Brighton Brian, Bhandari Mohit, Tornetta Paul, Felson David T
School of Medicine, Boston University, Boston, MA, USA.
Clin Orthop Relat Res. 2003 Aug(413):19-24. doi: 10.1097/01.blo.0000079323.41006.12.
In the hierarchy of research designs, the results of randomized controlled trials are considered the highest level of evidence. Randomization is the only method for controlling for known and unknown prognostic factors between two comparison groups. Lack of randomization predisposes a study to potentially important imbalances in baseline characteristics between two study groups. There is a hierarchy of evidence, with randomized controlled trials at the top, controlled observational studies in the middle, and uncontrolled studies and opinion at the bottom. This hierarchy has not been supported in two recent publications in the New England Journal of Medicine which identified nonsignificant differences in results between randomized, controlled trials, and observational studies. The current authors provide an approach to organizing published research on the basis of study design, a hierarchy of evidence, a set of principles and tools that help clinicians distinguish ignorance of evidence from real scientific uncertainty, distinguish evidence from unsubstantiated opinions, and ultimately provide better patient care.
在研究设计的层次体系中，随机对照试验的结果被视为最高级别的证据。随机化是控制两个比较组之间已知和未知预后因素的唯一方法。缺乏随机化会使一项研究易于在两个研究组的基线特征之间出现潜在的重要失衡。存在一个证据层次体系，随机对照试验处于顶端，对照观察性研究处于中间，而无对照研究和观点则处于底层。《新英格兰医学杂志》最近的两篇出版物对这一层次体系提出了质疑，这两篇文章指出随机对照试验与观察性研究的结果并无显著差异。本文作者提供了一种基于研究设计来组织已发表研究的方法，一个证据层次体系，以及一套原则和工具，这些原则和工具可帮助临床医生区分对证据的无知与真正的科学不确定性，区分证据与未经证实的观点，并最终提供更好的患者护理。
