Ondansetron home use for pediatric acute gastroenteritis vomiting after ED discharge

IMPORTANCE: Children with acute gastroenteritis-associated vomiting discharged from emergency departments (EDs) have improved outcomes when provided with ondansetron for home use. However, only one-third of children who present with significant vomiting experience ongoing vomiting after discharge. OBJECTIVE: To identify characteristics associated with 3 or more vomiting episodes among pediatric patients within 24 hours of ED discharge. DESIGN, SETTING, AND PARTICIPANTS: This nonprespecified secondary analysis of a randomized clinical trial of children aged 6 months to less than 18 years presenting to EDs between September 14, 2019, and June 27, 2024, with acute gastroenteritis-associated vomiting and who were followed up for 7 days. A prognostic score was derived using generalized linear mixed models across 10 imputed datasets. Data analysis was performed between May 9, 2025, and February 13, 2026. MAIN OUTCOMES AND MEASURES: The primary outcome was 3 or more episodes of vomiting within 24 hours of ED discharge. Secondary outcomes included unscheduled health care revisits, intravenous fluid administration, and hospitalization within 7 days after the ED visit. RESULTS: Of 1030 children enrolled, 977 had follow-up data available and were included in this analysis (median age, 47.0 months [IQR, 22.1-80.1 months]; 493 [50.5%] girls; 925 [89.8%] with complete follow-up data). Eighty of 927 children (8.6%) had 3 or more episodes of vomiting in the 24 hours after ED discharge. In unadjusted analysis, only age 6 months to less than 2 years was associated with ongoing vomiting after discharge (odds ratio [OR], 2.17; 95% CI, 1.37-3.43). In multivariable regression analysis, variables associated with postdischarge vomiting included age 6 months to less than 2 years, symptom duration of 24 to 48 hours, or 10 or more vomiting episodes in the 24 hours preceding the ED visit. In a predictive model, a score of 4 points or more was associated with a 13.6% (95% CI, 9.9%-18.1%) probability of 3 or more vomiting episodes within 24 hours of ED discharge, with a sensitivity of 0.50 (95% CI, 0.39-0.61) and specificity of 0.70 (95% CI, 0.67-0.73). Children with 3 or more vomiting episodes within 24 hours of discharge, compared with those without, were more likely to have an unscheduled health care visit (33 of 80 [41.3%] vs 65 of 846 [7.7%]; difference, 33.6%; 95% CI, 22.6%-44.5%), receive intravenous fluids (9 of 80 [11.3%] vs 15 of 846 [1.8%]; difference, 9.5%; 95% CI, 2.5%-16.5%), and be hospitalized (5 of 80 [6.2%] vs 9 of 846 [1.1%]; difference, 5.2%; 95% CI, -0.2% to 10.5%) within 7 days of discharge. CONCLUSIONS AND RELEVANCE: In this analysis of children presenting for ED care with vomiting, younger children and those unwell for 24 to 48 hours with 10 or more episodes of vomiting at presentation were more likely to have persistent vomiting after discharge. Based on these findings, these children are most likely to benefit from being provided ondansetron for home administration. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03851835.