Kent Seamus, Briggs Andrew, Eckermann Simon, Berry Colin
Health Economics Research Centre, University of Oxford.
Int J Technol Assess Health Care. 2013 Oct;29(4):435-42. doi: 10.1017/S0266462313000433.
The use of value of information methods to inform trial design has been widely advocated but there have been few empirical applications of these methods and there is little evidence they are widely used in decision making. This study considers the usefulness of value of information models in the context of a real clinical decision problem relating to alternative diagnostic strategies for patients with a recent non-ST elevated myocardial infarction.
A pretrial economic model is constructed to consider the cost-effectiveness of two competing strategies: coronary angiography alone or in conjunction with fractional flow reserve measurement. A closed-form solution to the expected benefits of information is used with optimal sample size estimated for a range of models reflecting increasingly realistic assumptions and alternative decision contexts.
Fractional flow reserve measurement is expected to be cost-effective with an incremental cost-effectiveness ratio of GBP 1,621, however, there is considerable uncertainty in this estimate and consequently a large expected value to reducing this uncertainty via a trial. The recommended sample size is strongly affected by the reality of the assumptions of the expected value of information (EVI) model and the decision context.
Value of information models can provide a simple and flexible approach to clinical trial design and are more consistent with the constraints and objectives of the healthcare system than traditional frequentist approaches. However, the variation in sample size estimates demonstrates that it is essential that appropriate model parameters and decision contexts are used in their application.
信息价值方法在试验设计中的应用已得到广泛倡导，但这些方法的实证应用较少，且几乎没有证据表明它们在决策中得到广泛使用。本研究在与近期非ST段抬高型心肌梗死患者的替代诊断策略相关的实际临床决策问题背景下，考虑信息价值模型的实用性。
构建一个审前经济模型，以考虑两种相互竞争策略的成本效益：单独进行冠状动脉造影或结合血流储备分数测量。信息预期收益的闭式解用于为一系列反映越来越现实假设和替代决策背景的模型估计最优样本量。
血流储备分数测量预计具有成本效益，增量成本效益比为1621英镑，然而，这一估计存在相当大的不确定性，因此通过试验降低这种不确定性具有很大的预期价值。推荐的样本量受到信息预期价值（EVI）模型假设的现实性和决策背景的强烈影响。
信息价值模型可为临床试验设计提供一种简单灵活的方法，并且比传统的频率学派方法更符合医疗保健系统的限制和目标。然而，样本量估计的差异表明，在应用这些模型时，使用适当的模型参数和决策背景至关重要。
