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Agreement in quality of life assessment between adolescents with intellectual disability and their parents
Research in Developmental Disabilities 34 (2013) 1863–1869
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Research in Developmental Disabilities
Agreement in quality of life assessment between adolescents with intellectual disability and their parents Sˇpela Golubovic´, Renata Sˇkrbic´ * University of Novi Sad, Faculty of Medicine, Department of Special Rehabilitation and Education, Serbia
A R T I C L E I N F O
A B S T R A C T
Article history: Received 24 January 2013 Received in revised form 8 March 2013 Accepted 8 March 2013 Available online 10 April 2013
Intellectual disability affects different aspects of functioning and quality of life, as well as the ability to independently assess the quality of life itself. The paper examines the agreement in the quality of life assessments made by adolescents with intellectual disability and their parents compared with assessments made by adolescents without intellectual disability and their parents. Participants included 67 adolescents with intellectual disability and the same number of their parents. Control group consisted of 122 typically developed adolescents and an equal number of their parents. In order to assess the quality of life we used The PedsQL 4.0 Generic Core Scale questionnaire, for adolescents aged between 13 and 18 and their parents. Agreement in assessing quality of life between adolescents and parents was analyzed using t-test, Kappa Statistics and Pearson correlation. The agreement between adolescents with intellectual disability and their parents was found to be acceptable (k = 0.43), while the agreement between adolescent from control group and their parents was judged to be good (k = 0.84). Correlations between adolescents with intellectual disability and their parents varied across subscales from weak (r = 0.31) on the physical health subscale to moderate (r = 0.56) on the social subscale. Adolescents with intellectual disability were less satisfied with their social functioning. The highest agreement, as well as the lowest means value was found on the social agreement scale. Assessment of the quality of life by both adolescents and their parents provides a comprehensive insight into functioning and different aspects of quality of life in these adolescents. ß 2013 Elsevier Ltd. All rights reserved.
Keywords: Developmental disability Health-related quality of life PedsQL Assessment
1. Introduction Quality of life is a multidimensional construct that depends on our physical and social environment, as well as on our emotional and existential reactions to the environment (Cummins, 2005; Fairclough, 2010). Renwick and Brown (1996) considered that quality of life should be viewed as a dynamic process that can change over time and can be assessed at any point in time (Renwick & Brown, 1996). The quality of life of persons with disabilities has been studied through the prism of rehabilitation, health and medical care, health promotion and to a lesser extent education (Brown & Brown, 2003). To date,
* Corresponding author at: University of Novi Sad, Faculty of Medicine, Department of Special Rehabilitation and Education, Hajduk Veljkova 3, 21000 Novi Sad, Serbia. Tel.: +381 21420677. E-mail address: [email protected] (R. Sˇkrbic´). 0891-4222/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2013.03.006
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researches have shown that the quality of life for children with developmental disabilities is lower than the quality of life for children without developmental disabilities, as well as that different disabilities have different effects on the quality of life in general and in specific aspects of functioning (Watson & Keith, 2002). In recent years, attention has been given to the quality of life of children with different types of disability and thus the subject of researches were children with multiple disabilities (cerebral palsy, attention deficit hyperactivity disorder, children with developmental disabilities due to cognitive and sensory impairments (Arkkila et al., 2009; Boulton, Haines, Smyth, & Fielder, 2006; Limbers, Heffer, & Varni, 2009; Rajendran & Roy, 2010; Shipman, Sheldrick, & Perrin, 2011; Tadic´ et al., 2010; Thurston, Paul, Loney, Wong, & Browne, 2010; Varni & Burwinkle, 2006). Results of these researches showed that the quality of life of children with developmental disabilities is lower than the quality of life for children without developmental disabilities (Arkkila et al., 2009; Boulton et al., 2006; Limbers et al., 2009; Rajendran & Roy, 2010; Shipman et al., 2011; Tadic´ et al., 2010; Thurston, Paul, Loney, Wong, & Browne, 2010; Thurston, Paul, Ye, Loney, Browne & Thabane, 2010; Varni & Burwinkle, 2006). The quality of life of children has declined in proportion to the severity of impairment, as well as the presence of related disorders or other chronic diseases. Also, the quality of life decreased with the age of children and the older children had lower quality of life than younger children (Thurston, Paul, Ye, et al., 2010). A number of studies have shown that the psycho-social aspects of life were more in danger than physical aspects. Due to the inability to obtain an adequate response of children with developmental disabilities, assessment was most often made by their parents, teachers, educators and therapists (Limbers et al., 2009; Thurston, Paul, Loney, et al., 2010). A certain number of researches have taken into account the self-assessment of a child with developmental disabilities and the assessment of his/her parents, thus gaining a holistic picture of the child’s quality of life (Eiser & Morse, 2001; Shipman et al., 2011; Varni & Burwinkle, 2006; Varni, Limbers, & Burwinkle, 2007). In some studies where assessments were made by the children and their parents, there was a low to moderate agreement between the responses, especially when it comes to children with intellectual disability (Janssen, Schuengel, & Stolk, 2005; McVilly, Burton-Smith, & Davidson, 2000). Parents tend to assess the quality of life of their children lower than do children (Shipman et al., 2011; Varni & Burwinkle, 2006). Although self-assessment is seen as the standard for measuring quality of life, in some cases, when a child is too young, with developmental and cognitive disability, too sick or exhausted, it is necessary to take into account the assessment of the quality of life of the child performed by a parent, guardian, educator, teacher and so on. In order for a child to be eligible to perform the assessment of his/her quality of life, he/she needs to reach a certain developmental level, which includes competency in verbal comprehension, understanding and use of the concepts of time, differences in developmental milestones and identification of the quality of life domains and important milestones (Wallander, Schmitt, & Koot, 2001). Taking into account the specificities of certain types of disabilities, as well as the individual needs of children and their parents should serve the process of making a plan to provide developmental disability services, programs, individual interventions and treatments, monitoring the effects of new strategies (guidelines) in practical work with these children, with the aim to establish an optimal quality of life for children with developmental disabilities. The main objective of this study was to determine whether there is an agreement in the quality of life assessments made by adolescents with intellectual disability and their parents compared with assessments made by adolescents without intellectual disability and their parents. 2. Materials and methods 2.1. Participants The study included 189 adolescents aged 13–18 years and the same number of parents. The sample was divided into two groups. Group I comprised 67 adolescents, of which 35 (52.24%) boys and 32 (47.76%) girls with intellectual disability, with the mean age of 15 years and 10 months (SD = 14.74) and 67 parents of adolescents with intellectual disability. Based on data from school records on intellectual functioning level, in this group of adolescents 62 (92.54%) were students with the mild intellectual disability and 5 students (7.46%) were adolescents with moderate intellectual disability. All the participants in this group were recruited from special schools. The mean age of the parent/guardian/other person who completed the questionnaire related to the quality of life of the child was 44.3 years. Criteria for inclusion in the study were: intellectual disability without comorbidities, 13–18 year age range, knowledge of Serbian language and that participants lived with their parents or guardians. We obtained parent or guardian consent forms. Exclusion criteria included presence of hearing and visual impairments orthopedic, neurological, and severe behavioral disorders. These criteria were chosen in order to maintain homogeneity of the samples. Group II was the control group and comprised 122 adolescents with typical development and their 122 parents. Regarding gender this group comprised 62 (50.82%) boys and 60 (49.18%) girls, with the mean age of 15 years and 6 months. (SD = 15.70). Control group participants were selected from schools located in the same area as those attended by participants with ID. The mean age of the parents who completed the questionnaire was 43.55 years. Criteria for participation in the study were: parents or guardians consent form, children aged 13–18 years, knowledge of Serbian language and that children live with their parents or guardians. 2.2. Instruments The PedsQL 4.0 Generic Core Scale for adolescents aged 13–18 years has been used to assess the quality of life in this research (Varni, Seid, & Rode, 1999).
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The PedsQL Measurement Model is designed as a modular approach to measuring health-related quality of life in healthy children and adolescents and those with acute and chronic health conditions. It consists of parallel questionnaires for the child (self-report) by ages: 5–7, 8–12 and 13–18, and the parent (proxy-report) 2–5, 5–7, 8–12 and 13–18 year old children. The instructions are simple and clear, and it takes 5–10 min to complete it. The PedsQL 4.0 questionnaire consists of 23 items which include: (1) Physical functioning (8 items), (2) Emotional functioning (5 items), (3) Social functioning (5 items), and (4) School functioning (5 items). In each item, the question is how much a child has a problem in performing certain functions or activities during the past one month. Response scale contains five levels of scoring: 0 = never a problem, 1 = almost never a problem, 2 = sometimes a problem, 3 = often a problem, and 4 = almost always a problem. Data processing is performed by reverse scoring and linear transformation of the 0–100 scale, so that higher scores indicate a better quality of life (PedsQL: Scoring instruction, 2012). This scale showed satisfactory metric properties. Compared with the same purpose scales, it confirmed exceptionally substantial and constructive validity and easy interpretability (Matza, Swensen, Flood, Secnik, & Leidy, 2004). The scale is also shown to be sensitive and reliable (Varni, Seid, & Kurtin, 2001). Due to good psychometric reliability (Cronbach alpha coefficient 0.68–0.90) and validity, forms suitable for both children and parents, and adaptability to the child’s age, it is considered to be a well thought instrument for measuring quality of life (Palermo, Long, Lewandowski, Drotar, Quittner, & Walker, 2008). Version of the scale in Serbian language, culturally adopted, and permission for the use of the scale for this study was obtained from Mapi Research Trust. 2.3. Procedures The survey was conducted at three primary, three secondary and one special school. The questionnaires were sent to everyone who was within the same age group. A total of 350 questionnaires were distributed. There was 54% returned questionnaires with a signed consent. Adolescents with intellectual disability have been able to complete the questionnaire, but 83.58% were in need of help, in terms of reading the questionnaire aloud, and individual completion of the questionnaire. Time of completing the questionnaire was not limited. The questionnaire was completed by 63 (94.03%) parents of adolescents with intellectual disability and by 2 (2.98%) guardians. In two cases (2.98%), the questionnaire was completed by third parties (teacher and cousin). Of these, 27 (40.3%) were males and 40 (59.7%) females. In all 122 cases in the group of tipically developed adolescents, the questionnaire was completed or consented by the parents. In 103 (84.43%), the questionnaire was completed by the mother, while in 19 cases (15.57%) father did. 3. Results Reliability of PedsQL 4.0 was computed on the whole sample, separately for adolescents and parents. Cronbach alpha coefficient (a) ranged from 0.61 to 0.78 for questionnaire subscales completed by adolescents and between 0.68 and 0.85 completed by their parents .The coefficient of the summary scale of the questionnaire completed by adolescents was a = 0.86, and a little higher for parents a = 0.89. The lowest level on the basis of responses obtained from adolescents referred to the subscale related to the school functioning (a = 0.61). In both cases, the highest inter-item correlation referred to the social subscale. In adolescents it was 0.42, and in parents 0.55. Reliability of PedsQL 4.0 in the group of adolescents with intellectual disability ranged from a = 0.69 on the emotional functioning subscale to 0.82 on the physical health and psychosocial health subscales. The coefficient of the summary scale was a = 0.87. Reliability in the group of typically developing adolescents ranged from a = 0.59 on the school subscale to 0.73 on the physical health subscale. The coefficient of the summary scale was a = 0.80. In Table 1 are given the minimum and maximum values of the scale and subscale scores and using t test investigating differences between adolescents and parents reports for the group with intellectual disability. Adolescents with intellectual disability assessed their physical health as better than other aspects of quality of life. The mean value of the Total Score on the scale, on the basis of self-report in adolescents with intellectual disability was 76.78 (SD = 15.27). The widest range in this group was obtained on the social subscale, from 20 to 100. Two adolescents assessed quality of life with 100 points. Physical health was assessed by 16 adolescents with maximum score, emotional functioning – 12, social functioning – 16, and school functioning – 8. Parents of adolescents with intellectual disability assessed the quality of life of their children with the mean score of 66.99 (SD = 15.52). And they assessed the physical health of their children something better than other aspects of quality of life. Adolescents with intellectual disability, assessed their quality of life higher on all scales and subscales in relation to their parents. Significant differences were found between adolescents and
Table 1 The Quality of life of adolescents with intellectual disability (N = 67). Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents
Parents
Mean
Min
Max
SD
Mean
Min
Max
SD
80.60 74.75 71.87 76.94 75.45 76.78
25 41.67 35 20 30 41.30
100 100 100 100 100 100
18.52 16.08 20.45 21.90 17.23 15.27
69.64 65.57 64.18 64.93 67.61 66.99
12.50 8.33 15 0 10 9.78
100 100 100 100 100 100
20.21 15.87 20.09 21.40 18.37 15.52
t
p
3.28 2.20 3.40 2.58 3.46 3.79
0.000 0.03 0.00 0.01 0.00 0.00
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Table 2 The Quality of life of adolescents with typical development (N = 122). Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents
Parents
t
Mean
Min
Max
SD
Mean
Min
Max
SD
84.17 84.13 76.97 93.77 81.64 84.14
50 60 30 65 30 57.61
100 100 100 100 100 100
11.74 8.52 14.38 8.61 13.61 8.51
81.10 82.67 75.43 90.74 81.84 82.12
34.38 50 45 55 40 57.61
100 100 100 100 100 100
12.99 9.37 12.70 10.94 13.82 9.48
p
1.94 0.89 2.41 0.12 1.27 1.70
0.05 0.37 0.01 0.90 0.20 0.08
Table 3 Correlation between adolescent self- report and parent proxy-report for PedsQl 4.0. Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents with intellectual disability
Adolescents with typical development
Adolescents (Mean)
Parents (Mean)
Correlation (r)
Adolescents (Mean)
Parents (Mean)
Correlation (r)
80.60 74.75 71.87 76.94 75.45 76.78
69.64 65.57 64.18 64.93 67.61 66.99
0.31* 0.48** 0.39** 0.56** 0.42** 0.45**
84.17 84.13 76.97 93.77 81.64 84.14
81.10 82.67 75.43 90.74 81.84 82.12
0.50** 0.61** 0.59** 0.54** 0.51** 0.62**
* p 0.05. ** p 0.01.
parents mean scores in all subscales and on the total score, that is, adolescents rated their quality of life better than that reported by parents. Table 2 shows the maximum and minimum scale and subscale scores and differences between adolescents and parents reports estimated by the adolescents of typical development and their parents. Adolescents in the control group, on average, assessed equally their quality of life, so the mean Total Score of the scale was 84.14. In this group, the largest range of values obtained was in physical health, from 34.38 to 100 (SD = 12.99). In 10 cases parents assessed physical health of their children with the highest possible score. In 5 cases the maximum score was obtained on the emotional subscale, 53 on the social, and 17 on the school functioning subscale. Significant differences were found between adolescents and parents mean scores in the emotional functioning subscales, that is, adolescents rated their emotional life better than that reported by parents. The overall agreement between children and parents was analyzed using the Kappa Statistics (k). For Kappa values, the benchmarks published by Peat (2001) were used: values below 0.4 indicate poor agreement; 0.41–0.60, fair agreement; 0.61–0.80, good; and 0.81–1.00, very good agreement (Peat, 2001). Agreement between children with intellectual disability and their parents was found to be moderate k = 0.43, p < 0.01 while, it was shown high agreement between children from control group and their parents k = 0.84, p < 0.00 in assessment of quality of life. After analyzing the data obtained from the questionnaires for adolescents and parents about the quality of life of adolescents, agreement between their assessments was observed by Pearson correlation coefficient (r). The correlation can be: low (r < 0.40), moderate (0.41–0.60), high (0.61– 0.80), very high (0.81–1.00) (Varni et al., 2007b). The correlation between the assessment of adolescents with intellectual disability and their parents, is between 0.31 and 0.56 (Table 3). Low correlation was obtained on the scale of physical health (r = 0.31) and the emotional subscales (r = 0.39). Moderate correlation was found on the school functioning subscale (r = 0.42), the psychosocial summary scale (r = 0.48) and the social subscale (r = 0.56), and the total scale (r = 0.45). Adolescents with typical development also assessed their quality of life higher than it was assessed by their parents. The correlation between scales and subscales ranged between 0.50 and 0.62 (Table 3). 4. Discussion By analyzing questionnaires on the given sample based on Cronbach coefficient and average inter item correlation, we can say that the applied the PedsQL 4.0 Generic Core Scale has satisfactory reliability, and can be applied on the group data analysis. If we compare the reliability values, we obtained in the analysis of data, depending on who is completing the questionnaire, we can conclude that questionnaires completed by parents showed better reliability compared with those completed by adolescents By analyzing scores on the subscales, and the overall summary scale, based on self-report of adolescents, it was found that there is a difference in assessing the quality of life of adolescents with disability in relation to adolescents with typical development. Group of adolescents with intellectual disability assessed their quality of life lower than adolescents with typical development in most aspects of functioning. The highest scores reported by adolescents with
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intellectual disability were on the physical functioning subscale. Given that about 24% of children with intellectual disability on a scale of physical health had 100 points, it is possible that they do not fully understand the meaning of items or out of a desire to present themselves in the best light, as ‘‘strong’’, assessed more positively their physical health. Groups of adolescents with typical development, on average, had similar results as children of the general population in the researches in the world (Stevanovic´, Laketic´, & Damjanovic´, 2011; Varni et al., 2001). Previous studies conducted by the questionnaire PedsQl 4.0 showed that the average value of the psychosocial health scale on the sample of a group of children with typical development ranged from 79 to 82 (Varni & Burwinkle, 2006; Varni et al., 2007a). In children with developmental disability and chronic illnesses significantly lower score was obtained, below 70 (Varni & Burwinkle, 2006; Varni et al., 2007a). Based on the data obtained in this study, on the other total scale related to psychosocial health, statistically significant differences (p < 0.001) were found between adolescents with intellectual disability and children with typical development. Viewed individually, the psychosocial health scales gave an insight into which of functioning domains is more or less vulnerable. Interestingly, on the emotional subscale, where adolescents with intellectual disability rated their functioning lower, there was no statistically significant difference. In literature, in children without disabilities and without the presence of disease, emotional functioning ranges from the mean values of 77–82 points (Keilmann, Limberger, & Mann, 2007; Varni & Burwinkle, 2006). Compared to these values, the authors have encountered a significant difference between the groups of children with developmental disabilities and without developmental disabilities, which were not shown in our study, even though the value of emotional functioning in children without developmental disabilities was within limits obtained in the above research. Stevanovic´ et al. (2011) in his research on our population obtained the lower values of this aspect of functioning than the values obtained in both of our respondent groups. That developmental disability has a significant impact on social functioning showed a study of children with autism, psychiatric and attention deficit hyperactivity, and cerebral palsy (Shipman et al., 2011; Varni & Burwinkle, 2006; Varni et al., 2007a). In our study, adolescents with intellectual disability assessed lower their social functioning, compared to the second group. Adolescents in the control group markedly higher assessed this aspect of functioning, with a mean score of 93.77, which is higher than the value obtained by Stevanovic´ et al. (2011) for the general population of children from 8 to 18 years. Of all subscales related to psycho-social health, social functioning subscale gave the highest mean scores. As many as 67 (54.92%) of the adolescents with typical development assessed their social functioning with the maximum score. Almost 1/5 of adolescents with intellectual disability also assessed their social functioning with the maximum score. Based on our sample, we can say that the disability adversely affects the social aspects of quality of life. Children with typical development, in most studies have assessed their school functioning with the mean score of 75–82 (Varni & Burwinkle, 2006; Varni et al., 2001, 2007a). Group of adolescents with intellectual disability, assessed their school functioning lower compared to children with typical development, and the results obtained in the control group correspond to the previous research with the same questionnaire. The obtained values for the Total Score Scale indicate the fact that the quality of life of adolescents with intellectual disability is lower than in children with typical development. Compared with the data from the literature, adolescents with intellectual disability in our sample assessed their quality of life significantly better than children with autism, cerebral palsy, psychiatric disorders, attention deficit hyperactivity disorder (Shipman et al., 2011; Varni & Burwinkle, 2006; Varni et al., 2007a). ‘‘Who should be asked?’’ or whose opinion is to be relied upon, is the question specifically dealt with authors who have studied the quality of life for children with developmental disabilities (Zekovic & Renwick, 2003). The importance of taking into account the parents’ perception is reflected in the fact that the parent is still the one who knows the child best, and will make the final decision concerning treatment application. Agreement in assessing the quality of life of children and parents of general population shows that in most cases was found moderate agreement between the answers given by the children and their parents (Eiser & Morse, 2001). Among the factors that influenced the agreement were domains of functioning, the child’s age, living standards and targets, and health status (the presence of chronic illness, developmental disabilities) (McVilly, BurtonSmith, & Davidson, 2000). For children with intellectual disability, previous studies have shown a positive mild and moderate agreement between assessments of children and their parents (Janssen, Schuengel, & Stolk, 2005; McVilly et al., 2000). In our study, we got low and moderate agreement between the assessments of adolescents and their parents. This discrepancy might be explained by the fact that adolescents with intellectual disability socialize mostly with peers who have the same impairments, thus reporting greater satisfaction with their own functioning in all aspects of quality of life. Parents, on the other hand, tend to consider a broader context of their children’s functioning and are aware of the problems and social isolation they experience. Another possible explanation is that emotional reasons/factors (difficulty accepting children’s problems, parental stress) prevent parents from objectively judging their children’s situation and prompt them to overemphasize the influence of intellectual disability on quality of life. Low agreement was obtained on the physical functioning scale. Possible reason for such low agreement is the unrealistic picture of children on their physical functioning and the desire to appear in a better light. Interestingly, in another study of quality of life for children with developmental disabilities the highest agreement was obtained right on this scale (Shipman et al., 2011; Varni & Burwinkle, 2006). On the emotional subscale, was also obtained lower value than moderate agreement. Adolescents with intellectual disability and their parents assessed this aspect of functioning lower than other aspects. However, adolescents are more satisfied with their emotional functioning in terms of what their parents think. Other subscales had moderate agreement. Highest correlations between the agreement of adolescents and their parents had the social subscale, which supports the notion that parents and children experience in a similar way this aspect of functioning, and that adolescents are aware of their isolation in relation to the wider social framework. The obtained values are in favor of the fact that the adolescents with intellectual disability are able to assess the quality of their lives, but because we cannot be entirely sure that they understand the time and other
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abstract concepts that are included in the questionnaire, to obtain a more complete picture, it is also necessary to take into account the assessment of the parents (Janssen, Schuengel, & Stolk, 2005). In a sample of adolescents with typical development a high level of agreement in relation to the Total scale of assessments was obtained between adolescents and their parents. On the other subscales, there was a moderate correlation, except on the summary scale of psychosocial health, where the correlation was high. In this group, adolescents have higher average scores of their quality of life on all subscales, except for the school functioning, which parents assessed with slightly higher average score. Both parents and adolescents assessed with the lowest mean scores emotional functioning, and social functioning with the highest. This may be indicative of similar perspectives of parents and children, as well as the parents’ closeness and knowing of their children. Adolescents with typical development and their parents showed significantly higher agreement in perceptions of quality of life of adolescents compared to adolescents with intellectual disability and their parents. There is a need for further research of the reasons for the low agreement in children with intellectual disability, inter-item associations, the effects of children’s age and the degree of interference. 4.1. Limitations of the study, and the implications of the findings Our study has several potential limitations. We did not consider whether cognitive functioning level (mild intellectual disability or moderate intellectual disability), might be a factor influencing the level of agreement. Moreover, the study was conducted in one area, and it should be replicated to determine whether other socio-demographic factors might influence quality of life. Further studies should include adolescents with other disabilities in order to assess agreement between adolescent and parent reports. We believe that PedsQL 4.0 is suitable for adolescents with intellectual disability and that the obtained results can provide a greater insight into their needs, and consequently help us identify the fields in which they need further support or require adjustments of existing support programs. 5. Conclusion Obtained research results suggest that to improve the quality of life for children with intellectual disability, ongoing commitment is needed in providing expert support, assistance, and services, particularly in the domain of psychosocial health. By analyzing some aspects of quality of life, it was found that the psychosocial health was assessed lower than physical functioning both by adolescents with intellectual disability and their parents. There is a moderate agreement between adolescent self-report of quality of life and parent-proxy report. The lower correlation between assessments by adolescents with intellectual disability and their parents was obtained on the physical and emotional subscale, while on the others was a moderate correlation. The highest correlation, as well as the lowest average values were obtained on the social functioning subscale To obtain a more complete picture of the quality of life for children with developmental disability, requires further investigation, which would determine the effects of various factors on the quality of life of these children, follow up the success of applied treatments and determine further guidelines in working with children with developmental disability. References Arkkila, E., Ra¨sa¨nen, P., Roine, R. P., Sintonen, H., Saar, V., & Vilkman, E. (2009). Health-related quality of life of adolescents with childhood diagnosis of specific language impairment. International Journal of Pediatric Otorhinolaryngology, 73(9), 1288–1296. 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Stevanovic´, D., Laketic´, A., & Damjanovic´, M. (2011). Some psychometric properties of the Pediatric Quality of Life InventoryTM Version 4.0 Generic Core Scales (PedsQLTM) in the general Serbian population. Quality of Life Research, 20(6), 945–949. Tadic´, V., Hamblion, E. L., Keeley, S., Cumberland, P., Hundt, G. L., & Rahi, J. S. (2010). ‘Silent voices’ in health services research: Ethnicity and socioeconomic variation in participation in studies of quality of life in childhood visual disability. Investigative Ophthalmology and Visual Science, 51(4), 1886–1890. Thurston, S., Paul, L., Loney, P., Wong, M., & Browne, G. (2010). The quality of life of a multidiagnosis group of special needs children: Associations and costs. International Journal of Pediatrics. http://www.hindawi.com/journals/ijped/2010/940101/. Accessed 10.12.2012. Thurston, S., Paul, L., Ye, C., Loney, P., Brown, G., Thabane, L., et al. (2010). Interactions among ecological factors that explain the psychosocial quality of life of children with complex needs. International Journal of Pediatrics. http://www.hindawi.com/journals/ijped/2010/404687/. Accessed 10.12.2012. Varni, J. W., & Burwinkle, T. M. (2006). The PedsQLTM as a patient-reported outcome in children and adolescents with attention-deficit/hyperactivity disorder: A population-based study. Health and Quality of Life Outcomes, 4(1), 26. Varni, J. W., Seid, M., & Kurtin, P. S. (2001). PedsQL 4.0TM: Reliability and validity of the pediatric quality of life inventory TM version 4.0 Generic Core Scales in healthy and patient populations. Medical Care, 39(8), 800–812. Varni, J., Limbers, C., & Burwinkle, T. (2007a). Impaired health-related quality of life in children and adolescents with chronic conditions: A comparative analysis of 10 disease clusters and 33 disease categories/severities utilizing the PedsQLTM 4.0 Generic Core Scales. Health and Quality of Life Outcomes, 5(1), 43. Varni, J., Limbers, C., & Burwinkle, T. (2007b). How young can children reliably and validly self-report their health-related quality of life? An analysis of 8591 children across age subgroups with the PedsQLTM 4.0 Generic Core Scales. Health and Quality of Life Outcomes, 5, 1. Varni, J., Seid, M., & Rode, C. (1999). The PedsQLTM: Measurement model for the pediatric quality of life inventory. Medical Care, 37(2), 126–139. Wallander, J., Schmitt, M., & Koot, H. (2001). Quality of life measurement in children and adolescents: Issues, instruments and applications. Journal of Clinical Psychology, 57(4), 571–585. Watson, S. M. R., & Keith, K. D. (2002). Comparing the quality of life of school-age children with and without disabilities. Mental Retardation, 40(4), 304–312. Zekovic, B., & Renwick, R. (2003). Quality of life for children and adolescents with developmental disabilities: Review of conceptual and methodological issues relevant to public policy. Disability & Society, 18(1), 19–34.
Contents lists available at SciVerse ScienceDirect
Research in Developmental Disabilities
Agreement in quality of life assessment between adolescents with intellectual disability and their parents Sˇpela Golubovic´, Renata Sˇkrbic´ * University of Novi Sad, Faculty of Medicine, Department of Special Rehabilitation and Education, Serbia
A R T I C L E I N F O
A B S T R A C T
Article history: Received 24 January 2013 Received in revised form 8 March 2013 Accepted 8 March 2013 Available online 10 April 2013
Intellectual disability affects different aspects of functioning and quality of life, as well as the ability to independently assess the quality of life itself. The paper examines the agreement in the quality of life assessments made by adolescents with intellectual disability and their parents compared with assessments made by adolescents without intellectual disability and their parents. Participants included 67 adolescents with intellectual disability and the same number of their parents. Control group consisted of 122 typically developed adolescents and an equal number of their parents. In order to assess the quality of life we used The PedsQL 4.0 Generic Core Scale questionnaire, for adolescents aged between 13 and 18 and their parents. Agreement in assessing quality of life between adolescents and parents was analyzed using t-test, Kappa Statistics and Pearson correlation. The agreement between adolescents with intellectual disability and their parents was found to be acceptable (k = 0.43), while the agreement between adolescent from control group and their parents was judged to be good (k = 0.84). Correlations between adolescents with intellectual disability and their parents varied across subscales from weak (r = 0.31) on the physical health subscale to moderate (r = 0.56) on the social subscale. Adolescents with intellectual disability were less satisfied with their social functioning. The highest agreement, as well as the lowest means value was found on the social agreement scale. Assessment of the quality of life by both adolescents and their parents provides a comprehensive insight into functioning and different aspects of quality of life in these adolescents. ß 2013 Elsevier Ltd. All rights reserved.
Keywords: Developmental disability Health-related quality of life PedsQL Assessment
1. Introduction Quality of life is a multidimensional construct that depends on our physical and social environment, as well as on our emotional and existential reactions to the environment (Cummins, 2005; Fairclough, 2010). Renwick and Brown (1996) considered that quality of life should be viewed as a dynamic process that can change over time and can be assessed at any point in time (Renwick & Brown, 1996). The quality of life of persons with disabilities has been studied through the prism of rehabilitation, health and medical care, health promotion and to a lesser extent education (Brown & Brown, 2003). To date,
* Corresponding author at: University of Novi Sad, Faculty of Medicine, Department of Special Rehabilitation and Education, Hajduk Veljkova 3, 21000 Novi Sad, Serbia. Tel.: +381 21420677. E-mail address: [email protected] (R. Sˇkrbic´). 0891-4222/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2013.03.006
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researches have shown that the quality of life for children with developmental disabilities is lower than the quality of life for children without developmental disabilities, as well as that different disabilities have different effects on the quality of life in general and in specific aspects of functioning (Watson & Keith, 2002). In recent years, attention has been given to the quality of life of children with different types of disability and thus the subject of researches were children with multiple disabilities (cerebral palsy, attention deficit hyperactivity disorder, children with developmental disabilities due to cognitive and sensory impairments (Arkkila et al., 2009; Boulton, Haines, Smyth, & Fielder, 2006; Limbers, Heffer, & Varni, 2009; Rajendran & Roy, 2010; Shipman, Sheldrick, & Perrin, 2011; Tadic´ et al., 2010; Thurston, Paul, Loney, Wong, & Browne, 2010; Varni & Burwinkle, 2006). Results of these researches showed that the quality of life of children with developmental disabilities is lower than the quality of life for children without developmental disabilities (Arkkila et al., 2009; Boulton et al., 2006; Limbers et al., 2009; Rajendran & Roy, 2010; Shipman et al., 2011; Tadic´ et al., 2010; Thurston, Paul, Loney, Wong, & Browne, 2010; Thurston, Paul, Ye, Loney, Browne & Thabane, 2010; Varni & Burwinkle, 2006). The quality of life of children has declined in proportion to the severity of impairment, as well as the presence of related disorders or other chronic diseases. Also, the quality of life decreased with the age of children and the older children had lower quality of life than younger children (Thurston, Paul, Ye, et al., 2010). A number of studies have shown that the psycho-social aspects of life were more in danger than physical aspects. Due to the inability to obtain an adequate response of children with developmental disabilities, assessment was most often made by their parents, teachers, educators and therapists (Limbers et al., 2009; Thurston, Paul, Loney, et al., 2010). A certain number of researches have taken into account the self-assessment of a child with developmental disabilities and the assessment of his/her parents, thus gaining a holistic picture of the child’s quality of life (Eiser & Morse, 2001; Shipman et al., 2011; Varni & Burwinkle, 2006; Varni, Limbers, & Burwinkle, 2007). In some studies where assessments were made by the children and their parents, there was a low to moderate agreement between the responses, especially when it comes to children with intellectual disability (Janssen, Schuengel, & Stolk, 2005; McVilly, Burton-Smith, & Davidson, 2000). Parents tend to assess the quality of life of their children lower than do children (Shipman et al., 2011; Varni & Burwinkle, 2006). Although self-assessment is seen as the standard for measuring quality of life, in some cases, when a child is too young, with developmental and cognitive disability, too sick or exhausted, it is necessary to take into account the assessment of the quality of life of the child performed by a parent, guardian, educator, teacher and so on. In order for a child to be eligible to perform the assessment of his/her quality of life, he/she needs to reach a certain developmental level, which includes competency in verbal comprehension, understanding and use of the concepts of time, differences in developmental milestones and identification of the quality of life domains and important milestones (Wallander, Schmitt, & Koot, 2001). Taking into account the specificities of certain types of disabilities, as well as the individual needs of children and their parents should serve the process of making a plan to provide developmental disability services, programs, individual interventions and treatments, monitoring the effects of new strategies (guidelines) in practical work with these children, with the aim to establish an optimal quality of life for children with developmental disabilities. The main objective of this study was to determine whether there is an agreement in the quality of life assessments made by adolescents with intellectual disability and their parents compared with assessments made by adolescents without intellectual disability and their parents. 2. Materials and methods 2.1. Participants The study included 189 adolescents aged 13–18 years and the same number of parents. The sample was divided into two groups. Group I comprised 67 adolescents, of which 35 (52.24%) boys and 32 (47.76%) girls with intellectual disability, with the mean age of 15 years and 10 months (SD = 14.74) and 67 parents of adolescents with intellectual disability. Based on data from school records on intellectual functioning level, in this group of adolescents 62 (92.54%) were students with the mild intellectual disability and 5 students (7.46%) were adolescents with moderate intellectual disability. All the participants in this group were recruited from special schools. The mean age of the parent/guardian/other person who completed the questionnaire related to the quality of life of the child was 44.3 years. Criteria for inclusion in the study were: intellectual disability without comorbidities, 13–18 year age range, knowledge of Serbian language and that participants lived with their parents or guardians. We obtained parent or guardian consent forms. Exclusion criteria included presence of hearing and visual impairments orthopedic, neurological, and severe behavioral disorders. These criteria were chosen in order to maintain homogeneity of the samples. Group II was the control group and comprised 122 adolescents with typical development and their 122 parents. Regarding gender this group comprised 62 (50.82%) boys and 60 (49.18%) girls, with the mean age of 15 years and 6 months. (SD = 15.70). Control group participants were selected from schools located in the same area as those attended by participants with ID. The mean age of the parents who completed the questionnaire was 43.55 years. Criteria for participation in the study were: parents or guardians consent form, children aged 13–18 years, knowledge of Serbian language and that children live with their parents or guardians. 2.2. Instruments The PedsQL 4.0 Generic Core Scale for adolescents aged 13–18 years has been used to assess the quality of life in this research (Varni, Seid, & Rode, 1999).
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The PedsQL Measurement Model is designed as a modular approach to measuring health-related quality of life in healthy children and adolescents and those with acute and chronic health conditions. It consists of parallel questionnaires for the child (self-report) by ages: 5–7, 8–12 and 13–18, and the parent (proxy-report) 2–5, 5–7, 8–12 and 13–18 year old children. The instructions are simple and clear, and it takes 5–10 min to complete it. The PedsQL 4.0 questionnaire consists of 23 items which include: (1) Physical functioning (8 items), (2) Emotional functioning (5 items), (3) Social functioning (5 items), and (4) School functioning (5 items). In each item, the question is how much a child has a problem in performing certain functions or activities during the past one month. Response scale contains five levels of scoring: 0 = never a problem, 1 = almost never a problem, 2 = sometimes a problem, 3 = often a problem, and 4 = almost always a problem. Data processing is performed by reverse scoring and linear transformation of the 0–100 scale, so that higher scores indicate a better quality of life (PedsQL: Scoring instruction, 2012). This scale showed satisfactory metric properties. Compared with the same purpose scales, it confirmed exceptionally substantial and constructive validity and easy interpretability (Matza, Swensen, Flood, Secnik, & Leidy, 2004). The scale is also shown to be sensitive and reliable (Varni, Seid, & Kurtin, 2001). Due to good psychometric reliability (Cronbach alpha coefficient 0.68–0.90) and validity, forms suitable for both children and parents, and adaptability to the child’s age, it is considered to be a well thought instrument for measuring quality of life (Palermo, Long, Lewandowski, Drotar, Quittner, & Walker, 2008). Version of the scale in Serbian language, culturally adopted, and permission for the use of the scale for this study was obtained from Mapi Research Trust. 2.3. Procedures The survey was conducted at three primary, three secondary and one special school. The questionnaires were sent to everyone who was within the same age group. A total of 350 questionnaires were distributed. There was 54% returned questionnaires with a signed consent. Adolescents with intellectual disability have been able to complete the questionnaire, but 83.58% were in need of help, in terms of reading the questionnaire aloud, and individual completion of the questionnaire. Time of completing the questionnaire was not limited. The questionnaire was completed by 63 (94.03%) parents of adolescents with intellectual disability and by 2 (2.98%) guardians. In two cases (2.98%), the questionnaire was completed by third parties (teacher and cousin). Of these, 27 (40.3%) were males and 40 (59.7%) females. In all 122 cases in the group of tipically developed adolescents, the questionnaire was completed or consented by the parents. In 103 (84.43%), the questionnaire was completed by the mother, while in 19 cases (15.57%) father did. 3. Results Reliability of PedsQL 4.0 was computed on the whole sample, separately for adolescents and parents. Cronbach alpha coefficient (a) ranged from 0.61 to 0.78 for questionnaire subscales completed by adolescents and between 0.68 and 0.85 completed by their parents .The coefficient of the summary scale of the questionnaire completed by adolescents was a = 0.86, and a little higher for parents a = 0.89. The lowest level on the basis of responses obtained from adolescents referred to the subscale related to the school functioning (a = 0.61). In both cases, the highest inter-item correlation referred to the social subscale. In adolescents it was 0.42, and in parents 0.55. Reliability of PedsQL 4.0 in the group of adolescents with intellectual disability ranged from a = 0.69 on the emotional functioning subscale to 0.82 on the physical health and psychosocial health subscales. The coefficient of the summary scale was a = 0.87. Reliability in the group of typically developing adolescents ranged from a = 0.59 on the school subscale to 0.73 on the physical health subscale. The coefficient of the summary scale was a = 0.80. In Table 1 are given the minimum and maximum values of the scale and subscale scores and using t test investigating differences between adolescents and parents reports for the group with intellectual disability. Adolescents with intellectual disability assessed their physical health as better than other aspects of quality of life. The mean value of the Total Score on the scale, on the basis of self-report in adolescents with intellectual disability was 76.78 (SD = 15.27). The widest range in this group was obtained on the social subscale, from 20 to 100. Two adolescents assessed quality of life with 100 points. Physical health was assessed by 16 adolescents with maximum score, emotional functioning – 12, social functioning – 16, and school functioning – 8. Parents of adolescents with intellectual disability assessed the quality of life of their children with the mean score of 66.99 (SD = 15.52). And they assessed the physical health of their children something better than other aspects of quality of life. Adolescents with intellectual disability, assessed their quality of life higher on all scales and subscales in relation to their parents. Significant differences were found between adolescents and
Table 1 The Quality of life of adolescents with intellectual disability (N = 67). Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents
Parents
Mean
Min
Max
SD
Mean
Min
Max
SD
80.60 74.75 71.87 76.94 75.45 76.78
25 41.67 35 20 30 41.30
100 100 100 100 100 100
18.52 16.08 20.45 21.90 17.23 15.27
69.64 65.57 64.18 64.93 67.61 66.99
12.50 8.33 15 0 10 9.78
100 100 100 100 100 100
20.21 15.87 20.09 21.40 18.37 15.52
t
p
3.28 2.20 3.40 2.58 3.46 3.79
0.000 0.03 0.00 0.01 0.00 0.00
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Table 2 The Quality of life of adolescents with typical development (N = 122). Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents
Parents
t
Mean
Min
Max
SD
Mean
Min
Max
SD
84.17 84.13 76.97 93.77 81.64 84.14
50 60 30 65 30 57.61
100 100 100 100 100 100
11.74 8.52 14.38 8.61 13.61 8.51
81.10 82.67 75.43 90.74 81.84 82.12
34.38 50 45 55 40 57.61
100 100 100 100 100 100
12.99 9.37 12.70 10.94 13.82 9.48
p
1.94 0.89 2.41 0.12 1.27 1.70
0.05 0.37 0.01 0.90 0.20 0.08
Table 3 Correlation between adolescent self- report and parent proxy-report for PedsQl 4.0. Scale
Physical health Psychosocial health Emotional functioning Social functioning School functioning Total score
Adolescents with intellectual disability
Adolescents with typical development
Adolescents (Mean)
Parents (Mean)
Correlation (r)
Adolescents (Mean)
Parents (Mean)
Correlation (r)
80.60 74.75 71.87 76.94 75.45 76.78
69.64 65.57 64.18 64.93 67.61 66.99
0.31* 0.48** 0.39** 0.56** 0.42** 0.45**
84.17 84.13 76.97 93.77 81.64 84.14
81.10 82.67 75.43 90.74 81.84 82.12
0.50** 0.61** 0.59** 0.54** 0.51** 0.62**
* p 0.05. ** p 0.01.
parents mean scores in all subscales and on the total score, that is, adolescents rated their quality of life better than that reported by parents. Table 2 shows the maximum and minimum scale and subscale scores and differences between adolescents and parents reports estimated by the adolescents of typical development and their parents. Adolescents in the control group, on average, assessed equally their quality of life, so the mean Total Score of the scale was 84.14. In this group, the largest range of values obtained was in physical health, from 34.38 to 100 (SD = 12.99). In 10 cases parents assessed physical health of their children with the highest possible score. In 5 cases the maximum score was obtained on the emotional subscale, 53 on the social, and 17 on the school functioning subscale. Significant differences were found between adolescents and parents mean scores in the emotional functioning subscales, that is, adolescents rated their emotional life better than that reported by parents. The overall agreement between children and parents was analyzed using the Kappa Statistics (k). For Kappa values, the benchmarks published by Peat (2001) were used: values below 0.4 indicate poor agreement; 0.41–0.60, fair agreement; 0.61–0.80, good; and 0.81–1.00, very good agreement (Peat, 2001). Agreement between children with intellectual disability and their parents was found to be moderate k = 0.43, p < 0.01 while, it was shown high agreement between children from control group and their parents k = 0.84, p < 0.00 in assessment of quality of life. After analyzing the data obtained from the questionnaires for adolescents and parents about the quality of life of adolescents, agreement between their assessments was observed by Pearson correlation coefficient (r). The correlation can be: low (r < 0.40), moderate (0.41–0.60), high (0.61– 0.80), very high (0.81–1.00) (Varni et al., 2007b). The correlation between the assessment of adolescents with intellectual disability and their parents, is between 0.31 and 0.56 (Table 3). Low correlation was obtained on the scale of physical health (r = 0.31) and the emotional subscales (r = 0.39). Moderate correlation was found on the school functioning subscale (r = 0.42), the psychosocial summary scale (r = 0.48) and the social subscale (r = 0.56), and the total scale (r = 0.45). Adolescents with typical development also assessed their quality of life higher than it was assessed by their parents. The correlation between scales and subscales ranged between 0.50 and 0.62 (Table 3). 4. Discussion By analyzing questionnaires on the given sample based on Cronbach coefficient and average inter item correlation, we can say that the applied the PedsQL 4.0 Generic Core Scale has satisfactory reliability, and can be applied on the group data analysis. If we compare the reliability values, we obtained in the analysis of data, depending on who is completing the questionnaire, we can conclude that questionnaires completed by parents showed better reliability compared with those completed by adolescents By analyzing scores on the subscales, and the overall summary scale, based on self-report of adolescents, it was found that there is a difference in assessing the quality of life of adolescents with disability in relation to adolescents with typical development. Group of adolescents with intellectual disability assessed their quality of life lower than adolescents with typical development in most aspects of functioning. The highest scores reported by adolescents with
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intellectual disability were on the physical functioning subscale. Given that about 24% of children with intellectual disability on a scale of physical health had 100 points, it is possible that they do not fully understand the meaning of items or out of a desire to present themselves in the best light, as ‘‘strong’’, assessed more positively their physical health. Groups of adolescents with typical development, on average, had similar results as children of the general population in the researches in the world (Stevanovic´, Laketic´, & Damjanovic´, 2011; Varni et al., 2001). Previous studies conducted by the questionnaire PedsQl 4.0 showed that the average value of the psychosocial health scale on the sample of a group of children with typical development ranged from 79 to 82 (Varni & Burwinkle, 2006; Varni et al., 2007a). In children with developmental disability and chronic illnesses significantly lower score was obtained, below 70 (Varni & Burwinkle, 2006; Varni et al., 2007a). Based on the data obtained in this study, on the other total scale related to psychosocial health, statistically significant differences (p < 0.001) were found between adolescents with intellectual disability and children with typical development. Viewed individually, the psychosocial health scales gave an insight into which of functioning domains is more or less vulnerable. Interestingly, on the emotional subscale, where adolescents with intellectual disability rated their functioning lower, there was no statistically significant difference. In literature, in children without disabilities and without the presence of disease, emotional functioning ranges from the mean values of 77–82 points (Keilmann, Limberger, & Mann, 2007; Varni & Burwinkle, 2006). Compared to these values, the authors have encountered a significant difference between the groups of children with developmental disabilities and without developmental disabilities, which were not shown in our study, even though the value of emotional functioning in children without developmental disabilities was within limits obtained in the above research. Stevanovic´ et al. (2011) in his research on our population obtained the lower values of this aspect of functioning than the values obtained in both of our respondent groups. That developmental disability has a significant impact on social functioning showed a study of children with autism, psychiatric and attention deficit hyperactivity, and cerebral palsy (Shipman et al., 2011; Varni & Burwinkle, 2006; Varni et al., 2007a). In our study, adolescents with intellectual disability assessed lower their social functioning, compared to the second group. Adolescents in the control group markedly higher assessed this aspect of functioning, with a mean score of 93.77, which is higher than the value obtained by Stevanovic´ et al. (2011) for the general population of children from 8 to 18 years. Of all subscales related to psycho-social health, social functioning subscale gave the highest mean scores. As many as 67 (54.92%) of the adolescents with typical development assessed their social functioning with the maximum score. Almost 1/5 of adolescents with intellectual disability also assessed their social functioning with the maximum score. Based on our sample, we can say that the disability adversely affects the social aspects of quality of life. Children with typical development, in most studies have assessed their school functioning with the mean score of 75–82 (Varni & Burwinkle, 2006; Varni et al., 2001, 2007a). Group of adolescents with intellectual disability, assessed their school functioning lower compared to children with typical development, and the results obtained in the control group correspond to the previous research with the same questionnaire. The obtained values for the Total Score Scale indicate the fact that the quality of life of adolescents with intellectual disability is lower than in children with typical development. Compared with the data from the literature, adolescents with intellectual disability in our sample assessed their quality of life significantly better than children with autism, cerebral palsy, psychiatric disorders, attention deficit hyperactivity disorder (Shipman et al., 2011; Varni & Burwinkle, 2006; Varni et al., 2007a). ‘‘Who should be asked?’’ or whose opinion is to be relied upon, is the question specifically dealt with authors who have studied the quality of life for children with developmental disabilities (Zekovic & Renwick, 2003). The importance of taking into account the parents’ perception is reflected in the fact that the parent is still the one who knows the child best, and will make the final decision concerning treatment application. Agreement in assessing the quality of life of children and parents of general population shows that in most cases was found moderate agreement between the answers given by the children and their parents (Eiser & Morse, 2001). Among the factors that influenced the agreement were domains of functioning, the child’s age, living standards and targets, and health status (the presence of chronic illness, developmental disabilities) (McVilly, BurtonSmith, & Davidson, 2000). For children with intellectual disability, previous studies have shown a positive mild and moderate agreement between assessments of children and their parents (Janssen, Schuengel, & Stolk, 2005; McVilly et al., 2000). In our study, we got low and moderate agreement between the assessments of adolescents and their parents. This discrepancy might be explained by the fact that adolescents with intellectual disability socialize mostly with peers who have the same impairments, thus reporting greater satisfaction with their own functioning in all aspects of quality of life. Parents, on the other hand, tend to consider a broader context of their children’s functioning and are aware of the problems and social isolation they experience. Another possible explanation is that emotional reasons/factors (difficulty accepting children’s problems, parental stress) prevent parents from objectively judging their children’s situation and prompt them to overemphasize the influence of intellectual disability on quality of life. Low agreement was obtained on the physical functioning scale. Possible reason for such low agreement is the unrealistic picture of children on their physical functioning and the desire to appear in a better light. Interestingly, in another study of quality of life for children with developmental disabilities the highest agreement was obtained right on this scale (Shipman et al., 2011; Varni & Burwinkle, 2006). On the emotional subscale, was also obtained lower value than moderate agreement. Adolescents with intellectual disability and their parents assessed this aspect of functioning lower than other aspects. However, adolescents are more satisfied with their emotional functioning in terms of what their parents think. Other subscales had moderate agreement. Highest correlations between the agreement of adolescents and their parents had the social subscale, which supports the notion that parents and children experience in a similar way this aspect of functioning, and that adolescents are aware of their isolation in relation to the wider social framework. The obtained values are in favor of the fact that the adolescents with intellectual disability are able to assess the quality of their lives, but because we cannot be entirely sure that they understand the time and other
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abstract concepts that are included in the questionnaire, to obtain a more complete picture, it is also necessary to take into account the assessment of the parents (Janssen, Schuengel, & Stolk, 2005). In a sample of adolescents with typical development a high level of agreement in relation to the Total scale of assessments was obtained between adolescents and their parents. On the other subscales, there was a moderate correlation, except on the summary scale of psychosocial health, where the correlation was high. In this group, adolescents have higher average scores of their quality of life on all subscales, except for the school functioning, which parents assessed with slightly higher average score. Both parents and adolescents assessed with the lowest mean scores emotional functioning, and social functioning with the highest. This may be indicative of similar perspectives of parents and children, as well as the parents’ closeness and knowing of their children. Adolescents with typical development and their parents showed significantly higher agreement in perceptions of quality of life of adolescents compared to adolescents with intellectual disability and their parents. There is a need for further research of the reasons for the low agreement in children with intellectual disability, inter-item associations, the effects of children’s age and the degree of interference. 4.1. Limitations of the study, and the implications of the findings Our study has several potential limitations. We did not consider whether cognitive functioning level (mild intellectual disability or moderate intellectual disability), might be a factor influencing the level of agreement. Moreover, the study was conducted in one area, and it should be replicated to determine whether other socio-demographic factors might influence quality of life. Further studies should include adolescents with other disabilities in order to assess agreement between adolescent and parent reports. We believe that PedsQL 4.0 is suitable for adolescents with intellectual disability and that the obtained results can provide a greater insight into their needs, and consequently help us identify the fields in which they need further support or require adjustments of existing support programs. 5. Conclusion Obtained research results suggest that to improve the quality of life for children with intellectual disability, ongoing commitment is needed in providing expert support, assistance, and services, particularly in the domain of psychosocial health. By analyzing some aspects of quality of life, it was found that the psychosocial health was assessed lower than physical functioning both by adolescents with intellectual disability and their parents. There is a moderate agreement between adolescent self-report of quality of life and parent-proxy report. 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