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Impact of socioeconomic factors on paediatric cochlear implant outcomes
International Journal of Pediatric Otorhinolaryngology 102 (2017) 90e97
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Impact of socioeconomic factors on paediatric cochlear implant outcomes Shalabh Sharma a, *, Khyati Bhatia a, **, Satinder Singh a, Asish Kumar Lahiri a, Asha Aggarwal a, b a b
Sir Ganga Ram Hospital, India Asha Speech and Hearing Clinic, India
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 January 2017 Received in revised form 9 September 2017 Accepted 11 September 2017 Available online 14 September 2017
Objectives: The study was aimed at evaluating the impact of certain socioeconomic factors such as family income, level of parents' education, distance between the child's home and auditory verbal therapy clinic, and age of the child at implantation on postoperative cochlear implant outcomes. Methods: Children suffering from congenital bilateral profound sensorineural hearing loss and a chronologic age of 4 years or younger at the time of implantation were included in the study. Children who were able to complete a prescribed period of a 1-year follow-up were included in the study. These children underwent cochlear implantation surgery, and their postoperative outcomes were measured and documented using categories of auditory perception (CAP), meaningful auditory integration (MAIS), and speech intelligibility rating (SIR) scores. Children were divided into three groups based on the level of parental education, family income, and distance of their home from the rehabilitation– auditory verbal therapy clinic. Results: A total of 180 children were studied. The age at implantation had a significant impact on the postoperative outcomes, with an inverse correlation. The younger the child's age at the time of implantation, the better were the postoperative outcomes. However, there were no significant differences among the CAP, MAIS, and SIR scores and each of the three subgroups. Children from families with an annual income of less than $7,500, between $7,500 and $15,000, and more than $15,000 performed equally well, except for significantly higher SIR scores in children with family incomes more than $15,000. Children with of parents who had attended high school or possessed a bachelor's or Master's master's degree had similar scores, with no significant difference. Also, distance from the auditory verbal therapy clinic failed to have any significantimpact on a child's performance. Discussion: These results have been variable, similar to those of previously published studies. A few of the earlier studies concurred with our results, but most of the studies had suggested that children in families of higher socioeconomic status had have better speech and language acquisition. Conclusions: Cochlear implantation significantly improves auditory perception and speech intelligibility of children suffering from profound sensorineural hearing loss. Younger The younger the age at implantation, the better are the results. Hence, early implantation should be promoted and encouraged. Our study suggests that children who followed the designated program of postoperative mapping and auditory verbal therapy for a minimum period of 1 year seemed to do equally well in terms of hearing perception and speech intelligibility, irrespective of the socioeconomic status of the family. Further studies are essential to assess the impact of these factors on long-term speech acquisition andlanguage development. © 2017 Published by Elsevier Ireland Ltd.
Keywords: Cochlear implant outcomes Socioeconomic status
* Corresponding author. Department of Otorhinolaryngology and Head and Neck Surgery, Sir Ganga Ram Hospital, New Delhi, E4/14B, Vasant Vihar, New Delhi 110057, India. ** Corresponding author. Department of Otorhinolaryngology and Head and Neck Surgery, Sir Ganga Ram Hospital, New Delhi, 8/6, second floor, South Patel Nagar, New Delhi 110008, India. E-mail addresses: [email protected] (S. Sharma), [email protected] (K. Bhatia). http://dx.doi.org/10.1016/j.ijporl.2017.09.010 0165-5876/© 2017 Published by Elsevier Ireland Ltd.
S. Sharma et al. / International Journal of Pediatric Otorhinolaryngology 102 (2017) 90e97
1. Introduction A cochlear implant is a device that can help children with severe to profound hearing loss acquire the ability to hear and develop communication skills like their normally hearing peers [1,2]. Significant advances have been made in the field of cochlear implantation technology, which have led to marked improvements in postoperative outcomes. However, postimplantation outcomes vary widely [3]. There still remains a subset of children who fail to gain maximal benefit, even after years of persistent usage of the device on a daily basis [4]. There is apparently a multitude of factors affecting the performance of a child postimplantation. These include patient characteristics such as cochleovestibular anatomy [3], duration of deafness [5], age at onset of deafness, age at implantation [6,7], duration of implant use, length of daily device use [8], and preoperative level of residual hearing [9]. A younger age at implantation, especially before the age of 24 months, is associated with an increased rate of speech acquisition. This rate is comparable with the rate of speech acquisition in normally hearing peer groups [10]. Other factors that have been reported to influence the performance of children after cochlear implantation involve social and educational considerations. These include predominant mode of communication, such as oral or sign language [11], parental and familial expectations [12], socioeconomic status, family income [13], and postimplantation auditory verbal therapy [14]. Cochlear implantation outcomes can be affected by socioeconomic factors in many ways. The earlier a child undergoes cochlear implantation, the greater are the chances that the child will develop near-normal linguistic skills [15]. Furthermore, spoken language scores are known to slope downward with increasing age at the time of implantation [16]. Parental education and familial income constitute the main factors on the basis of which families are categorized into various socioeconomic groups. These factors are known to be predictive of communication skills in children with normal hearing [17]. Children belonging to families of higher socioeconomic status have been found to have better reading skills [18]. One factor contributing to this finding may be that a higher family income has been associated with a higher level of maternal education and increased involvement of the mother when communicating with the child. Wu et al. have observed that implanted children belonging to predominantly noneEnglish-speaking, socioeconomically disadvantaged backgrounds develop speech perception at a significantly slower rate as compared to a normalized national cohort [13]. They concluded that socioeconomic status is inextricably linked to causative factors, such as parental education and support, patient compliance with the device, mode of communication, and type of school and rehabilitation program attended. All these factors are known to have a significant impact on the overall outcome after cochlear implantation [19e23]. There is a direct relationship between socioeconomic status and spoken language comprehension skills that has been observed in all the above-cited studies. This is attenuated when a multivariable analysis is carried out, taking into account factors such as family income, maternal education, and maternal involvement in enhancing the communication of the child [3]. Cochlear implantation, along with aural rehabilitation, results in increased access to acoustic information and spoken language, leading to higher rates of placement in mainstream schools [24]. This decreases the overall educational cost of an implantee. Hence, auditory verbal therapy is known to improve postimplantation performance significantly because it is associated with a higher rate of improvement in auditory resolution and speech perception [25,26]. Therefore, parents are advised to have the child attend
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auditory verbal therapy sessions for up to 2 years after implantation because an increased number of therapy hours has been associated with greater speech emphasis [11]. The demanding schedules of therapy sessions require a considerable deal of zeal and compliance among parents. This becomes increasingly difficult for patients from a lower socioeconomic group who may have time constraints, loss of work, expenses involved, and increasing distance of the patient's residence from the therapy clinic. Patients who live at a distance more than about 30 miles (50 km) from the therapy clinic usually have to apply for leave from work and be absent from their families and homes to be able to attend auditory verbal therapy sessions according to the designated time schedule. Families who live far from the implant center often have to shift their households temporarily and rent a home near the implant center to obtain maximal benefit. This applies especially to younger children, who always need to be accompanied by parents [14]. We have conducted a retrospective study in a tertiary care hospital in a city in India. This was done in an attempt to ascertain the impact of socioeconomic factors such as parental education, family income, and distance from the therapy clinic on postoperative cochlear implant outcomes. India is a land of extremely diverse landscapes, with a wide socioeconomic disparity in society. With a population of over 1.25 billion people [27], the country has relatively few cochlear implant centers, most of which are located in and around the major metropolitan cities. Consequently, parents often have to travel a significant distance to obtain access to a cochlear implant center for their deaf child. There is a paucity of studies investigating relationships among socioeconomic factors such as parental education, family income, and distance from the child's residence to the therapy clinic. These factors are thought to have a significant impact on postoperative mapping and rehabilitation and hence on overall cochlear implantation outcomes. To design programs that would optimize the benefits of cochlear implantation for children from diverse socioeconomic groups, these factors should be investigated further. 2. Materials and methods This was a retrospective observational study in which no power calculations were made. The study data were retrieved from patients' records from January 1, 2006 until December 1, 2014. Children younger than 4 years who underwent unilateral cochlear implantation were included. In each case, a few socioeconomic variables, such as parents' education, family income, and distance of the residence from the speech therapy clinic were documented based on parent report, education certificate, income certificate, and proof of address. The distance between the patient's home and the clinic was recorded using Google maps. These factors were then analyzed and correlated with postimplantation outcome. India boasts of a rich cultural and linguistic diversity; thus, there are about 1652 languages and many dialects that are spoken throughout the country [28]. We have used categories of auditory perception (CAP), meaningful auditory integration (MAIS), and the speech intelligibility rating (SIR) to assess the postoperative outcomes uniformly because very few standardized questionnaires for speech perception are available in languages other than English. 2.1. Participants Children with a chronologic age of 4 years or younger at the time of implantation, with bilateral congenital profound sensorineural hearing loss, normal intellect, and radiologically normal
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cochleovestibular anatomy were included for analysis. 2.2. Preoperative workup As a routine clinical workup, children presenting with severe to profound hearing loss underwent a number of audiologic investigations, including free field, behavioral observation, and pure tone audiometry, otoacoustic emissions, auditory steady-state responses, brainstem-evoked audiometry, and aided audiometry. All children underwent a hearing aid trial for a stipulated period of 3 months. The duration was decided arbitrarily based on clinical experience. Those children deriving minimal or no benefit from hearing aids were considered for cochlear implantation and underwent preoperative investigations, which included highresolution computed tomography (CT) scanning of the temporal bone and magnetic resonance imaging (MRI) of the brain. Children with sensorineural hearing loss who were diagnosed with additional disabilities, such as delayed milestones, cerebral palsy, and autism, were excluded from the study. Children with abnormal radiologic findings, including Mondini dysplasia and other incomplete partition defects, were also excluded. Parents of all the children were counseled extensively regarding the need for regular follow-up, the requirement for auditory verbal therapy, and the need to devote extra care and time to the child. As part of our routine protocol, selected children were inoculated preoperatively with meningococcal, pneumococcal, and Haemophilus influenzae vaccination prior to cochlear implantation. Most of the children underwent unilateral cochlear implantation. However, some children underwent bilateral implantations as well. All the children receiving bilateral implants underwent the implantations sequentially. There were no patients who underwent simultaneous bilateral implantation in the study population. None of the children underwent sequential bilateral implantation in the 1-year follow-up period. These children attended postoperative auditory verbal therapy sessions for a prescribed period of 24 months. The auditory verbal therapist began with an initial assessment of the child's preoperative baseline performance, followed by auditory training, which included recognition, discrimination, and perception. This was followed by language training according to the child's performance. Postoperatively, CAP and MAIS scores were documented at 3, 6, 9, and 12 months of implant age. SIR scores were documented at 12 and 24 months of implant age in all the children who completed 2 years of follow-up. Children whose CAP, MAIS, and SIR scores were unavailable at the age of 1 year postimplantation were excluded from the analysis. All the available data were used for analysis until the time children were kept on a regular schedule for follow-up. Parents' education, family income, and distance of their residence from the therapy clinic were documented in each patient's case file. Either parent's highest educational qualifications were recorded. The CAP, MAIS, and SIR scores were compared at 12 months of age among the subcategories. A time period of 12 months was chosen because most of the children obtained maximum scores on the MAIS questionnaire by 1 year of implant age. However, speech intelligibility ratings could only be scored after the children had acquired some degree of understandable speech, which usually occurs by 1 year postimplantation.
able to talk on the phone with a familiar speaker. This was chosen because it reflects auditory performance in a more practical way [29]. 2.3.2. Meaningful auditory integration scale The MAIS is a parent-reported questionnaire in an interview format. The scoring system consists of 10 questions, which each question rated from 1 to 5 points. The lowest score is marked as 0 and the highest score is marked as 4. The total score is obtained by adding the points in each of the 10 questions. The MAIS examines the child's ability to associate sounds with events in his or her environment, which does not require the child to demonstrate word recognition skills [30]. This scale was chosen to assess children with different languages so as to achieve comparable results. 2.3.3. Speech intelligibility rating The SIR is a scale used to measure the intelligibility of spoken language in real life. It is a scale with points ranging from 1 to 5, wherein a score of 1 represents the fact that the child can speak prerecognizable words in spoken language, and a score of 5 indicates that the child's connected speech is intelligible to all the listeners. It is an internationally accepted measure of speech intelligibility in real-life situations [31]. The CAP and SIR scores were determined by the auditory verbal therapist who was responsible for the training and therapy of the selected children. Questionnaires for the MAIS were given to the parents by the auditory verbal therapist, and responses to each of the questions were noted in the respective patient's case file by the therapist. The CAP, MAIS, and SIR scores of all the 180 children, obtained at 12 months of implant age, were correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic. According to World Bank statistics, the per capita income in India is $1590 [32]. As per the Global Wealth Report by the Credit Suisse Research Institute, the mean wealth in India in 2016 was $3835 per adult. A nuclear family would have an average of $7670 in accumulated wealth [33]. The cost of cochlear implantation ranges from $11,000 to $22,000 (multiple device configurations are available at varying cost), which includes the costs of preoperative investigations and the device, surgical expenses, and postoperative auditory verbal therapy sessions. Families in a lower socioeconomic group often have to face a massive financial crisis to arrange adequate resources for treatment of their profoundly deaf child. We must take into account the fact that the parents of a child born with severe to profound hearing impairment are usually young and are still in the early part of their earning cycle; hence, they would have less accumulated wealth than if they were older. We divided our families into three income groups on the basis of their ability to afford an implant. Group 3 consisted of families who would be able to afford implantation only with a considerable part of the expense paid with external financial assistance, such as by the government, nongovernmental organization, or bank loan. Group 2 consisted of families who would be able to afford implantation, albeit with some difficulty, and group 1 was comprised of families who would be able to afford implantation without any significant financial difficulty. 2.4. Categorization by parents' education
2.3. Assessment of postoperative outcomes 2.3.1. Categories of auditory performance CAP scores were used to measure the degree of auditory perception. This scale ranges from 0 to 7, wherein 0 represents no awareness of environmental sounds and 7 indicates that the child is
According to parents' education, children were divided in three groups, Group 1 consisted of children whose parents possessed a master's degree and higher, group 2 had children whose parents had completed a bachelor's degree, and group 3 had children whose parents had attended high school.
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Based on annual household income, children with families having an annual income of more than $15,000 were placed in group 1, those with families having an annual income between $7500 and $15,000 were placed in group 2, and those with families earning less than $7500 annually were placed in group 3. Similarly, children whose residence was within 30 miles from the auditory verbal therapy were categorized as group 1, those with a residence between the range of 30 miles and 310 miles were categorized as group 2, and those with a residence more than 310 miles from the auditory verbal therapy clinic were categorized as group 3. 2.5. Statistical analyses Statistical analyses were performed by the SPSS program for Windows, version 24.0. CAP, MAIS, and SIR scores of all the children obtained at 12 months of implant age were adjusted for age at implantation and were correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic using a generalized linear model. CAP and MAIS scores available at 6 and 9 months were also correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic using a generalized linear model. Quantitative data were expressed in terms of mean and standard deviation. Categorical data were expressed as absolute number and percentage. Cross tables were generated, and the Pearson chi-squared test was used for the testing of associations. A p value less than 0.05 was considered statistically significant. Relative risks and odds ratios, along with 95% confidence intervals, were the preferred measures of effect size. The age at implantation was calculated with respect to date of birth. Age was used as a continuous variable for statistical analysis. However, in many cases, the age information elicited from parents was recorded as an approximate figure of 1, 2, 3 or 4 years as compared to other children whose exact date of birth and exact age were known. This resulted in the heaping of ages at certain age points. In view of this, the level of significance considered for age was 10% as against the conventional 5%. 3. Results Between January 1, 2006 and December 1, 2014, 364 patients with bilateral profound sensorineural deafness underwent cochlear implant surgery in our center. Of these 364 patients, there were 205 children whose chronologic age at the time of implantation was 4 years or younger. Of these 205 children, 180 children with normal intellect and radiologically normal cochleovestibular anatomy completed a minimum period of 1 year of follow-up (see Chart 1). 3.1. Age at implantation Children up to the chronologic age of 4 years at the time of implantation were included, with a mean age of 2.7 years, minimum age of 8 months, and maximum age of 4 years. Out of 180 children, 111 children's ages were available as approximate figures of 1, 2, 3, and 4 years and the rest of the children's ages were available as exact figures. Socioeconomic status was also correlated with age at implantation. Rising socioeconomic status showed a significant correlation, with children belonging to a higher socioeconomic group receiving implants at a younger age as compared to children of a lower socioeconomic group, with a p value of 0.018 (see Tables 1e4).
Chart 1. Selection of patients based on exclusion criteria.
Table 1 Chronologic age at the time of implantation. Age at implant
Number of children
Less than 1 year 1 - 2 year 2-3 year 3-4 year
6 68 53 53
3.2. Categorization There were 41 children (22.7%) whose parents attended high school, 110 children (61.1%) whose parents possessed a bachelor's degree (graduates), and 29 children (16.12%) whose parents had completed a master's degree or higher qualification (e.g., postgraduate, postdoctoral). Children's postimplantation performance scores were also correlated with their family incomes and were subdivided into three groups. Group 1 had 20 children (11.11%), group 2 had 101 children (56.11%), and group 3 had 59 children (32.78%). Children were also divided into three groups based on the distance of the auditory verbal therapy clinic from their residence. There were 85 children (47.22%) in group 1 with a distance less than 30 miles (50 km), 46 children (26.11%) in group 2 with a distance between 30 miles (50 km) and 310 miles (500 km), and 49 children in group 3 (26.67%) with a distance greater than 310 miles (500 km). Also, CAP and MAIS scores were correlated with all the measured parameters at 6 and 9 months postimplantation in 136 children. Scoring at 6 and 9 months could only be done for 136
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Table 2 Correlation between socioeconomic status and age at implantation. Age group at implant (Years)
Income per annum < $ 7500 n ¼ 59 (32.78%)
$ 7500e15,000 n ¼ 101(56.11%)
> $ 15,000 n ¼ 20(11.11%)
Total n ¼ 180
< ¼ 1.5 1.6e1.9 2.0e2.4 2.5e2.9 3.0e3.4 3.5e3.9 3.9e4.0
2 (3.4%) 3 (5.1%) 17 (28.8%) 8 (13.6%) 10 (13.6%) 8 (13.6%) 11 (18.6%)
14 (13.9%) 9 (8.9%) 21 (20.8%) 7 (6.9%) 26 (25.7%) 3 (3.0%) 21 (20.8%)
1 5 4 0 6 1 3
17 17 42 15 42 12 35
(5.0%) (25.0%) (20.0%) (0.0%) (30.0%) (5.0%) (15.0%)
(9.4%) (9.41%) (23.3%) (8.3%) (23.3%) (6.7%) (19.4%)
Pearson Chi-Square value ¼ 24.447; p-value ¼ 0.018*.
Table 3 Number of children in all the three groups in the three categories. Category
Parents Education
Annual Family income
Distance of patient's residence from speech therapy clinic
Group 1 Group 2 Group 3
29 (16.12%) 110 (61.11%) 41 (22.7%)
20 (11.11%) 101(56.11%) 59 (32.78%)
85(47.22%) 46(26.11%) 49(26.67%)
Parents Education. Group 1 e possessing master's degree and above, Group 2 e possessing bachelor's degree, Group 3 e attended high school. Annual Family income. Group 1 - > $ 15,000, Group 2 - $ 7500 e $15,000, Group 3 - < $7500. Distance of speech therapy clinic from patient's residence. Group 1 - < 30 miles, Group 2 - 30e310 miles, Group 3 - > 310 miles.
children because scores for the rest of the children were available only at 12 months postimplantation. Scoring for the rest of the children was carried out at 5, 8, or 10 months after implantation and hence could not be used for statistical analysis at 6 and 9 months.
Children in families having an annual family income higher than $15,000 performed significantly better as compared to families with an annual family income from $7500 to $15,000, with a p value of 0.008. No correlation was observed for CAP and MAIS scores obtained at 6 and 9 months with annual family income.
3.3. Interpretation
3.3.4. Distance from speech therapy clinic This was also a categorical variable. Children living within a 30mile (50-km) radius from the speech therapy clinic were chosen as the reference category because it was hypothesized that there would be a better outcome as compared to other groups. No correlation was observed between MAIS and SIR scores, but CAP scores were found to be significantly higher in children residing at a distance of 30 miles (50 km) and 310 miles (500 km) from the speech therapy clinic, with a p value of 0.022. Also, CAP and MAIS scores at 6 and 9 months showed no correlation with distance from the speech therapy clinic.
3.3.1. Age at implantation CAP, MAIS, and SIR scores at 12 months were found to be higher with decreasing age at implantation, with p values of 0.061, 0.099, and 0.087, respectively. CAP scores at 6 months were higher in children with a younger age at implantation, with a p value of 0.01. However, a similar correlation was not observed with MAIS scores at 6 months. CAP and MAIS scores at 9 months also showed a similar correlation, with higher scores attained by children of younger ages and p values of 0.022 and 0.077, respectively. 3.3.2. Parents' education Because this was a categorical variable, children whose parents possessed a master's degree or higher (e.g., postgraduate, postdoctoral) were chosen as a reference category for comparison with other groups, assuming that the children of these parents would perform the best as compared to the other groups. However, no correlation was observed among the CAP, MAIS, and SIR scores obtained at 1 year of age with the education level of the parents in our study. Also, no correlation was obtained between CAP and MAIS scores obtained at 6 and 9 months of implant age with parents' education. 3.3.3. Annual family incomes This was also a categorical variable, so families with an annual income higher than $15,000 were chosen as reference category because they were considered to be most advantaged of the groups studied. No correlation was observed between CAP and MAIS scores obtained at 12 months of age between any of the three categories. However, a significant correlation was observed in SIR scores.
4. Discussion Our subset of children is unique in that we have multicultural diversity, ethnicity, and, languages in India. Through this study, our goal was to assess the impact of age at implantation, socioeconomic status of the family and parents' education on postimplantation outcome. Our study has concurred with the results of previous studiesdthat a younger age at implantation leads to better outcomes in terms of speech perception and language acquisition [2,10]. CAP scores at 6 months were found to be higher in children with a younger age at implantation, whereas similar results were not duplicated in MAIS scores at 6 months. This may be because MAIS is a parent-reported questionnaire, which is a measure of gross auditory skills with a lesser requirement for fine skills and speech understanding. Hence, most children are able to achieve similar scores postimplantation, even if they are of an older age at the time of implantation. According to our study, socioeconomic status did not seem to have a significant impact on the performance of children after
0.486 0.646 0.137 1.071 1.5351 0.763 1.6591 0.993 0.6684 0.512 0.3188 0.404 0.3461 0.36 0.1388 0.671 0.309 0.077 0.466 0.3458 0.369 0.3753 0.35 0.1506
0.178 0.325 0.022
0.467 1.0989 1.208 1.1877 0.847 0.4785
4.1. Comparison with previous studies
Reference category (#). Education e Parents possessing Post Graduate/Post Doctoral degrees. Income e Parents with annual familial income > 15,000 $. Distance e Families having residences < 50 km (30 miles) from the speech therapy clinic.
0.212 0.421 0.087 0.24 0.1953 0.16 0.1982 0.15 0.088 0.08 0.393 0.099 1.666 0.9522 0.826 0.9663 0.708 0.4292 0.022 0.466 0.061 0.48 0.2082 0.15 0.2113 0.18 0.0938
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cochlear implantation. Also, the assumption that the distance of the parents' residence from the speech therapy clinic would affect the child's frequency of attending speech therapy sessions and thereby affect the final outcome of the child was not supported by our results. However, the SIR was significantly higher in children in families with an annual income more than $15,000. This is may be explained by the fact that CAP and MAIS scores assess the child's auditory perception and response and integration with sound, whereas SIR scores measure the intelligibility of spoken language. The intelligibility of speech can be affected by the quality of education, access to books, and better schooling. Speech perception and auditory integration were acquired by most children appreciably well postimplantation, irrespective of socioeconomic status. However, speech intelligibility could have differed due to differing familial and social environments and exposure to improved auditory visual stimulation in households with higher annual incomes.
0.108 0.243 0.011
0.829 0.349 0.545 2.5167 1.424 1.5199 0.402 0.302 0.306 0.188 0.32 0.3163 0.37 0.28
1.212 1.4468 1.323 1.2808
0.54 0.2967 0.7 0.2627
0.069 0.008
0.121 0.1
0.5672 0.3433
0.831 0.775
0.672 1.8016 1.351 1.0881
0.5229 0.3166 0.152 0.01 0.709 0.215
0.771 0.974
0.32 0.656 2.3826 1.8282 0.437 0.533 0.785 0.346 0.09 0.3137 0.232 0.246
1.115 1.435 0.701 1.125
0.09 0.2943 0.2 0.2307
0.763 0.378
0.654 0.364
0.54 0.4154
0.226 0.381
1.005 1.251
1.7056 1.3088
0.4979 0.383 0.61 0.345 0.556 0.339
0.22 0.367
2.367 0.814
2.5922 33.46 0.5413 5.148 1.8557 39.113 0.5871 6.524 0.3751 2.895 1.8289 41.104 0.3999 7.107
(Intercept) Education# Graduation School Income# Less than 7500 $ 7500e 15,000 $ Distance# 50 - 500 km >500 km Age at implant
Std. Error p-value
MAIS at 6 months
Std. Error p-value B
CAP at 6 months
Std. Error p-value B
MAIS at 9 months
Std. Error p-value B
CAP at 9 months
Std. Error p-value B
SIR at 12 months
Std. Error p-value B
MAIS at 12 months
Std. Error p-value B B
CAP at 12 months Parameter
Table 4 CAP, MAIS and SIR scores at 12, 9 and 6 months of age being adjusted for age at implant and correlated with annual family income, parents education, and distance of residence from speech therapy clinic.
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Previous studies investigating the relationship between socioeconomic factors and cochlear implant outcomes have shown varied results. In Turkey, a study by Ozcebe et al. has shown that poor socioeconomic status and low levels of education in the family are responsible for a delay in cochlear implantation [15]. This may partly be attributed to a lack of awareness regarding the existence and benefits of cochlear implantation and difficult access to medical facilities. Our study has shown similar results, with children from a higher socioeconomic group receiving implants at younger ages as compared to children of a lower socioeconomic group. Niparko et al.’s study of language development following cochlear implantation has concluded that children with a higher socioeconomic status achieve greater improvement in spoken language and comprehension [34]. This was somewhat similar to the results of our study because in our study the children of families with a higher income achieved higher SIR scores, although similar results were not seen in the CAP and MAIS scores. Chang et al. have observed that children in a lower socioeconomic group had higher rates of postoperative complications, decreased follow-up compliance, and lower rates of sequential bilateral implantation [35]. A study by Holt and Svirsky [36] has reflected results similar to those in our study. They found no relationship between estimated family income and spoken word recognition of children with cochlear implants, although they did establish a relationship between estimated income and receptive and expressive language. Children from families with a higher estimated income had faster rates of receptive language development but slower rates of expressive language development. 4.2. Reasons for difference in results The lack of a clinically significant difference in postimplantation outcomes because of the presence of varying distances between the child's home and speech therapy clinic could partly be attributed several factors. For example, families whose residence was far from the clinic often temporarily shifted their household to a residence near the therapy clinic for 6e12 weeks to ensure regular and intensive auditory verbal therapy sessions, three to five sessions per week. After completion of this period, parents were instructed to bring their children to the clinic every 6e8 weeks for a minimum of 3 or 4 days for assessment and therapy. Children's vacations and midterm holidays were also used to account for missed classes. In contrast, children who resided in the same city as the speech therapy clinic averaged two sessions per week. We hypothesize that parents who had to spend a large part of
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their savings or take loans for the peri-implantation expenses were highly motivated in their attempts to get the best possible outcome for the child, essentially as much value for their money as possible. Most of them appeared to belong to the lower socioeconomic group. These parents took the time and sacrificed their routine for work to follow the program set out for their child. This may be one of the factors that would have helped children from a lower socioeconomic group make up for the difference and perform as well as their peers from a higher socioeconomic group. This could have been facilitated by exhaustive preoperative counseling sessions for the parents to help them understand the importance of protracted postoperative auditory verbal therapy, along with maximal aural stimulation at home. Staff at the speech therapy clinic made special efforts to contact children who had missed their appointments. In particular, reminders were sent to children in remote locations to inform them about their next appointment to ensure better compliance. Even after the surgery, parents were regularly counseled about maximizing verbal communication with their child. The need for regular follow-up was also emphasized. 4.3. Limitations This study was a pragmatic, retrospective, observational study in which no power calculations or predetermined size of relevant differences was made. There are a few other limitations as well. CAP, MAIS, and SIR, which are measures of gross auditory development and speech intelligibility, were used to evaluate outcomes. However, comprehensive test scores for receptive or expressive language were not recorded for all the children. CAP and SIR are internationally accepted for the assessment of postoperative outcomes with those who speak different languages. They are nonlinear and hierarchic scales, with poor accuracy [37]. Nevertheless, these tests are suitable for very young children who have yet not developed requisite linguistic skills and the behavior necessary for a more formal assessment [38]. Further studies are needed in the Indian subcontinent to analyze the effects of socioeconomic status on receptive and expressive language development after cochlear implantation. Another shortcoming of our study has been the short duration of follow-up. Many of the families live far from the clinic and belong to the lower socioeconomic group; hence, they were unable to follow up regularly after 1-year postimplantation due to factors related to financial constraints and absenteeism from work, and the outcomes were compared at 1 year of age. Consequently, SIR ratings could not be determined for all the children at 2 years of age. To offset these deficiencies and limitations, the speech therapy clinic has started enrolling children for remote mapping sessions because this provides a service for families who live far from the clinic. To ensure regular follow-up and for consistent monitoring of outcomes, the clinic has also started regular therapy sessions via Skype for families who are unable to visit the clinic in person. Postoperative cochlear implantation outcomes are influenced by numerous factors, of which only a few could be investigated here. Further studies are required to assess the long-term implications of socioeconomic variables on postimplantation outcomes. A greater understanding of these factors or variables would help clinicians make better and more informed decisions regarding counseling and intervention for implantees with poor performance. 5. Conclusion Cochlear implantation significantly improves auditory perception and the speech intelligibility of children suffering from profound sensorineural hearing loss. Earlier implantation leads to
significantly better results, so implantation at a younger age should be promoted and encouraged. Our study suggests that children who follow the designated program of postoperative mapping and auditory verbal therapy for a minimum period of 1 year seemed to do equally well in terms of hearing perception and speech intelligibility, irrespective of the socioeconomic status of the family. However, further studies are required to assess the impact of socioeconomic factors on long-term speech and language development after cochlear implantation, which may or may not replicate the results obtained after a short follow-up period of 1 year. Conflict of interest statement The authors report no conflict of interest. Institutional Review Board clearance has been obtained for this study. References [1] S. Archbold, M. Harris, G. O'Donoghue, T. Nikolopoulos, A. White, H.L. Richmond, Reading abilities after cochlear implantation: the effect of age at implantation on outcomes at 5 and 7 years after implantation, Int. J. Pediatr. Otorhinolaryngol. 72 (2008) 1471e1478. [2] M.A. Svirsky, A.M. Robbins, K.I. Kirk, D.B. Pisoni, R.T. Miyamoto, Language development in profoundly deaf children with cochlear implants, Psychol. Sci. 11 (2000) 153e158. [3] M.K. Cosetti, S.B. Waltzman, Outcomes in cochlear implantation: variables affecting performance in adults and children, Otolaryngol. Clin. North Am. 45 (2012) 155e171. [4] H. Zhou, Z. Chen, H. Shi, Y. Wu, S. Yin, Categories of auditory performance and speech intelligibility ratings of early-implanted children without speech training, PLoS One 8 (2013) e53852. [5] H. Hiraumi, J. Tsuji, S. Kanemaru, K. Fujino, Cochlear implants in post-lingually deafened patients, Ito J. Acta Otolaryngol. Suppl. 557 (2007) 17e21. [6] C. O'Neill, G.M. O'Donoghue, S.M. Archbold, T.P. Nikolopoulos, T. Sach, Variations in gains in auditory performance from pediatric cochlear implantation, Otol. Neurotol. 23 (2002) 44e48. [7] A.F. Snik, M.J. Makhdoum, A.M. Vermeulen, J.P. Brokx, P.I. van den Broek, The relation between age at the time of cochlear implantation and long-term speech perception abilities in congenitally deaf subjects, Int. J. Pediatr. Otorhinolaryngol. 41 (1997) 121e131. [8] H. Fryauf-Bertschy, R.S. Tyler, D.M. Kelsay, B.J. Gantz, G.G. Woodworth, Cochlear implant use by prelingually deafened children: the influences of age at implant and length of device use, J. Speech Lang. Hear Res. 40 (1997) 183e199. [9] B. Pyman, P. Blamey, P. Lacy, G. Clark, R. Dowell, The development of speech perception in children using cochlear implants: effects of etiologic factors and delayed milestones, Am. J. Otol. 21 (2000) 57e61. [10] D.R. Moore, R.V. Shannon, Beyond cochlear implants: awakening the deafened brain, Nat. Neurosci. 12 (2009) 686e691. [11] A. Geers, C. Brenner, Background and educational characteristics of prelingually deaf children implanted by five years of age, Ear Hear 24 (Suppl) (2003) 2Se14S. [12] T.P. Nikolopoulos, H. Lloyd, S. Archbold, G.M. O'Donoghue, Pediatric cochlear implantation: the parents' perspective, Arch. Otolaryngol. Head. Neck Surg. 127 (2001) 363e367. [13] D. Wu, E.W. Woodson, J. Masur, J. Bent, Pediatric cochlear implantation: role of language, income, and ethnicity, Int. J. Pediatr. Otorhinolaryngol. 79 (2015) 721e724. [14] J.L. Wu, H.M. Yang, Y.H. Lin, Q.J. Fu, Effects of computer-assisted speech training on Mandarin-speaking hearing-impaired children, Audiol. Neurootol 12 (2007) 307e312. [15] E. Ozcebe, S. Sevinc, E. Belgin, The ages of suspicion, identification, amplification and intervention in children with hearing loss, Int. J. Pediatr. Otorhinolaryngol. 69 (2005) 1081e1087. [16] J. Nicholas, A. Geers, Expected test scores for preschoolers with a cochlear implant who use spoken language, Am. J. Speech Lang. Pathol. 17 (2008) 121e138. [17] R.I. Arriaga, L.C.T. Fenson, S.J. Pethick, Scores on the MacArthur communicative development inventory of children from low- and middle-income families, Appl. Psycholinguist. 19 (1998) 209e223. [18] C.M. Connor, T.A. Zwolan, Examining multiple sources of influence on the reading comprehension skills of children who use cochlear implants, J. Speech Lang. Hear Res. 47 (2004) 509e526. [19] A.V. Hodges, M. Dolan Ash, T.J. Balkany, J.J. Schloffman, S.L. Butts, Speech perception results in children with cochlear implants: contributing factors, Otolaryngol. Head. Neck Surg. 121 (1999) 31e34. [20] G.M. O'Donoghue, T.P. Nikolopoulos, S.M. Archbold, Determinants of speech perception in children after cochlear implantation, Lancet 356 (2005)
S. Sharma et al. / International Journal of Pediatric Otorhinolaryngology 102 (2017) 90e97 466e468. [21] E. Kirkham, C. Sacks, F. Baroody, J. Siddique, M.E. Nevins, A. Woolley, D. Suskind, Health disparities in pediatric cochlear implantation: an audiologic perspective, Ear Hear 30 (2009) 515e525. [22] F. Brkic, L. Piric, N. Salihovic, J. Kabil, Cochlear implantation in children: socioeconomic family characteristics, Med. Arh. 64 (2010) 25e27. lu, The impact of social and [23] B. Polat, B. Bas¸aran, H.C. Kara, A. Atas¸, Y. Süog demographic features on comprehensive receptive and expressive performance in cochlear implant patients, Kulak Burun Bogaz Ihtis. Derg. 23 (2013) 90e95. [24] H.W. Francis, M.E. Koch, J.R. Wyatt, J.K. Niparko, Trends in educational placement and cost-benefit considerations in children with cochlear implants, Arch. Otolaryngol. Head. Neck Surg. 125 (1999) 499e505. [25] Q.J. Fu, J.J. Galvin 3rd, Maximizing cochlear implant patients' performance with advanced speech training procedures, Hear Res. 242 (2008) 198e208. [26] E. Yucel, G. Sennaroglu, E. Belgin, The family-oriented musical training for children with cochlear implants: speech and musical perception results of two-year follow-up, Int. J. Pediatr. Otorhinolaryngol. 73 (2009) 1043e1052. [27] The World Bank, GDP per capita (current US$), Retrieved from, http://data. worldbank.org/indicator/NY.GDP.PCAP.CD?end¼2014&start¼1960. [28] Mhrd.gov.in/sites/upload_files/mhrd/files/upload_document/languagebr. pdf. [29] S. Archbold, M.E. Lutman, D.H. Marshall, Categories of auditory performance, Ann. Otol. Rhinol. Laryngol. Suppl. 166 (1995) 312e314. [30] A.M. Robbins, J.J. Renshaw, S.W. Berry, Evaluating meaningful auditory
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integration in profoundly hearing-impaired children, Am. J. Otol. 12 (Suppl) (1991) 144e150. M.C. Allen, T.P. Nikolopoulos, G.M. O'Donoghue, Speech intelligibility in children after cochlear implantation, Am. J. Otol. 19 (1998) 742e746. LivePopulation.com. Population of India (2017). Retrieved from http://www. livepopulation.com/country/india.html. Credit Suisse Research Institute Global Wealth report 2016, India. Retrieved from https://www.credit-suisse.com/in/en.html. J.K. Niparko, E.A. Tobey, D.J. Thal, L.S. Eisenberg, N.Y. Wang, A.L. Quittner, N.E. Fink, CDaCI Investigative Team. Spoken language development in children following cochlear implantation, JAMA 303 (2010) 1498e1506. D.T. Chang, A.B. Ko, G.S. Murray, J.E. Arnold, C.A. Megerian, Lack of financial barriers to pediatric cochlear implantation: impact of socioeconomic status on access and outcomes, Arch. Otolaryngol. Head. Neck Surg. 136 (2010) 648e657. R.F. Holt, M.A. Svirsky, An exploratory look at pediatric cochlear implantation: is earliest always best? Ear Hear 29 (2008) 492e511. P.J. Govaerts, C. De Beukelaer, K. Daemers, G. De Ceulaer, M. Yperman, T. Somers, et al., Outcome of cochlear implantation at different ages from 0 to 6 years, Otol. Neurotol. 23 (2002) 885e890. C. Allen, T.P. Nikolopoulos, D. Dyar, G.M. O'Donoghue, Reliability of a rating scale for measuring speech intelligibility after pediatric cochlear implantation, Otol. Neurotol. 22 (2001) 631e633.
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: http://www.ijporlonline.com/
Impact of socioeconomic factors on paediatric cochlear implant outcomes Shalabh Sharma a, *, Khyati Bhatia a, **, Satinder Singh a, Asish Kumar Lahiri a, Asha Aggarwal a, b a b
Sir Ganga Ram Hospital, India Asha Speech and Hearing Clinic, India
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 January 2017 Received in revised form 9 September 2017 Accepted 11 September 2017 Available online 14 September 2017
Objectives: The study was aimed at evaluating the impact of certain socioeconomic factors such as family income, level of parents' education, distance between the child's home and auditory verbal therapy clinic, and age of the child at implantation on postoperative cochlear implant outcomes. Methods: Children suffering from congenital bilateral profound sensorineural hearing loss and a chronologic age of 4 years or younger at the time of implantation were included in the study. Children who were able to complete a prescribed period of a 1-year follow-up were included in the study. These children underwent cochlear implantation surgery, and their postoperative outcomes were measured and documented using categories of auditory perception (CAP), meaningful auditory integration (MAIS), and speech intelligibility rating (SIR) scores. Children were divided into three groups based on the level of parental education, family income, and distance of their home from the rehabilitation– auditory verbal therapy clinic. Results: A total of 180 children were studied. The age at implantation had a significant impact on the postoperative outcomes, with an inverse correlation. The younger the child's age at the time of implantation, the better were the postoperative outcomes. However, there were no significant differences among the CAP, MAIS, and SIR scores and each of the three subgroups. Children from families with an annual income of less than $7,500, between $7,500 and $15,000, and more than $15,000 performed equally well, except for significantly higher SIR scores in children with family incomes more than $15,000. Children with of parents who had attended high school or possessed a bachelor's or Master's master's degree had similar scores, with no significant difference. Also, distance from the auditory verbal therapy clinic failed to have any significantimpact on a child's performance. Discussion: These results have been variable, similar to those of previously published studies. A few of the earlier studies concurred with our results, but most of the studies had suggested that children in families of higher socioeconomic status had have better speech and language acquisition. Conclusions: Cochlear implantation significantly improves auditory perception and speech intelligibility of children suffering from profound sensorineural hearing loss. Younger The younger the age at implantation, the better are the results. Hence, early implantation should be promoted and encouraged. Our study suggests that children who followed the designated program of postoperative mapping and auditory verbal therapy for a minimum period of 1 year seemed to do equally well in terms of hearing perception and speech intelligibility, irrespective of the socioeconomic status of the family. Further studies are essential to assess the impact of these factors on long-term speech acquisition andlanguage development. © 2017 Published by Elsevier Ireland Ltd.
Keywords: Cochlear implant outcomes Socioeconomic status
* Corresponding author. Department of Otorhinolaryngology and Head and Neck Surgery, Sir Ganga Ram Hospital, New Delhi, E4/14B, Vasant Vihar, New Delhi 110057, India. ** Corresponding author. Department of Otorhinolaryngology and Head and Neck Surgery, Sir Ganga Ram Hospital, New Delhi, 8/6, second floor, South Patel Nagar, New Delhi 110008, India. E-mail addresses: [email protected] (S. Sharma), [email protected] (K. Bhatia). http://dx.doi.org/10.1016/j.ijporl.2017.09.010 0165-5876/© 2017 Published by Elsevier Ireland Ltd.
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1. Introduction A cochlear implant is a device that can help children with severe to profound hearing loss acquire the ability to hear and develop communication skills like their normally hearing peers [1,2]. Significant advances have been made in the field of cochlear implantation technology, which have led to marked improvements in postoperative outcomes. However, postimplantation outcomes vary widely [3]. There still remains a subset of children who fail to gain maximal benefit, even after years of persistent usage of the device on a daily basis [4]. There is apparently a multitude of factors affecting the performance of a child postimplantation. These include patient characteristics such as cochleovestibular anatomy [3], duration of deafness [5], age at onset of deafness, age at implantation [6,7], duration of implant use, length of daily device use [8], and preoperative level of residual hearing [9]. A younger age at implantation, especially before the age of 24 months, is associated with an increased rate of speech acquisition. This rate is comparable with the rate of speech acquisition in normally hearing peer groups [10]. Other factors that have been reported to influence the performance of children after cochlear implantation involve social and educational considerations. These include predominant mode of communication, such as oral or sign language [11], parental and familial expectations [12], socioeconomic status, family income [13], and postimplantation auditory verbal therapy [14]. Cochlear implantation outcomes can be affected by socioeconomic factors in many ways. The earlier a child undergoes cochlear implantation, the greater are the chances that the child will develop near-normal linguistic skills [15]. Furthermore, spoken language scores are known to slope downward with increasing age at the time of implantation [16]. Parental education and familial income constitute the main factors on the basis of which families are categorized into various socioeconomic groups. These factors are known to be predictive of communication skills in children with normal hearing [17]. Children belonging to families of higher socioeconomic status have been found to have better reading skills [18]. One factor contributing to this finding may be that a higher family income has been associated with a higher level of maternal education and increased involvement of the mother when communicating with the child. Wu et al. have observed that implanted children belonging to predominantly noneEnglish-speaking, socioeconomically disadvantaged backgrounds develop speech perception at a significantly slower rate as compared to a normalized national cohort [13]. They concluded that socioeconomic status is inextricably linked to causative factors, such as parental education and support, patient compliance with the device, mode of communication, and type of school and rehabilitation program attended. All these factors are known to have a significant impact on the overall outcome after cochlear implantation [19e23]. There is a direct relationship between socioeconomic status and spoken language comprehension skills that has been observed in all the above-cited studies. This is attenuated when a multivariable analysis is carried out, taking into account factors such as family income, maternal education, and maternal involvement in enhancing the communication of the child [3]. Cochlear implantation, along with aural rehabilitation, results in increased access to acoustic information and spoken language, leading to higher rates of placement in mainstream schools [24]. This decreases the overall educational cost of an implantee. Hence, auditory verbal therapy is known to improve postimplantation performance significantly because it is associated with a higher rate of improvement in auditory resolution and speech perception [25,26]. Therefore, parents are advised to have the child attend
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auditory verbal therapy sessions for up to 2 years after implantation because an increased number of therapy hours has been associated with greater speech emphasis [11]. The demanding schedules of therapy sessions require a considerable deal of zeal and compliance among parents. This becomes increasingly difficult for patients from a lower socioeconomic group who may have time constraints, loss of work, expenses involved, and increasing distance of the patient's residence from the therapy clinic. Patients who live at a distance more than about 30 miles (50 km) from the therapy clinic usually have to apply for leave from work and be absent from their families and homes to be able to attend auditory verbal therapy sessions according to the designated time schedule. Families who live far from the implant center often have to shift their households temporarily and rent a home near the implant center to obtain maximal benefit. This applies especially to younger children, who always need to be accompanied by parents [14]. We have conducted a retrospective study in a tertiary care hospital in a city in India. This was done in an attempt to ascertain the impact of socioeconomic factors such as parental education, family income, and distance from the therapy clinic on postoperative cochlear implant outcomes. India is a land of extremely diverse landscapes, with a wide socioeconomic disparity in society. With a population of over 1.25 billion people [27], the country has relatively few cochlear implant centers, most of which are located in and around the major metropolitan cities. Consequently, parents often have to travel a significant distance to obtain access to a cochlear implant center for their deaf child. There is a paucity of studies investigating relationships among socioeconomic factors such as parental education, family income, and distance from the child's residence to the therapy clinic. These factors are thought to have a significant impact on postoperative mapping and rehabilitation and hence on overall cochlear implantation outcomes. To design programs that would optimize the benefits of cochlear implantation for children from diverse socioeconomic groups, these factors should be investigated further. 2. Materials and methods This was a retrospective observational study in which no power calculations were made. The study data were retrieved from patients' records from January 1, 2006 until December 1, 2014. Children younger than 4 years who underwent unilateral cochlear implantation were included. In each case, a few socioeconomic variables, such as parents' education, family income, and distance of the residence from the speech therapy clinic were documented based on parent report, education certificate, income certificate, and proof of address. The distance between the patient's home and the clinic was recorded using Google maps. These factors were then analyzed and correlated with postimplantation outcome. India boasts of a rich cultural and linguistic diversity; thus, there are about 1652 languages and many dialects that are spoken throughout the country [28]. We have used categories of auditory perception (CAP), meaningful auditory integration (MAIS), and the speech intelligibility rating (SIR) to assess the postoperative outcomes uniformly because very few standardized questionnaires for speech perception are available in languages other than English. 2.1. Participants Children with a chronologic age of 4 years or younger at the time of implantation, with bilateral congenital profound sensorineural hearing loss, normal intellect, and radiologically normal
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cochleovestibular anatomy were included for analysis. 2.2. Preoperative workup As a routine clinical workup, children presenting with severe to profound hearing loss underwent a number of audiologic investigations, including free field, behavioral observation, and pure tone audiometry, otoacoustic emissions, auditory steady-state responses, brainstem-evoked audiometry, and aided audiometry. All children underwent a hearing aid trial for a stipulated period of 3 months. The duration was decided arbitrarily based on clinical experience. Those children deriving minimal or no benefit from hearing aids were considered for cochlear implantation and underwent preoperative investigations, which included highresolution computed tomography (CT) scanning of the temporal bone and magnetic resonance imaging (MRI) of the brain. Children with sensorineural hearing loss who were diagnosed with additional disabilities, such as delayed milestones, cerebral palsy, and autism, were excluded from the study. Children with abnormal radiologic findings, including Mondini dysplasia and other incomplete partition defects, were also excluded. Parents of all the children were counseled extensively regarding the need for regular follow-up, the requirement for auditory verbal therapy, and the need to devote extra care and time to the child. As part of our routine protocol, selected children were inoculated preoperatively with meningococcal, pneumococcal, and Haemophilus influenzae vaccination prior to cochlear implantation. Most of the children underwent unilateral cochlear implantation. However, some children underwent bilateral implantations as well. All the children receiving bilateral implants underwent the implantations sequentially. There were no patients who underwent simultaneous bilateral implantation in the study population. None of the children underwent sequential bilateral implantation in the 1-year follow-up period. These children attended postoperative auditory verbal therapy sessions for a prescribed period of 24 months. The auditory verbal therapist began with an initial assessment of the child's preoperative baseline performance, followed by auditory training, which included recognition, discrimination, and perception. This was followed by language training according to the child's performance. Postoperatively, CAP and MAIS scores were documented at 3, 6, 9, and 12 months of implant age. SIR scores were documented at 12 and 24 months of implant age in all the children who completed 2 years of follow-up. Children whose CAP, MAIS, and SIR scores were unavailable at the age of 1 year postimplantation were excluded from the analysis. All the available data were used for analysis until the time children were kept on a regular schedule for follow-up. Parents' education, family income, and distance of their residence from the therapy clinic were documented in each patient's case file. Either parent's highest educational qualifications were recorded. The CAP, MAIS, and SIR scores were compared at 12 months of age among the subcategories. A time period of 12 months was chosen because most of the children obtained maximum scores on the MAIS questionnaire by 1 year of implant age. However, speech intelligibility ratings could only be scored after the children had acquired some degree of understandable speech, which usually occurs by 1 year postimplantation.
able to talk on the phone with a familiar speaker. This was chosen because it reflects auditory performance in a more practical way [29]. 2.3.2. Meaningful auditory integration scale The MAIS is a parent-reported questionnaire in an interview format. The scoring system consists of 10 questions, which each question rated from 1 to 5 points. The lowest score is marked as 0 and the highest score is marked as 4. The total score is obtained by adding the points in each of the 10 questions. The MAIS examines the child's ability to associate sounds with events in his or her environment, which does not require the child to demonstrate word recognition skills [30]. This scale was chosen to assess children with different languages so as to achieve comparable results. 2.3.3. Speech intelligibility rating The SIR is a scale used to measure the intelligibility of spoken language in real life. It is a scale with points ranging from 1 to 5, wherein a score of 1 represents the fact that the child can speak prerecognizable words in spoken language, and a score of 5 indicates that the child's connected speech is intelligible to all the listeners. It is an internationally accepted measure of speech intelligibility in real-life situations [31]. The CAP and SIR scores were determined by the auditory verbal therapist who was responsible for the training and therapy of the selected children. Questionnaires for the MAIS were given to the parents by the auditory verbal therapist, and responses to each of the questions were noted in the respective patient's case file by the therapist. The CAP, MAIS, and SIR scores of all the 180 children, obtained at 12 months of implant age, were correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic. According to World Bank statistics, the per capita income in India is $1590 [32]. As per the Global Wealth Report by the Credit Suisse Research Institute, the mean wealth in India in 2016 was $3835 per adult. A nuclear family would have an average of $7670 in accumulated wealth [33]. The cost of cochlear implantation ranges from $11,000 to $22,000 (multiple device configurations are available at varying cost), which includes the costs of preoperative investigations and the device, surgical expenses, and postoperative auditory verbal therapy sessions. Families in a lower socioeconomic group often have to face a massive financial crisis to arrange adequate resources for treatment of their profoundly deaf child. We must take into account the fact that the parents of a child born with severe to profound hearing impairment are usually young and are still in the early part of their earning cycle; hence, they would have less accumulated wealth than if they were older. We divided our families into three income groups on the basis of their ability to afford an implant. Group 3 consisted of families who would be able to afford implantation only with a considerable part of the expense paid with external financial assistance, such as by the government, nongovernmental organization, or bank loan. Group 2 consisted of families who would be able to afford implantation, albeit with some difficulty, and group 1 was comprised of families who would be able to afford implantation without any significant financial difficulty. 2.4. Categorization by parents' education
2.3. Assessment of postoperative outcomes 2.3.1. Categories of auditory performance CAP scores were used to measure the degree of auditory perception. This scale ranges from 0 to 7, wherein 0 represents no awareness of environmental sounds and 7 indicates that the child is
According to parents' education, children were divided in three groups, Group 1 consisted of children whose parents possessed a master's degree and higher, group 2 had children whose parents had completed a bachelor's degree, and group 3 had children whose parents had attended high school.
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Based on annual household income, children with families having an annual income of more than $15,000 were placed in group 1, those with families having an annual income between $7500 and $15,000 were placed in group 2, and those with families earning less than $7500 annually were placed in group 3. Similarly, children whose residence was within 30 miles from the auditory verbal therapy were categorized as group 1, those with a residence between the range of 30 miles and 310 miles were categorized as group 2, and those with a residence more than 310 miles from the auditory verbal therapy clinic were categorized as group 3. 2.5. Statistical analyses Statistical analyses were performed by the SPSS program for Windows, version 24.0. CAP, MAIS, and SIR scores of all the children obtained at 12 months of implant age were adjusted for age at implantation and were correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic using a generalized linear model. CAP and MAIS scores available at 6 and 9 months were also correlated with parents' education, family income levels, and distance of the residence from the speech therapy clinic using a generalized linear model. Quantitative data were expressed in terms of mean and standard deviation. Categorical data were expressed as absolute number and percentage. Cross tables were generated, and the Pearson chi-squared test was used for the testing of associations. A p value less than 0.05 was considered statistically significant. Relative risks and odds ratios, along with 95% confidence intervals, were the preferred measures of effect size. The age at implantation was calculated with respect to date of birth. Age was used as a continuous variable for statistical analysis. However, in many cases, the age information elicited from parents was recorded as an approximate figure of 1, 2, 3 or 4 years as compared to other children whose exact date of birth and exact age were known. This resulted in the heaping of ages at certain age points. In view of this, the level of significance considered for age was 10% as against the conventional 5%. 3. Results Between January 1, 2006 and December 1, 2014, 364 patients with bilateral profound sensorineural deafness underwent cochlear implant surgery in our center. Of these 364 patients, there were 205 children whose chronologic age at the time of implantation was 4 years or younger. Of these 205 children, 180 children with normal intellect and radiologically normal cochleovestibular anatomy completed a minimum period of 1 year of follow-up (see Chart 1). 3.1. Age at implantation Children up to the chronologic age of 4 years at the time of implantation were included, with a mean age of 2.7 years, minimum age of 8 months, and maximum age of 4 years. Out of 180 children, 111 children's ages were available as approximate figures of 1, 2, 3, and 4 years and the rest of the children's ages were available as exact figures. Socioeconomic status was also correlated with age at implantation. Rising socioeconomic status showed a significant correlation, with children belonging to a higher socioeconomic group receiving implants at a younger age as compared to children of a lower socioeconomic group, with a p value of 0.018 (see Tables 1e4).
Chart 1. Selection of patients based on exclusion criteria.
Table 1 Chronologic age at the time of implantation. Age at implant
Number of children
Less than 1 year 1 - 2 year 2-3 year 3-4 year
6 68 53 53
3.2. Categorization There were 41 children (22.7%) whose parents attended high school, 110 children (61.1%) whose parents possessed a bachelor's degree (graduates), and 29 children (16.12%) whose parents had completed a master's degree or higher qualification (e.g., postgraduate, postdoctoral). Children's postimplantation performance scores were also correlated with their family incomes and were subdivided into three groups. Group 1 had 20 children (11.11%), group 2 had 101 children (56.11%), and group 3 had 59 children (32.78%). Children were also divided into three groups based on the distance of the auditory verbal therapy clinic from their residence. There were 85 children (47.22%) in group 1 with a distance less than 30 miles (50 km), 46 children (26.11%) in group 2 with a distance between 30 miles (50 km) and 310 miles (500 km), and 49 children in group 3 (26.67%) with a distance greater than 310 miles (500 km). Also, CAP and MAIS scores were correlated with all the measured parameters at 6 and 9 months postimplantation in 136 children. Scoring at 6 and 9 months could only be done for 136
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Table 2 Correlation between socioeconomic status and age at implantation. Age group at implant (Years)
Income per annum < $ 7500 n ¼ 59 (32.78%)
$ 7500e15,000 n ¼ 101(56.11%)
> $ 15,000 n ¼ 20(11.11%)
Total n ¼ 180
< ¼ 1.5 1.6e1.9 2.0e2.4 2.5e2.9 3.0e3.4 3.5e3.9 3.9e4.0
2 (3.4%) 3 (5.1%) 17 (28.8%) 8 (13.6%) 10 (13.6%) 8 (13.6%) 11 (18.6%)
14 (13.9%) 9 (8.9%) 21 (20.8%) 7 (6.9%) 26 (25.7%) 3 (3.0%) 21 (20.8%)
1 5 4 0 6 1 3
17 17 42 15 42 12 35
(5.0%) (25.0%) (20.0%) (0.0%) (30.0%) (5.0%) (15.0%)
(9.4%) (9.41%) (23.3%) (8.3%) (23.3%) (6.7%) (19.4%)
Pearson Chi-Square value ¼ 24.447; p-value ¼ 0.018*.
Table 3 Number of children in all the three groups in the three categories. Category
Parents Education
Annual Family income
Distance of patient's residence from speech therapy clinic
Group 1 Group 2 Group 3
29 (16.12%) 110 (61.11%) 41 (22.7%)
20 (11.11%) 101(56.11%) 59 (32.78%)
85(47.22%) 46(26.11%) 49(26.67%)
Parents Education. Group 1 e possessing master's degree and above, Group 2 e possessing bachelor's degree, Group 3 e attended high school. Annual Family income. Group 1 - > $ 15,000, Group 2 - $ 7500 e $15,000, Group 3 - < $7500. Distance of speech therapy clinic from patient's residence. Group 1 - < 30 miles, Group 2 - 30e310 miles, Group 3 - > 310 miles.
children because scores for the rest of the children were available only at 12 months postimplantation. Scoring for the rest of the children was carried out at 5, 8, or 10 months after implantation and hence could not be used for statistical analysis at 6 and 9 months.
Children in families having an annual family income higher than $15,000 performed significantly better as compared to families with an annual family income from $7500 to $15,000, with a p value of 0.008. No correlation was observed for CAP and MAIS scores obtained at 6 and 9 months with annual family income.
3.3. Interpretation
3.3.4. Distance from speech therapy clinic This was also a categorical variable. Children living within a 30mile (50-km) radius from the speech therapy clinic were chosen as the reference category because it was hypothesized that there would be a better outcome as compared to other groups. No correlation was observed between MAIS and SIR scores, but CAP scores were found to be significantly higher in children residing at a distance of 30 miles (50 km) and 310 miles (500 km) from the speech therapy clinic, with a p value of 0.022. Also, CAP and MAIS scores at 6 and 9 months showed no correlation with distance from the speech therapy clinic.
3.3.1. Age at implantation CAP, MAIS, and SIR scores at 12 months were found to be higher with decreasing age at implantation, with p values of 0.061, 0.099, and 0.087, respectively. CAP scores at 6 months were higher in children with a younger age at implantation, with a p value of 0.01. However, a similar correlation was not observed with MAIS scores at 6 months. CAP and MAIS scores at 9 months also showed a similar correlation, with higher scores attained by children of younger ages and p values of 0.022 and 0.077, respectively. 3.3.2. Parents' education Because this was a categorical variable, children whose parents possessed a master's degree or higher (e.g., postgraduate, postdoctoral) were chosen as a reference category for comparison with other groups, assuming that the children of these parents would perform the best as compared to the other groups. However, no correlation was observed among the CAP, MAIS, and SIR scores obtained at 1 year of age with the education level of the parents in our study. Also, no correlation was obtained between CAP and MAIS scores obtained at 6 and 9 months of implant age with parents' education. 3.3.3. Annual family incomes This was also a categorical variable, so families with an annual income higher than $15,000 were chosen as reference category because they were considered to be most advantaged of the groups studied. No correlation was observed between CAP and MAIS scores obtained at 12 months of age between any of the three categories. However, a significant correlation was observed in SIR scores.
4. Discussion Our subset of children is unique in that we have multicultural diversity, ethnicity, and, languages in India. Through this study, our goal was to assess the impact of age at implantation, socioeconomic status of the family and parents' education on postimplantation outcome. Our study has concurred with the results of previous studiesdthat a younger age at implantation leads to better outcomes in terms of speech perception and language acquisition [2,10]. CAP scores at 6 months were found to be higher in children with a younger age at implantation, whereas similar results were not duplicated in MAIS scores at 6 months. This may be because MAIS is a parent-reported questionnaire, which is a measure of gross auditory skills with a lesser requirement for fine skills and speech understanding. Hence, most children are able to achieve similar scores postimplantation, even if they are of an older age at the time of implantation. According to our study, socioeconomic status did not seem to have a significant impact on the performance of children after
0.486 0.646 0.137 1.071 1.5351 0.763 1.6591 0.993 0.6684 0.512 0.3188 0.404 0.3461 0.36 0.1388 0.671 0.309 0.077 0.466 0.3458 0.369 0.3753 0.35 0.1506
0.178 0.325 0.022
0.467 1.0989 1.208 1.1877 0.847 0.4785
4.1. Comparison with previous studies
Reference category (#). Education e Parents possessing Post Graduate/Post Doctoral degrees. Income e Parents with annual familial income > 15,000 $. Distance e Families having residences < 50 km (30 miles) from the speech therapy clinic.
0.212 0.421 0.087 0.24 0.1953 0.16 0.1982 0.15 0.088 0.08 0.393 0.099 1.666 0.9522 0.826 0.9663 0.708 0.4292 0.022 0.466 0.061 0.48 0.2082 0.15 0.2113 0.18 0.0938
95
cochlear implantation. Also, the assumption that the distance of the parents' residence from the speech therapy clinic would affect the child's frequency of attending speech therapy sessions and thereby affect the final outcome of the child was not supported by our results. However, the SIR was significantly higher in children in families with an annual income more than $15,000. This is may be explained by the fact that CAP and MAIS scores assess the child's auditory perception and response and integration with sound, whereas SIR scores measure the intelligibility of spoken language. The intelligibility of speech can be affected by the quality of education, access to books, and better schooling. Speech perception and auditory integration were acquired by most children appreciably well postimplantation, irrespective of socioeconomic status. However, speech intelligibility could have differed due to differing familial and social environments and exposure to improved auditory visual stimulation in households with higher annual incomes.
0.108 0.243 0.011
0.829 0.349 0.545 2.5167 1.424 1.5199 0.402 0.302 0.306 0.188 0.32 0.3163 0.37 0.28
1.212 1.4468 1.323 1.2808
0.54 0.2967 0.7 0.2627
0.069 0.008
0.121 0.1
0.5672 0.3433
0.831 0.775
0.672 1.8016 1.351 1.0881
0.5229 0.3166 0.152 0.01 0.709 0.215
0.771 0.974
0.32 0.656 2.3826 1.8282 0.437 0.533 0.785 0.346 0.09 0.3137 0.232 0.246
1.115 1.435 0.701 1.125
0.09 0.2943 0.2 0.2307
0.763 0.378
0.654 0.364
0.54 0.4154
0.226 0.381
1.005 1.251
1.7056 1.3088
0.4979 0.383 0.61 0.345 0.556 0.339
0.22 0.367
2.367 0.814
2.5922 33.46 0.5413 5.148 1.8557 39.113 0.5871 6.524 0.3751 2.895 1.8289 41.104 0.3999 7.107
(Intercept) Education# Graduation School Income# Less than 7500 $ 7500e 15,000 $ Distance# 50 - 500 km >500 km Age at implant
Std. Error p-value
MAIS at 6 months
Std. Error p-value B
CAP at 6 months
Std. Error p-value B
MAIS at 9 months
Std. Error p-value B
CAP at 9 months
Std. Error p-value B
SIR at 12 months
Std. Error p-value B
MAIS at 12 months
Std. Error p-value B B
CAP at 12 months Parameter
Table 4 CAP, MAIS and SIR scores at 12, 9 and 6 months of age being adjusted for age at implant and correlated with annual family income, parents education, and distance of residence from speech therapy clinic.
S. Sharma et al. / International Journal of Pediatric Otorhinolaryngology 102 (2017) 90e97
Previous studies investigating the relationship between socioeconomic factors and cochlear implant outcomes have shown varied results. In Turkey, a study by Ozcebe et al. has shown that poor socioeconomic status and low levels of education in the family are responsible for a delay in cochlear implantation [15]. This may partly be attributed to a lack of awareness regarding the existence and benefits of cochlear implantation and difficult access to medical facilities. Our study has shown similar results, with children from a higher socioeconomic group receiving implants at younger ages as compared to children of a lower socioeconomic group. Niparko et al.’s study of language development following cochlear implantation has concluded that children with a higher socioeconomic status achieve greater improvement in spoken language and comprehension [34]. This was somewhat similar to the results of our study because in our study the children of families with a higher income achieved higher SIR scores, although similar results were not seen in the CAP and MAIS scores. Chang et al. have observed that children in a lower socioeconomic group had higher rates of postoperative complications, decreased follow-up compliance, and lower rates of sequential bilateral implantation [35]. A study by Holt and Svirsky [36] has reflected results similar to those in our study. They found no relationship between estimated family income and spoken word recognition of children with cochlear implants, although they did establish a relationship between estimated income and receptive and expressive language. Children from families with a higher estimated income had faster rates of receptive language development but slower rates of expressive language development. 4.2. Reasons for difference in results The lack of a clinically significant difference in postimplantation outcomes because of the presence of varying distances between the child's home and speech therapy clinic could partly be attributed several factors. For example, families whose residence was far from the clinic often temporarily shifted their household to a residence near the therapy clinic for 6e12 weeks to ensure regular and intensive auditory verbal therapy sessions, three to five sessions per week. After completion of this period, parents were instructed to bring their children to the clinic every 6e8 weeks for a minimum of 3 or 4 days for assessment and therapy. Children's vacations and midterm holidays were also used to account for missed classes. In contrast, children who resided in the same city as the speech therapy clinic averaged two sessions per week. We hypothesize that parents who had to spend a large part of
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S. Sharma et al. / International Journal of Pediatric Otorhinolaryngology 102 (2017) 90e97
their savings or take loans for the peri-implantation expenses were highly motivated in their attempts to get the best possible outcome for the child, essentially as much value for their money as possible. Most of them appeared to belong to the lower socioeconomic group. These parents took the time and sacrificed their routine for work to follow the program set out for their child. This may be one of the factors that would have helped children from a lower socioeconomic group make up for the difference and perform as well as their peers from a higher socioeconomic group. This could have been facilitated by exhaustive preoperative counseling sessions for the parents to help them understand the importance of protracted postoperative auditory verbal therapy, along with maximal aural stimulation at home. Staff at the speech therapy clinic made special efforts to contact children who had missed their appointments. In particular, reminders were sent to children in remote locations to inform them about their next appointment to ensure better compliance. Even after the surgery, parents were regularly counseled about maximizing verbal communication with their child. The need for regular follow-up was also emphasized. 4.3. Limitations This study was a pragmatic, retrospective, observational study in which no power calculations or predetermined size of relevant differences was made. There are a few other limitations as well. CAP, MAIS, and SIR, which are measures of gross auditory development and speech intelligibility, were used to evaluate outcomes. However, comprehensive test scores for receptive or expressive language were not recorded for all the children. CAP and SIR are internationally accepted for the assessment of postoperative outcomes with those who speak different languages. They are nonlinear and hierarchic scales, with poor accuracy [37]. Nevertheless, these tests are suitable for very young children who have yet not developed requisite linguistic skills and the behavior necessary for a more formal assessment [38]. Further studies are needed in the Indian subcontinent to analyze the effects of socioeconomic status on receptive and expressive language development after cochlear implantation. Another shortcoming of our study has been the short duration of follow-up. Many of the families live far from the clinic and belong to the lower socioeconomic group; hence, they were unable to follow up regularly after 1-year postimplantation due to factors related to financial constraints and absenteeism from work, and the outcomes were compared at 1 year of age. Consequently, SIR ratings could not be determined for all the children at 2 years of age. To offset these deficiencies and limitations, the speech therapy clinic has started enrolling children for remote mapping sessions because this provides a service for families who live far from the clinic. To ensure regular follow-up and for consistent monitoring of outcomes, the clinic has also started regular therapy sessions via Skype for families who are unable to visit the clinic in person. Postoperative cochlear implantation outcomes are influenced by numerous factors, of which only a few could be investigated here. Further studies are required to assess the long-term implications of socioeconomic variables on postimplantation outcomes. A greater understanding of these factors or variables would help clinicians make better and more informed decisions regarding counseling and intervention for implantees with poor performance. 5. Conclusion Cochlear implantation significantly improves auditory perception and the speech intelligibility of children suffering from profound sensorineural hearing loss. Earlier implantation leads to
significantly better results, so implantation at a younger age should be promoted and encouraged. Our study suggests that children who follow the designated program of postoperative mapping and auditory verbal therapy for a minimum period of 1 year seemed to do equally well in terms of hearing perception and speech intelligibility, irrespective of the socioeconomic status of the family. However, further studies are required to assess the impact of socioeconomic factors on long-term speech and language development after cochlear implantation, which may or may not replicate the results obtained after a short follow-up period of 1 year. Conflict of interest statement The authors report no conflict of interest. Institutional Review Board clearance has been obtained for this study. References [1] S. Archbold, M. Harris, G. O'Donoghue, T. Nikolopoulos, A. White, H.L. Richmond, Reading abilities after cochlear implantation: the effect of age at implantation on outcomes at 5 and 7 years after implantation, Int. J. Pediatr. Otorhinolaryngol. 72 (2008) 1471e1478. [2] M.A. Svirsky, A.M. Robbins, K.I. Kirk, D.B. Pisoni, R.T. Miyamoto, Language development in profoundly deaf children with cochlear implants, Psychol. Sci. 11 (2000) 153e158. [3] M.K. Cosetti, S.B. Waltzman, Outcomes in cochlear implantation: variables affecting performance in adults and children, Otolaryngol. Clin. North Am. 45 (2012) 155e171. [4] H. Zhou, Z. Chen, H. Shi, Y. Wu, S. Yin, Categories of auditory performance and speech intelligibility ratings of early-implanted children without speech training, PLoS One 8 (2013) e53852. [5] H. Hiraumi, J. Tsuji, S. Kanemaru, K. Fujino, Cochlear implants in post-lingually deafened patients, Ito J. Acta Otolaryngol. Suppl. 557 (2007) 17e21. [6] C. O'Neill, G.M. O'Donoghue, S.M. Archbold, T.P. Nikolopoulos, T. Sach, Variations in gains in auditory performance from pediatric cochlear implantation, Otol. Neurotol. 23 (2002) 44e48. [7] A.F. Snik, M.J. Makhdoum, A.M. Vermeulen, J.P. Brokx, P.I. van den Broek, The relation between age at the time of cochlear implantation and long-term speech perception abilities in congenitally deaf subjects, Int. J. Pediatr. Otorhinolaryngol. 41 (1997) 121e131. [8] H. Fryauf-Bertschy, R.S. Tyler, D.M. Kelsay, B.J. Gantz, G.G. Woodworth, Cochlear implant use by prelingually deafened children: the influences of age at implant and length of device use, J. Speech Lang. Hear Res. 40 (1997) 183e199. [9] B. Pyman, P. Blamey, P. Lacy, G. Clark, R. Dowell, The development of speech perception in children using cochlear implants: effects of etiologic factors and delayed milestones, Am. J. Otol. 21 (2000) 57e61. [10] D.R. Moore, R.V. Shannon, Beyond cochlear implants: awakening the deafened brain, Nat. Neurosci. 12 (2009) 686e691. [11] A. Geers, C. Brenner, Background and educational characteristics of prelingually deaf children implanted by five years of age, Ear Hear 24 (Suppl) (2003) 2Se14S. [12] T.P. Nikolopoulos, H. Lloyd, S. Archbold, G.M. O'Donoghue, Pediatric cochlear implantation: the parents' perspective, Arch. Otolaryngol. Head. Neck Surg. 127 (2001) 363e367. [13] D. Wu, E.W. Woodson, J. Masur, J. Bent, Pediatric cochlear implantation: role of language, income, and ethnicity, Int. J. Pediatr. Otorhinolaryngol. 79 (2015) 721e724. [14] J.L. Wu, H.M. Yang, Y.H. Lin, Q.J. Fu, Effects of computer-assisted speech training on Mandarin-speaking hearing-impaired children, Audiol. Neurootol 12 (2007) 307e312. [15] E. Ozcebe, S. Sevinc, E. Belgin, The ages of suspicion, identification, amplification and intervention in children with hearing loss, Int. J. Pediatr. Otorhinolaryngol. 69 (2005) 1081e1087. [16] J. Nicholas, A. Geers, Expected test scores for preschoolers with a cochlear implant who use spoken language, Am. J. Speech Lang. Pathol. 17 (2008) 121e138. [17] R.I. Arriaga, L.C.T. Fenson, S.J. Pethick, Scores on the MacArthur communicative development inventory of children from low- and middle-income families, Appl. Psycholinguist. 19 (1998) 209e223. [18] C.M. Connor, T.A. Zwolan, Examining multiple sources of influence on the reading comprehension skills of children who use cochlear implants, J. Speech Lang. Hear Res. 47 (2004) 509e526. [19] A.V. Hodges, M. Dolan Ash, T.J. Balkany, J.J. Schloffman, S.L. Butts, Speech perception results in children with cochlear implants: contributing factors, Otolaryngol. Head. Neck Surg. 121 (1999) 31e34. [20] G.M. O'Donoghue, T.P. Nikolopoulos, S.M. Archbold, Determinants of speech perception in children after cochlear implantation, Lancet 356 (2005)
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