Cost-effectiveness of ondansetron for postoperative nausea and vomiting

The decision as to whether prophylaxis against postoperative nausea and vomiting is better than treatment of established postoperative nausea and vomiting could be made on the basis of cost-effectiveness. The cost-effectiveness of ondansetron was calculated using data from published quantitative systematic reviews of randomised trials. Milligrams of ondansetron required to achieve a desired endpoint were chosen as a cost unit. Modelling was based on a cohort of 1000 patients, and examined control event rates (i.e. incidence of postoperative nausea and vomiting without prophylaxis) of between 10 and 90%. In a sensitivity analysis, cost-effectiveness of recommended intravenous doses (4 mg for treatment and prophylaxis) was compared with minimal effective doses as shown by meta-analysis (1 mg for treatment, 8 mg for prophylaxis). Fewer patients experience any postoperative nausea and vomiting symptoms with prophylaxis compared with treatment. But prophylaxis is only marginally more effective than treatment, and treatment of established postoperative nausea and vomiting with effective doses (i.e. 1 or 4 mg) is more cost-effective and safer than prophylaxis with effective doses (i.e. 4 or 8 mg). Reasons for this are the selective treatment of patients who actually need treatment, the high success rate with a lowest dose tested (1 mg) in established postoperative nausea and vomiting, and the disappointing antinausea effect of prophylactic ondansetron even at an eight-fold higher dose.