Validity and reliability of the Thai version of Food Allergy Quality of Life Questionnaire - Adult Form (FAQLQ-AF) and Food Allergy Independent Measure - Adult Form (FAIM-AF).

Background: Food allergy affects the patient's quality of life (QoL) and leads to anxiety and depression. In addition to routine treatment, QoL evaluation should also be performed in patients with food allergies. The validated Food Allergy Quality of Life Questionnaire - Adult Form (FAQLQ-AF) and Food Allergy Independent Measure - Adult Form (FAIM-AF) have been well accepted and available in many languages.

Objective: Translate FAQLQ-AF and FAIM-AF into Thai and perform reliability and validity tests in Thai adult patients with food allergies.

Methods: The translation process was performed according to the ISPOR Task Force for Translation and Cultural Adaptation. Participants 18 years or older and with physician-diagnosed food allergies were included in the study. Thai versions of FAQLQ-AF and FAIM-AF were administered to participants at baseline and after two weeks. The intraclass correlation coefficient and Cronbach's α coefficient were evaluated to demonstrate both questionnaires' test-retest reliability and internal consistency.

Results: The study included 104 participants. The Thai version of FAQLQ-AF and FAIM-AF demonstrated good reliability, with intraclass correlation coefficients of 0.83 (95%CI 0.76, 0.88) and 0.85 (95%CI 0.79, 0.90), respectively. The validity was excellent, with Cronbach's α coefficient of 0.91 and 0.92, respectively. Both questionnaires were moderately correlated (r = 0.69, P < 0.001), but poorly correlated with the 36-Item Short Form Survey, which is usually used to evaluate general health status.

Conclusions: To evaluate the QoL in adult patients with food allergies, the Thai versions of FAQLQ-AF and FAIM-AF are valid, reliable, and more suitable than the general questionnaire.