Garcia Raquel, Benet Marta, Arnau Catalina, Cobo Erik
Institut Municipal d'Investigació Mèdica, Barcelona, Spain.
Stat Med. 2004 Dec 30;23(24):3773-80. doi: 10.1002/sim.2072.
The aim of the present study is to estimate the relative efficiency of cross-over clinical trials as compared to the corresponding parallel designs. A MEDLINE 'full text' search covering years 2000-2003 over the word 'cross-over' identified 40 true cross-over studies with the parametric approach published in leading medical journals. A parallel design is expected to need, in order to achieve the same power, between 4 and 10 times more subjects than the corresponding cross-over design, meaning that cost of a parallel design can be between 2 and 5 times higher. There is a high proportion (18/40 = 45.0 per cent) of cross-over studies recently published in leading medical journals that, disregarding the CONSORT recommendations, does not provide estimates for the effect size and its standard error, hence, not allowing for the posterior use of the data in a meta-analysis.
本研究的目的是评估交叉临床试验相对于相应平行设计的相对效率。通过在MEDLINE中对2000年至2003年期间的“交叉”一词进行“全文”搜索，确定了40项采用参数方法并发表在主要医学期刊上的真正交叉研究。为了达到相同的检验效能，预计平行设计所需的受试者数量比相应的交叉设计多4至10倍，这意味着平行设计的成本可能高出2至5倍。最近在主要医学期刊上发表的交叉研究中有很大一部分（18/40 = 45.0%）无视CONSORT声明，没有提供效应量及其标准误的估计值，因此无法在荟萃分析中对数据进行后续使用。
