Primary Care Ondansetron Use and Subsequent Emergency Department Utilization in Children With Acute Gastroenteritis

AIM: Evaluate whether outpatient ondansetron prescription or in-office administration during a primary care (PC) visit was associated with subsequent emergency department (ED) utilization and downstream healthcare recourse utilization among children with acute gastroenteritis (AGE). METHODS: We conducted a retrospective cohort study of children aged 6 months to < 18 years presenting to 39 PC clinics with vomiting, diarrhoea, or AGE between 2017 and 2023. Only the first eligible visit for each child was included. The primary outcome was an ED visit within 7 days of the index PC visit. Secondary outcomes included ED acuity, hospital admission, and ED healthcare resource utilization among children subsequently presenting to the ED. Associations were evaluated using logistic and negative binomial regression models. RESULTS: We included 11 343 unique children. Ondansetron was prescribed during 3789 (33.4%) index PC visits, including 782 (20.6%) children who also received an in-office dose. Overall, 63 children (0.6%) presented to the ED within 7 days. Outpatient ondansetron prescription was not associated with subsequent ED utilization (OR 1.07, 95% CI 0.63-1.78; p = 0.798). Among children subsequently presenting to the ED, prior ondansetron exposure was not associated with ED acuity, hospital admission, or overall healthcare resource utilization, although fewer laboratory tests were performed (IRR 0.45, 95% CI 0.22-0.89; p = 0.026). CONCLUSION: Outpatient ondansetron prescription during PC visits for paediatric AGE was not associated with reduced ED utilization within 7 days. These findings should not be interpreted as evidence that ondansetron lacks clinical benefit but rather that downstream healthcare utilization is influenced by factors beyond symptom control alone. Ondansetron should continue to be considered an adjunct to oral rehydration therapy in appropriately selected children with AGE.