Validation of the Dutch cystic fibrosis questionnaire (CFQ) in adolescents and adults.

BACKGROUND This study assesses the reliability and validity of the Dutch version of a disease-specific measure of health-related quality of life (HRQOL) for adolescents and adults with CF (CFQ-14+). The 47-item CFQ-14+ covers nine domains, three symptom scales and one health perception scale. METHODS To assess psychometric characteristics of the CFQ-14+, cross-sectional (homogeneity, discriminative and construct validity) and test-retest designs were used. Eighty-four adolescents and adults with CF (mean age: 21.4 years, range 14.0-46.5 years) and a wide range of lung function (mean FEV1: 59.9% predicted, range 15-121%) completed the questionnaire during a routine visit. RESULTS Internal consistency was acceptable for most domains of the CFQ-14+ (alpha = 0.43-0.92) and test-retest reliability was high for all domain scores (0.72-0.98). Several domains of the CFQ-14+ were able to differentiate between individuals with varying disease severity and between nourished and malnourished patients. Construct validity of the questionnaire was fair, with moderate to strong correlation between physically orientated domains and pulmonary function (rs = 0.36-0.62). CONCLUSION The results demonstrate that the CFQ-14+ questionnaire is a well-validated measure of HRQOL assessment in adolescents and adults with CF.