BackgroundAcute gastroenteritis (AGE) in children is a leading cause of emergency department (ED) visits, resulting in substantial health care costs and stress for families and caregivers. The majority of pediatric AGE cases are caused by viral infections and can be managed at home using strategies to prevent dehydration. To increase knowledge of, and support health decision-making for, pediatric AGE, we developed a knowledge translation (KT) tool (fully automated web-based whiteboard animation video).ObjectiveThe aim of this study was to assess the potential effectiveness of the web-based KT tool in terms of knowledge, health care decision-making, use of resources, and perceived benefit and value.MethodsA convenience sample of parents was recruited between December 18, 2020, and August 10, 2021. Parents were recruited in the ED of a pediatric tertiary care hospital and followed for up to 14 days after the ED visit. The eligibility criteria included parent or legal guardian of a child aged <16 years presenting to the ED with an acute episode of diarrhea or vomiting, ability to communicate in English, and agreeable to follow-up via email. Parents were randomized to receive the web-based KT tool (intervention) about AGE or a sham video (control) during their ED visit. The primary outcome was knowledge assessed before the intervention (baseline), immediately after the intervention, and at follow-up 4 to 14 days after ED discharge. Other outcomes included decision regret, health care use, and KT tool usability and satisfaction. The intervention group participants were invited to participate in a semistructured interview to gather additional feedback about the KT tool.ResultsA total of 103 parents (intervention: n=51, 49.5%, and control: n=52, 50.5%) completed the baseline and postintervention assessments. Of these 103 parents, 78 (75.7%; intervention: n=36, 46%, and control: n=42, 54%) completed the follow-up questionnaire. Knowledge scores after the intervention (mean 8.5, SD 2.6 vs mean 6.3, SD 1.7;P<.001) and at follow-up (mean 9.1, SD 2.7 vs mean 6.8, SD 1.6;P<.001) were significantly higher in the intervention group. After the intervention, parents in the intervention group reported greater confidence in knowledge than those in the control group. No significant difference in decision regret was found at any time point. Parents rated the KT tool higher than the sham video across 5 items assessing usability and satisfaction.ConclusionsThe web-based KT tool improved parental knowledge about AGE and confidence in their knowledge, which are important precursors to behavior change. Further research is needed into understanding what information and delivery format as well as other factors influence parents’ decision-making regarding their child’s health.Trial RegistrationClinicalTrials.gov NCT03234777; https://clinicaltrials.gov/ct2/show/NCT03234777International Registered Report Identifier (IRRID)RR2-10.1186/s40814-018-0318-0