The items for the KIDSCREEN questionnaires were developed in three more or less parallel steps: literature research, expert interviews using the Delphi method, and focus groups with children and adolescents. Subsequently, the extremely extensive item pool was reduced for a first preliminary pilot version of the questionnaire using different techniques.
First, a computer-assisted literature review was conducted with the aim of obtaining an overview of the relevant literature and existing instruments for assessing health-related quality of life in children and adolescents. Results from international as well as intercultural research were to be given special attention. The basis of this literature review was publications from the years 1985 to 2000, which were recorded in the MEDLINE database. A total of 9,029 abstracts met the previously defined search criteria. All publications were subjected to an internal project review, with the help of which relevant dimensions of health-related quality of life in children and adolescents were to be identified.
What is the current state of quality of life research in children and adolescents? According to experts, which concepts and operationalizations are appropriate when measuring health-related quality of life in children and adolescents? To answer these and other questions, an international Delphi survey was conducted. The Delphi process included three waves of interviews involving a multidisciplinary group of 24 experts from 7 European countries. A consensus was reached that the new instrument should be a multidimensional profile with 30-49 items in 5 to 8 dimensions. The processing time should not exceed 10-15 minutes. The experts agreed on 8 specific dimensions to be covered by the questionnaire: psychological (well-being, self-esteem, body image, cognitive functions), physical (mobility, energy/vitality), social (social relationships, family/home) and other aspects (e.g. environment).
Interviews mit Focus groups
In addition to expert opinion, the children's and adolescents' view of their health and quality of life played a major role in the construction of the KIDSCREEN questionnaires. What do children and adolescents imagine as a good life? What role does health play in this? What is important for children to feel good about themselves?
These and other questions were discussed within the focus groups, which were conducted in all participating countries. The focus groups, each with 4 to 6 children or adolescents, were divided by gender and age. In addition, focus groups were also conducted with parents and caregivers, as well as more in-depth interviews with individual children. To ensure comparability of results, the process of the focus group discussions was standardized to the greatest extent possible. Subsequently, the recorded discussions were transcribed and subjected to content analysis. The results of the focus group work were original statements by children and adolescents on health, well-being and quality of life, which could be classified into several dimensions and subcategories in terms of content analysis. In addition, the layout and response categories of existing quality-of-life questionnaires for children and adolescents were evaluated with the help of the participants.
A total of 2505 statements on health-related quality of life in children and adolescents were formulated on the basis of the focus group discussions. This item pool was checked for redundancies and further reduced using a card sort method, so that in the end 185 items in 7 dimensions and 24 categories were included in the upcoming pilot test. The preliminary pilot questionnaire used a five-point response scale (frequency or intensity) and asked about the subjective well-being of the children and adolescents during the last week.