Development and Validation of the Food Expectation Questionnaire (FEX-Q): An Image-Based Instrument to Assess Food-Related Perceptions and Symptom Expectations.

BACKGROUND

Food-related gastrointestinal (GI) symptoms are highly prevalent in patients with IBS. Although dietary components may trigger symptoms through luminal mechanisms, cognitive expectations may also shape symptom perception within the gut-brain axis. No validated instrument exists to measure food-related symptom expectations. We developed and validated the Food Expectation Questionnaire (FEX-Q).

METHODS

The FEX-Q was developed using a stepwise process including patient input, face-to-face validation, and an online validation. The finalized questionnaire presents food images rated on six visual analogue scale items, with food-related GI symptom expectation as the core measure, alongside taste preference, willingness to eat, perceived healthiness, and perceived fat and carbohydrate content. Adults with IBS and non-IBS controls completed the FEX-Q together with validated questionnaires assessing GI symptoms, psychological distress, food-related quality of life, and food avoidance.

RESULTS

Face-to-face validation supported food recognition, item comprehension, and response processes, resulting in the final 44-image version. In the online survey including 134 patients with IBS and 126 non-IBS controls, the FEX-Q demonstrated known-groups validity with higher symptom expectation scores in IBS than in non-IBS controls (50.1 vs. 18.4). Validity of the nutrient-perception items was supported by correlations between perceived and calculated fat (r = 0.78) and carbohydrate content (r = 0.59). Convergent validity was demonstrated through significant associations with GI symptom severity (r = 0.42) and food-related quality of life (r = -0.39). Split-half reliability was high (r = 0.88).

CONCLUSION

The FEX-Q is a promising instrument for assessing food-related symptom expectations and perceptions. It may facilitate future mechanistic research into food-related symptom generation and inform personalized dietary management in IBS.