选择合适的对照组是临床科研设计的核心问题之一，也是研究结果真实性与可靠性的重要保证。Ｗｉｌｉａｎｓｏｎ〔１〕调查发现，７０年代前，根本无对照或对照不适合的比例高达７１％，７０年代占６０％，８０年代后，国外Ａｖｒａｍ〔２〕调查表明，应该设立对照而未设立... Selecting a suitable control group is one of the core issues in clinical research design, and it is also an important guarantee for the authenticity and reliability of the research results. The Wilianson [1] survey found that before the 1970s, the proportion of uncontrolled or unsuitable controls was as high as 71%. In the 1970s, it accounted for 60%. After the 1980s, the foreign Avram [2] survey showed that a control should be established and not established. .