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The Pharmaceutical Journal Vol 265 No 7114 September 16, 2000
Pharmacy Practice Research
Papers presented at the British Pharmaceutical Conference, Birmingham, September 10 to 13, 2000 pR56

A pharmacoeconomic comparison of antiemetics used in established post-operative nausea and vomiting

By Abdalaziz Al-Ghadeer, James C. McElnay and Carmel M. Hughes

Introduction One of the most distressing side-effects following anaesthesia is the occurrence of post-operative nausea and vomiting (PONV). The incidence of this complication is in the range of 20-30 per cent and it is treated with a range of drugs, all of which have a different site of action in the vomiting centre of the medulla oblongata1.
The present study sought to evaluate the cost-effectiveness of ondansetron, metoclopramide and droperidol in established PONV.

Method The study covered all surgical wards in a large teaching hospital in Northern Ireland; a retrospective review study design was employed. All hospitalised patients who had developed PONV during 1997 and who received single doses of one of the three antiemetics of interest were included in the study. The episodes of emesis were recorded after the use of each antiemetic drug.
The cost-effectiveness analysis was performed from the perspective of the payer (hospital). This involved the direct costs (1997 £) of antiemetic therapy (drug acquisition costs, preparation and administration) and indirect costs associated with antiemetic failure (eg, nursing staff costs of dealing with vomiting episodes or adverse events). The main outcome assessed was the cost per successful controlled emesis resulting from the administration of a single dose of an antiemetic drug.

Focal points

  • The present study sought to evaluate the cost-effectiveness of ondansetron, metoclopramide and droperidol in established post-operative nausea and vomiting (PONV)
  • The main outcome assessed was the cost per successful controlled emesis resulting from the administration of a single dose of an anti-emetic drug
  • Ondansetron was shown to be the most effective in alleviating PONV; however, droperidol proved to be more cost-effective
  • The drug acquisition cost ratio of ondansetron to droperidol was 2.6; however, a 27 per cent shift in ondansetron acquisition costs would be required to reverse the findings on cost-effectiveness
  • Analysis did not take account of the delayed anxiety, restlessness and sedation associated with droperidol

Results Two-hundred-and-twenty-four patients fulfilled the entrance criteria for the study (79 receiving ondansetron, 60 receiving metoclopramide and 85 receiving droperidol). The patients in each drug group did not differ in relation to their age, gender distribution, body weight, type of surgery, duration of anaesthesia, use of opioid analgesics and duration of hospital admission (all P>0.05). Table 1 shows the costs and outcomes associated with the research.
Table 1

The mean cost per treated patient was higher in the ondansetron group compared with the other two groups, while the success rate (per cent of patients who stopped vomiting after a single dose) was higher in patients receiving ondansetron. Droperidol proved to be the most cost-effective of the three drugs at £34.69 per successfully treated patient and this finding was robust when subjected to sensitivity analysis.
The drug acquisition cost ratio of ondansetron to droperidol was 2.6. Decision tree analysis of the data indicated that if this ratio was reduced to 1.9 or below then ondansetron would become the more cost-effective treatment.

Discussion Ondansetron was shown to be the most effective in alleviating PONV as demonstrated by success rates and this is supported by other clinical work;2 however, the pricing structure for drug acquisition meant that droperidol proved to be more cost-effective within this patient group. This differential was relatively small; however, a 27 per cent shift in ondansetron acquisition costs would be required to reverse the findings on cost-effectiveness.
It should be noted that this analysis did not take account of the delayed anxiety, restlessness and sedation associated with droperidol.

School of pharmacy, Queen's University of Belfast, 97 Lisburn Road, Belfast BT9 7BL

References

1. 1. Hamik A, Peroutka SJ. Differential interactions of traditional and novel antiemetics with D2 and 5-hydroxytryptamine 3 receptor. Cancer Chemother Pharmacol 1989;24:307-10.
2. Diemunsch P, Conseller C, Clyti N, Mamet P. Ondansetron study group. Ondansetron compared with metoclopramide in the treatment of established postoperative nausea and vomiting. Br J Anaesthesia 1997;79: 322-26.