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Quality of life and associated factors among children with cochlear implants in Vietnam: Results from parents’ perception

Open AccessPublished:May 27, 2022DOI:https://doi.org/10.1016/j.cegh.2022.101078

      Abstract

      Objective

      This study was to assess the quality of life (QoL) of Vietnamese children with cochlear implants (CI) according to the perception of their parents, and to determine associated factors on the perceived QoL.

      Methods

      A cross – sectional study were conducted among 68 children (20 children aged 3–6 years, and 48 children aged 7–10 years) who had cochlear implantation at the Vietnam National Children's Hospital, Hanoi, from June 2020 to November 2021. Kiddy-KINDLR and KINDLR questionnaires were used to gather information on QoL of their children. Scores were transformed to a 100-point scale with 100 representing the most positive response.

      Results

      Parents of the 7–10 year group rated generic QoL more positively than the 3–6 year group, overall average scores were 72.1, and 69.6, respectively. Parents of 7–10 years also rated QoL of their children slightly below average than that of the standard hearing population in both girls, and boys. A significant inverse correlation was detected between the overall QoL and age at first cochlear implant (r = −0.284, p = 0.019), and duration of cochlear implant experience was positively correlated with overall mean QoL score (r = 0.268, p = 0.027). Higher level of father's education level showed better QoL among their children (p = 0.015).

      Conclusion

      The QoL of Vietnamese children with CI were slight lower than average compared with normal hearing children. Age at cochlear implant, cochlear implant use duration, and education level of father were influencing factors of the QoL of children with CI in Vietnam.

      Keywords

      1. Introduction

      World Health Organization estimated that disabling hearing loss affects around 466 million people worldwide in 2018, considering hearing loss as the most frequent sensory impairment. It is also predicted that the number of people with disabling hearing loss will rise in the upcoming years. In Vietnam, no universal newborn hearing screening program is available, therefore, data on hearing loss in newborns and children is limited in the country.
      • Lam A.
      • Stringer P.
      • Toizumi M.
      • et al.
      An international partnership analysis of a cohort of Vietnamese children with hearing impairment.
      Several studies showed that prevalence of hearing among pre-school children were from 4.4%
      • Xuong N.
      • Tran V.D.
      Prevalence of hearing loss among preschool children in Hanoi, Vietnam.
      to 4.7%.
      • Xuong N.
      • Vung N.
      • Huong T.
      • et al.
      Situation of hearing loss among children aged 2 to 5 at kindergartens in Hai Duong province, Vietnam.
      Early intervention programs, and greater access to hearing technology in Vietnam are highly recommended to reduce the prevalence and adverse long-term effect of hearing impairment among children.
      • Lam A.
      • Stringer P.
      • Toizumi M.
      • et al.
      An international partnership analysis of a cohort of Vietnamese children with hearing impairment.
      ,
      • Xuong N.
      • Tran V.D.
      Risk factors of hearing loss among preschool children in Hanoi, Vietnam.
      Previous studies, across different countries, have indicated that deaf children have significantly poorer reading comprehension, literacy skills, and overall depressed academic achievement in general when compared to their hearing peers.
      • Qi S.
      • Mitchell R.E.
      Large-scale academic achievement testing of deaf and hard-of-hearing students: past, present, and future.
      In addition, studies suggested that specialized mental health services for deaf and hard of hearing children and adolescents should be installed in educational settings and could contribute to early identification and therapy of those at risk of mental disorders.
      • Fellinger J.
      • Holzinger D.
      • Sattel H.
      • et al.
      Mental health and quality of life in deaf pupils.
      In recent years, cochlear implants (CI) has become an increasingly common aid for children born with sensorineural deafness in the western world. A cochlear implant is a hearing device that, through a surgically inserted electrode array in the cochlea, provides the acoustic nerve with electronic stimulation that is perceived as sound by the auditory cortex.
      • Wilson B.S.
      • Dorman M.F.
      • Woldorff M.G.
      • et al.
      Chapter 9 - cochlear implants: matching the prosthesis to the brain and facilitating desired plastic changes in brain function.
      CIs has enabled many children, and adults, to take part in mainstream society and education to a greater extent than what was previously possible for deaf individuals, by providing them the ability to hear and acquire spoken language.
      • Duarte I.
      • Santos C.C.
      • Rego G.
      • et al.
      School failure in students who are normal-hearing or deaf: with or without cochlear implants.
      Health-related QoL, which we refer to as QoL, encompasses the physical and psychosocial aspects of an individual's perception of their position in life.

      The WHOQOL Group, editor The Development of the World Health Organization Quality of Life Assessment Instrument (The WHOQOL)1994; Berlin, Heidelberg: Springer Berlin Heidelberg.

      QoL is an important outcome measure that is widely used for clinical and research purposes to assess the impact of acute and chronic diseases, to compare affected individuals with healthy individuals, and to measure progress after treatment. It is known that QoL of children with hearing loss increases after receiving auditory rehabilitation alongside their hearing device such as a hearing aid or cochlear implant.
      • Roland L.
      • Fischer C.
      • Tran K.
      • et al.
      Quality of life in children with hearing impairment: systematic review and meta-analysis.
      ,
      • Tanamati L.
      • Costa O.
      • Bevilacqua M.
      Long-term results by using cochlear Implants on children: systematic review.
      However, there appears to be a lack of consistency within the literature regarding the comparison of QoL of children with and without hearing loss. In terms of associated factors, previous studies showed the factors influencing the QoL of the implanted children, including older age at the evaluation, mothers' level of schooling, and the family receptiveness.
      • Silva JdM.
      • Yamada M.O.
      • Guedes E.G.
      • et al.
      Factors influencing the quality of life of children with cochlear implants.
      Additionally, research also reported that birth order, gender, and distance from the cochlear implant center had effect on the QoL dimensions.
      • Alnuhayer O.
      • Alshawi Y.
      • Julaidan B.
      • et al.
      Quality of life and cochlear implant: results in Saudi children.
      QoL can be measured using generic and condition specific instruments.
      • Palermo T.M.
      • Long A.C.
      • Lewandowski A.S.
      • et al.
      Evidence-based assessment of health-related quality of life and functional impairment in pediatric psychology.
      The strength of generic instruments lies in their ability to enable comparisons among children with different medical conditions, as well as make comparisons with healthy populations.
      • Limbers C.A.
      • Ripperger-Suhler J.
      • Boutton K.
      • et al.
      A comparative analysis of health-related quality of life and family impact between children with ADHD treated in a general pediatric clinic and a psychiatric clinic utilizing the PedsQL.
      ,
      • Nguyen S.N.
      • Phuong Thao N.T.
      • Quynh Van P.T.
      • et al.
      First report on health-related quality of life among children with chronic immune thrombocytopenia in Vietnam.
      However, they lack precision and sensitivity, particularly when the assessor wants to target outcomes for a specific health condition.
      • Davis E.
      • Mackinnon A.
      • Davern M.
      • et al.
      Description and psychometric properties of the CP QOL-Teen: a quality of life questionnaire for adolescents with cerebral palsy.
      In contrast, condition-specific (or disease-specific) QoL instruments are designed for application with a particular medical condition or sensory impairment.
      In Vietnam, CI has been performed for more than ten years. However, due to required complicated technical and facilities, this surgical has just been some national hospitals in Hanoi, Hue, and Ho Chi Minh City. In Hanoi, the National Children's Hospital is the main hospital to perform CI for children in the North of Vietnam. The purpose of this study was to assess the QoL of children were cochlear implanted according to the perception of their parents, and to determine associated factors on the perceived QoL.

      2. Methods

      2.1 Study design

      This cross-sectional study was performed between July 2020 to November 2021.

      2.2 Participants

      Parents of sixty-eight children using cochlear implants between 3 and 10 years of age who had cochlear implant in the Vietnam National Hospital's Children, Hanoi, Vietnam from June 2012 to July 2019 were invited in the study.

      2.3 Materials

      2.3.1 Demographic questionnaire

      This form collected socio-economic and demographic information to enable assessment of potential relationships between participant variables and QoL outcomes. This structured questionnaire contains socio-demographic variables (age, sex), educational variables (school system and school environment) of the children, auditory history variables (age of identification of hearing loss, age at activation of the cochlear implant, duration of cochlear implant experience, and chronologic age at time of testing), general information of parents of the children (education levels, occupations).

      2.3.2 KINDLR questionnaires

      To measure the QoL among the children with CI, this study used the Kiddy-KINDLR for 3-6-year-old children, and KINDLR 19 for 7-17 year-old children interview version for parents. The KINDLR 19 is an established generic health-related QoL measure designed for children between the ages of 3 and 17 years. The generic QoL instrument, Kiddy-KINDLR, and KINDLR, previously have been validated and translated into Vietnamese. They are available for free download [http://www.kindl.org/]. The questionnaires were tested and culturally adapted before using in this current study.
      The Kiddy-KINDLR and the KINDLR contain 24 items in six multi-dimensional subscales: emotional well-being, family, friends, physical well-being, school, and social well-being. These six subscales sum to an overall index score. Each score is transformed to a 100-point scale, with 0 denoting minimal QoL and 100 denoting maximal QoL. In addition to the 24 items, the parents’ version of Kiddy-KINDLR plus 22 items designed to supplement the limited information provided by the child self-report questionnaire.
      • Ravens-Sieberer U.
      • Monika B.
      KINDLR Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents - Manual.
      In this study, only 24 items in six dimensions were analyzed.
      Parents response categories included five points on a Likert scale: never, seldom, sometimes, often, and all of the time. We interviewed parents to response the questionnaire independently of the child to ensure the answers reflected the parent's assessment of the child's well-being.

      2.4 Procedure

      The parents of children who were cochlear implanted in the Vietnam National Children's Hospital were contacted and invited into study via telephone by investigator. In total, sixty-eight parents of children (20 children aged 3–6 years, 48 children aged 7–10 years) with CI agreed to participate phone interview. On average, the interview took less than 20 min to complete the questionnaires. Participants were free to ask for clarification for any of the questions, and were also informed that there was no right or wrong answer their honest opinion was all that was required. All completed questionnaires were verified by the investigator to ensure that the data was accurate, legible, and completed before the participants left.

      2.5 Ethic

      The research received approval of the Institutional Ethic Board of the Vietnam National Children's Hospital with approval number 514/BVNTW-VNCSKTE dated April 17, 2020. All participants were informed about the purpose of the study and verbal consent were obtained before interviewing. The study ensured that the participant's data will be confidential, private, and only used for research purposes.

      2.6 Statistical analysis

      For data analysis, we followed instructions of the KINDL questionnaire for measuring health-related quality of life in children and adolescents manual.
      • Ravens-Sieberer U.
      • Monika B.
      KINDLR Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents - Manual.
      Collected data of each dimension were transformed from the two KINDLR questionnaires into 100. All aspects and the overall scores of QoL were subjected to statistical analysis. Sub-scale QoL scores among 7–10 years was compared to the reference values for corresponding age-groups and sexes.
      • Ravens-Sieberer U.
      • Monika B.
      KINDLR Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents - Manual.
      Non-parameter test were applied to compare the differences between the two groups. Spearman correlations were computed to investigate associations between the children's transformed scores for each dimension, and overall QoL and auditory history variables such as age of identification of hearing loss, age at cochlear implant, duration of cochlear implant experience, and chronologic age at time of testing. The significance level was set at 0.05, and SPSS 26.0 software was used for statistical analyses.

      3. Results

      Table 1 shows the general information of children with CI and their parents accordingly. Sixty-eight children with their parents participated in the study. The participants were divided into two groups 3–6 years (20 children), and 7–10 years (48 children). The average age of the participants were 8.2 years. They were diagnosed for hearing loss at 15 months. Age at first cochlear implant among the children is 2.9 years. Majority of the children have used CI for more than 4 years. More than 95% of the implanted children study in public mainstream.
      Table 1General information of the participants.
      CharacteristicsBoth3–6 year group (n = 20)7–10 year group (n = 48)
      Current age (years): mean (SD)8.2 (2.2)5.08 (0.96)9.59 (0.62)
      Gender: Boy n (%)45 (66.2)13 (65.0)32 (66.7)
      Birth order in the family
       First-born31 (45.6)8 (40.0)23 (47.9)
       Middle-born37 (54.4)7 (35.0)22 (45.8)
       Last-born8 (11.8)5 (25.0)3 (6.3)
      Age at diagnosis (in months): mean.(SD)15.4 (8.7)14.85 (8.65)15.69 (8.76)
      Degree of hearing loss
       Severe4 (5.9)04 (8.3)
       Deaf64 (94.1)20 (100)44 (91.7)
      Bilateral/unilateral implantation
       Unilateral67 (98.5)20 (100)47 (97.9)
       Bilateral1 (1.5)01 (2.1)
      Age at first cochlear implant (years): mean (SD)2.9 (1.2)2.6 (0.5)3.1 (1.4)
      Cochlear implant use duration (years): mean (SD)5.2 (2.3)2.4 (0.8)6.4 (1.6)
      Cochlear implant use duration (year)
       ≤4 years22 (32.4)18 (90.0)4 (8.3)
       >4 years46 (67.6)2 (10.0)44 (91.7)
      Current school environment
       Mainstream public65 (95.6)20 (100)45 (93.8)
       Mainstream private1 (1.5)01 (2.1)
       Special needs2 (2.9)02 (4.2)
      Level of education of father
       Less high school12 (17.6)2 (10)10 (20.8)
       High school15 (22.1)7 (35.0)8 (16.7)
       College/University39 (57.4)10 (50)29 (60.4)
       Post-graduate2 (2.9)1 (5.0)1 (2.1)
      Level of education of mother
       Less high school14 (20.6)3 (15.0)11 (22.9)
       High school16 (23.5)8 (40.0)8 (16.7)
       College/University38 (55.9)9 (45.0)29 (60.4)
      Occupation of father
       Farmer14 (20.6)5 (25.0)9 (18.8)
       Worker8 (11.8)2 (10.0)6 (12.5)
       Public staff/clerk/teacher23 (33.8)2 (10.0)21 (43.8)
       Businessmen21 (30.9)10 (50.0)11 (22.9)
       Others2 (2.9)1 (5.0)1 (2.1)
      Occupation of mother
       Farmer14 (20.6)5 (25.0)9 (18.8)
       Worker6 (8.8)1 (5.0)5 (10.4)
       Public staff/clerk/teacher27 (39.7)5 (25.0)22 (45.8)
       Businesswomen15 (22.1)7 (35.0)8 (16.7)
       Others6 (8.8)2 (10.0)4 (8.3)
      The QoL of each dimension and total is reported in Table 2. For both group, the QoL ranges from 60.1 in school to 74.5 in physical well-being. The QoL of 3–6 year group is less than their counterpart in the 7–10 year group in all of the dimensions and total as well, however, the differences were only statistically significant in Emotional well-being and Self-Esteem dimensions (p < 0.05).
      Table 2Quality of life with KINDL QoL subscales and total scores among children with CI.
      DimensionsBoth

      Mean (SD)
      3–6 year group

      Mean (SD)
      7–10 year group

      Mean (SD)
      p
      Mann-Whitney test.
      Physical well-being74.5 (3.7)73.4 (5.6)75.0 (2.5)0.315
      Emotional well-being74.0 (3.7)72.1 (5.1)74.8 (2.7)0.018
      Self-Esteem67.6 (9.2)62.5 (10.7)69.7 (7.6)0.007
      Family76.0 (5.9)74.3 (6.9)76.6 (5.4)0.238
      Friends76.2 (5.7)75.3 (8.2)76.6 (4.4)0.936
      School or Nursery School60.1 (11.3)60.3 (13.4)60.0 (10.5)0.785
      Total71.4 (4.5)69.6 (6.4)72.1 (3.2)0.383
      a Mann-Whitney test.
      In comparison to the preliminary reference healthy children, the large sample of Hamburg school children, QoL of children aged 7–10 years in the current study are slightly below than their counterpart in both girls and boys in all dimensions except the self-esteem in both girls and boys. Scores for self-esteem in the present study were higher than that in the reference healthy group in both girls (71.6 compared to 66.6), and boys (68.9 compared to 66.5) (Table 3).
      Table 3Quality of life with KINDL QoL subscales and total scores (mean, transformed to 100, standard deviation) among children with CI and standard hearing ones by gender population (mean, transformed to 100 and standard deviation).
      Dimensions7–10 year group

      Mean (SD)
      Standard hearing

      Mean (SD)
      7–10 year group

      Mean (SD)
      Standard hearing

      Mean (SD)
      GirlsGirlsBoysBoys
      Physical well-being75.3 (4.2)74.4 (14.1)74.8 (1.1)76.6 (13.0)
      Emotional well-being74.6 (3.5)83.1 (11.3)75.0 (2.2)82.9 (10.6)
      Self-Esteem71.4 (6.8)66.6 (17.8)68.9 (8.0)66.5 (18.9)
      Family77.5 (4.9)84.4 (12.8)77.5 (4.9)83.5 (13.1)
      Friends77.3 (3.1)78.1 (13.7)76.3 (4.9)78.2 (12.7)
      School57.8 (10.3)74.1 (12.2)61.3 (10.6)72.3 (12.8)
      Total71.9 (3.2)76.8 (8.6)72.2 (3.3)76.6 (8.6)
      Table 4 illustrates the association of the studied factors with KINDL QoL subscales and total scores among children with CI. No statically differences between QoL subscales and total scores, and gender, birth order in the family, level of mother's education (p > 0.05). The father's education showed to be a significant predictor of School QoL (p = 0.006) and overall QoL score (p = 0.015). Fathers with higher education levels demonstrated better QoL in school and total scores among their children. We did not find any association between remaining factors (as shown in Table 1) with the QoL scores of the children (data not show).
      Table 4The association of the studied factors with KINDL QoL subscales and total scores among children with CI.
      VariablesPhysical well-being

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Emotional well-being

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Self-Esteem

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Family

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Friends

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      School or Nursery School

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Total

      Mean (SD)
      p
      Man-Whitney or Kruskal–Wallis test.
      Gender
      Boys74.7 (1.3)0.70574.3 (3.5)0.33867.0 (9.0)0.39376.8 (5.7)0.10675.9 (6.3)0.50460.0 (11.6)0.96971.4 (4.3)0.984
      Girls74.1 (6.3)73.6 (4.1)68.7 (9.6)74.4 (6.2)76.9 (4.3)60.3 (11.0)71.3 (4.9)
      Birth order in the family
      First-born75.0 (2.2)0.67374.7 (2.5)0.33569.1 (7.5)0.32877.4 (5.9)0.06575.6 (6.1)0.41259.2 (12.1)0.70271.8 (4.1)0.872
      Middle-born74.7 (2.6)74.1 (3.2)67.4 (9.6)75.2 (5.9)76.5 (5.7)60.1 (10.6)71.3 (4.3)
      Last-born71.8 (8.8)71.0 (7.4)62.5 (12.5)73.4 (5.5)78.1 (4.7)63.2 (11.7)70.0 (6.8)
      Level of education of father
      Less high school75.0 (2.6)0.96572.9 (6.1)0.61468.7 (8.4)0.12975.0 (4.6)0.05576.0 (3.6)0.06454.6 (10.0)0.00670.3 (3.2)0.015
      High school73.3 (6.8)73.3 (4.3)62.9 (10.9)72.9 (7.3)72.9 (7.7)53.7 (13.1)68.1 (5.9)
      College/University74.8 (2.2)74.6 (2.4)68.9 (8.5)77.2 (5.4)77.7 (5.1)64.2 (9.6)72.9 (3.6)
      Post-graduate75.0 (3.7)75.0 (0)71.8 (4.4)81.2 (0)75.0 (0)59.3 (4.4)72.9 (1.4)
      Level of education of mother
      Less high school75.0 (2.45)0.88473.2 (5.7)0.82968.3 (7.9)0.20775.8 (4.8)0.37274.5 (6.2)0.44654.0 (11.9)0.06770.1 (3.6)0.144
      High school73.4 (2.2)73.8 (4.0)64.0 (11.0)74.2 (7.1)75.7 (6.4)58.9 (13.4)70.0 (6.1)
      College/University74.8 (2.2)74.5 (2.6)68.9 (8.6)76.8 (5.7)77.1 (5.2)62.8 (9.4)72.5 (3.8)
      a Man-Whitney or Kruskal–Wallis test.
      Spearman correlations were computed to investigate associations between the children's transformed scores for overall QoL and auditory history variables such as age of identification of hearing loss, age at first cochlear implant, duration of cochlear implant experience, and chronologic age at time of testing (Table 5). A significant inverse correlation was detected between the overall QoL and age at first cochlear implant (r = −0.284, p = 0.019), suggesting that children were implanted earlier CI have better QoL. In addition, CI use duration (years) was positively correlated with overall mean QoL score (r = 0.268, p = 0.027). That is, children having longer time of CI have better QoL. No correlation between age of children and age of onset and overall mean QoL scores was found. We only found a significant positive correlation with current age of children and the QoL score in self-esteem (r = 0.335, p = 0.005).
      Table 5The correlation of the studied factors with KINDL QoL subscales and total scores among children with CI.
      VariablesPhysical well-beingEmotional well-beingSelf-EsteemFamilyFriendsSchool or Nursery SchoolTotal
      Age (years)r0.0030.1870.3350.0950.066−0.0430.126
      p0.9790.1260.0050.4390.5910.7250.305
      Age of identification of hearing loss (years)r−0.0050.043−0.128−0.010−0.067−0.173−0.140
      p0.9650.7300.2990.9340.5890.1580.255
      Age at cochlear implant (months)r−0.093−0.146−0.183−0.168−0.174−0.157−0.284
      p0.4500.2340.1340.1710.1560.2010.019
      Cochlear implant use duration (years)r0.0780.2290.4240.1970.1370.0210.268
      p0.5250.061<0.0010.1080.2670.8650.027
      r: Spearman correlation.
      p: p values.

      4. Discussion

      To the best of our knowledge, this is the first study assessing the QoL among children aged 3–10 years with CI in Vietnam from the perspective of their parents and examining some possible associated factors. The study found that parents rated QoL scores of children aged 3–6 years less positively than that among the 7–10 year group. In comparison to the standard hearing children,
      • Ravens-Sieberer U.
      • Monika B.
      KINDLR Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents - Manual.
      our study found that QoL scores of the 7–10 year group are slightly worse in almost all subscales and overall scores in boys, and girls. In the view of the parents the age at implantation, the length of time with CI have significant correlated with QoL in their children (p < 0.05).
      Warner-Czyz et al. (2009)
      • Warner-Czyz A.D.
      • Loy B.
      • Roland P.S.
      • et al.
      Parent versus child assessment of quality of life in children using cochlear implants.
      showed that parents rated QoL among children with CI aged 4–6 years using the Kiddy KINDL questionnaire as 78.1 (9.6) in overall score, higher than that among the present study. For the 7–10 year group, our study found similar overall QoL score with previous study, 72.1 (SD = 3.2) in the present study compared to 75.4 (SD = 9.2) in study conducted in America
      • Warner-Czyz A.D.
      • Loy B.
      • Tobey E.A.
      • et al.
      Health-related quality of life in children and adolescents who use cochlear implants.
      but better QoL in comparison to the study conducted by Huber, M (2005)
      • Huber M.
      Health-related quality of life of Austrian children and adolescents with cochlear implants.
      using the same KINDL questionnaire. It is noted that the QoL scores among 7–10 year group in the current study are only slightly less than the overall scores of the standard hearing boys and girls
      • Ravens-Sieberer U.
      • Monika B.
      KINDLR Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents - Manual.
      in almost all of the dimensions, and overall, suggesting that the effectiveness of the CI among children. Previous studies, both original and systematic review assessing the long term results by using CI on children, showed that CI effectively contributed to develop the functional communication abilities, hearing performance, and an appropriate language acquisition, comparable to normal hearing children.
      • Tanamati L.
      • Costa O.
      • Bevilacqua M.
      Long-term results by using cochlear Implants on children: systematic review.
      ,
      • Peixoto M.C.
      • Spratley J.
      • Oliveira G.
      • et al.
      Effectiveness of cochlear implants in children: long term results.
      Regarding associated factors of QoL among children with CI, our finding is consistent with the previous studies in which age of CI is significantly correlated with QoL of children.
      • Alnuhayer O.
      • Alshawi Y.
      • Julaidan B.
      • et al.
      Quality of life and cochlear implant: results in Saudi children.
      ,
      • Warner-Czyz A.D.
      • Loy B.
      • Tobey E.A.
      • et al.
      Health-related quality of life in children and adolescents who use cochlear implants.
      ,
      • Huber M.
      Health-related quality of life of Austrian children and adolescents with cochlear implants.
      ,
      • Noroozi M.
      • Nikakhlagh S.
      • Angali K.A.
      • et al.
      Relationship between age at cochlear implantation and auditory speech perception development skills in children.
      It has been reported that children who had earlier exposure to sounds (especially those who underwent implantation by 3.5 years of age) have better opportunities for age-appropriate auditory development, normal development of central auditory pathways, resulting in they were more integrated and involved with the surroundings and less likely to feel isolated and left behind.
      • Loy B.
      • Warner-Czyz A.D.
      • Tong L.
      • et al.
      The children speak: an examination of the quality of life of pediatric cochlear implant users.
      In addition, the present study also found that duration of CI use showed positive correlation with QoL of the children. This is inconsistent with study conducted by Warner-Czyz (2011)
      • Warner-Czyz A.D.
      • Loy B.
      • Tobey E.A.
      • et al.
      Health-related quality of life in children and adolescents who use cochlear implants.
      founding that a negative correlation between duration of CI use and QoL among the CI children was reported by children self-reported. Studies demonstrated that there are significant differences in rating QoL between children-self-reported and parental proxy.
      • Alnuhayer O.
      • Alshawi Y.
      • Julaidan B.
      • et al.
      Quality of life and cochlear implant: results in Saudi children.
      Therefore, the results may be influenced by different point of views. Previous studies confirmed the effectiveness of CI in improving QoL among children, and the benefits appear to keep stable over the years.
      • Peixoto M.C.
      • Spratley J.
      • Oliveira G.
      • et al.
      Effectiveness of cochlear implants in children: long term results.
      Majority of children in the current study have implanted the device for more than 4 years, their parents could be happy with the stabilized device. Although relatively weak associations between the QoL and the several factors found (r < 0.3), it is acceptable in research on QoL.
      • Warner-Czyz A.D.
      • Loy B.
      • Tobey E.A.
      • et al.
      Health-related quality of life in children and adolescents who use cochlear implants.
      Previous studies found more factors that can influence the perceived QoL among CI, including birth order, gender,
      • Sarant J.Z.
      • Harris D.C.
      • Galvin K.L.
      • et al.
      Social development in children with early cochlear implants: normative comparisons and predictive factors, including bilateral implantation.
      and level of parent's education.
      • Silva JdM.
      • Yamada M.O.
      • Guedes E.G.
      • et al.
      Factors influencing the quality of life of children with cochlear implants.
      However, in this study we only found the education level of father is the influencing factor of QoL among their CI children in addition to the age of CI and duration CI use. For birth order, although some might argue that first-born children might get more attention than their siblings, middle-born children were found to have a higher emotional, psychosocial, and total score compared to the first-born children. This might be explained by the fact that older siblings can enrich aspects of younger children's language development through “overheard” conversations.
      • Alnuhayer O.
      • Alshawi Y.
      • Julaidan B.
      • et al.
      Quality of life and cochlear implant: results in Saudi children.
      More research need to be conducted in the future to identify associated factors of QoL among children with CI.
      The strengths of this study include use of a qualified generic QoL instrument, exploring CI-specific QoL in a large cohort of children aged 3–10 years using CI, and the impact of some social characteristics on the results. The generic QoL instruments, Kiddy-KINDL, and KINDLR, previously have been validated and translated into Vietnamese. However, this study has some limitations. First, this is a cross sectional study design. Therefore, at this stage no causing variables can be specified and no information can be provided on changes of QoL of deaf children, caused by the medical treatment of cochlear implantation. Second, lack of data for QoL scores of a Vietnamese healthy matched age, sex group for comparison is another limitation of the current study. Although the study compared the obtained QoL scores of the Vietnamese 7–10 year children with the reference values, it may not well reflex the truth as Vietnamese children differ from European children in terms of characteristics and socio-economic status. Further follow-up studies are necessary to be conducted to measure the changes of QoL before and after CI.
      • Velanovich V.
      The quality of quality of life studies in general surgical journals.
      Regardless of the limitation the study has yielded for the first time basic information on the level of health-related QoL of children with CI. This is obviously not only relevant for professionals, but also very important for other parents.

      5. Conclusion

      From the parents’ perspective, QoL of their children with CI were slightly below average in comparison to hearing counterparts. Age at cochlear implant, cochlear implant use duration, and education level of father were influencing factors of the QoL of children with CI.

      Source of funding

      The study received no funding

      Declaration of competing interest

      The authors declare that they have no competing interests.

      Acknowledgement

      The authors wish to thank all the parents who participated in this study for their time and collaboration.

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