Socio-Emotional Development of Children with Cochlear Implant: A Systematic Review

Background Attaining socio-emotional competence is challenging for children with hearing impairment. There is wide recognition of children with cochlear implant (CI) indicating significant improvement in their speech and language abilities, however many factors may restrict their chance of having reciprocal social interactions. A significant improvement in speech and language does not automatically affirm the quality of social interactions. This present observation on social-emotional development addressed a more current representative population of children with hearing loss who have benefitted from cochlear implantation. Methods The research conducted a systematic review of selected articles from Scopus and PubMed databases, retrieved through three search-process keywords, namely socio-emotional, children and CI. The inclusion criteria only included journal articles published in English with empirical data from the year 2010–2019. The initial search had identified 189 potential abstracts and after removal of duplicates, only 38 eligible studies met the inclusion criteria. Results Among 38 studies reviewed, 19 studies showed comparable socio-emotional skills with peers in social interaction, empathy, emotion theory of mind and comprehension skills. Conversely, the other 19 studies presented underprivileged results in socio-emotional functioning mainly in identifying facial expression, regulating emotion and emotional cues in the auditory domain. Conclusion This review concluded that the socio-emotional development among children with CI, both at preschool-age and school-age, was not justified due to the heterogeneity in studies across measurement and small sample size. Also, the conclusion recommended extensive cross-referencing, mixed-mode research design, detailed distinguishing of socio-emotional functioning and identification of diverse groups of the population with impaired hearing as an approach to provide empirical evidence on socio-emotional functioning among children with CI in the future.


Introduction
In childhood curriculum among those with severe to profound hearing-impairment and children with cochlear implant (CI), certain key areas focus particularly on the auditory development such as hearing, sound, speech and language abilities (1)(2)(3)(4). However, it is evident that other micro areas, such as social and emotional, do not get the same emphasis.
Intervention among children with CI should not only be limited to auditory and language development, in that it should also focus on socio-emotional development to achieve holistic child development (5). The broadly reported socio-emotional development plays a crucial role in predicting different areas, such as mental health, academic achievement and even job performance (6)(7). Such development also hinges on an individual's self-esteem, the capability to form relationships and empathy skills (8).
Review Article | Socio-emotional development of CI children their development of social abilities (22)(23)(24)(25). Thus, the significant improvement of speech and language does not automatically project the good quality of social interaction.
The post-CI stage is a transition phase marked by major psychological and cognitive changes of emerging adulthood. Socio-emotional development among children with CI, neither in preschool-nor school-aged, was yet to be correlated with any specific causal reasons to poor social interaction. This study, therefore, systematically reviewed socio-emotional development concerning children with CI from the year 2010 onwards to address a more current representative population of children with hearing loss who have benefitted from cochlear implantation.

Methods
The study employed a systematic review that complies with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines to define clear objectives and permit a rigorous search of terms interrelated to socio-emotional development among children with CI (26).

Resources
An electronic search was executed on various forms of socio-emotional skills among children with CI by covering relevant literature databases (i.e. Scopus and PubMed). Scopus is one of the most robust databases of peerreviewed literature with more than 22,800 journals covering various subject areas such as health professions, medicine, psychology and social science. PubMed comprises more than 29 million citations for literature from MEDLINE, NLM's database of citations and abstracts in the fields of, among others, medicine, healthcare systems and preclinical sciences. All articles in the PubMed database are tagged with organised words on content and main topics to help accessor obtain better search results.

Systematic Review Process
The study performed a systematic review process in March 2019 involving four stages, namely literature identification, screening, selection of eligible articles and data extraction from the selected articles.
Accomplishing socio-emotional competence is challenging for children with impaired hearing as seen in the prevalence of socio-emotional difficulties in them that may range from 8% (9)-41.3% (10). Nowadays, the population size of children with hearing loss shows a decline due to early detection and identification of hearing loss among infants with hearing problems (11). Some of these children who went through early detection had the opportunity to access sound with the help of CI and digital amplification systems and therefore showed significant improvement in their speech and language abilities as compared to those without CI (12)(13)(14)(15)(16). Several studies suggested that the outcomes in terms of language abilities were compatible among children with CI and their peers (11)(12).
Theoretically, given the positive result in speech and language development among children with CI, the hypothesis indicates a boost in socio-emotional abilities after cochlear implantation (17). The past studies noted the expectation for these children to be able to overcome many of the socio-emotional problems. Unfortunately, reports indicated varying results among children with CI despite the oral language was a predominant mode of social communication and peer interaction. Logically, children with immature language ability may face difficulties in making friends within a mainstream setting (18). Nevertheless, the results suggested that children with CI who have comparable language abilities with their peers were persistently challenged by the social settings as they, too, encountered problems in establishing friendships (19). Such observations were evident in the children's population in Malaysia. Since 2015, parents have relatively expressed concerns about the below-average level of socio-emotional school readiness skills among children with CI compared to children with normal hearing at the centre for cochlear implantations established in Universiti Kebangsaan Malaysia (UKM) (20)(21).
Limited research is available in identifying the factors that may contribute to social incompetence among children with CI. Previous studies reported that a poor listening environment or the inability to differentiate an auditory signal may minimise the chances for reciprocal interactions. Other factors such as inappropriate pragmatic skills practised, immature perception of emotion and lack of strategies to remain in a group or constant failure to initiate communication may exacerbate

Selection of Eligible Articles
After exclusion of articles from screening and removal of duplicates, the targeted articles were assessed and analysed. Specific studies that answered to the formulated questions were then verified through understanding the abstracts and reading the full articles.

Data Extraction
Two investigators independently screened all unique article titles and abstracts to identify related articles. Disagreements were resolved by consensus. Thirty-eight eligible studies met the inclusion criteria. Data were extracted by reviewer using a pre-piloted form which was developed to list study characteristics including: measurement, research design, sample, findings and limitations. Data were then analysed using thematic method to identify the social and emotional functioning of children with CI.

Identification
The study performed a systematic search in Scopus and PubMed using keywords similar and related to social, emotion, children and CI based on thesaurus and past studies (Table 1). Table 2 highlights the eligibility and exclusion criteria for the studies reviewed. Selectively, the screening process only included journal articles published in English from the year 2010-2019 with empirical data to avoid any unnecessary confusions and difficulties in translation. The screening process also excluded review articles, book series, books, chapters in books and conference proceedings. All duplicates of articles were removed during screening. The identified period of nine years (from 2010-2019) worked as a timeline sufficient for the growth of research and related publications.

Socio-Emotional Development Among Preschool-Aged Children with Cochlear Implant
For preschool-aged children with CI, the study identified and reviewed a total of 15 studies (Table 3). Eight studies reported that children with CI showed positive social and emotional skills with peers (27)(28)(29)(30)(31)(32)(33)(34). Whilst findings from six studies among young preschoolers with an average age of 3 years old reported that these children were able to demonstrate equivalent skills of social interaction (27)(28)(29)(30)(33)(34) and empathy (28,30) in the survey, causalcomparative and correlational studies. The remaining two studies among preschoolers with an average age of 6 years old observed comparable social competency in older preschool-aged children with CI evident in their choice of recognising, processing and producing emotional content relevant to their environment (31)(32). The combination of early implantation and a regular auditory-oral-based therapy both played a crucial part in the positive outcomes for social and emotional functioning reported.
In contrast to the eight studies that reported positive social and emotional skills with peers in the children with CI, samples from the remaining seven studies reported underprivileged results of socio-emotional functioning among preschoolers with CI compared to their peers (5,(35)(36)(37)(38)(39)(40). In these studies, preschoolers' ages ranged 2 years old-6 years old and their

Results
Overall, the investigators managed to systematically review 38 studies published on the socio-emotional development of children with CI. All of the studies were quantitative in nature, despite the smaller sample size used. From the total of 38 studies, the majority of the study design, with a total number of 17, was reported to be survey whilst seven were crosssectional type and 10 were the longitudinal type. Other non-experiment research designs reported included seven correlational studies and 11 causal-comparative studies. Lastly, three studies provided a quasi-experiment research design with matching post-test-only control group type to support this review.

Discussion
From the review, there were only two studies that integrated child, caregiver and teacher's responses (50,56). Such limitation restricted the holistic view for researchers who attempted to create a triangulated profile of the socio-emotional development of children with CI. Triangulated profile is a two-pronged approach that can provide better results of socio-emotional skills and reduce bias with its numerous perspectives from different groups of the respondent. Indeed, one must factor in the time consumption and cost in collecting data from diverse groups, especially given the typically low-response rates of young children due to their immaturity in verbal expression. Furthermore, researchers may take a longer time to observe and interpret children's behaviours or performance. However, following the relatively low concurrence between child, caregiver and teacher's responses in this area, child's task performance and caregiver's view are still the priority in measuring the socio-emotional development among children with CI.
It is worth noting that there were different measures used to determine the socio-emotional development of children with CI, creating difficulties for researchers to conclude this area of research. Based on the systematically reviewed studies among preschool-and schoolaged children with CI, the results reported almost equal distribution, neither average nor poor socio-emotional development, compared to peers. The focus area of every research for child's task performance may be different, varying wide-range areas of empathy and social interaction (59), facial expression recognition (5,37), and emotional identification and regulation (36,54,58,61,63) among others. Meanwhile, a variety of caregiver-based questionnaires may report different socio-emotional outcomes of children due to the non-standardised scales of each questionnaire. For example, SDQ emphasised the domains of emotional symptoms, conducted problems, hyperactivity, peer-relationship problems and prosocial behaviour (30,36,39,50,(56)(57) whilst BASC-2 showed the domains of externalising problems, internalising problems, behavioural symptoms index, and adaptive skills (38). The result also suggested that an effective intervention plan included developing a practical, standardised measurement to capture certain socio-emotional domains of children with CI. social skills impairment were studied using the quasi-experiment, survey, causal-comparative and correlational studies.  (36,(38)(39) were administered to determine the poor socio-emotional development among these children with CI. Delayed facial expression identification (5, 37), poor emotional regulation strategies (36) and the limited ability to understand conveyed messages (40) contributed to low social competency among these preschoolers with CI.

Socio-Emotional Development Among School-Aged Children with CI
A total of 23 studies were reviewed for socio-emotional development among schoolaged children with CI (Table 4). Eleven studies showed a diminutive difference in the level of social and emotional skills between children with CI and those with normal hearing (41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51). Children with CI with an average younger schoolaged 6 years old-9 years old were observed to present compatible emotion theory of mind and comprehension skills (48, 52) compared to their peers (53). Whilst the result informed that older school-aged children with CI (10 years old-12 years old) were less likely to experience difficulties in emotion (42,46). These children were able to show voice emotion recognition comparable to adults with normal hearing (43).
On the contrary, 12 studies testified below the age-appropriateness level of socio-emotional development among school-aged children with CI. Certain studies reported that, although some CIs were implanted at an earlier age, school-aged CI children still persistently showed difficulties in socio-emotional functioning irrespective of their age groups (38,(53)(54)(61)(62)(63). Moreover, some results outlined that the socio-emotional development of children with CI was significant in a clinical range, although CI were implanted since below the age of 4 years old (60). A few studies reported that children with CI had poor emotional perception (58, 61) and were less accurate in identifying emotion cues in the auditory domain (54,63). They also presented a lack of empathy and lack of prosocial motivation to interact with peers (59).      Note: HA = Hearing-aid design were highly suggested for the future to circumvent the limitations of small sample size in order to obtain more conclusive and convincing outcomes. Some studies also indicated that music was one of the optimal stimuli to examine the abilities of children with CI as a way to distinguish emotions (54,58,61,(63)(64). A capability in identifying emotional content from the auditory stimuli, such as music with variations in pitch, amplitude and timing characters, may play an essential role in the lives of these children. CI provides the opportunity to restore not only sound but also the access to emotional cues through hearing. However, children with CI with good ability in distinguishing music emotions may not be able to anticipate quality social interaction. The lack of human voice stimuli may still potentially affect these children's ability in vocal emotion identification and may indirectly interfere with their socio-emotional functioning.
Majority of the studies that underwent systematic review here were reliant on caregivers for the questionnaires (i.e. SDQ and Empathy questionnaire) assessing socio-emotional functioning of children with CI (33, 35-36, 38-39, 50-51, 57, 60, 62). These questionnaires were short, easy to be administered and useful for caregivers to screen the children's level of socio-emotional development. However, these questionnaires did not measure socioemotional extensively. The child would need to be immediately referred to mental health professionals for a more in-depth and precise examination of overall development functioning. It is uncertain how the absence of more clinically sensitive methods may affect the level of socioemotional development in children with CI.

Conclusion
This systematic review highlighted the trend of research on socio-emotional development among children with CI. Overall outcomes of these research were varied. As discussed, a limited number of studies and heterogeneity factors (i.e. age, sample size, design and instruments) may have caused the failure to draw a considerable conclusion in this review. Many of the measure in the studies reviewed did not precisely distinguish between different categories and degree of social and emotional abilities. Furthermore, the bias in results interpretation was likely to happen as most data collection Another observation from this review denotes the imbalance among the types of data collection. Many more data collections tapped into the quantitative, as opposed to the qualitative or the mixed-mode method. The majority of reviewed studies indicated a preference for reports on quantitative data, although numbers of respondents were mostly small due to the unique population of cochlear implantation. On the contrary, qualitative research is almost always the starting point to discover new problems of a special population. Researchers might have overlooked certain areas of socio-emotional development as there was a myriad of studies designed to focus on quantitative data collection. Thus, it is advisable to find a balance between in-width and in-depth in data analysis to draw a reliable and comprehensive understanding of socioemotional development among children with CI. More qualitative and/or mixed-mode research are encouraged to justify the components of socio-emotional development feasible to cochlear implantation population.

Recommendations
This systematic review has thoroughly analysed the 38 selected studies. The studies comprised both preschool-and school-aged children with CI. A clear conclusion on the socio-emotional functioning among children with CI, however, could not be drawn due to the heterogeneity of these selected studies evident in several factors such as age, sample size, and varying designs and instruments. Another explanation for having divergent conclusions is likely due to the insufficient numbers of studies included in this study. The review did not include unpublished studies and the studies published in the non-English medium. Moreover, it did not perform an extensive cross-referencing of the reference lists from the papers retrieved in the electronic database. These methodological limitations could have, therefore, potentially excluded several relevant past studies.
Most of the studies involved were conducted using a small sample size. Reporting convincing results and generalising observations to the population level when sampling was deemed limited was difficult. The population with hearing impairment was considered a special group, therefore, reaching out and recruiting participants from this population were challenging. More studies with a mixed-mode was not based on a triangulated profile, which mostly only included the child and the caregiver's responses. Health professionals for children with CI and mental health researchers should put more effort to encourage more extensive future studies, particularly qualitative and/or mixedmode methods on socio-emotional development among children with CI. Future studies should take into account of diversities among children with hearing impairment too because that will provide the empirical evidence and the prevalence of socio-emotional development in Malaysia.