A factorial study of ondansetron, metoclopramide, and dexamethasone for emesis prophylaxis after adenotonsillectomy in children.

BACKGROUND

We conducted a factorial study of emesis prophylaxis with ondansetron (OND), metoclopramide (MET), and dexamethasone (DEX).

METHODS

After informed parental consent, 240 children having adenotonsillectomy were randomized to one of 15 combinations of OND (0-60 microg.kg(-1)), MET (0-400 microg.kg(-1)), and/or DEX (0-500 microg.kg(-1)). Using multivariable logistic regression, models were generated for the probability of emesis before discharge, after discharge and overall for 24 h.

RESULTS

Odds of emesis increased by a factor of three to four for children older than 7 years. Before discharge, odds of emesis decreased by factors of 0.29 for each 15 microg.kg(-1) of OND and 0.37 for each 100 microg.kg(-1) of MET. After discharge, odds of emesis decreased by a factor of 0.67 for each 125 microg.kg(-1) of DEX and increased by a factor of 3.5 for emesis before discharge. Over 24 h, odds of emesis decreased with OND, MET, and DEX (ORs as above). A negative interaction between OND and MET was seen before discharge and over 24 h, reducing the efficacy of their combination.

CONCLUSIONS

We present novel study design and methods of analysis which are uniquely suited to studies of multiple interventions. Factorial design was a powerful tool, allowing simultaneous determination of dose-response relationships for three drugs and identifying a previously unreported negative interaction between OND and MET.