Boussageon R, Gueyffier F, Moreau A, Gansel Y, Boussageon V
Département de médecine générale, université Claude-Bernard, 69600 Lyon, France.
Encephale. 2008 Sep;34(4):347-51. doi: 10.1016/j.encep.2007.05.001. Epub 2008 Jan 11.
Randomized, double blind, placebo-controlled clinical trials are currently the best means of demonstrating the clinical effectiveness of drugs. The double blind procedure, when ethically and technically feasible, is a necessary condition for validating results and for causal attribution of the observed difference between the two groups to the tested drug's pharmacological effect.
In practice, however, it appears that patients and independent investigators can guess who receives the drug and who receives a placebo through side effects, which are usually more frequent in patients receiving the drug. This phenomenon effectively "breaks the blind" and represents as such a major methodological bias, which cannot be avoided as it is inseparable of the drug's effect.
The impact of this "unavoidable" double blind breach nevertheless remains unclear. While it can reasonably be assumed that it may modify subjective symptoms such as anxiety or pain through suggestion, its influence on objective criteria remains to be demonstrated.
随机、双盲、安慰剂对照临床试验是目前证明药物临床疗效的最佳方法。在伦理和技术可行的情况下，双盲程序是验证结果以及将两组间观察到的差异归因于受试药物药理作用的必要条件。
然而在实际中，患者和独立研究者似乎能够通过副作用猜出谁服用了药物、谁服用了安慰剂，而副作用通常在服药患者中更常见。这种现象实际上“打破了盲态”，构成了一种主要的方法学偏差，由于其与药物效应不可分割，所以无法避免。
这种“不可避免的”双盲破盲的影响仍不明确。虽然可以合理推测它可能通过暗示改变诸如焦虑或疼痛等主观症状，但其对客观标准的影响仍有待证实。
