Murray David M, Pals Sherri L, Blitstein Jonathan L, Alfano Catherine M, Lehman Jennifer
Division of Epidemiology, College of Public Health, The Ohio State University, Columbus, OH, USA.
J Natl Cancer Inst. 2008 Apr 2;100(7):483-91. doi: 10.1093/jnci/djn066. Epub 2008 Mar 25.
Previous reviews have identified problems in the design and analysis of group-randomized trials in a number of areas. Similar problems may exist in cancer research, but there have been no comprehensive reviews.
We searched Medline and PubMed for group-randomized trials focused on cancer prevention and control that were published between 2002 and 2006. We located and reviewed 75 articles to determine whether articles included evidence of taking group randomization into account in establishing the size of the trial, such as reporting the expected intraclass correlation, the group component of variance, or the variance inflation factor. We also examined the analytical approaches to determine their appropriateness.
Only 18 (24%) of the 75 articles documented appropriate methods for sample size calculations. Only 34 (45%) limited their reports to analyses judged to be appropriate. Fully 26 (34%) failed to report any analyses that were judged to be appropriate. The most commonly used inappropriate analysis was an analysis at the individual level that ignored the groups altogether. Nine articles (12%) did not provide sufficient information.
Many investigators who use group-randomized trials in cancer research do not adequately attend to the special design and analytic challenges associated with these trials. Failure to do so can lead to reporting type I errors as real effects, mislead investigators and policy-makers, and slow progress toward control and prevention of cancer. A collaborative effort by investigators, statisticians, and others will be required to ensure that group-randomized trials are planned and analyzed using appropriate methods so that the scientific community can have confidence in the published results.
以往的综述已在多个领域发现了群组随机试验在设计和分析方面存在的问题。癌症研究中可能也存在类似问题，但尚未有全面的综述。
我们在Medline和PubMed数据库中检索了2002年至2006年发表的聚焦于癌症预防与控制的群组随机试验。我们查找并审阅了75篇文章，以确定这些文章是否包含在确定试验规模时考虑群组随机化的证据，例如报告预期的组内相关系数、方差的群组成分或方差膨胀因子。我们还检查了分析方法以确定其适用性。
75篇文章中只有18篇（24%）记录了计算样本量的合适方法。只有34篇（45%）将其报告局限于被判定为合适的分析。足足有26篇（34%）未报告任何被判定为合适的分析。最常用的不恰当分析是完全忽略群组的个体水平分析。9篇文章（12%）未提供足够信息。
许多在癌症研究中使用群组随机试验的研究者没有充分关注与这些试验相关的特殊设计和分析挑战。不这样做可能会导致将I型错误报告为真实效应，误导研究者和政策制定者，并减缓癌症控制和预防方面的进展。研究者、统计学家和其他人员需要共同努力，以确保使用合适的方法来规划和分析群组随机试验，以便科学界能够对发表的结果有信心。
