Finnish diabetes-related quality of life questionnaire for children and adolescents: Reliability and validity

Aim: To study the psychometric properties, reliability and validity of the FinDiab quality-of-life questionnaire (FDQL), a strength-oriented quality-of-life (QOL) questionnaire for children and adolescents with type 1 diabetes (T1D). Methods: Participants were 215 youths with T1D (aged 10-17 years). They completed FDQL and comparison questionnaires (KINDL-R and SDQ). Demographic and disease measures were collected from the participants’ medical records. The questionnaire's psychometric properties were investigated. Construct validity was studied through principal component analysis using Promax rotation, reliability with alphas, and criterion and convergent validity with correlations between sum scale, subscales, demographic and disease factors, and comparison measures. Results: FDQL demonstrated an adequate range of measurement and feasibility. The four-factor solution was found to be optimal, resulting in the subscales of flexibility with diabetes, well-being, social relations and health behaviour. The sum scale correlated significantly with glycaemic control and the psychosocial and QOL comparison measures. Construct, criterion and convergent validity of the subscales was also good. Children under 14 years of age reported better QOL than older adolescents. Conclusion: FDQL is a practical QOL assessment method focusing on strengths. The questionnaire has good validity and reliability and is easy to use as a clinical tool.