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.