JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Original Paper Measurement Properties of the Online EuroQol-5D-Youth Instrument in Children and Adolescents With Type 1 Diabetes Mellitus: Questionnaire Study Karina Mayoral1,2,3, MPH; Luis Rajmil4, MPH, PhD, MD; Marta Murillo5, PhD, MD; Olatz Garin1,3,6, MPH, PhD; Angels Pont1,3, BSc; Jordi Alonso1,3,6, MPH, PhD, MD; Joan Bel5, PhD, MD; Jacobo Perez7,8, MD; Raquel Corripio7,8, PhD, MD; Gemma Carreras9,10, MD; Javier Herrero11, MD; Jose-Maria Mengibar12, MD; Dolors Rodriguez-Arjona4, BASoc; Ulrike Ravens-Sieberer13, MPH, PhD, MD; Hein Raat14, MBA, PhD, MD; Vicky Serra-Sutton3,4, BASoc, PhD; Montse Ferrer1,2,3, MPH, PhD, MD 1 Health Services Research Group, Hospital del Mar Medical Research Institute, Barcelona, Spain 2 Department of Paediatrics, Obstetrics and Gynaecology and Preventive Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain 3 Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública, Madrid, Spain 4 Agency for Health Quality & Assessment of Catalonia, Barcelona, Spain 5 Pediatric Service, Department of Pediatric Endocrinology, University Hospital Germans Trias i Pujol, Barcelona, Spain 6 Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain 7 Department of Pediatric Endocrine, Hospital of Sabadell, Corporació Sanitària Parc Taulí, Sabadell, Spain 8 University Institute Parc Taulí, Universitat Autònoma de Barcelona, Sabadell, Spain 9 Pediatric Endocrinology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain 10 Medicine Department, Universitat Autònoma de Barcelona, Barcelona, Spain 11 Corporació de Salut del Maresme i la Selva, Hospital de Calella, Calella, Spain 12 Corporació de Salut del Maresme i la Selva, Hospital de Blanes, Blanes, Spain 13 Department of Child and Adolescent Psychiatry, Psychotherapy, and Psychosomatics, University Medical Center Hamburg - Eppendorf, Hamburg, Germany 14 Department of Public Health, Erasmus University Medical Center Rotterdam, Rotterdam, Netherlands Corresponding Author: Montse Ferrer, MPH, PhD, MD Health Services Research Group Hospital del Mar Medical Research Institute Doctor Aiguader, 88 Office 144 Barcelona, 08003 Spain Phone: 34 933160763 Email: mferrer@imim.es Abstract Background: The lack of continuity between health-related quality of life (HRQoL) instruments designed for children and adults hinders change analysis with a life course approach. To resolve this gap, EuroQol (EQ) developed the EQ-5D-Youth (EQ-5D-Y), derived from the EQ-5D for adults. Few studies have assessed the metric properties of EQ-5D-Y in children with specific chronic conditions, and none have done so for children with type I diabetes mellitus (T1DM). Objective: This study aimed to evaluate the acceptability, validity, reliability, and responsiveness of the EQ-5D-Y in children and adolescents with T1DM, when administered online. Methods: Participants with T1DM were consecutively recruited from July to December 2014, from a list of potential candidates aged 8-19 years, who attended outpatient pediatric endocrinology units. Before every quarterly routine visit, participants received an email/telephone reminder to complete the online version of two generic HRQoL questionnaires: EQ-5D-Y and KIDSCREEN-27. The EQ-5D-Y measures five dimensions, from which an equally weighted summary score was constructed (range: 0-100). http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 1 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Completion rate and distribution statistics were calculated. Construct validity was evaluated through known group comparisons based on general health, acute diabetic decompensations, mental health, family function, and a multitrait, multimethod matrix between EQ-5D-Y and KIDSCREEN by using Spearman correlations. Construct validity hypotheses were stated a priori. Reliability was assessed with the intraclass correlation coefficient and responsiveness by testing changes over time and calculating the effect size. Reliability and responsiveness were tested among the stable and improved subsamples defined by a KIDSCREEN-10 index change of <4.5 points or ≥4.5 points, respectively, from the first to the fourth visit. Results: Of the 136 participants, 119 (87.5%) responded to the EQ-5D-Y at the last visit. The dimensions that showed higher percentages of participants with problems were “having pain/discomfort” (34.6%) and “worried/sad/unhappy” (28.7%). The mean (SD) of the EQ-5D-Y summary score was 8.5 (10.9), with ceiling and floor effects of 50.7% and 0%, respectively. Statistically significant HRQoL differences between groups defined by their general health (excellent/very good and good/regular/bad) and mental health (Strengths and Difficulties Questionnaire score ≤15 and >16, respectively) were found in three EQ-5D-Y dimensions (“doing usual activities,” “having pain/discomfort,” and “feeling worried/sad/unhappy”), summary score (effect size for general health and mental health groups=0.7 and 1.5, respectively), and KIDSCREEN-10 index (effect size for general health and mental health groups=0.6 and 0.9, respectively). Significant differences in the EQ-5D-Y dimensions were also found according to acute diabetic decompensations in “looking after myself” (P=.005) and according to family function in “having pain/discomfort” (P=.03). Results of the multitrait, multimethod matrix confirmed three of the four relationships hypothesized as substantial (0.21, 0.58, 0.50, and 0.46). The EQ-5D-Y summary score presented an intraclass correlation coefficient of 0.83. Statistically significant change between visits was observed in the improved subsample, with an effect size of 0.7 (P<.001). Conclusions: These results support the use of the EQ-5D-Y administered online as an acceptable, valid, reliable, and responsive instrument for evaluating HRQoL in children and adolescents with T1DM. (J Med Internet Res 2019;21(11):e14947) doi: 10.2196/14947 KEYWORDS health-related quality of life; type 1 diabetes; EQ-5D-Y; EuroQol; validity version for children (5-12 years of age), but its administration Introduction burden is substantially greater. Type 1 diabetes mellitus (T1DM) is one of the most common The EQ-5D-Y is a very short (2-3 minutes) and simple chronic childhood illnesses, affecting approximately 1 in every instrument to fill out. There are several studies assessing the 400-600 children and adolescents [1]. Treatment includes a metric properties of the EQ-5D-Y in the general population multifaceted regimen with daily subcutaneous insulin injections [11,12] or in school environments [13-16]. A Swedish study (or insulin infusion), blood glucose monitoring, carbohydrate [12] suggested that the EQ-5D-Y was comprehensible, counting, dietary plan, and physical activity [2]. Due to its acceptable, and feasible for self-completion. A multicountry complexity, T1DM management can be overwhelming even study supported its feasibility, reliability, and validity [11]. for the most competent patient [3]. Children might feel different Furthermore, a Spanish study [16] compared the paper and from their peers because of their need for disruptive self-care Web-based versions of EQ-5D-Y, showing acceptable levels activities [4] and the impact of T1DM on psychological aspects of agreement. [5]. Health-related quality of life (HRQoL) captures the individual’s health perception, adding the patients’ perspective Only a few studies have assessed the metric properties of into T1DM clinical monitoring and research. EQ-5D-Y in children with specific chronic conditions. A multicenter study among patients with cystic fibrosis [17] The lack of correspondence and continuity between HRQoL concluded that the EQ-5D-Y can be considered a valid instruments designed for children and those designed for adults instrument, which reflects the differences in health according hinders the analysis of HRQoL changes using a life course to the progression of this life-long chronic disease. A approach. To solve this gap, in 2006, the EuroQol Group comparison between the EQ-5D-Y and the Pediatric Asthma developed the EQ-5D-Youth (EQ-5D-Y) as a version of the Quality of Life Questionnaire [18] supported EQ-5D-Y’s EQ-5D for adults. The EQ-5D-Y was designed by adapting the convergent validity for asthmatic children and adolescents. In EQ-5D dimensions to the requirements of HRQoL measurement addition, a study in youth with chronic kidney disease provided in children and adolescents aged 8 years or older [6,7]. The evidence of the EQ-5D-Y validity, as it discriminated among main rationale of the new version was to enable young groups that differed with regard to the disease-related clinical individuals to self-report their health [6,8]. A EQ-5D-Y proxy burden [19]. Finally, we have only identified one descriptive version was also developed [9] for children below 8 years of study of HRQoL in children with T1DM [20] measured with age. Given its generic and econometric nature, it allows the EQ-5D-Y, but without assessing its metric properties. Our comparison between different populations and conditions, and aim was to evaluate acceptability, validity, reliability and cost-utility analysis for economic evaluation. Another responsiveness of the EQ-5D-Y administered online in children econometric instrument, the Health Utility Index [10], has a and adolescents with T1DM. self-administered version for adults and adolescents and a proxy http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 2 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Data was obtained from a clinical trial on children and registered: hypoglycemia (<60 mg/dL) with decreased level of adolescents with T1DM, designed to evaluate the impact of consciousness, requiring glucagon or the help of others to routine use of HRQoL assessment in clinical practice by using recover, and hyperglycemia (>400-450 mg/dL), which required the KIDSCREEN-27 as the primary outcome. Previous intervention of professionals or presented with diabetic publications of this trial reported that the baseline HRQoL of ketoacidosis. children and adolescents with T1DM [21] was similar to that HRQoL evaluation consisted of the administration of the of the European population of the same age, but with slightly Spanish online version of the KIDSCREEN-27 and the worse physical well-being, and that routine assessment and EQ-5D-Youth (EQ-5D-Y). The descriptive system of the face-to-face patient-physician discussion of HRQoL results EQ-5D-Y [6] consists of five dimensions (“mobility,” “looking improved after a year of follow-up, especially psychological after myself,” “doing usual activities,” “having pain/discomfort,” well-being and school environment [22]. and “feeling worried/sad/unhappy”) with three-level Likert scale responses (no problems, moderate problems, and serious Methods problems). It includes also a visual analogue scale (EQ-VAS) Participants and Study Design on the general health status rated from 0 (worst health status) to 100 (best health status possible). The time frame for both Subjects were consecutively recruited from July to December dimensions and EQ-VAS is “today.” As no preference weights 2014, from a list of 205 potential candidates with T1DM, aged were available for the EQ-5D-Y to estimate utilities [23], an between 8 and 19 years, attending outpatient pediatric equally weighted summary score of the five dimensions was endocrinology units of 5 hospitals. Exclusion criteria were as calculated [24-26], ranging from 0 (no problem in any follows: T1DM diagnosed within the last 6 months and presence dimension) to 100 (serious problems in all dimensions). of cognitive problems that prevented comprehension of the questionnaires. Seven pediatricians were randomly assigned to The KIDSCREEN-27 [27] contains 5 dimensions: physical either the intervention or control group (four and three well-being (5 items), psychological well-being (7 items), pediatricians, respectively). autonomy and relationships with parents (7 items), social support and relationship with friends (4 items), and school environment Families of children that fulfilled the inclusion criteria were (4 items). Responses were categorized into five-option Likert informed about the project, and those who agreed to participate scales that assess the frequency or intensity of the attribute, with received a reminder by email and then by telephone, if a recall period of 1 week in most questions. Scores were necessary, before every quarterly routine visit to complete the calculated following developers’ recommendations [27] for the online questionnaires within the 48 hours prior to the visit (for KIDSCREEN-27 dimensions and for the KIDSCREEN-10 children with limited access to internet, a laptop was available index, constructed with 10 items that sufficiently represent the at the doctor’s office). longer KIDSCREEN profiles. The KIDSCREEN scores are The intervention involved a discussion of the HRQoL scores standardized to a mean of 50 and a SD of 10, from a reference between the doctor and the participant at each routine visit. The sample of 22,000 European children and adolescents [28]. KIDSCREEN-27 and EQ-5D-Y results were displayed with In addition to HRQoL, children’s mental health status and family different colors, similar to a traffic light, marking green for function were assessed. The Strengths and Difficulties good, yellow for medium, and red for poor outcomes. Questionnaire (SDQ) [29] consists of 25 items measuring a Evolutionary results were displayed in the second, third, and range of mental health symptoms including conduct problems, fourth visits, to show a comparison with the previous results. hyperactivity-inattention, emotional symptoms and peer At each visit, pediatricians invited the patients to comment and problems, and prosocial behaviors. All items are scored on a discuss the results, identifying dimensions with low value scores, 3-point scale (0=not true, 1=somewhat true, and 2=certainly exploring possible solutions and actions, and coming back to true). Items are summed to give a total difficulties score ranging these actions over time with advice. Before starting the study, from 0 (no problems) to 40 (maximum problems). The Spanish the pediatricians in this group had received standardized training version of the SDQ has shown to be reliable and valid [30]. The in the use and interpretation of HRQoL questionnaires. family function questionnaire [31,32] was designed to measure The control group also completed the questionnaires online. the patient’s satisfaction with the support from the family However, the questionnaires completed by the control group through five items: Adaptation, Partnership, Growth, Affection, 48 h before each visit were about physical activity and diet, and and Resolve (APGAR). These items have three response options the HRQoL questionnaires were completed only before the first (from almost always to hardly ever), and the total score ranges and fourth visits. During the consultation, the patients received from 0 to 10 (low to high satisfaction). usual care without commenting on the results of the Ethics Considerations questionnaires (physicians did not receive any instruction on clinical management). The study was approved by the ethics committee of participant hospitals in accordance with national and international Study Variables guidelines (code of ethics, Helsinki Declaration) as well as Information collected from clinical records included age, gender, legislation on data confidentiality (Organic Law 15/1999 of weight, height, and glycated hemoglobin (HbA1c) levels. Acute December 13 Data Protection character staff). Signed consent diabetic decompensations during the previous 3 months were to participate was requested from parents and children over 12 http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 3 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al years. The collection and transfer of data were carried out categorized as convergent and discriminant. For the convergent according to strict security and data encryption. validity [7] (different instruments measuring a similar concept), we hypothesized substantial correlations between “mobility” Analytical Strategy (EQ-5D-Y) and “physical well-being” (KIDSCREEN-27), Considering the 136 patients included in the T1DM clinical “feeling worried/sad/unhappy” (EQ-5D-Y) and “psychological trial, this sample size gave a statistical power of 0.80 to detect wellbeing” (KIDSCREEN-27), and the KIDSCREEN-10 index a moderate-to-large difference of 0.65 SDs in the EQ-5D-Y with the EQ-5D-Y summary score and EQ-VAS. In contrast, summary score between unequally distributed known groups for the discriminant validity [7] (different instruments measuring (80% and 20% of participants in each category) using a different traits or constructs), we hypothesized low correlations two-sided test with type I error of 5%. Statistical power was between the EQ-5D-Y dimension of “looking after myself” and calculated using published formulas [33]. the following three KIDSCREEN-27 dimensions: “autonomy Characteristics of the sample were described by calculating and relationships with parents,” “social support and relationship percentages, or means and SDs, according to the type of with friends,” and “school environment.” The strength of variable. To evaluate the acceptability of the EQ-5D-Y, we Spearman correlations was defined [41] as insignificant (≤0.30), calculated the completion rate and the distribution of the moderate (0.31-0.44), or substantial (0.45-0.60). response options in each dimension. Distribution of the The reliability was assessed in terms of reproducibility (stability EQ-5D-Y summary score, EQ-VAS, and the KIDSCREEN-10 of an instrument over time) in a subsample of stable index was described by calculating the observed range, floor, participants—those in the control group with an absolute change and ceiling effects (proportion of participants with the worst <4.5 points in the KIDSCREEN-10 index from the first to the and best possible score, respectively) and statistics of central fourth visit, which corresponds to a small magnitude of change tendency and dispersion. (effect size<0.45). To measure the agreement in EQ-5D-Y Construct validity was assessed by applying two different summary score and EQ-VAS between both administrations, the approaches: (1) comparison of known groups and (2) the intraclass correlation coefficient (ICC) was calculated. To assess multitrait, multimethod matrix with data from the first visit. responsiveness, we classified participants experiencing Known groups were defined according to the general health “improvement” as those with a change in KIDSCREEN-10 (through a question from KIDSCREEN-27), dichotomized as index ≥4.5 points (moderate effect size) between the first and excellent/very good and good/regular/bad; acute diabetic the fourth visits. Differences for the EQ-5D-Y dimensions were decompensations during the previous 3 months; mental health, compared using the McNemar paired test, while differences dichotomized by the total SDQ score cutoff of 15; and family, between the EQ-5D-Y summary score and EQ-VAS were tested classified as dysfunctional (total APGAR score≤6) or functional with the Wilcoxon paired test. The magnitude of change was (total APGAR score=7-10) [32]. To assess differences between also measured by the effect size coefficient (mean of change/SD known groups, a Chi-square test was used for proportions of of change). Program STATA.14 software (StateCorp LP, participants with problems, Wilcoxon nonparametric test was College Station, Texas) was used in the analysis. used for the EQ-5D-Y summary score and EQ-VAS, and unpaired t-test was used for KIDSCREEN scores. The Results magnitude of the differences between groups was assessed by Sample Characteristics the Cohen effect size (difference of mean/pooled SD) [34]. General guidelines define an effect size of 0.2 as small, 0.5 as Of 205 potential candidates with T1DM, 61 were not included moderate, and 0.8 as large [35]. The hypotheses raised a priori, due to change of address, transfer to the adult unit, or no based on available evidence, were higher EQ-5D-Y summary attendance at the follow-up visits; in addition, 8 subjects rejected score (worse HRQoL) in children reporting worse general health participation. Finally, 136 participants were included in the [11], with previous acute diabetic decompensations [36,37], study. Table 1 shows the characteristics of the sample. Mean worse mental health [11,38], and with a dysfunctional family age was 14 years, around half of the participants were girls, 71 [39,40]. (52.2%) had HbA1c levels ≤7.5% (58 mmol/mL), 123 (90.4%) did not present acute diabetic decompensations during the The multitrait, multimethod matrix between the EQ-5D-Y and previous 3 months, and the majority (n=95) rated their health the KIDSCREEN was constructed using Spearman correlations. as good or very good. The logical relationship between two instruments can be http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 4 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Table 1. Demographic and clinical characteristics of the participants (N=136). Characteristic Value Age (years)a, mean (SD) 13.99 (0.2) 8-12, n (%) 45 (33.3) 13-15, n (%) 54 (40.0) 16-18, n (%) 35 (25.9) >18, n (%) 1 (0.7) Sex, n (%) Girls 72 (52.9) Boys 64 (47.1) Metabolic control, HbA1cb, mean (SD) 7.7 (1.3) >7.5, n (%) 65 (47.8) ≤7.5, n (%) 71 (52.2) Acute diabetic decompensations (previous 3 months), n (%) Yes 13 (9.6) No 123 (90.4) General Health Question (KIDSCREEN-27), n (%) Excellent 19 (13.9) Very good 44 (32.4) Good 54 (39.7) Regular 17 (12.5) Bad 2 (1.5) Mental health (total SDQc score), mean (SD) 10.64 (5.3) 0-15, n (%) 113 (83.1) 16-40, n (%) 23 (16.9) Family function (APGARd), n (%) Dysfunctional 52 (38.2) Functional 84 (61.8) a The age of one participant is missing (N=135). b HbA1c: glycated hemoglobin. c SDQ: Strengths and Difficulties Questionnaire. d APGAR: Adaptation, Partnership, Growth, Affection, and Resolve. (Table 3) were below 50 (European sample mean [28]) for Distribution of Dimensions and Indices of “physical well-being” (46.2, 95% CI 44.7-47.7) and over 50 for Health-Related Quality of Life “school environment” (52.0, 95% CI 50.4-53.6) and “social Children and adolescents with T1DM reported relatively fewer support/relationship with friends” (53.6, 95% CI 52.1-55.1). As health problems in the EQ-5D-Y dimensions (Table 2), shown in Table 4, the mean (SD) of the EQ-5D-Y summary especially for “mobility” (n=3, 2.2%) and “looking after myself” score was 8.5 (10.9), with ceiling and floor effects of 50.7% (n=4, 2.9%). Dimensions showing higher percentages of and 0%, respectively. The EQ-VAS ranged in our sample from participants with problems were “having pain or discomfort” 31 to 100, with a mean (SD) of 80.4 (14.7). The KIDSCREEN (n=47, 34.6%) and “feeling worried/sad/unhappy” (n=39, index ranged from 40.0 to 83.8, and the mean (SD) was 49.7 28.6%). Means and 95% CI of KIDSCREEN-27 dimensions (8.3). http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 5 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Table 2. Distribution of the EuroQol-5D-Youth (EQ-5D-Y) dimensions. EQ-5D-Y dimensions No problems, n (%) Some problems, n (%) A lot of problems, n (%) Mobility 133 (97.8) 3 (2.2) 0 (0.0) Looking after myself 132 (97.1) 4 (2.9) 0 (0.0) Doing usual activities 119 (87.5) 17 (12.5) 0 (0.0) Having pain/discomfort 89 (65.4) 45 (33.1) 2 (1.5) Feeling worried/sad/unhappy 97 (71.3) 35 (25.7) 4 (2.9) Table 3. Distribution of KIDSCREEN-27 dimensions. KIDSCREEN-27 dimensions Mean (SD), 95% CI Median Physical well-being 46.2 (9.0), 44.7-47.7 44.7 Autonomy/relationships with parents 50.5 (8.2), 49.1-51.9 49.5 School environment 52.0 (9.3), 50.4-53.6 51.1 Social support and relationship with friends 53.6 (9.1), 52.1-55.1 53.3 Psychological well-being 49.7 (9.7), 48.1-51.3 48.5 Table 4. Distribution of the EuroQol-5D-Youth (EQ-5D-Y) summary score, EuroQol-Visual Analog Scale (EQ-VAS), and KIDSCREEN-10 index. Distribution of scores EQ-5D-Y summary score EQ-VAS KIDSCREEN-10 index Theoretical range 0-100 0-100 –3.54 to 83,81 Observed range 0-40 31-100 40.0-83.81 Proportion of participants with the best health (%) 50.7 8.1 0.7 Proportion of participants with the worst health (%) 0 0 0 Mean (SD) 8.5 (10.9) 80.4 (14.7) 49.7 (8.3) were found according to mental health with large effect sizes, Construct Validity of the EuroQol-5D-Youth Online except for the EQ-VAS. The only significant difference between Table 5 shows statistically significant HRQoL differences those with and without acute diabetic decompensations was between groups defined by their general health in three of five found in the “looking after myself” dimension (P=.005). Finally, EQ-5D-Y dimensions as well as EQ-5D-Y summary score, HRQoL differences between functional and dysfunctional EQ-VAS, and KIDSCREEN-10 index (P<.001, P<.001, and families were statistically significant for the “having pain and P=.02, respectively) with moderate-large effect sizes (0.7, 1.0, discomfort” EQ-5D-Y dimension (P=.03) and KIDSCREEN-10 and 0.6, respectively). Similar significant HRQoL differences index (P<.001). http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 6 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Table 5. Comparison of health-related quality of life between known groups measured at baseline. Variables EQ-5D-Ya dimensions EQ-5D-Y summary EQ-VASb, mean KIDSCREEN-10 score, mean (SD), (SD), median index, mean (SD), median median Mc LAMd DUAe HP/Df W/S/Ug General health question Excellent/very good 0.0% 3.2% 4.8% 22.2% 19.1% 5.08 (8.4), 0 87.6 (10.5), 90 52.24 (6.9), 53.1 Good/regular/bad 4.1% 2.7% 19.2% 45.2% 37.0% 11.51 (12.1), 10 74.1 (15.0), 75 47.47 (8.9), 45.7 P value .25 1.00 .02h <.01h .02h <.001h <.001h .02h Effect size (95% CI) N/Ai N/A N/A N/A N/A 0.7 (0.39-1.09) 1.0 (0.66-1.38) 0.6 (0.25-0.94) Acute diabetic decompensations Yes 7.7% 15.4% 23.1% 38.5% 46.2% 13.85 (13.2), 10.0 74.9 (18.0), 75 50.21 (9.8), 46.9 No 1.6% 1.6% 11.4% 34.2% 26.8% 7.97 (10.6), 0 80.9 (14.3), 81 49.63 (8.2), 48.3 P value .26 .005h .23 .76 .14 .08 .21 .81 Effect size (95% CI) N/A N/A N/A N/A N/A 0.5 (–0.04 to 1.12) 0.4 (–0.17 to 0.99) 0.07 (–0.5 to 0.65) j Mental health (SDQ ) Score 0-15 0.9% 2.7% 8.9% 28.3% 20.4% 6.11 (8.4), 0 81.3 (14.8), 81 50.84 (8.3), 49.8 Score 16-40 8.7% 4.4% 30.4% 65.2% 69.6% 20.43 (14.3), 20 75.7 (13.5), 75 44.01 (5.6), 43.4 P value .07 .53 .004h .001h <.001h <.001h .06 <.001h Effect size (95% CI) N/A N/A N/A N/A N/A 1.5 (1.01-1.98) 0.4 (–0.07 to 0.83) 0.9 (0.40-1.32) Family function (APGAR k ) Score≤6 1.2% 4.8% 10.7% 27.4% 25.0% 7.02 (9.9), 0 81.6 (15.1), 85 51.46 (8.6), 50.6 Score 7-10 3.9% 0.0% 15.4% 46.2% 34.6% 10.96 (12.3), 10 78.3 (13.9), 80 46.81 (6.9), 46.9 P value .56 .30 .42 .03h .23 .06 .12 <.001h Effect size (95% CI) N/A N/A N/A N/A N/A 0.4 (0.01-0.71) 0.2 (–0.12 to 0.58) 0.6 (0.22-0.93) a EQ-5D-Y: EuroQol-5D-Youth. b EQ-VAS: EuroQol-Visual Analog Scale. c M: mobility. d LAM: looking after myself. e DUA: doing usual activities. f HP/D: having pain/discomfort. g W/S/U: feeling worried/sad/unhappy. h Statistically significant difference. i N/A: not applicable. j SDQ: Strengths and Difficulties Questionnaire. k APGAR: Adaptation, Partnership, Growth, Affection, and Resolve. Table 6 presents the multitrait, multimethod matrix between between the EQ-VAS and KIDSCREEN-10 index. In contrast, EQ-5D-Y and KIDSCREEN. Regarding convergent validity, the correlation between the mobility dimension of the EQ-5D-Y of the four correlations previously hypothesized as substantial, and the physical well-being dimension of the KIDSCREEN-27 subscript a), three obtained coefficient values of 0.45 or greater: was 0.21. For discriminant validity, the three relationships 0.58 between EQ-5D-Y “feeling worried/sad/unhappy” and hypothesized as insignificant (subscript b) ranged from 0.02 to KIDSCREEN “psychological wellbeing,” 0.50 between the 0.06, as expected. EQ-5D-Y summary score and KIDSCREEN-10 index, and 0.46 http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 7 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Table 6. Multitrait, multimethod matrix between the EuroQol-5D-Youth (EQ-5D-Y) and the KIDSCREEN in children and adolescents with type 1 diabetes mellitus at baseline evaluation. EQ-5D-Y KIDSCREEN-27 KIDSCREEN-10 index Physical well- Psychological Autonomy and Social support and School environment being well-being relationships relationship with with parents friends Mobility 0.21a 0.19 0.02 0.06 0.12 0.16 Looking after myself 0.02 0.07 0.06b 0.02b 0.06b 0.03 Doing usual activities 0.17 0.29 0.08 0.14 0.25 0.25 Having pain/discomfort 0.27 0.31 0.23 0.13 0.17 0.32 Feeling worried/sad/unhappy 0.30 0.58a 0.22 0.36 0.40 0.56 EQ-5D-Y summary score 0.23 0.10 0.01 0.18 0.00 0.50a EuroQol-Visual Analog Scale 0.38 0.31 0.21 0.14 0.35 0.46a a Correlations hypothesized as substantial (0.45-0.60). b Correlations hypothesized as insignificant (≤0.30). responsiveness, this “improvement” subsample presented Reproducibility and Responsiveness significant changes in three dimensions, in the EQ-5D-Y Table 7 shows EQ-5D-Y test-retest results in the “stable” summary score, and EQ-VAS between the first visit and the subsample between the first and the fourth visit. The ICC was fourth visit. The effect sizes were 0.70 and 0.74, indicating an 0.83 and 0.74 for the EQ-5D-Y summary score and EQ-VAS, improvement of moderate-to-large magnitude. demonstrating stability over time for this subsample. Regarding Table 7. Reproducibility and responsiveness of EuroQol-5D-Youth (EQ-5D-Y): problems reported by each dimension, summary score, and EuroQol-Visual Analog Scale (EQ-VAS) at the first and fourth visits. EQ-5D-Y Test-retest reproducibility among stable participants Responsiveness among participants with improve- (n=18) ment (n=58) First visit Fourth visit P value First visit Fourth visit P value EQ-5D-Y dimensions Mobility, n (%) 0 (0.0) 1 (5.6) —a 3 (5.2) 1 (1.7) .63 Looking after myself, n (%) 1 (5.6) 0 (0.0) — 2 (3.5) 1 (1.7) >.99 Doing usual activities, n (%) 1 (5.6) 1 (5.6) .06 9 (15.5) 2 (3.5) .02b Having pain/discomfort, n (%) 4 (22.2) 4 (22.2) .13 27 (46.6) 11 (18.9) <.001b Feeling worried/sad/unhappy, n (%) 6 (33.3) 5 (27.8) .14 23 (39.7) 10 (17.2) <.001b EQ-5D-Y summary score .71 <.001b Mean (SD) 6.67 (9.1) 6.11 (7.8) 11.90 (12.6) 4.31(7.0) Effect size (95% CI) N/Ac 0.07 (–0.61 to 0.74) N/A 0.70 (0.31 to 1.02) ICCd (95% CI) N/A 0.83 (0.55 to 0.94) N/A N/A EQ-VAS .15 <.001b Mean (SD) 82 (13.5) 86 (9.1) 76.0 (16.6) 86.9 (13.0) Effect size (95% CI) N/A 0.35 (–0.34 to 1.03) N/A 0.74 (0.36 to 1.12) ICC (95% CI) N/A 0.74 (0.31 to 0.90) N/A N/A a Not available. b Statistically significant difference. c N/A: not applicable. d ICC: intraclass correlation coefficient. http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 8 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al are consistent with a previous study [44] showing this latter Discussion EQ-5D-Y dimension as the most affected in children and To the best of our knowledge, this is the first study evaluating adolescents with T1DM. They are also consistent with studies metric properties of the new EQ-5D-Y in T1DM children and using the 21-item Beck Depression Inventory and the Child adolescents. We found this generic preference-based instrument Health Questionnaire PF-50 [45,46], which highlighted the to be acceptable for children and adolescents with T1DM and impact of T1DM on the psychological dimension, especially easy to administer online, but with a high ceiling effect (50.7% due to the lack of autonomy, worrying for future chronic of participants reported no problem in any dimension). The complications and the self-care routines that these children and EQ-5D-Y showed good validity, considering the results obtained adolescents have to experience. in the known groups’ analysis based on general health, acute As hypothesized, the EQ-5D-Y presented a good discrimination diabetic decompensations, mental health, and family function, capacity between groups defined by the general health question and those obtained from the multitrait, multimethod matrix with and SDQ score in the summary score and in three dimensions: KIDSCREEN. Test-retest reproducibility was high, indicating “doing usual activities,” “having pain/discomfort,” and “feeling good reliability, and the moderate-large change observed worried/sad/unhappy.” These dimensions presented the highest between the first and fourth visits among the selected subsample correlations with general and mental health in previous studies of “improvement” supports its responsiveness. of children and adolescents with T1DM [41] or chronic Of the 136 participants in the T1DM study, all responded to the conditions [10]. The magnitude of the difference between groups EQ-5D-Y at the first visit and 119 (87.5%) responded at the defined by these constructs was larger when HRQoL was fourth visit, which is similar to the response rates reported by measured with the EQ-5D-Y summary score (effect size for studies carried out in the clinical (96% [18]) and school (77% general health and mental health groups=0.7 and 1.5, [16]) settings. It is important to remark that the participants respectively) than with the KIDSCREEN-10 index (effect size answering the EQ-5D-Y entirely completed the instrument, for general health and mental health groups=0.6 and 0.9, including the five dimensions, and the EQ-VAS. These rates of respectively). completion support the acceptability of the EQ-5D-Y among It is important to highlight the problems reported in the “looking children and adolescents with T1DM when administered online. after myself” dimension among those participants who had Taking into account the quick expansion of online recreational previously experienced acute diabetic decompensations, which habits among the new generations born in the digital era, is consistent with previous studies comparing good and bad acceptability could be even higher with the incorporation of metabolic control [37,47]. These participants showed differences other devices such as apps for smartphones or tablets. However, in the physical well-being and health perception dimensions, completion rates in routine clinical practice could be lower than measured with KINDL-R [37] and the Diabetes Quality of Life under clinical trial conditions, which indicates the need for questionnaire [42]. A priori hypotheses on the relationship closer monitorization. between family function and HRQoL were based on studies Ceiling effect in the sample of children and adolescents with that reported an increased risk for depressive symptoms in T1DM was high for the EQ-5D-Y summary score (50.7%) and families with a disadvantaged socioeconomic status [39,48]. for the three out of its five dimensions, which exceeded 85% Our results, showing problems of “having pain and discomfort” of participants reporting no problem (“mobility,” “looking after more frequently and poorer HRQoL with KIDSCREEN-10 myself,” and “doing usual activities”). A European multicountry index in children and adolescents with dysfunctional families, study of EQ-5D-Y metric properties [11] reported a similar are in line with the social component of health [39,48]. ceiling effect for these dimensions, which was up to 80% in Correlations between EQ-5D-Y and KIDSCREEN showed the children with chronic conditions. Half of the children and expected pattern for convergent and divergent validity, which adolescents with no problem in any dimension (value=0 in were very similar to those obtained in the abovementioned EQ-5D-Y summary score) could be considered to show a really European multicountry study [11]. The dimensions reflecting high ceiling effect, taking into account the established the emotional aspects of EQ-5D-Y (“feeling recommendations of 15% for HRQoL scores [42]. However, worried/sad/unhappy”) and KIDSCREEN-27 (“psychological this is a general standard, as there are none specific for children. well-being”), in addition to the EQ-5D-Y summary score and This high ceiling effect could be considered coherent with the EQ-VAS, presented a substantial correlation with the relative low impact of diabetes on HRQoL for most children KIDSCREEN-10 index, which provides a summary of the and adolescents, partially explained by their capacity of HRQoL. The EQ-5D-Y “mobility” dimension failed to display adaptation to the demanding tasks related to care [43]. The main convergent validity with the KIDSCREEN dimension “physical disadvantage of this high ceiling effect is that it avoids the wellbeing,” similar to a previous study [11] (r=0.10-0.25). detection of improvement in children and adolescents who Considering the content of the instruments, it can be argued that reported the highest level of health, which could affect the KIDSCREEN is more focused on the energy level and less instrument’s responsiveness. focused on the physical functioning, which is the case of the On the other hand, our study showed a substantial proportion EQ-5D-Y. of children and adolescents with T1DM reporting problems in Our study shows good reproducibility of the questionnaire the dimensions of “having pain or discomfort” (n=47, 34.6%) according to the established standards [7] for reliability and “feeling worried/sad/unhappy” (n=43, 28.7%). These results coefficients: 0.7 and 0.9 for group and individual measurements, http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 9 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al respectively. The ICC of 0.83 and 0.74 obtained for the this summary score did not allow cost-utility analysis. Third, EQ-5D-Y summary score and EQ-VAS allows recommending the EQ-5D-Y does not cover social dimension, a key aspect of its use. Nine months between the first and the fourth visit is too children’s HRQoL, but it presents an acceptable capacity of long a period to evaluate reproducibility, since HRQoL could discrimination between functional and dysfunctional families change considerably during this time. This long period explains in our study. There are other generic pediatric instruments that the low number of children and adolescents in the stable cover social dimensions, such as KIDSCREEN [50] (“autonomy subsample (n=18). Previous EQ-5D-Y studies used the kappa and relationships with parents,” “social support,” “relationship coefficient to evaluate test-retest reporting from good to fair with friends,” and “school environment”), PedsQol [51] (“social agreement, according to dimensions [11,15]. functioning” and “school functioning”), or the Child Health Questionnaire [52] (“role/social emotional and behavioral The EQ-5D-Y detected differences in the selected subsample functioning”). Fourth, this is a secondary analysis of a study of children and adolescents with T1DM classified as designed for purposes other than the evaluation of the metric experiencing “improvement” between the first and the fourth properties of EQ-5D-Y. For example, as commented above, the visit, showing the capacity of this instrument to detect change. 9-month period between test and retest is too long for measuring It is important to highlight that no other studies testing the reproducibility, and no large change is expected with the responsiveness of the EQ-5D-Y have been found. A systematic intervention applied. Furthermore, results on stability should review assessing metric properties of diabetes-specific HRQoL be interpreted with caution due to the small sample size. Finally, instruments also highlighted that the lack of testing for regarding external validity, the results of this study should not responsiveness is a major shortcoming [49]. The EQ-5D-Y be generalized to other chronic conditions. summary score indicates a moderate-large improvement over time, a magnitude which can be considered reasonable when Despite the limitations discussed above, our results provide accounting for the length of the follow-up of participants (9 considerable evidence supporting the appropriate metric months), the nature of the intervention, and the course of the properties of the EQ-5D-Y in patients with T1DM. In T1DM. conclusion, these findings suggest that the EQ-5D-Y administered online is an acceptable, valid, reliable, and The T1DM clinical trial provides a comprehensive and complete responsive instrument for evaluating HRQoL in children and database of EQ-5D-Y and disease-related variables to allow adolescents with this chronic condition. Since it is a assessment of metric properties including validity, reliability, preference-based health status measure, it will allow calculating and responsiveness. However, some limitations need to be quality-adjusted life-years (combining both the quantity and addressed. First, the assessment of the acceptability is not quality of life) for economic evaluations, once social preferences complete: Other indicators such as administration time needed specifically for children become available. Given its short and to complete the questionnaire and patient views about the easy administration, the EQ-5D-Y is a practical instrument to instrument should be included in further studies. Second, since implement in primary care to routine monitoring. It is a the EuroQol group has not developed the value set for the promising instrument to compare the efficiency of different EQ-5D-Y yet [23], the unweighted summary score was programs or treatment strategies, helping prioritize and invest calculated as was done in previous studies [24-26]. However, at different levels. Acknowledgments Financial support for this study was provided by the Instituto de Salud Carlos III FEDER: Fondo Europeo de Desarrollo Regional (PI12/01296 and FI16/00071) and DIUE of Generalitat de Catalunya (2017 SGR 452). The funding agreements ensure the authors’ independence in designing the study, interpreting the data, and writing and publishing the report. The authors would like to acknowledge Aurea Martin for her help in the English editing and proofreading process and in finalizing this manuscript. Author LR has now retired from the Agency for Health Quality & Assessment of Catalonia. Authors' Contributions KM contributed to the conception and design of the article, conceptualized and oversaw analyses, contributed to the interpretation of data, and wrote the article; LR conceived the study, participated in the design and coordination, and carried out the fieldwork; MM participated in the design and coordination of the study and carried out the fieldwork; OG contributed to the conception and design of the article, conceptualized and oversaw analyses, and contributed to the interpretation of data; AP contributed to the analysis and provided statistical support; JA contributed to the conception and design of the article, conceptualized and oversaw analyses, and contributed to the interpretation of data; JB participated in the design of the study and carried out the fieldwork; JP, RC, GC, XH, JMM, and DRA participated in the design of the study and carried out the fieldwork; URS conceived the study and participated in the design and coordination of the study; HR conceived the study and participated in the coordination of the study; VSS revised important intellectual content and the draft versions of the manuscript; MF oversaw all aspects, contributed to the conception and design of the article, contributed to the statistical analyses, carried out the interpretation of data, and contributed to the writing of the article. All the coauthors critically revised the manuscript and approved the final draft before submission, can attest to the validity and legitimacy of the data in the manuscript, and agree to be named as author of the manuscript. http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 10 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al Conflicts of Interest None declared. References 1. Kalyva E, Malakonaki E, Eiser C, Mamoulakis D. Health-related quality of life (HRQoL) of children with type 1 diabetes mellitus (T1DM): self and parental perceptions. Pediatr Diabetes 2011 Feb;12(1):34-40. [doi: 10.1111/j.1399-5448.2010.00653.x] [Medline: 20546163] 2. American Diabetes Association. 13. Children and Adolescents: Standards of Medical Care in Diabetes-2019. Diabetes Care 2019 Jan;42(Suppl 1):S148-S164. [doi: 10.2337/dc19-S013] [Medline: 30559239] 3. Mcdowell I. 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[doi: 10.1007/s11136-018-1873-9] [Medline: 29777459] Abbreviations APGAR: Adaptation, Partnership, Growth, Affection, and Resolve DUA: doing usual activities EQ-5D-Y: Youth EuroQoL version EQ-VAS: EuroQol-Visual Analog Scale EQ: EuroQol ES: effect size HbA1c: glycated hemoglobin HP/D: having pain/discomfort HRQoL: health-related quality of life ICC: intraclass correlation coefficient LAM: looking after myself SDQ: Strengths and Difficulties Questionnaire T1DM: type I diabetes mellitus W/S/U: feeling worried/sad/unhappy Edited by G Eysenbach; submitted 07.06.19; peer-reviewed by G Hu, T Oser; comments to author 31.08.19; revised version received 13.09.19; accepted 24.09.19; published 08.11.19 Please cite as: Mayoral K, Rajmil L, Murillo M, Garin O, Pont A, Alonso J, Bel J, Perez J, Corripio R, Carreras G, Herrero J, Mengibar JM, Rodriguez-Arjona D, Ravens-Sieberer U, Raat H, Serra-Sutton V, Ferrer M Measurement Properties of the Online EuroQol-5D-Youth Instrument in Children and Adolescents With Type 1 Diabetes Mellitus: Questionnaire Study J Med Internet Res 2019;21(11):e14947 URL: http://www.jmir.org/2019/11/e14947/ doi: 10.2196/14947 PMID: ©Karina Mayoral, Luis Rajmil, Marta Murillo, Olatz Garin, Angels Pont, Jordi Alonso, Joan Bel, Jacobo Perez, Raquel Corripio, Gemma Carreras, Javier Herrero, Jose-Maria Mengibar, Dolors Rodriguez-Arjona, Ulrike Ravens-Sieberer, Hein Raat, Vicky Serra-Sutton, Montse Ferrer. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 15.11.2019. This is an open-access article distributed under the terms of the Creative Commons Attribution License http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 13 (page number not for citation purposes) XSL• FO RenderX JOURNAL OF MEDICAL INTERNET RESEARCH Mayoral et al (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on http://www.jmir.org/, as well as this copyright and license information must be included. http://www.jmir.org/2019/11/e14947/ J Med Internet Res 2019 | vol. 21 | iss. 11 | e14947 | p. 14 (page number not for citation purposes) XSL• FO RenderX