Deriving health utility indices from a food allergy quality‐of‐life questionnaire

BACKGROUND: The Food Allergy Quality‐of‐Life Questionnaire‐Parent Form (FAQLQ‐PF) is widely used to assess food allergy–specific health‐related quality of life (FAQL), but cannot be used directly in cost‐utility analyses, which require health state utility (HSU) scores. Currently, limited evidence is available regarding the HSU of food‐allergic children/adolescents. This study aimed to develop mapping algorithms from the FAQLQ‐PF onto HSU scores generated by generic, preference‐based, health‐related quality‐of‐life (HRQL) instruments. METHODS: Caregivers of children aged 7 to 17 years with a clinician diagnosis of IgE‐mediated food allergy, recruited via Allergy & Anaphylaxis Australia, completed an online FAQLQ‐PF questionnaire and proxy generic preference‐based pediatric instruments (Assessment of Quality of Life [AQoL]‐6D and Child Health Utility 9D [CHU9D]). Optimal statistical methods were based on series of goodness‐of‐fit statistics. RESULTS: Mean FAQLQ‐PF total score, AQoL‐6D, and CHU9D utility scores of 238 food‐allergic children/adolescents were 3.49 (SD: 1.41), 0.78 (SD: 0.22), and 0.74 (SD: 0.22), respectively. The Spearman correlation coefficients of FAQLQ‐PF with AQoL‐6D and CHU9D were rho = −0.56 and rho = −0.45, respectively. Optimal mapping algorithms were generated from selected FAQLQ‐PF items, mapped onto AQoL‐6D or CHU9D utility scores, with AQoL‐6D demonstrating better performance. CONCLUSIONS: This study generated mapping algorithms to help facilitate the use of FAQLQ‐PF for cost‐utility analyses, which are essential for health economic evaluation. External validation of the reported mapping algorithms is warranted.