Collins R, Gray R, Godwin J, Peto R
Stat Med. 1987 Apr-May;6(3):245-54. doi: 10.1002/sim.4780060308.
In order to avoid selective biases and to minimize random errors, inference about the effects of treatment on serious endpoints needs to be based not on one, or a few, of the available trial results, but on a systematic overview of the totality of the evidence from all the relevant unconfounded randomized trials. But, only where coverage of all, or nearly all, randomized patients in all relevant trials (or a reasonably unbiased sample of such trials) can be assured, is a systematic overview of trials reasonably trustworthy, for then any selective biases are likely to be small in comparison with any moderate effects of treatment. Checks for the existence of such biases can best be conducted if reasonably detailed data are available from each trial. Future trials should take into account the results of any relevant overviews in their design, and should plan to obtain sufficient numbers of events to contribute substantially to such overviews. In many cases, this implies the need for randomized trials that are much larger than is currently standard.
为避免选择性偏倚并尽量减少随机误差，关于治疗对严重终点影响的推断不应基于一个或几个现有试验结果，而应基于所有相关无混杂因素的随机试验证据的系统综述。但是，只有在能够确保涵盖所有或几乎所有相关试验中的随机患者（或此类试验的合理无偏样本）时，试验的系统综述才具有合理的可信度，因为此时与治疗的任何中度效应相比，任何选择性偏倚可能都很小。如果每个试验都有合理详细的数据，就可以最好地检查此类偏倚的存在情况。未来的试验应在设计中考虑任何相关综述的结果，并应计划获得足够数量的事件，以便对这些综述做出重大贡献。在许多情况下，这意味着需要比目前标准大得多的随机试验。
