May G S, DeMets D L, Friedman L M, Furberg C, Passamani E
Circulation. 1981 Oct;64(4):669-73. doi: 10.1161/01.cir.64.4.669.
The realization that bias in patient selection may influence the results of clinical studies has helped to establish the randomized controlled clinical trial in medical research. However, bias can be equally important at other stages of a trial, especially at the time of analysis. Withdrawing patients from consideration in the analysis because of ineligibility on account of study entry criteria, lack of compliance to the protocol, or data of poor quality may be a source of systematic error. Examples to illustrate the possible consequences are taken from trials in the cardiovascular field. We recommended that reported study results should include outcome data from all subjects randomized in the group to which they were originally assigned.
认识到患者选择中的偏倚可能会影响临床研究结果，这有助于在医学研究中确立随机对照临床试验。然而，偏倚在试验的其他阶段同样重要，尤其是在分析阶段。由于不符合研究入选标准、未遵守方案或数据质量差等原因而将患者排除在分析之外，可能会成为系统误差的一个来源。为说明可能产生的后果所举的例子取自心血管领域的试验。我们建议，报告的研究结果应包括最初分配到该组的所有随机分组受试者的结局数据。
