McPherson K, Britton A R, Wennberg J E
Department of Public Health & Policy, London School of Hygiene and Tropical Medicine, UK.
J R Soc Med. 1997 Dec;90(12):652-6. doi: 10.1177/014107689709001205.
The most reliable information about treatment effects comes from randomized controlled trials (RCTs). However, the possibility of subtle interactions--for example, between treatment preferences and treatment effects--is generally subordinated in the quest for evidence about main treatment effects. If patient preferences can influence the effectiveness of treatments through poorly understood (psychological) pathways, then RCTs, particularly when unblinded, may wrongly attribute effects solely to a treatment's physiological/pharmacological properties. To interpret the RCT evidence base it is important to know whether any preference effects exist and, if so, by how much they affect outcome. Reliable measurement of these effects is difficult and will require new approaches to the conduct of trials. In view of the fanciful image with which such effects are portrayed and the uncertainties about their true nature and biological mechanisms, existing evidence is unlikely to provide sufficient justification for investment in trials. This is a Catch 22. Until an escape is found we might never know, even approximately, how much of modern medicine is attributable to psychological processes.
关于治疗效果的最可靠信息来自随机对照试验（RCT）。然而，在寻求关于主要治疗效果的证据时，微妙相互作用的可能性——例如，治疗偏好与治疗效果之间的相互作用——通常被置于次要地位。如果患者偏好能够通过尚未充分理解的（心理）途径影响治疗效果，那么随机对照试验，尤其是在未设盲的情况下，可能会错误地将效果完全归因于治疗的生理/药理特性。为了解释随机对照试验的证据基础，了解是否存在任何偏好效应以及如果存在，它们对结果的影响程度至关重要。对这些效应进行可靠测量很困难，需要采用新的试验方法。鉴于此类效应被描绘出的奇特形象以及它们真实性质和生物学机制的不确定性，现有证据不太可能为试验投资提供充分理由。这是一个两难困境。在找到解决办法之前，我们可能永远无法确切知道，甚至大致了解，现代医学中有多少可归因于心理过程。
