A systematic review of the antiemetic efficacy of prophylactic ondansetron compared with metoclopramide and with droperidol in adults

Objective: To determine the pooled relative risk (RR) of prophylactic ondansetron relative to metoclopramide and relative to droperidol for prevention of post-operative (p.o.) vomiting in adults. Design: Meta-analysis of published randomized trials of p.o. emesis. Study Selection: Of 33 articles reviewed in detail by the three authors, 25 met the eligibility criteria. The meta-analysis of ondansetron versus metoclopramide included 16 studies. The droperidol meta-analysis included 13. Main Outcome: p.o. vomiting aver a 24-hour period. Results: There was no clear benefit of ondansetron compared with metoclopramide (pooled RR 0.74, 95% confidence interval 0.54-1.00, p=0.051) or with droperidol (pooled RR 0.91, 95% CI 0.65- 1.29, p=0.61). The heterogeneity seen among the metoclopramide studies was explained by type of surgery (major gynaecological, minor gynaecological or non-gynaecological) and duration of outcome assessment (<6 or 6 hours p.o.). Significant benefit of ondansetron compared to metoclopramide was seen in the studies of minor gynaecological surgery (pooled subgroup RR 0.57, 95% CI 0.38-0.84) and when outcomes were assessed less than 6 hours p.o. (pooled subgroup RR 0.44, 95% CI 0.22-0.87). There was no apparent effect of drug dose, study quality or type of outcome (vomiting or nausea). There was no evidence of heterogeneity among the droperidol studies. Conclusions: Adequately powered studies are needed to clearly establish the relative efficacy of ondansetron compared to droperidol and to metoclopramide. Further studies need also to explore the cost-effectiveness of the drug. Summary statement: There is insufficient evidence from the available studies to clearly determine the relative efficacy of ondansetron compared with metoclopramide and with droperidol. Adequately powered studies are needed to address this and to determine relative cost-effectiveness of the drugs.