p u b l i c h e a l t h x x x ( 2 0 1 5 ) 1 e7
Available online at www.sciencedirect.com
Public Health journal homepage: www.elsevier.com/puhe
Original Research
Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL E. Villalonga-Olives a,b,*, C. Kiese-Himmel a, C. Witte a, J. Almansa c, I. Dusilova a, K. Hacker a, N. von Steinbuechel a University Medical Center Go€ttingen Georg-August-University (UMG), Department of Medical Psychology and Medical Sociology, G€ ottingen, Germany b Social and Behavioral Sciences Department, Harvard T.H. Chan School of Public Health, Boston, USA c Department of Health Sciences, Division of Community and Occupational Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands a
article info
abstract
Article history:
Objectives: To assess the psychometric properties of the German self-reported version of the
Received 24 April 2014
Kiddy-KINDL that measures Health Related Quality of Life (HRQoL) in 3 to 5 year old
Received in revised form
kindergarten children.
29 January 2015
Study design: The population of the study comprised baseline data of a longitudinal study
Accepted 23 April 2015
whose main aim is to investigate self-reported health outcomes in young children (N ¼ 317).
Available online xxx
Methods: Missing values, the distribution of data, internal consistency (Cronbach’s alpha and Guttman’s lambda), and reliability (split half and two weeks test-retest) were analysed.
Keywords:
To assess discriminant validity, mean differences were tested splitting the sample
Children
regarding socio-emotional competences (VBV 3-6), age and gender. Structural validity was
Self-report
investigated with Confirmatory Factor Analysis (CFA).
Health related quality of life
Results: Mean HRQoL was 69.79 (SD 16.84). Overall missing values were 8.1%, overall
Psychometric properties
Cronbach’s alpha was 0.75 and overall Guttman’s lambda was 0.77; for the whole scale
Confirmatory factor analysis
Spearman-Brown test for split half reliability resulted in 0.80 and ICC for test-retest in 0.83.
KINDL
Discriminant validity investigation differentiated groups with high and low socioemotional competence and those children who were 4.5 years or older, compared to the younger ones. Differences between boys and girls were also found. CFA suggested two main dimensions: physical and socio-emotional. Conclusion: This preliminary validation of the Kiddy-KINDL in very young children shows satisfactory psychometric properties. However, results of the Cronbach’s alpha, Guttman’s lambda and the CFA depicted problems, mainly in the psychological dimension. Due to these we recommend to use the Kiddy-KINDL as an instrument with only two dimensions. Further studies in general population samples are needed. © 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Department of Medical Psychology & Medical Sociology, University Medical Center, Waldweg 37, D-37073 € ttingen, Germany. Tel.: þ49 551 39 8192. Go E-mail address: [email protected] (E. Villalonga-Olives). http://dx.doi.org/10.1016/j.puhe.2015.04.020 0033-3506/© 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Villalonga-Olives E, et al., Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL, Public Health (2015), http://dx.doi.org/10.1016/j.puhe.2015.04.020
2
p u b l i c h e a l t h x x x ( 2 0 1 5 ) 1 e7
Introduction To evaluate outcomes in children in terms of prevention, treatment and rehabilitation, it is important to assess Health Related Quality of Life (HRQoL).1 Measures of HRQoL provide a broad view of child health, encompassing aspects of perceived health, health behavior, and well-being. Therefore, HRQoL has the potential to describe the health of children in the general and specific populations more comprehensively than conventional health measures and provide better identification of specific groups with high rates of complex conditions, social and emotional problems, and poor well-being and functioning.2 Research in HRQoL in children can be used in many ways. It may allow to identify children needing particular attention (help, care and interventions) or to monitor the progress of a person after an intervention or to screen for psychological problems.3 For example, child and adolescent psychological problems burden not only the individual, but also their families and their social environment and may, therefore, be regarded as a highly relevant public health issue.4 HRQoL measures have shown to discriminate among population groups with different levels of health.5 Hence the measurement of HRQoL is crucial in the developmental and public health field. HRQoL research in children represents a relatively recent field.6 After the development of definitions of HRQoL in children, generic HRQoL measures for this population started to be developed.7 Some examples of measures that have been developed are the KIDSCREEN, the PedsQL, and the KINDL.1,8,9 These measures exist for different age ranges and they provide proxy and self-reported versions. However, only the KINDL supplies a self-reported version for very young children measuring general HRQoL in an interview. Children are often regarded as unreliable respondents, and for this reason, attempts to rate children's HRQoL in young children have been predominantly based on data provided by parents. However, children and parents do not necessarily share similar views. This version is important since the disagreement of responses of adults (proxies) and children to the same questionnaire has been widely reported.10e12 In addition, because it is subjective, HRQoL should be assessed whenever possible, and be reliable and valid from the child's perspective.13 The KINDL has three forms for children at different ages: Kiddy-KINDL (4e6 years old), Kid-KINDL (7e13 years old) and Kiddo-KINDL (14e17 years old). On account of the particular difficulties associated with assessing young children, the structure of the Kiddy-KINDL differs from that of the other questionnaires (Kid/Kiddo). This self-reported version is simpler and shorter than the Kid/Kiddo versions; it consists of only 12 items, two for each dimension, and less response categories.14 Despite the other forms of the KINDL (Kid/Kiddo) have a psychometric properties test,1,15 there are no studies yet that evaluate the psychometric properties of the selfreported Kiddy-KINDL (KK) version in German, its original language, in kindergarten children. The widely reported disagreement between parents and children makes testing the performance of the KK in kindergarten children using self-reports important. It is necessary to assess if children outcomes are reliable and valid and can substitute the parents' version of the KK. Therefore, the
purpose of the present study was to assess the psychometric properties of the German form of the KK in a sample of kindergarten children using self-reports in an interview form. We hypothesize that the KK will be a reliable and valid measure to be used in kindergarten children.
Methods Design, sample and procedure The population of the study comprises baseline data of a longitudinal multimethod study mostly in families with low socioeconomic backgrounds. The main aim is to investigate health outcomes in children 3e5 years old with low socioeconomic backgrounds, and to assess the development of these children longitudinally. The study was conducted in five kindergartens in Frankfurt/Main and Darmstadt, Germany. Participants were enrolled there. The parents of 95% of the children enrolled in these kindergartens consented to their children forming part of the study (N ¼ 356 children). The psychometric properties testing of the KK was performed in our convenience sample. Informed consent was obtained from the participating families, with the approval of the kindergarten councils. Families received detailed information regarding the background and implementation of the study and were offered the opportunity to withdraw the participation of their children at any time. We evaluated the self-reported KK in the age range available in our study. Hence, we amplified the original age range of the questionnaire to three years olds, since authors of the KINDL questionnaires suggested the KK was also suitable for children that age. 32 children were part of a test-retest evaluation.
Measures Socioeconomic variables We collected information about occupation and level of education of the main breadwinner of the family to characterize the family's socioeconomic status. Here the international ISCO categorization was followed.16 To perform the analysis of these data, we created a final categorical variable: unemployed (0), unskilled workers (1), skilled workers (2), professionals (3) and professionals with advanced qualifications (4). The KINDL questionnaire measures general HRQoL in children and it is available in three age versions: Kiddy-KINDL (4e6 years), Kid-KINDL (7e13 years) and Kiddo-KINDL (14e17 years) with both parents and self-reports. The KINDL questionnaires comprise 24 items (with five answer categories for the latter two versions) yielding a general HRQoL score of six dimensions: Physical well-being (Ph), Psychological well-being (Psy), Self-esteem (Sst), Family (Fa), Friends (Fr) and Everyday Functioning (Fu). Reverse scoring is applied to some items so that higher item scores represent better HRQoL. Item scores are summed up to give dimension scores, and dimension scores summed up to give an overall score. The raw score is transformed to a scale of 0e100 to facilitate interpretation. The recall period covers the last week.1,14 In this study, we
Please cite this article in press as: Villalonga-Olives E, et al., Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL, Public Health (2015), http://dx.doi.org/10.1016/j.puhe.2015.04.020
p u b l i c h e a l t h x x x ( 2 0 1 5 ) 1 e7
used the self-report version of the KK not yet validated in very young children. The structure differs from the other KINDL questionnaires (Kid/Kiddo) on account of the particular difficulties associated with interviewing young children between four and six years old. The KK self-report version only consists of 12 items, two for each dimension. Items are answered on a three point Likert scale (never; sometimes; very often). The final dimensions are the same as for the other versions just mentioned, but here no scores are calculated for the individual dimensions but only a total score. The value range spreads from 0 to 100, with higher scores indicating better HRQoL.17 Discriminant validity of the KK was evaluated with the Verhaltensbeurteilungsbogen fu¨r Vorschulkinder (VBV 3e6). The instrument is an observation- and rating scale for behavioral performance that comprises four scales (93 items): socialemotional competence; oppositional-aggressive behavior, attention deficit/hyperactivity and emotional disturbances.18 Responses are arranged on a five point rating-scale (never; once a week; several times a week; every day and several times a day). Sum scores range from 0 to 84 with higher scores indicating better performance. The sum score of each scale can be transferred into a stanine norm score (ranging from one to nine). In this study we tested the social-emotional competence scale. The instrument has acceptable psychometric properties.18 All information was collected at the kindergarten during day care. Children were interviewed by psychologists and educational scientists, and answered the KK. The same interviewers collected information concerning the socioeconomic status of the family in an interview with the parents at the kindergarten. Finally, they also collected information of the social-emotional scale of the VBV 3-6 in an interview with the kindergarten teachers.
Data analysis The distribution of data and missings were explored. Floor/ ceiling effects analyses were considered not appropriate, as the response scale consists of only three categories. Internal consistency was tested using Cronbach's alpha to use the same methodology as the psychometric properties test of the Kid/Kiddo versions. We also calculated Guttman's lambda l2, a more accurate measure of reliability than Cronbach's alpha.19 Split half reliability was investigated with the SpearmaneBrown prediction formula. Reliability test-retest was measured with the Intraclass Correlation Coefficient (ICC). Values of these coefficients over 0.7 were judged acceptable.20e22 The KK does not allow to calculate ICC for every dimension because each dimension has two items and no final scores. Hence, the ICC test-retest could only be calculated for the overall score. Discriminant validity was determined by distinguishing subgroups within the sample. It was divided into three groups regarding social-emotional competence, age and gender.23e25 First, we divided the sample into children that showed low social-emotional competence with a score lower than five versus those with high social-emotional competence with a score equal to or more than five (VBV 3e6).18 We also split the sample in those that were below 4.5 years of age, and equal to or above 4.5 years of age, and tested gender differences. We selected the cutoffs considering the range and the distribution of the continuous
3
variables. Finally, we assessed mean differences using t-tests in the groups. It was expected to find better HRQoL in children with higher performance in the above-mentioned instrument, and to observe age and gender differences. Structural validity of the KK was tested with Confirmatory Factor Analysis (CFA), based on polychoric correlations and using Weighted Least Squares estimation (wlsmv). Analyses were conducted in Mplus software, version 6.26 We investigated a six-factor model for the KK suggested for the original questionnaire.15 To reproduce the structure of the original model we had two items per dimension, which is limited for a CFA: therefore the model is identifiable only if factors are intercorrelated.27 In case we encounter estimation problems, we could investigate if another structure was more appropriate in this case such as one-factor or a second factor model to examine a possible reduction of the number of dimensions of the instrument. Model fit was tested considering different fit indices: Comparative Fit Index (CFI), Tucker Lewis Index (TLI) and the Root Mean Square Error of Approximation (RMSEA). Cutoff values for an acceptable fit are CFI > 0.95, TLI > 0.95 and RMSEA
Available online at www.sciencedirect.com
Public Health journal homepage: www.elsevier.com/puhe
Original Research
Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL E. Villalonga-Olives a,b,*, C. Kiese-Himmel a, C. Witte a, J. Almansa c, I. Dusilova a, K. Hacker a, N. von Steinbuechel a University Medical Center Go€ttingen Georg-August-University (UMG), Department of Medical Psychology and Medical Sociology, G€ ottingen, Germany b Social and Behavioral Sciences Department, Harvard T.H. Chan School of Public Health, Boston, USA c Department of Health Sciences, Division of Community and Occupational Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands a
article info
abstract
Article history:
Objectives: To assess the psychometric properties of the German self-reported version of the
Received 24 April 2014
Kiddy-KINDL that measures Health Related Quality of Life (HRQoL) in 3 to 5 year old
Received in revised form
kindergarten children.
29 January 2015
Study design: The population of the study comprised baseline data of a longitudinal study
Accepted 23 April 2015
whose main aim is to investigate self-reported health outcomes in young children (N ¼ 317).
Available online xxx
Methods: Missing values, the distribution of data, internal consistency (Cronbach’s alpha and Guttman’s lambda), and reliability (split half and two weeks test-retest) were analysed.
Keywords:
To assess discriminant validity, mean differences were tested splitting the sample
Children
regarding socio-emotional competences (VBV 3-6), age and gender. Structural validity was
Self-report
investigated with Confirmatory Factor Analysis (CFA).
Health related quality of life
Results: Mean HRQoL was 69.79 (SD 16.84). Overall missing values were 8.1%, overall
Psychometric properties
Cronbach’s alpha was 0.75 and overall Guttman’s lambda was 0.77; for the whole scale
Confirmatory factor analysis
Spearman-Brown test for split half reliability resulted in 0.80 and ICC for test-retest in 0.83.
KINDL
Discriminant validity investigation differentiated groups with high and low socioemotional competence and those children who were 4.5 years or older, compared to the younger ones. Differences between boys and girls were also found. CFA suggested two main dimensions: physical and socio-emotional. Conclusion: This preliminary validation of the Kiddy-KINDL in very young children shows satisfactory psychometric properties. However, results of the Cronbach’s alpha, Guttman’s lambda and the CFA depicted problems, mainly in the psychological dimension. Due to these we recommend to use the Kiddy-KINDL as an instrument with only two dimensions. Further studies in general population samples are needed. © 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Department of Medical Psychology & Medical Sociology, University Medical Center, Waldweg 37, D-37073 € ttingen, Germany. Tel.: þ49 551 39 8192. Go E-mail address: [email protected] (E. Villalonga-Olives). http://dx.doi.org/10.1016/j.puhe.2015.04.020 0033-3506/© 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Villalonga-Olives E, et al., Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL, Public Health (2015), http://dx.doi.org/10.1016/j.puhe.2015.04.020
2
p u b l i c h e a l t h x x x ( 2 0 1 5 ) 1 e7
Introduction To evaluate outcomes in children in terms of prevention, treatment and rehabilitation, it is important to assess Health Related Quality of Life (HRQoL).1 Measures of HRQoL provide a broad view of child health, encompassing aspects of perceived health, health behavior, and well-being. Therefore, HRQoL has the potential to describe the health of children in the general and specific populations more comprehensively than conventional health measures and provide better identification of specific groups with high rates of complex conditions, social and emotional problems, and poor well-being and functioning.2 Research in HRQoL in children can be used in many ways. It may allow to identify children needing particular attention (help, care and interventions) or to monitor the progress of a person after an intervention or to screen for psychological problems.3 For example, child and adolescent psychological problems burden not only the individual, but also their families and their social environment and may, therefore, be regarded as a highly relevant public health issue.4 HRQoL measures have shown to discriminate among population groups with different levels of health.5 Hence the measurement of HRQoL is crucial in the developmental and public health field. HRQoL research in children represents a relatively recent field.6 After the development of definitions of HRQoL in children, generic HRQoL measures for this population started to be developed.7 Some examples of measures that have been developed are the KIDSCREEN, the PedsQL, and the KINDL.1,8,9 These measures exist for different age ranges and they provide proxy and self-reported versions. However, only the KINDL supplies a self-reported version for very young children measuring general HRQoL in an interview. Children are often regarded as unreliable respondents, and for this reason, attempts to rate children's HRQoL in young children have been predominantly based on data provided by parents. However, children and parents do not necessarily share similar views. This version is important since the disagreement of responses of adults (proxies) and children to the same questionnaire has been widely reported.10e12 In addition, because it is subjective, HRQoL should be assessed whenever possible, and be reliable and valid from the child's perspective.13 The KINDL has three forms for children at different ages: Kiddy-KINDL (4e6 years old), Kid-KINDL (7e13 years old) and Kiddo-KINDL (14e17 years old). On account of the particular difficulties associated with assessing young children, the structure of the Kiddy-KINDL differs from that of the other questionnaires (Kid/Kiddo). This self-reported version is simpler and shorter than the Kid/Kiddo versions; it consists of only 12 items, two for each dimension, and less response categories.14 Despite the other forms of the KINDL (Kid/Kiddo) have a psychometric properties test,1,15 there are no studies yet that evaluate the psychometric properties of the selfreported Kiddy-KINDL (KK) version in German, its original language, in kindergarten children. The widely reported disagreement between parents and children makes testing the performance of the KK in kindergarten children using self-reports important. It is necessary to assess if children outcomes are reliable and valid and can substitute the parents' version of the KK. Therefore, the
purpose of the present study was to assess the psychometric properties of the German form of the KK in a sample of kindergarten children using self-reports in an interview form. We hypothesize that the KK will be a reliable and valid measure to be used in kindergarten children.
Methods Design, sample and procedure The population of the study comprises baseline data of a longitudinal multimethod study mostly in families with low socioeconomic backgrounds. The main aim is to investigate health outcomes in children 3e5 years old with low socioeconomic backgrounds, and to assess the development of these children longitudinally. The study was conducted in five kindergartens in Frankfurt/Main and Darmstadt, Germany. Participants were enrolled there. The parents of 95% of the children enrolled in these kindergartens consented to their children forming part of the study (N ¼ 356 children). The psychometric properties testing of the KK was performed in our convenience sample. Informed consent was obtained from the participating families, with the approval of the kindergarten councils. Families received detailed information regarding the background and implementation of the study and were offered the opportunity to withdraw the participation of their children at any time. We evaluated the self-reported KK in the age range available in our study. Hence, we amplified the original age range of the questionnaire to three years olds, since authors of the KINDL questionnaires suggested the KK was also suitable for children that age. 32 children were part of a test-retest evaluation.
Measures Socioeconomic variables We collected information about occupation and level of education of the main breadwinner of the family to characterize the family's socioeconomic status. Here the international ISCO categorization was followed.16 To perform the analysis of these data, we created a final categorical variable: unemployed (0), unskilled workers (1), skilled workers (2), professionals (3) and professionals with advanced qualifications (4). The KINDL questionnaire measures general HRQoL in children and it is available in three age versions: Kiddy-KINDL (4e6 years), Kid-KINDL (7e13 years) and Kiddo-KINDL (14e17 years) with both parents and self-reports. The KINDL questionnaires comprise 24 items (with five answer categories for the latter two versions) yielding a general HRQoL score of six dimensions: Physical well-being (Ph), Psychological well-being (Psy), Self-esteem (Sst), Family (Fa), Friends (Fr) and Everyday Functioning (Fu). Reverse scoring is applied to some items so that higher item scores represent better HRQoL. Item scores are summed up to give dimension scores, and dimension scores summed up to give an overall score. The raw score is transformed to a scale of 0e100 to facilitate interpretation. The recall period covers the last week.1,14 In this study, we
Please cite this article in press as: Villalonga-Olives E, et al., Self-reported health-related quality of life in kindergarten children: psychometric properties of the Kiddy-KINDL, Public Health (2015), http://dx.doi.org/10.1016/j.puhe.2015.04.020
p u b l i c h e a l t h x x x ( 2 0 1 5 ) 1 e7
used the self-report version of the KK not yet validated in very young children. The structure differs from the other KINDL questionnaires (Kid/Kiddo) on account of the particular difficulties associated with interviewing young children between four and six years old. The KK self-report version only consists of 12 items, two for each dimension. Items are answered on a three point Likert scale (never; sometimes; very often). The final dimensions are the same as for the other versions just mentioned, but here no scores are calculated for the individual dimensions but only a total score. The value range spreads from 0 to 100, with higher scores indicating better HRQoL.17 Discriminant validity of the KK was evaluated with the Verhaltensbeurteilungsbogen fu¨r Vorschulkinder (VBV 3e6). The instrument is an observation- and rating scale for behavioral performance that comprises four scales (93 items): socialemotional competence; oppositional-aggressive behavior, attention deficit/hyperactivity and emotional disturbances.18 Responses are arranged on a five point rating-scale (never; once a week; several times a week; every day and several times a day). Sum scores range from 0 to 84 with higher scores indicating better performance. The sum score of each scale can be transferred into a stanine norm score (ranging from one to nine). In this study we tested the social-emotional competence scale. The instrument has acceptable psychometric properties.18 All information was collected at the kindergarten during day care. Children were interviewed by psychologists and educational scientists, and answered the KK. The same interviewers collected information concerning the socioeconomic status of the family in an interview with the parents at the kindergarten. Finally, they also collected information of the social-emotional scale of the VBV 3-6 in an interview with the kindergarten teachers.
Data analysis The distribution of data and missings were explored. Floor/ ceiling effects analyses were considered not appropriate, as the response scale consists of only three categories. Internal consistency was tested using Cronbach's alpha to use the same methodology as the psychometric properties test of the Kid/Kiddo versions. We also calculated Guttman's lambda l2, a more accurate measure of reliability than Cronbach's alpha.19 Split half reliability was investigated with the SpearmaneBrown prediction formula. Reliability test-retest was measured with the Intraclass Correlation Coefficient (ICC). Values of these coefficients over 0.7 were judged acceptable.20e22 The KK does not allow to calculate ICC for every dimension because each dimension has two items and no final scores. Hence, the ICC test-retest could only be calculated for the overall score. Discriminant validity was determined by distinguishing subgroups within the sample. It was divided into three groups regarding social-emotional competence, age and gender.23e25 First, we divided the sample into children that showed low social-emotional competence with a score lower than five versus those with high social-emotional competence with a score equal to or more than five (VBV 3e6).18 We also split the sample in those that were below 4.5 years of age, and equal to or above 4.5 years of age, and tested gender differences. We selected the cutoffs considering the range and the distribution of the continuous
3
variables. Finally, we assessed mean differences using t-tests in the groups. It was expected to find better HRQoL in children with higher performance in the above-mentioned instrument, and to observe age and gender differences. Structural validity of the KK was tested with Confirmatory Factor Analysis (CFA), based on polychoric correlations and using Weighted Least Squares estimation (wlsmv). Analyses were conducted in Mplus software, version 6.26 We investigated a six-factor model for the KK suggested for the original questionnaire.15 To reproduce the structure of the original model we had two items per dimension, which is limited for a CFA: therefore the model is identifiable only if factors are intercorrelated.27 In case we encounter estimation problems, we could investigate if another structure was more appropriate in this case such as one-factor or a second factor model to examine a possible reduction of the number of dimensions of the instrument. Model fit was tested considering different fit indices: Comparative Fit Index (CFI), Tucker Lewis Index (TLI) and the Root Mean Square Error of Approximation (RMSEA). Cutoff values for an acceptable fit are CFI > 0.95, TLI > 0.95 and RMSEA
