The Short Food Allergy Quality of Life Questionnaire (FAQLQ-12) for Adults

Background: The Food Allergy Quality of Life Questionnaire (FAQLQ) is the most widely used measure to assess health-related quality of life in food allergy. However, its length can lead to a series of disadvantages, such as reduced or incomplete participation and boredom and disengagement, affecting data quality, reliability, and validity. Objective: We shortened the well-known FAQLQ for adults and propose the FAQLQ-12. Methods: We applied reference-standard statistical analyses, mixing classic test theory and item response theory to identify relevant items for the new short form and confirm its structure fit and reliability. More specifically, we employed discrimination, difficulty, and information levels (item response theory), confirmatory factor analysis, Pearson's correlations, and reliability analysis (McDonald ω and Cronbach α). Results: We chose items with the highest discrimination values to compose the shortened FAQLQ because they were among the ones with the best difficulty levels and the highest amount of individual information. We retained three items per factor because this number allowed for acceptable reliability levels, resulting in 12 items. The FAQLQ-12 presented a better model fit compared with the complete version. The correlation patterns and reliability levels were similar for both the 29 and 12 versions. Conclusions: Although the full version of the FAQLQ remains a reference standard to assess food allergy quality of life, the FAQLQ-12 is introduced as a powerful and beneficial alternative. It can help participants, researchers, and clinicians in specific settings, such as dealing with time and budget limitations, and provides high-quality and reliable responses.