Background To date, there is no food allergy-specific questionnaire that allows parents to report children's health-related QoL (HRQL) from the child's perspective.
Objective The aim of this study was to develop a sensitive, multi-dimensional measure to assess parental perception of HRQL in children aged 0–12 years with food allergy.
Methods The Food Allergy QoL – Parent Form (FAQLQ-PF) was developed and validated in four stages: (1) item generation using focus groups, expert opinion, and literature review; (2) item reduction, using clinical impact and factor analysis; (3) internal and test–retest reliability and construct validity were evaluated using relevant scales of the Child Health Questionnaire (CHQ)-28 and the disease-specific food allergy independent measure (FAIM); and (4) cross-cultural and content validity was examined by administering the questionnaire in a US sample.
Results Stage 1: Saturation was reached at 110 items.
Stage 2: The reduced instrument has 14 items for children <4 years and 26 and 30 items for children aged 4–6 years and 7–12 years, respectively. Factor analysis revealed three subscales: emotional impact, food anxiety, and social and dietary limitations, accounting for 68% of the variance.
Stage 3: Cronbach's α >0.7 for subscales and total score. Construct validity was demonstrated by significant correlations between relevant scales of the CHQ-28 and FAQLQ-PF subscales (r=0.69–0.77, P<0.01), and between FAQLQ-PF subscales and the FAIM. Sensitivity was shown by significant within-group differences in a sample of 124 food-allergic children.
Stage 4: The FAQLQ-PF was validated in a sample of US children, Cronbach's α >0.7 for subscales and total score. Construct validity was demonstrated by significant correlations between FAQLQ-PF and the FAIM (parent report) and between the FAQLQ-PF and the FAIM (child report). No differences were observed between the US and Irish scores.
Conclusion The FAQLQ-PF is psychometrically robust, with excellent reliability and validity.