Development and validation of a self-administered Food Allergy Quality of Life Questionnaire for children.

BACKGROUND: Having a food allergy may affect health-related quality of life (HRQL). Currently, no validated, self-administered, disease-specific HRQL questionnaire exists for children with food allergy.
OBJECTIVE: The aim of this study was to develop and validate the Food Allergy Quality of Life Questionnaire--Child Form (FAQLQ-CF) in the Dutch language.
METHODS: Interviews with food-allergic children (n=13, 8-12 years) generated 139 HRQL items. The most important items were identified by 51 food-allergic children using the clinical impact method. This resulted in the FAQLQ-CF containing 24 items (total score range 1 'not troubled' to 7 'extremely troubled'). The FAQLQ-CF, the Food Allergy Independent Measure (FAIM) and a generic HRQL questionnaire (CHQ-CF87) were sent to 115 food-allergic children for cross-sectional validation of the FAQLQ-CF.
RESULTS: Construct validity was demonstrated by the correlation between the FAQLQ-CF and the FAIM (rho=0.60, P<0.001). The FAQLQ-CF had an excellent internal consistency (Cronbach's alpha=0.94) and discriminated between children who differed in number of food allergies (>2 food allergies vs. < or =2 food allergies; total FAQLQ-CF score, 4.3 vs. 3.6; P=0.036), but did not discriminate between reported anaphylaxis or not. The total FAQLQ-CF score correlated with 8 of the 11 CHQ-CF87 sub-scales which demonstrated convergent/discriminant validity.
CONCLUSION: The FAQLQ-CF is the first self-administered disease-specific HRQL questionnaire for food-allergic children. This questionnaire has a strong internal consistency and cross-sectional validity. It discriminates between children who differ in number of food allergies, and it was short and easy to use in the population studied. Therefore, the FAQLQ-CF may be a useful tool in clinical research.