Volume 12 • Number 4 • 2009 VA L U E I N H E A LT H
Economic Evaluations Alongside Equivalence and Noninferiority Trials vhe_490
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To the Editor—Judith Bosmans et al. [1] present a method for conducting economic evaluations alongside equivalence and noninferiority trials. In analogy to the noninferiority or equivalence margin for clinical effects, they define a noninferiority or equivalence margin for costs. In their example trial on patients with minor depression, they choose a noninferiority margin for clinical effects of -0.03 quality-adjusted life years (QALYs) and a noninferiority margin for costs of €500. In other words, the new intervention was considered to be noninferior to the existing standard if the incremental benefit was no less than -0.03 QALYs and incremental costs were not higher than €500. Nevertheless, it is unclear why the noninferiority margin for costs should be a positive figure such as €500. An intervention that is clinically noninferior but leads to higher costs should not be considered noninferior from an economic viewpoint. For example, suppose that all bootstrap replications in the costeffectiveness plane fall between -0.03 and 0 QALYs as well as between €0 and €500. In this case, the new intervention is dominated (i.e., considered inferior) by conventional standards, and
it seems questionable to consider such an intervention noninferior from an economic viewpoint. But even if the noninferiority margin were close to zero (say, €1), we could not consider an intervention with costs below this margin economically noninferior because, in a high-prevalence disease, such as minor depression population costs may easily add up to millions of Euros. Only if the noninferiority margin were infinitely small (i.e., practically €0), we could safely consider an intervention with costs below this margin noninferior from an economic viewpoint. Therefore, the noninferiority margin for costs should be 0.—Afschin Gandjour MD, PhD, MA, The James A. Baker III Institute for Public Policy, Rice University, Houston, TX.
Reference 1 Bosmans JE, de Bruijne MC, van Hout HP, et al. Practical guidelines for economic evaluations alongside equivalence trials. Value Health 2008;11:251–8.
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© 2008, International Society for Pharmacoeconomics and Outcomes Research (ISPOR)
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