On effect-measure modification: Relationships among changes in the relative risk, odds ratio, and risk difference
On effect-measure modification: Relationships among changes in the relative risk, odds ratio, and risk difference
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DOI：
10.1002/sim.3246
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发表时间：
2008-08-15
影响因子：
2
通讯作者：
Berg, Arthur
中科院分区：
文献类型：
--
作者：
Brumback, Babette;Berg, Arthur
众所周知，效果测量修正的存在与否取决于所选择的测量方法。也许更令人不安的是，一项措施的积极变化可能伴随着另一项措施的消极变化。因此，研究表明一种效应在一个人群中比在另一个人群中“更强”，但仅基于一种测量方法，例如优势比，这可能难以解释对另一种测量方法感兴趣的研究人员。本文研究了不同阶层间相对风险、优势比和风险差异的变化之间的关系。蒙特卡罗积分表明，对于由四个基本比例定义的几何空间的78%或89%的体积，这三个测量值在同一方向上变化，这取决于地层是否被假定具有相同的影响方向。给出了措施向相反方向变化的充分必要条件的分析结果。总的来说，情况看起来相当复杂，尽管它们确实让位于一些有趣的结果。例如，当暴露增加了风险，但所有风险都小于0.5时，相对风险和风险差不可能与优势比的变化方向相反。提出了数据分析和假设的例子，以证明在哪种情况下，措施在相反的方向变化。版权所有(C) 2008约翰威利父子有限公司
It is well known that the presence or absence of effect-measure modification depends upon the chosen measure. What is perhaps more disconcerting is that a positive change in one measure may be accompanied by a negative change in another. Therefore, research demonstrating that an effect is 'stronger' in one population when compared with another, but based on only one measure, for example, the odds ratio, may be difficult to interpret for researchers interested in another measure. The present article investigates relationships among changes in the relative risk, odds ratio, and risk difference from one stratum to another. Monte Carlo integration shows that the three measures change in the same direction for 78 or 89 per cent of the volume of the geometric space defined by the four underlying proportions, depending on whether the strata are presumed to share the same direction of effect or not. Analytic results are presented concerning necessary and sufficient conditions for the measures to change in opposite directions. In general, the conditions are seen to be quite complicated, though they do give way to some interesting results. For example, when exposure increases risk but all risks are less than 0.5, it is impossible for the relative risk and risk difference to change in the same direction but opposite to that of the odds ratio. Both data-analytic and hypothetical examples are presented to demonstrate circumstances under which the measures change in opposite directions. Copyright (C) 2008 John Wiley & Sons, Ltd.