CORRESPONDENCE

Cost-Effectiveness of Cost­Effectiveness Studies

A recent 'Current Comment' by Hillman (1992) on our cost-effectiveness study (pashko et al. 1991) underscored an interesting and important differ­ence in perspective between consulting groups, like ours, and some grant-based researchers. The issues highlighted in the 'Current Comment' reflect dif­ferences of opinion in the usefulness of evaluating limited, but important, aspects of clinical econom­ics in contrast with evaluations which are much larger in scope. We often choose the former be­cause of its practical utility in detailing findings on limited, but very crucial, aspects of the cost-effec­tiveness of new drug therapies (e.g. costs to achieve complete remission for patients with leukaemia). As there are cost-effectiveness issues involved in the decision to undertake cost-effectiveness stud­ies, we feel studies such as the one we performed provide good value.

Our objective was to evaluate the cost-effec­tiveness of 2 chemotherapy drugs for all acute myeloid leukaemia (AML) patients who completed a single phase III clinical trial. The a priori eco­nomic study period was limited to the time be­tween study drug randomisation and a patient either obtaining a complete remission or failing 2 attempts at induction of remission of leukaemia (i.e. a standard treatment approach using the best competitive agent). The project was constrained by budgetary limitations, a relatively short comple­tion time of a few months and by the fact that eco­nomic resource use information had to be obtained from a completed clinical trial. The clinical trial was not originally designed to consider the eco­nomic impact of therapy on outcome. Informed consent to obtain patient-specific data was limited to information generated by the clinical trial. How­ever, the results included all patients from the ran­domised trial, itemised, not average, patient-spe­cific hospital charges were analysed such that cost of the therapy to society could be determined and

a senSItIvIty analysis across 2 settings was per­formed to evaluate variability in cost outcomes. Costs and resultant benefits of treatment were clearly defined.

The economic time period utilised did not allow us to capture the entire scope of the value of re­sources used and the outcomes obtained over the entire treatment lifetime of patients with AML. To do this more fully, however, we would have had to significantly increase budgetary and time re­quirements. Additionally, we would face the chal­lenge of an increasing reliance on estimations of resource use and quality of life. In a situation free of practical constraints, a more complete evalua­tion of actual or expected future treatments for all patients could have had some incremental value. It is important to evaluate the economic impact of future treatments such as consolidation therapy and bone marrow transplantation as they, themselves, may not be cost-effective. Additionally, the quality oflife of the treatment survivors could be captured to determine whether differences in chronological survival are modified by relative enhancement in life quality of a patient's survival after the initial chemotherapy regimen. Quality of life of the sur­vival after all subsequent treatments could also be obtained in order to come to a more com­plete understanding of the total value of all treat­ments.

The point illustrated above is simply that a cost­effectiveness decision is made before performing a cost-effectiveness study. Completing a larger scale economic analysis of AML treatment would re­quire evaluation of all above-listed factors. The study would cost much more and take consider­ably longer to complete, even if we could practi­cally collect all of the necessary data without hav­ing the assessment unduly influenced by an increasing reliance in economic modelling.

The cost-effectiveness of cost-effectiveness stud­ies relates to a willingness to bear some cost to pro­duce a given quantity of information. Only if the value of the information potentially provided in the study outcome has sufficient importance to warrant its expense is any project undertaken. A cost-effectiveness study that rigorously examines

Correspondence

the economics of a dominant aspect of treatment (i.e. chemotherapy treatment to induce a complete remission for a leukaemia patient), such as the one we performed, has practical value. It is efficient in obtaining information on critical aspects of the drug therapy in relatively short order and at a modest cost. As long as drug therapies and economic cli­mates continue to be dynamic, good studies that address important, specific issues relating to the pharmacoeconomcis of treatment will always have their place. Added to the existing fund of economic information about treatments, studies such as these

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enhance our knowlege of the cost-effectiveness of therapeutics.

Steven Pashko Project Director

Center for Economic Studies in Medicine Reston, V A, USA.

References

Hilman A. Idarubicin: more cost·effective than daunorubicin? PharmacoEconomics 1: 68-89, 1992

Pashko S, Jacobs J, Santorsa J-A. The cost-effectivness of ida­rubicin/cytosine arabinoside versus daunorubicin/cytosine ar­abinoside in the treatment of adults with acute myeloid leu­kaemia (AML). Clinical Therapeutics 13: 353-360, 1991