Sample size calculation in cost-effectiveness cluster randomized trials: optimal and maximin approaches
Sample size calculation in cost-effectiveness cluster randomized trials: optimal and maximin approaches
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DOI：
10.1002/sim.6112
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发表时间：
2014-07-10
影响因子：
2
通讯作者：
Berger, Martijn P. F.
中科院分区：
文献类型：
--
作者：
Abu Manju, Md;Candel, Math J. J. M.;Berger, Martijn P. F.
在本文中，针对连续规模的治疗成本效益研究的整群随机试验，获得了两个治疗组各自在整群和个人水平上的最佳样本量。最佳样本大小可以最大化给定预算的效率或功率，或者最小化给定效率或功率的预算。最佳样本量需要有关效应和成本的簇内相关性 (ICC)、个体和簇层面的成本和效应之间的相关性、转化为成本的效应方差与成本方差之比（方差比）、抽样和测量成本以及预算等信息。在规划时，通常无法获得有关模型参数的研究信息。为了克服这个局部最优问题，本文还提出了最大最小样本量。事实证明，最大最小样本量对于错误指定集群和个体级别的成本和效果之间的相关性相当稳健，但在错误指定方差比时可能会损失很多效率。最大最小样本量针对错误指定 ICC 的稳健性取决于方差比。对于大于 1 的方差比的实际值，最大最小样本量在 ICC 成本错误指定的情况下是稳健的，但在 ICC 效应错误指定的情况下不稳健。最后，我们展示了如何计算最佳或最大样本量，以产生足够的功效来测试干预的成本效益。版权所有 (c) 2014 约翰·威利父子有限公司
In this paper, the optimal sample sizes at the cluster and person levels for each of two treatment arms are obtained for cluster randomized trials where the cost-effectiveness of treatments on a continuous scale is studied. The optimal sample sizes maximize the efficiency or power for a given budget or minimize the budget for a given efficiency or power. Optimal sample sizes require information on the intra-cluster correlations (ICCs) for effects and costs, the correlations between costs and effects at individual and cluster levels, the ratio of the variance of effects translated into costs to the variance of the costs (the variance ratio), sampling and measuring costs, and the budget. When planning, a study information on the model parameters usually is not available. To overcome this local optimality problem, the current paper also presents maximin sample sizes. The maximin sample sizes turn out to be rather robust against misspecifying the correlation between costs and effects at the cluster and individual levels but may lose much efficiency when misspecifying the variance ratio. The robustness of the maximin sample sizes against misspecifying the ICCs depends on the variance ratio. The maximin sample sizes are robust under misspecification of the ICC for costs for realistic values of the variance ratio greater than one but not robust under misspecification of the ICC for effects. Finally, we show how to calculate optimal or maximin sample sizes that yield sufficient power for a test on the cost-effectiveness of an intervention. Copyright (c) 2014 John Wiley & Sons, Ltd.