We very much appreciate the opportunity to respond to the letter of Drs. Loop and Priebe and help to interpret the result of our study on pharmacoeconomic issues when comparing a total intravenous technique using propofol-remifentanil with balanced anaesthesia using isoflurane and alfentanil.
It is well recognized that calculating the total costs of an anaesthetic strongly depends on the actual drug acquisition costs and these can change dramatically over the years. This is well illustrated by reference to propofol following the loss of patent and introduction of some generic products of the drug. Even more, total costs depend on personnel costs and these vary greatly from country to country.
These variations have led us to the approach used in our latest study allowing individual calculations for various clinical settings given in table 3 of our manuscript. This should allow the interested reader to repeat our analysis with present-day data. In this context, readers of papers dealing with pharmaco-economic studies should be aware that conclusions drawn from these studies are only valid for the country, the year and the institution where a trial was performed under circumstances standardized according to a study protocol.
Finally we would like to draw Drs. Loop and Priebe's attention to some facts that they might have overlooked or misunderstood. First, time to extubation was not longer in our study but actually significantly shorter than in the reports they cited. Some potential reasons for this were discussed in our manuscripts. Second, we did include costs associated with wastage of intravenous drugs by counting the numbers of broken ampoules and including costs for disposal of waste.
Department of Anaesthesiology and Critical Care Medicine, Philipps-University of Marburg, Marburg, Germany