Quality of life in children with Type 1 diabetes: a comparison of general and diabetes-specific measures and support for a unitary diabetes quality-of-life construct

Aims To assess the factor structure of the Pediatric Quality of Life Inventory (PedsQL) Diabetes Module and to compare the PedsQL general and diabetes-specific quality of life (QOL) measures regarding psychometric properties and relations to relevant outcomes. Methods The instruments were completed by 447 children age 9 to 15.5 years with Type 1 diabetes > 1 year from four US paediatric diabetes clinics; parents completed the parallel parent-proxy measures. Principal components factor analysis was used to examine the factor structure of the PedsQL diabetes module. Analyses of the generic and diabetes QOL measures included psychometric properties, parent-child correlations and correlations with depression, adherence and glycated haemoglobin (HbA(1c)). Results The factor structure of the PedsQL diabetes module did not support the original five subscales. Both one- and two-factor models were supported; however, parallel parent and child subscales did not emerge. While the generic and diabetes-specific measures of QOL were moderately to highly correlated with each other, the constructs were differentially associated with relevant diabetes outcomes. Generic QOL was more highly associated with depression than diabetes QOL. Conversely, diabetes QOL was more highly associated with adherence and HbA(1c), although this was seen to a greater extent for parent-proxy report than for child report. Conclusions Factor analysis of the PedsQL diabetes module supports the use of a total diabetes QOL score. Findings regarding the associations of the generic and diabetes modules with diabetes outcomes underscore the unique contribution provided by both generic and diabetes QOL.