Italian translation, cultural adaptation and validation of the PedsQL™ 3.0 Diabetes Module questionnaire in children with type 1 diabetes and their parents

BACKGROUND The PedsQL™3.0 Diabetes Module is a widely used instrument to measure the disease-specific health-related quality of life summary measures in children and adolescents with type 1 diabetes. After cultural adaptation, we confirmed reliability and validity of PedsQL™3.0 Diabetes Module in its Italian version. METHODS Participants were 169 Italian children and adolescents with type 1 diabetes aged 5-18 years and 100 parents. Reliability was determined by internal consistency using Cronbach's coefficient alpha, and test-retest reliability by intra-class correlation coefficient (ICC). Validity was assessed through factor validity examined by exploratory factor analysis, and discriminant validity examined through multitrait/multi-item scaling analysis. Discriminant validity with respect to dichotomous patients' characteristics at baseline was also examined through a multivariate analysis on the summary measures using the Wilks' Lambda test. RESULTS Data completeness was optimal. Item internal consistency was satisfied at 89% for the child self-report scales and at 100% for the parents' proxy-report scales. Most diabetes module scales was acceptable for group comparisons. Discriminant validity was satisfied for 71% of children and adolescents and for 82% of parents. A ≥70% Cronbach's α coefficient was found for the summary measures of both reports. For the test-retest reliability, the ICC coefficients ranged from 0.66 (i.e., the Worry scale) to 0.82 for the other scales of the child self-report. The ICC coefficients were ≥0.87 for all the parents' proxy-report scales. Factor analysis showed that the PedsQL™3.0 Diabetes Module for child self-report could be summarized in 10 components, which explained the 62% of the variance. For the parent proxy-report the statistical analysis selected 9 factors, which explained about 68% of variance. The external discriminant validity of the PedsQL™3.0 Diabetes Module summary measures were compared across gender, age, time since diagnosis and HbA1c mean cut off values. Significant differences in the "Treatment adherence" scale and in the "Communication" scale were observed across age, and by time since diagnosis. CONCLUSIONS The results show the reliability and validity of the Italian translation of the PedsQL™3.0 Diabetes Module, supporting therefore its use as an outcome measure for diabetes cross-national clinical trials and research.