Health-related quality of life in children with cystic fibrosis: validation of the German CFQ-R

Background: This study evaluates the psychometric properties of the Child and Parent versions of the German CFQ-R (Cystic Fibrosis Questionnaire Revised), a disease-specific measure of Health-Related Quality of Life (HRQoL) in children with cystic fibrosis (CF). Self-Rating is combined with proxy-rating by parents in the use of the questionnaire. Methods: 136 children with CF (6-13 years) and their parents were recruited to evaluate internal consistency (Cronbach's alpha) and validity, 20 children and parents to examine reproducibility (ICC). Results: Cronbach's alpha is high in all but two dimensions of the Child version (alpha = 0.23-0.77) and for all dimensions of the Parent version (alpha = 0.69-0.89). For both questionnaires, reproducibility is moderate to high (ICC = 0.50-0.94). Factor analysis shows loadings of >0.4 in the majority of items. Higher HRQoL is reported by children with mild disease compared to those with moderate/severe disease and by boys compared to girls. Convergence between self-rating and proxy-rating depends on the dimension. Conclusion: The German CFQ-R, Child and Parent versions, are reliable and valid measures of HRQoL. They should be administered in combination as both, child and parent, provide important information. The measure offers a new patient-reported outcome for clinical purposes as well as for national and international studies in schoolchildren.