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KCE Reports 82 Multislice CT in Coronary Heart Disease 77
CHALLENGING THE ECONOMIC CONCLUSIONS
OF GOLDSTEIN ET AL.
Several international articles refer to the paper by Goldstein et al. 67 to claim costeffectiveness
of MSCT. In this appendix, we challenge the economic conclusions of the
authors, by fully using their findings to assess the economic benefit of the technology.
This analysis was a simple exercise to evaluate the validity of the economic conclusions
drawn from the Goldstein study. Not too much weight should be given to the precise
figures resulting from this exercise, as the initial clinical trial was not set up to do an
economic evaluation. Patient numbers were too small for instance to draw firm
conclusions about the therapeutic impact of MSCT or the standard of care as defined in
the study. In the study, the number of invasive treatments was higher in the MSCT arm
than in the standard of care arm (6 versus 1). This might be due to coincidence.
However, in the absence of better data, applying these crude figures in the economic
model has an important impact on the costs and effects of the initial diagnostic strategy.
Because of the limited value of the precise figures resulting from this evaluation, the
evaluation has been put in appendix. It substantiates, however, the argument that
erroneous conclusions about the economic benefit of MSCT might be drawn if based
only on an RCT that was not initially set up to assess economic benefit of this
technology.
METHODOLOGY
Design
The principles of the methodological guidelines for pharmacoeconomic evaluations in
Belgium were applied in this excercise. 161
Three outcome studies were identified in the clinical literature review, one being a
randomised controlled trial comparing a diagnostic strategy with MSCT with standard of
care (serial ECGs + cardiac biomarkers + MPS). 67 The study was a cost-outcome
description, drawing conclusions about the economic benefits, defined as the difference
between median costs of MSCT and standard of care.
For the evaluation of the incremental costs and effects of a diagnostic strategy with
MSCT and a standard diagnostic strategy in patients with chest pain, we used the data
from this RCT. In contrast to the authors of the study, we decided to extrapolate the
economic results to include the costs of invasive angiography, revascularisations and
complications up to 6 months after initial admission to the emergency department for
acute chest pain.
The basic idea is that the cost-effectiveness of MSCT depends not only on the costs and
effects of the diagnostic strategy, but also the costs and effects of its sequelae, i.e. the
changes in therapeutic behaviour and the consequent impact on patient outcomes.
Therefore, it is insufficient to consider only the technique’s diagnostic accuracy
(sensitivity and specificity) in an economic evaluation. An economic evaluation should
also incorporate the technique’s effect on patients’ outcomes (life years gained or
quality-adjusted life years gained).
The design of our economic evaluation is a piggy-back economic evaluation, based on a
data from one RCT. A decision tree was constructed based on the observed
movements of patients in that RCT. In that sense, the decision tree is a limited
representation of the expected reality, as the number of patients in the RCT was
limited and not all branches of a more realistic model could be filled with data from the
trial. However, with the limited data available in literature, it was unfortunately
unrealistic to fill a decision tree that included all possible real-life scenarios.
The economic evaluation was performed in Microsoft® Excel 2002, using @RISK 4.5.5
for the bootstrapping.