Single-parent family 10 (9.1)
Two-parent family 99 (90.9)
Tab le 1. Characteristics of pediatric CI (Cochlear Implant) users and their families
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father’s education level (interaction p = 0.028) and there was also a signicant dierence in the outcome change
of K-ling-reading (phoneme) and K-ling-speech (phoneme, phonology) over time according to the mother’s
education level. e interaction p values for these were 0.015, 0.006 and 0.013, respectively. Furthermore, the
degree of change in CAP score over time was statistically signicantly lower in single-parent families than in
two-parent families, indicating that successful auditory perception was not attained in single-parent families.
ere was no signicant dierence in language evaluation outcomes according to other socioeconomic factors,
including monthly household income, location of residence and family dual-income status. Table5 details the
changes in language evaluation outcomes based on the father’s education level. e interaction was signicant
for K-ling-speech (phoneme) because the p value for the group by time was 0.028, which was below the
Variables Mean ± SD (years) p value
Education level (father) Less than university graduation 2.900 ± 1.828 0.070
University graduation or higher 2.322 ± 1.351
Education level (mother) Less than university graduation 3.165 ± 1.896 < 0.001
University graduation or higher 2.105 ± 1.010
Monthly household income (Korean won) 0–1,000,000 2.893 ± 1.451 0.838
1,000,000–2,000,000 2.788 ± 1.780
2,000,000–3,000,000 2.517 ± 1.583
> 3,000,000 2.817 ± 1.851
Location of residence Capital city or near capital city 2.395 ± 1.341 0.398
6 major cities 2.897 ± 1.953
Other cities 2.843 ± 1.732
Tab le 3. Correlation between socioeconomic factors and age at the time of rst CI surgery
Variables Mean ± SD Range N (%)
Age at the time of rst CI surgery Age (years) 2.710 ± 1.665 (0.7, 8.8)
< 2yr - - 42 (38.5)
2yr ≤ < 4yr - - 47 (43.1)
≥ 4yr - - 20 (18.4)
Modality Unilateral CI - - 10 (9.2)
Bimodal (Unilateral CI and H-aid on the other side) - - 35 (32.1)
Bilateral CI (sequential) - - 52 (47.7)
Bilateral CI (simultaneous) - - 12 (11.0)
CAP score Pre 1.106 ± 1.552 (0.0, 5.0)
3mo 2.633 ± 1.556 (0.0, 6.0)
6mo 3.450 ± 1.424 (0.0, 7.0)
1yr 4.110 ± 1.315 (1.0, 7.0)
K-Ling-Reading (phoneme) Pre 1.523 ± 1.772 (0.0, 8.0)
3mo 2.578 ± 1.707 (0.0, 8.0)
6mo 3.495 ± 1.596 (0.0, 8.0)
1yr 4.138 ± 1.500 (0.0, 8.0)
K-Ling-Reading (phonology) Pre 1.670 ± 2.009 (0.0, 8.0)
3mo 3.028 ± 1.898 (0.0, 8.0)
6mo 3.881 ± 1.809 (0.0, 8.0)
1yr 4.587 ± 1.695 (0.0, 8.0)
K-Ling-Speech (phoneme) Pre 0.727 ± 1.328 (0.0, 7.0)
3mo 1.432 ± 1.388 (0.0, 6.0)
6mo 2.250 ± 1.416 (0.0, 7.0)
1yr 3.126 ± 1.445 (0.0, 7.0)
K-Ling-Speech (phonology) Pre 0.886 ± 1.458 (0.0, 7.0)
3mo 1.807 ± 1.667 (0.0, 6.0)
6mo 2.591 ± 1.616 (0.0, 7.0)
1yr 3.356 ± 1.517 (0.0, 7.0)
Tab le 2. Age at the time of rst CI surgery, hearing aid modality (aer CI) and language evaluation results
over time
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signicance criterion of 0.05. However, in the other language evaluation outcomes, CAP score, K-ling-reading
(phoneme and phonology) and K-ling-reading (phonology), the p value for group by time was more than 0.05.
As a result, with the exception of K-ling-speech (phoneme), we concluded that language evaluation outcomes
did not change signicantly over time based on the father’s education level. Post hoc analysis was also applied
to determine if there was a dierence in the score change in the language evaluation outcomes at each time
point (pre-CI and at three months, six months and one aer CI surgery). At one year aer CI surgery, K-ling
reading (phoneme) and K-ling-speech (phoneme) scores were higher in the high-education group than in the
low-education group by 0.702 and 0.808, respectively, showing a statistically signicant dierence (p values were
0.013 and 0.012, respectively). In Table6, changes in language evaluation outcomes according to the mother’s
education level are analyzed in detail. K-ling-reading (phoneme), K-ling-speech (phoneme) and K-ling-speech
(phonology) showed a signicant correlation for group by time with a p value of less than 0.05. P values were
0.015, 0.006 and 0.013, respectively. In a post hoc analysis, all language evaluation outcomes, CAP test, K-ling-
reading (phoneme), K-ling-reading (phonology), K-ling-speech (phoneme) and K-ling-speech (phonology), at
one year aer CI surgery were higher in the high-education group than in the low-education group by 0.676,
0.845, 0.778, 1.043 and 0.382, respectively. P values were 0.007, 0.003, 0.012, < 0.001 and 0.002, respectively.
Table7 shows the correlation between parental status (single-parent or not) and language evaluation outcomes
over time. CAP score showed a signicant correlation for the group by time (p = 0.04). One year aer CI surgery,
post hoc analysis revealed no signicant dierence in scores.
Discussion
CI is the most eective treatment option for children with severe to profound hearing loss, and many previous
studies have tried to identify what factors can impact their outcomes.
Outcome Time
(1) Less than university graduation (2) University graduation
or higher
Overall p value
Post-hoc analysis: (1)
vs. (2)
Estimated mean (SE) Estimated mean (SE) Di (SE) p value
CAP score Pre 1.195 (0.212) 1.239 (0.244) Group*Time 0.173 0.044 (0.262) 0.868
3mo 2.574 (0.215) 3.164 (0.249) Group 0.075 0.590 (0.269) 0.030
6mo 3.461 (0.213) 3.964 (0.246) Time < 0.001 0.503 (0.265) 0.060
1yr 4.139 (0.204) 4.589 (0.233) 0.450 (0.245) 0.069
K-Ling-Reading (phoneme) Pre 1.794 (0.242) 1.956 (0.279) Group*Time 0.170 0.163 (0.298) 0.586
3mo 2.826 (0.233) 3.081 (0.266) Group 0.138 0.255 (0.279) 0.361
6mo 3.729 (0.235) 4.106 (0.268) Time < 0.001 0.377 (0.282) 0.184
1yr 4.229 (0.233) 4.931 (0.266) 0.702 (0.278) 0.013
K-Ling-Reading (phonology) Pre 1.776 (0.258) 2.072 (0.298) Group*Time 0.868 0.296 (0.321) 0.358
3mo 3.115 (0.254) 3.522 (0.292) Group 0.122 0.408 (0.313) 0.195
6mo 4.002 (0.250) 4.422 (0.287) Time < 0.001 0.421 (0.304) 0.170
1yr 4.647 (0.248) 5.197 (0.284) 0.550 (0.300) 0.069
K-Ling-Speech (phoneme) Pre 0.792 (0.272) 0.934 (0.308) Group*Time 0.028 0.141 (0.273) 0.607
3mo 1.498 (0.273) 1.579 (0.309) Group 0.184 0.081 (0.276) 0.770
6mo 2.243 (0.283) 2.579 (0.323) Time < 0.001 0.335 (0.300) 0.267
1yr 2.964 (0.289) 3.772 (0.332) 0.808 (0.315) 0.012
K-Ling-Speech (phonology) Pre 0.913 (0.296) 1.030 (0.335) Group*Time 0.546 0.117 (0.296) 0.693
3mo 1.776 (0.313) 2.062 (0.359) Group 0.267 0.287 (0.338) 0.399
6mo 2.580 (0.307) 2.901 (0.350) Time < 0.001 0.321 (0.323) 0.323
1yr 3.272 (0.308) 3.804 (0.352) 0.532 (0.327) 0.107
Tab le 5. Correlation between father’s education level and speech and language performance by time
Variables CAP score K-Ling-Reading
(phoneme) K-Ling-Reading
(phonology) K-Ling-Speech
(phoneme) K-Ling-Speech
(phonology)
Education level (father) 0.173 0.170 0.868 0.028 0.546
Education level (mother) 0.144 0.015 0.077 0.006 0.013
Monthly household income 0.068 0.659 0.506 0.488 0.434
Location of residence 0.999 0.553 0.715 0.671 0.647
Dual-income family 0.104 0.545 0.888 0.999 0.889
Single-parent family 0.040 0.078 0.134 0.545 0.377
Tab le 4. Association of socioeconomic factors and speech and language performance aer CI (interaction p
value)
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Socioeconomic factors have been identied to signicantly inuence speech and language development
aer CI surgery, including household income11, parental expectations20, receipt of nancial support21, and
eective language rehabilitation therapy15–18. In particular, For pediatric patients who underwent CI surgery
before the age of 36 months, higher maternal education levels and greater annual household income were
associated with signicantly improved expressive and receptive language development18. is outcome can
Outcome Time
(1) Single-parent family (2) Two-parent family
Overall p value
Post-hoc analysis: (1)
vs. (2)
Estimated mean (SE) Estimated mean (SE) Di (SE) p value
CAP score Pre 2.137 (0.423) 1.054 (0.185) Group*Time 0.040 -1.083 (0.427) 0.012
3mo 3.037 (0.457) 2.645 (0.193) Group 0.403 -0.392 (0.463) 0.399
6mo 3.437 (0.448) 3.504 (0.191) Time < 0.001 0.067 (0.454) 0.883
1yr 4.037 (0.417) 4.170 (0.184) 0.134 (0.420) 0.751
K-Ling-Reading (phoneme) Pre 2.292 (0.480) 1.697 (0.211) Group*Time 0.078 -0.595 (0.484) 0.221
3mo 3.192 (0.464) 2.768 (0.208) Group 0.786 -0.424 (0.466) 0.364
6mo 3.492 (0.474) 3.747 (0.210) Time < 0.001 0.256 (0.477) 0.593
1yr 4.092 (0.480) 4.394 (0.211) 0.302 (0.483) 0.533
K-Ling-Reading (phonology) Pre 2.396 (0.518) 1.757 (0.224) Group*Time 0.134 -0.639 (0.523) 0.224
3mo 3.896 (0.512) 3.101 (0.223) Group 0.352 -0.796 (0.517) 0.126
6mo 4.196 (0.508) 4.010 (0.222) Time < 0.001 -0.186 (0.512) 0.716
1yr 4.796 (0.511) 4.727 (0.223) -0.069 (0.516) 0.893
K-Ling-Speech (phoneme) Pre 0.906 (0.503) 0.835 (0.252) Group*Time 0.545 -0.071 (0.464) 0.878
3mo 1.906 (0.507) 1.514 (0.253) Group 0.842 -0.392 (0.468) 0.404
6mo 2.335 (0.544) 2.366 (0.260) Time < 0.001 0.031 (0.511) 0.952
1yr 3.192 (0.582) 3.278 (0.267) 0.087 (0.555) 0.876
K-Ling-Speech (phonology) Pre 1.155 (0.541) 0.983 (0.274) Group*Time 0.377 -0.172 (0.496) 0.729
3mo 2.441 (0.610) 1.872 (0.286) Group 0.601 -0.569 (0.577) 0.327
6mo 2.726 (0.594) 2.699 (0.283) Time < 0.001 -0.027 (0.558) 0.960
1yr 3.726 (0.611) 3.482 (0.286) -0.244 (0.578) 0.673
Tab le 7. Correlation between single-parent family and speech and language performance by time
Outcome Time
(1) Less than university graduation (2) University graduation
or higher
Overall p value
Post-hoc analysis: (1)
vs. (2)
Estimated mean (SE) Estimated mean (SE) Di (SE) p value
CAP score Pre 1.116 (0.214) 1.229 (0.234) Group*Time 0.144 0.113 (0.263) 0.668
3mo 2.457 (0.219) 3.051 (0.240) Group 0.027 0.594 (0.271) 0.030
6mo 3.235 (0.217) 3.873 (0.238) Time < 0.001 0.638 (0.269) 0.019
1yr 3.886 (0.207) 4.562 (0.225) 0.676 (0.248) 0.007
K-Ling-Reading (phoneme) Pre 1.749 (0.242) 1.759 (0.263) Group*Time 0.015 0.010 (0.293) 0.972
3mo 2.701 (0.236) 2.959 (0.256) Group 0.109 0.258 (0.281) 0.360
6mo 3.510 (0.238) 4.048 (0.257) Time < 0.001 0.537 (0.284) 0.061
1yr 4.003 (0.237) 4.848 (0.257) 0.845 (0.283) 0.003
K-Ling-Reading (phonology) pre 1.819 (0.258) 1.828 (0.282) Group*Time 0.077 0.010 (0.316) 0.976
3mo 3.072 (0.257) 3.317 (0.281) Group 0.181 0.244 (0.315) 0.438
6mo 3.850 (0.254) 4.295 (0.276) Time < 0.001 0.444 (0.307) 0.151
1yr 4.406 (0.253) 5.184 (0.275) 0.778 (0.305) 0.012
K-Ling-Speech (phoneme) Pre 0.731 (0.268) 1.024 (0.297) Group*Time 0.006 0.293 (0.260) 0.263
3mo 1.457 (0.269) 1.718 (0.298) Group 0.031 0.262 (0.262) 0.321
6mo 2.182 (0.276) 2.690 (0.308) Time < 0.001 0.508 (0.280) 0.073
1yr 2.849 (0.281) 3.892 (0.315) 1.043 (0.293) < 0.001
K-Ling-Speech (phonology) Pre 0.891 (0.289) 1.181 (0.321) Group*Time 0.013 0.290 (0.278) 0.299
3mo 1.793 (0.307) 2.154 (0.344) Group 0.062 0.361 (0.322) 0.266
6mo 2.577 (0.301) 2.959 (0.336) Time < 0.001 0.382 (0.307) 0.217
1yr 3.107 (0.302) 4.093 (0.338) 0.986 (0.311) 0.002
Tab le 6. Correlation between mother’s education level and speech and language performance by time
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be attributed to increased parent-child interactions in families with higher socioeconomic status, which foster
better comprehension and expression abilities aer CI surgery. Studies have further shown that socioeconomic
status acts as a prognostic factor for language development aer CI surgery because families with higher
socioeconomic status tend to have closer parent-child relationships and place greater emphasis on their child’s
education. As a result, language communication between parents and children is frequent, compliance with use
of CI devices is better and participation in language rehabilitation programs is more consistent22–24. Another
study found that families with lower socioeconomic status establish a negative nurturing environment because
of more frustration, guilt and depression than economically stable families. is lack of a nurturing environment
interferes with the physical and psycho-emotional development of the children25,26.
Following an adequate screening process, the author’s institution provided all CI related expenses, including
language rehabilitation program funding of 5,000,000 Korean won (3,600 US$) per year for up to 4 years, to
pediatric patients from low-income families. is aided the families of pediatric patients in decision-making
when hesitant to have CI surgery and language rehabilitation therapy due to nancial restraints. For pediatric
patients, studies highlight that a minimum of two years of dedicated language rehabilitation therapy aer
cochlear implant surgery is vital for successful language development27. However, access to and participation in
such therapy are strongly inuenced by socioeconomic status28. Placement of the child in language rehabilitation
therapy requires money and time from parents. erefore, eective language rehabilitation therapy is frequently
unavailable in low-income families due to time constraints, costs and diculty maintaining sustained attention.
erefore, providing these parents with appropriate hearing rehabilitation aer surgery can make a signicant
dierence in postoperative outcome.
Privious studies that exploring the connection between socioeconomic factors and CI outcomes Previous
studies that investigated the relationship between socioeconomic factors and CI outcomes lacked the ability to
control for disparities in access to language rehabilitation therapy inuenced by socioeconomic status. is is
the rst study to explore whether factors like parental education level, household income, location of residence,
and type of family inuence CI outcomes, even when language rehabilitation therapy is fully guaranteed. We
aimed to analyze the eect of third-party nancial support on speech and language development aer surgery
for pediatric CI patients from low-income families. In conclusion, this study showed that language development
aer CI surgery was eective if the parents had a two-parent household and a higher education level. In addition,
the study also showed that the higher the mother’s education level, the younger the child at the time of the rst
CI surgery. ese ndings highlight the signicance of the primary intrinsic familial factors even when adequate
language rehabilitation therapy is provided.
Even with guaranteed funding for language rehabilitation, higher parental education levels and the presence
of a two-parent family lead to more active parental involvement in daily life. Parents with higher education also
can provide better-quality education at home within the same amount of time, which may explain dierences in
language evaluation outcomes aer CI surgery inuenced by socioeconomic factors.
Furthermore, the mother’s education level is directly correlated with her active involvement in the child’s
education and in the post-surgery rehabilitation process. As a result, the higher the mother’s education level, the
earlier the tendency for CI surgery. Socioeconomic factors, including household income and parental education
level, are also important prognostic factors for children with normal hearing to develop communication skills10
as cultural and intellectual activities within the family are involved in children’s development and positively
aect psycho-emotional and language development29. Monthly household income, which had previously been
identied as a prognostic factor for CI surgery in several studies11, had no signicant eect on speech and
language development aer CI surgery in this study. It implies that third-party support including language
rehabilitation therapy, can oset the dierence in speech and language performance following CI surgery caused
by dierences in familial economic status.
ere are some limitations to this study. First, because we needed information about pediatric patients’
socioeconomic factors, only data from patients who provided all information through the CIDP were analyzed.
As a result, there was no control group with similar socioeconomic factors who did not receive adequate support
for speech rehabilitation therapy. Second, because the number of single-parent and dual-income families in each
type of family was small, bias could occur. Finally, the end point of the language evaluation results is relatively
short, one year aer CI surgery. Due to the short follow-up period, there were limitations in analyzing how well
pediatric patients who had CI surgery adjusted to mainstream education and how their academic performances
diered from those of normal-hearing peers. In the future, when follow-up of all children is performed through
the h year, additional analysis will be conducted.
Despite these limitations, the study’s ndings oer meaningful information about the relationship between
socioeconomic factors and pediatric CI patients’ speech and language development. If more robust research
results are acquired in the future through additional studies, the counseling and encouragement of parents of
pediatric patients to consider CI surgery will be improved.
Conclusion
Although adequate nancial support and language rehabilitation were provided for children with CI from low-
income families, the importance of the parents’ role in language development aer surgery was substantial.
Children in two-parent families and with more highly educated parents experienced better language development
aer CI. In addition, the higher the mother’s educational background, the younger the child was at the time of
the rst CI surgery. However, further prospective research is needed to determine the long-term impact of
socioeconomic factors on speech and language development aer CI.
Scientic Reports | (2025) 15:8750 7
| https://doi.org/10.1038/s41598-025-90073-5
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Content courtesy of Springer Nature, terms of use apply. Rights reserved

Data availability
e datasets used and/or analysed during the current study available from the corresponding author on reason-
able request.
Received: 30 July 2024; Accepted: 10 February 2025
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Author contributions
Conceptualization: CHL and YSC jointly conceptualized the study.Data curation: CHL and S-ES were respon-
sible for data curation.Formal analysis: CHL conducted the formal analysis.Methodology: CHL and YSC con-
tributed to dening the methodology.Project administration: CHL and YSC oversaw the project administration.
Visualization: CHL handled the visualization aspects.Writing – original dra: CHL draed the initial version of
the manuscript.Writing - review & editing: CHL, IJM, W-HC, Y-SC, YSC, and SHH collectively contributed to
reviewing and editing the manuscript.All authors have thoroughly reviewed and approved the nal manuscript.
Funding
is research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health
Industry Development Institute (KHIDI), funded by the Ministry of Health Welfare (grant number: HR21C0885)
and supported by the electroceutical technology development project, National Research Foundation of South
Korea (NRF), funded by the Ministry of Science (grant number: NRF-2022M3E5E908221711).
Scientic Reports | (2025) 15:8750 8
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Declarations
Competing interests
e authors declare no competing interests.
Ethics Statement
is study was reviewed and approved by the Institutional Review Board of Samsung Medical Center (IRB No.
2022-07-091), and the requirement of informed consent was waived.
Additional information
Correspondence and requests for materials should be addressed to Y.S.C.
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