Economic Aspects of Evaluation - Evaluation Methods in Biomedical Informatics - page 313

ferent values, the assessed values may change over time, and the values may
vary systematically with characteristics of the individuals responding to
questionnaires. For these reasons, one should include an expert in utility or
quality of life assessment if the analysis is intended to be done with QALYs
as the outcome measure.
Cost-Minimizing Analysis
As noted above, the fundamental assumption in cost-minimizing analyses
is that the clinical outcomes expected under each possible option are the
same. The best example of such studies in health care are therapeutic sub-
stitution policies, where less expensive (usually generic) drugs are substi-
tuted for more expensive brand name drugs if the more expensive drug is
ordered. Such therapeutic substitution policies are commonly embedded
in clinical information systems that have pharmacy components. As an
example, we will examine a simple case of an antibiotic substitution
program.
Example 1: Antibiotic Substitution
The chair of the hospital formulary committee has requested that the phar-
macy system institute an automatic therapeutic substitution program of a
less expensive antibiotic (Cheapocillin) for the commonly ordered new
antibiotic Cephokillumall. This program is to be built directly into the phar-
macy component of the hospital's clinical information system (CIS). The
argument is that Cheapocillin is substantially less expensive and by all
reports equally effective for the treatment of infections. The infectious
disease service agrees, and does not object to the therapeutic substitution
on clinical grounds. Therefore, the most important prerequisite for con-
ducting a cost-minimization study has been met: there is good evidence and
agreement that the two strategies have equivalent outcomes. This allows the
economic analysis of the new information system to concentrate entirely
on costs.
The most important concept in cost-minimizing studies is the appro-
priate identification and enumeration of the costs of the various strate-
gies. Table 11.2 outlines the costs of the various therapeutic strategies.
Cheapocillin has very low pharmaceutical costs per dose ($0.50), but comes
as a powder that must be reconstituted with saline by the pharmacist. This
procedure is calculated to cost $11.00 per dose. Because of its short half-
life, Cheapocillin must be administered four times a day, resulting in a daily
cost of $46.00. Cephokillumall is substantially more expensive for each dose
($22.00) but comes in a ready-to-administer vial, so preparation and admin-
istration costs for the pharmacy are reduced ($8.50). The recommended
regimen is one dose per day, producing a daily cost of $30.50. However,