Oral Ondansetron Reduces IV Fluid Use in the Emergency Department

Source: Powell EC, Roskind CG, Schnadower D, et al. Oral ondansetron administration in children seeking emergency department care for acute gastroenteritis: a patient-level propensity-matched analysis. Ann Emerg Med. 2022;79(1):66-74; doi:10.1016/j.annemergmed.2021.06.003Investigators from multiple institutions conducted a retrospective analysis to assess the association between oral ondansetron administration for children evaluated in emergency departments (ED) for acute gastroenteritis and intravenous (IV) fluid administration, hospitalization, and subsequent vomiting and diarrhea. For the study, data from 2 previously conducted randomized controlled trials of probiotics for gastroenteritis at 10 US and 6 Canadian EDs were analyzed. For these trials, administration of ondansetron was at the discretion of the treating physician. Participants were children 3 to 48 months old with ≥3 episodes of diarrhea in the preceding 24 hours who were seen in a study ED and diagnosed with acute gastroenteritis. For the current study, only those participants with ≥3 episodes of vomiting, in addition to diarrhea, in the 24 hours prior to ED presentation were included. Information on demographics and clinical characteristics were collected. Level of dehydration in study patients was classified using the Clinical Dehydration Scale. Study patients who received oral ondansetron were matched 1:1 on propensity scores with children who did not receive ondansetron. The propensity score assessed likelihood of receiving oral ondansetron and was calculated using demographic data, severity of diarrhea and vomiting, Clinical Dehydration Scale, and overall illness severity. There were 6 principal outcomes: receipt of IV fluids at index ED visit or within 72 hours, hospitalization at the index visit or within 72 hours, and frequency of vomiting and diarrhea in the 24 hours following the ED visit. Regression analyses were conducted to assess the association of oral ondansetron and these outcomes using the propensity score-matched pairs of patients. Subgroup analyses were conducted based on presence of dehydration.Of 1,857 children enrolled in the prospective study, 794 meet criteria for inclusion in the current analysis. The median age of these patients was 16.0 months. A total of 512 children were included in the propensity scored-matched analysis, with 264 in each treatment group (oral ondansetron or no ondansetron). Among these patients, oral ondansetron was associated with a lower rate of receipt of IV fluids at the index ED visit (7.6% vs 14.0% for those not receiving oral ondansetron; odds ratio [OR], 0.50; 95% confidence interval [CI], 0.29, 0.88). There were no significant differences between groups for the other 5 principal outcomes. In the subgroup analyses, patients with evidence of dehydration who received ondansetron were significantly less likely to receive IV fluids at the index visit or be hospitalized within 72 hours. There were no significant differences related to use of ondansetron for any outcome in children without evidence of dehydration.The authors conclude oral ondansetron use was associated with less use of IV fluid at the index visit in children with acute gastroenteritis.Dr Bechtel has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Conflicting data exist on the usefulness of ondansetron for children with acute gastroenteritis (AGE) in the ED. While the results of several single-site studies demonstrated an association between decreased rates of IV rehydration and increased use of ondansetron,1,2 other multicenter ED administrative database studies failed to demonstrate similar reductions.3,4 Such findings served as the impetus for the current study.The authors of the current study sought to determine if oral ondansetron is associated with a decreased rate of intravenous rehydration, need for hospitalization, and vomiting and diarrhea following the ED visit. To do this, the investigators mimicked a randomized controlled trial from a retrospective dataset in which the probability of being in the exposure group (in this case, receiving ondansetron) was not randomized. They performed a propensity score analysis to account for confounding by degree of dehydration and other factors related to both the administration of oral ondansetron and IV rehydration.This approach allowed the investigators to demonstrate that oral ondansetron administration was associated with a reduction in the frequency of IV rehydration in dehydrated children with AGE. The rate of IV rehydration for dehydrated children with AGE was only 14% amongst children who did not receive ondansetron, compared with 7% in the ondansetron group. This is remarkable given the documented parental preference for IV rehydration over oral rehydration therapy for dehydrated children in higher income countries, such as the US.5 The investigators were unable, however, to show reductions in other outcome measures (eg, vomiting, diarrhea).There are several limitations of the current study. First, data were not collected about reduction in nausea or overall satisfaction with care associated with ondansetron administration. Second, while propensity score matching helps approximate ran-domization, it is possible that the 2 groups were still significantly different from each other due to unmeasured confounders.Oral ondansetron administration to preschool-aged children with AGE and dehydration is associated with reduced likelihood of IV rehydration in the ED. (See AAP Grand Rounds. 2021;46[2]:18.)5

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