Background: Abdominal pain is a common and often debilitating issue for children and adolescents. In many cases, it is not caused by a specific somatic condition but rather emerges from a complex interplay of bio-psycho-social factors, leading to functional abdominal pain (FAP). Given the complex nature of FAP, understanding its origins and how to effectively manage this condition is crucial. Until now, however, no questionnaire exists that targets knowledge in this specific domain. To address this, the Abdominal Pain Knowledge Questionnaire (A-PKQ) was developed. Methods: Two versions were created (one for children and one for parents) and tested in four gastroenterology clinics and one specialized pain clinic in Germany between November 2021 and February 2024. Children between 8 and 17 years of age (N = 128) and their accompanying parents (N = 131) participated in the study. Rasch analysis was used to test the performance of both versions of the questionnaire. Results: The original questionnaires exhibited good model and item fit. Subsequently, both questionnaires were refined to improve usability, resulting in final versions containing 10 items each. These final versions also demonstrated good model and item fit, with items assessing a variety of relevant domains. Conclusion: The A-PKQ is an important contribution to improving assessment in clinical trials focused on pediatric functional abdominal pain.
