Validation of the Danish version of the revised cystic fibrosis quality of life questionnaire in adolescents and adults (CFQ-R14+)

Background: Quality of life is an important parameter in the evaluation of quality and outcome of health care and treatment, especially in patients with chronic disorders. The aim of this study was to assess the validity and reliability of the Danish version of the revised disease-specific health-related quality of life questionnaire for adolescents and adults with cystic fibrosis (CFQ-R14+). Methods: A total of 196 cystic fibrosis (CF) patients completed the CFQ-R14+ (response rate 71%). Forced expiratory volume in 1 s in percentage of predicted (FEV1%) and body mass index (BMI) were included as measures of health status. Results: Internal consistency coefficients ranged from 0.54 to 0.95. Eight out of the twelve scales had alpha coefficients above 0.7. Test-retest correlations ranged from 0.42 to 0.88 and they were significant in eight scales. All the CFQ-R+14 scales except the digestive symptoms scale discriminated significantly (p<0.05) between patients with mild, moderate, and severe disease. Nine out of the twelve scales discriminated significantly (p<0.05) between nourished (BMI >= 19) and malnourished (BMI<19) patients. Significant differences between participants and non-responders were found for age, sex and FEV1 (higher age, more males and lower FEV1 among non-responders). All of the scales met standards for floor effects (<15% of the responders with the lowest score) but five of the scales failed to meet standards for ceiling effects (>15% of the responders with the highest score). Conclusion: The Danish CFQ-R14+ is a reliable and valid instrument for measuring the health-related quality of life in Danish adolescents and adults with CF, though with the exception from a few of its subscales. (C) 2008 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.