Ondansetron for Acute Gastroenteritis
Authors: Ron Keren
Journal: JAMA Pediatrics (2014)

Acute gastroenteritis (AGE) is one of the most common reasons for children seeking care in the emergency department (ED), accounting for nearly 2 million visits in the United States each year. For children with AGE and mild to moderate dehydration, oral rehydration therapy (ORT) is effective and recommended by the Centers for Disease Control and Prevention1 and American Academy of Pediatrics as first-line therapy. However, vomiting is common in children with AGE and may prevent the success of ORT. Ondansetron, which became available in generic formulation in 2006, is efficacious in reducing vomiting and the need for intravenous (IV) rehydration and hospital admission,2 but little is known about its effectiveness in real-world practice. In this issue of JAMA Pediatrics, Freedman and colleagues3 report the results of a multicenter retrospective cohort study that used time series analysis of Pediatric Health Information System data to determine whether increasing use of ondansetron over the last 10 years in children treated for AGE in US EDs was associated with reduced use of IV hydration and admissions to hospital. Focusing their analysis on 18 hospitals with high-quality data and an adequate range of ondansetron use (n = 804 000), they found that ondansetron use increased dramatically from a median institutional rate of 0.11% in 2002 to 42.2% in 2011. However, as hospitals transitioned from low ( 25%) use of ondansetron—a therapy designed to facilitate oral rehydration and avoid IV rehydration—use of IV rehydration decreased only minimally from 18.7% to 17.8% (−0.9%; 95% CI, −0.7% to −1.1%), and admission to hospital actually increased from 6.0% to 6.7% (+0.7%; 95% CI, 0.6-0.8). In addition, median adjusted total hospital costs increased from $252 to $307. The only clear benefit was reduction in ED revisit within 3 days (−0.7%) and revisit associated with hospitalization (−0.4%). These findings were confirmed in adjusted time series analyses. The Pediatric Health Information System database has become a rich source of information for demonstrating variation in care across children’s hospitals and comparing the effectiveness of different approaches for managing conditions in the emergency and inpatient settings. But the Freedman et al3 study is decidedly different in nature. The authors showed that actually there was not much difference in the ondansetron use across children’s hospitals—over a 10-year period all 18 of the hospitals had incorporated it into their management for a large percentage of children presenting with acute gastroenteritis. And the study was predicated on prior randomized clinical trial evidence that ondansetron is in fact efficacious for reducing vomiting, the need for intravenous hydration, and admission to the hospital. The Freedman et al3 study is unique in that it identifies an efficacious therapy that has been widely adopted but not proving effective in the real world probably because of a failure of implementation. The reasons for failed implementation cannot be discerned from this study or data source, but we can speculate about potential culprits. It is possible that the medicine is not being given to the right patients—those who are most likely to benefit from it. That is, if a child with gastroenteritis is having minimal to no vomiting, then administering ondansetron is not likely to change outcomes and will only lead to inefficient use of resources. Another potential explanation is that the drug is not being properly incorporated into a bundle of care delivered in the ED. More specifically, it may be that the sequencing and/or timing of its delivery with respect to the evaluation and decision making for these children is not appropriate. For example, the ondansetron may not be given early enough (eg, at triage) to have the desired effect, and so ORT is abandoned for IV rehydration. Or the ondansetron is given but its effect is never used to make a decision about whether a trial of ORT should be attempted or continued (eg, the patient arrives in the ED, is given a dose of ondansetron, and immediately is given IV fluids). While the overall study results are discouraging, the subgroup analyses provide some hope for improvement (although, like any subgroup analysis, they should be interpreted with caution). A full one-third of the hospitals (n = 6) had clinically and statistically significant reductions in IV rehydration use between low and high ondansetron use periods, and 3 of those had reduced admission rates, confirming the efficacy observed in clinical trials. It appears that some hospital EDs have figured out which patients are most likely to benefit from ondansetron and how to incorporate its administration into the sequence of care for these patients. If we are to achieve maximum return on our investment in this therapy, research is needed to understand how those hospitals got the desired results. Failure to do so is a lost opportunity to leverage an inexpensive drug to prevent outcomes (eg, need for IV rehydration and admission to hospital) that are both costly (to the health system and families) and disruptive (to children and their families). This will require qualitative research to tease out the best practices used by successful hospitals in deciding how to use a medicine known to be efficacious and implementation science research to figure out how to disseminate that knowledge and implement it in a variety of unique clinical settings. Freedman and colleagues have, in effect, provided us with a perfect use case for addressing one of the fundamental challenges facing US health care—figuring out how to translate knowledge of research findings into practice to derive maximum value from evidence-based therapies.4 Related article page 321 Opinion Editorial