Patterson R E, Eisner R L, Horowitz S F
Carlyle Fraser Heart Center, Emory, Atlanta, GA.
Circulation. 1995 Jan 1;91(1):54-65. doi: 10.1161/01.cir.91.1.54.
To compare cost-effectiveness and utility of four clinical algorithms to diagnose obstructive coronary atherosclerotic heart disease (CAD), we compared exercise ECG (ExECG), stress single photon emission computed tomography (SPECT), positron emission tomography (PET), and coronary angiography.
Published data and a straightforward mathematical model based on Bayes' theorem were used to compare strategies. Effectiveness was defined as the number of patients with diagnosed CAD, and utility was defined as the clinical outcome, ie, the number of quality-adjusted life years (QALY) extended by therapy after the diagnosis of CAD. Our model used published values for costs, accuracy, and complication rates of tests. Analysis of the model indicates the following results. (1) The direct cost (fee) for each test differs considerably from total cost per delta QALY. (2) As pretest likelihood of CAD (pCAD) in the population increases, there is a linear increase in cost per patient tested but a hyperbolic decrease in cost per effect and cost per utility unit, ie, increased cost-effectiveness and decreased cost per utility unit. (3) At pCAD < 0.70, analysis of the model indicates that stress PET is the most cost-effective test, with the lowest cost per utility, followed by SPECT, ExECG, and angiography, in that order. (4) Above a threshold value of pCAD of 0.70 (for example, middle-aged men with typical angina), proceeding directly to angiography as the first test showed the lowest cost per effect or utility. This quantitative model has the advantage of estimating a threshold value of pCAD (0.70) at which the rank order of cost-effectiveness and cost per utility unit change. The model also allows substitution of different values for any variable as a way to account for the uncertainties of clinical data, ie, changing costs, test accuracy and risk, etc. This procedure, called sensitivity analysis, showed that the rank order of cost-effectiveness did not change despite changes in several variables.
(1) Estimation of total costs of diagnostic tests for CAD requires consideration not only of the direct cost of the test per se (eg, test fees) but also of the indirect and induced costs of management algorithms based on the test (eg, cost/delta QALY). (2) It is essential to consider the clinical history (pCAD) when selecting the clinical algorithm to make a diagnosis with the lowest cost per effect or cost per utility unit. (3) Stress PET shows the lowest cost per effect or cost per utility unit in patients with pCAD < 0.70. (4) Angiography shows the lowest cost per effect or cost per utility unit in patients with pCAD > 0.70.
为比较四种诊断阻塞性冠状动脉粥样硬化性心脏病（CAD）的临床算法的成本效益和效用，我们比较了运动心电图（ExECG）、负荷单光子发射计算机断层扫描（SPECT）、正电子发射断层扫描（PET）和冠状动脉造影。
使用已发表的数据和基于贝叶斯定理的简单数学模型来比较策略。有效性定义为确诊CAD的患者数量，效用定义为临床结果，即CAD诊断后治疗延长的质量调整生命年（QALY）数量。我们的模型使用了已发表的检查成本、准确性和并发症发生率的值。模型分析得出以下结果。（1）每项检查的直接成本（费用）与每增加一个QALY的总成本有很大差异。（2）随着人群中CAD的预测试验概率（pCAD）增加，每位接受检查患者的成本呈线性增加，但每单位效果成本和每单位效用成本呈双曲线下降，即成本效益增加，每单位效用成本降低。（3）在pCAD < 0.70时，模型分析表明负荷PET是最具成本效益的检查，每单位效用成本最低，其次是SPECT、ExECG和冠状动脉造影，顺序依次为上述。（4）在pCAD阈值高于0.70时（例如，有典型心绞痛的中年男性），直接将冠状动脉造影作为首选检查显示每单位效果或效用成本最低。这个定量模型的优点是估计了pCAD的阈值（0.70），在该阈值时成本效益和每单位效用成本的排序会发生变化。该模型还允许用不同的值替代任何变量，以此来考虑临床数据的不确定性，即成本变化、检查准确性和风险等。这个过程称为敏感性分析，结果表明尽管几个变量发生了变化，但成本效益的排序并未改变。
（1）估计CAD诊断检查的总成本不仅需要考虑检查本身的直接成本（例如检查费用），还需要考虑基于该检查的管理算法的间接成本和诱导成本（例如成本/每增加一个QALY）。（2）在选择临床算法以实现每单位效果或每单位效用成本最低的诊断时，考虑临床病史（pCAD）至关重要。（3）对于pCAD < 0.70的患者，负荷PET显示每单位效果或每单位效用成本最低。（4）对于pCAD > 0.70的患者，冠状动脉造影显示每单位效果或每单位效用成本最低。
