ESTIMATING THE EFFECT OF THE RUN-IN ON THE POWER OF THE PHYSICIANS HEALTH STUDY
ESTIMATING THE EFFECT OF THE RUN-IN ON THE POWER OF THE PHYSICIANS HEALTH STUDY
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DOI：
10.1002/sim.4780101010
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发表时间：
1991-10-01
影响因子：
2
通讯作者：
HENNEKENS, CH
中科院分区：
文献类型：
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作者：
LANG, JM;BURING, JE;HENNEKENS, CH
医生健康研究是一项随机、安慰剂对照的双盲试验，阿司匹林降低心血管死亡率，β-胡萝卜素降低癌症发病率，33223名受试者符合条件并愿意参加试验。所有参与者都收到了含有活性阿司匹林和β-胡萝卜素安慰剂的相同日历包，而不是立即随机分组。经过18周的磨合，只有22,071名仍然符合条件和愿意并且至少服用了三分之二的药物的受试者被随机抽取。我们估计磨合的影响如下：服药依从性增加了20%-41%；样本量减少了34%；随访持续时间减少了7%，导致安慰剂组的预期事件发生率下降了7%。为了估计这些变化，我们对那些被磨合排除在外的人的合规性和结果风险做出了假设。然而，我们关于磨合对研究力量的净影响的结论，在这些假设中的不同变化中保持不变。有磨合的功率，有22,071个好的编译器，通常高于没有磨合的功率，永远不会超过可以忽略不计的低，有33,223个好的和差的编译器。此外，由于使用了磨合，试验中招募的受试者减少了11,152人，从而节省了费用。
In the Physicians' Health Study, a randomized, placebo-controlled, double-blind trial of aspirin in the reduction of cardiovascular mortality and beta-carotene in decreasing cancer incidence, 33,223 subjects were eligible and willing to enter the trial. Instead of randomizing this group immediately, all participants received identical calendar packs that contained active aspirin and beta-carotene placebo. Following an 18-week run-in, only 22,071 subjects who remained eligible and willing and had taken at least 2/3 of their pills were randomized. We estimated the effect of the run-in as follows: pill taking compliance increased 20-41 per cent; sample size decreased 34 per cent; duration of follow-up decreased 7 per cent which resulted in a 7 per cent decrease in the expected event rate for the placebo group. To estimate these changes, we made assumptions about compliance and outcome risk for those excluded by the run-in. Our conclusion, however, about the net effect of the run-in on the power of the study remains constant across variations in a number of those assumptions. The power with the run-in, with 22,071 good compliers was typically higher, and never more than negligibly lower, than the power without the run-in, with 33,223 good and poor compliers. In addition, savings from enrolling 11,152 fewer subjects in the trial resulted from the use of the run-in.