Propofol. A pharmacoeconomic appraisal of its use in day case surgery

Propofol is an intravenous anaesthetic agent that has become widely used in day case surgery. It induces anaesthesia rapidly and 'smoothly', is associated with a quick recovery and has a lower incidence of postoperative nausea and vomiting (PONV) than other agents. In studies comparing propofol with other intravenous anaesthetics (most commonly thiopental sodium) in day case surgery, the use of propofol as induction and/or maintenance anaesthesia was associated with a shorter time to intermediate recovery (street fitness or time to discharge), although the mean time difference was generally less than 1 hour. However, when compared with volatile anaesthetics (particularly desflurane), the differences in time to discharge were smaller. Propofol is also associated with less PONV than barbiturates, volatile anaesthetics or barbiturate/volatile anaesthetic combinations in the immediate postoperative period. The faster recovery time and the decreased incidence of PONV have potential pharmacoeconomic implications. Delayed recovery can increase the use of hospital resources and decrease patient throughput and PONV can incur costs due to an increase in adjunctive medications usage (e.g. antiemetics), nursing time or unintended admissions. The pharmacoeconomic significance of these properties of propofol requires formal evaluation. Pharmacoeconomic investigations, such as cost-effectiveness, cost-benefit and cost-minimisation studies, which include clinical outcome parameters are difficult to conduct in anaesthesia since there are no objective measures of equipotency between anaesthetic agents and because there is no specific health outcome associated with the delivery of anaesthesia. At present, cost-utility studies are not possible because there are no validated instruments for measuring utility in the provision of anaesthesia. To date, pharmacoeconomic analyses of propofol (and other anaesthetic agents) in day case surgery have been restricted to partial cost analyses. Only 2 of these have included the cost of drug wastage, an important consideration since propofol contains no preservative. With 1 exception, these studies have only included drug acquisition costs and propofol was reported to be approximately 1- to 3-fold as costly as other intravenous/inhalational agents. However, these limited analyses have little applicability since they do not include all relevant costs. In addition to drug acquisition costs, pharmacoeconomic studies should also include other direct costs such as the cost of adjunctive medications (including treatment necessary for adverse events), equipment and staff time, indirect costs such as loss of productivity and/or wages and intangible costs such as patient satisfaction and quality of life. A few studies have attempted to quantify some of these factors. Based on differences in recovery time, 2 studies have estimated a decreased demand for nursing staff time associated with the use of propofol compared with thiopental sodium/isoflurane. In addition, informal patient satisfaction assessments show propofol to be equal to or better than other anaesthetic agents. With these broader considerations, it thus remains for future studies to quantify the intangible and indirect costs associated with propofol anaesthesia, to determine whether differences in recovery between propofol and other agents (especially the newer inhalational anaesthetics) are of economic importance, and to identify those instances where propofol use provides the greatest value for available funds.