Design and analysis of studies evaluating smoking cessation interventions where effects vary between practices or practitioners.
Design and analysis of studies evaluating smoking cessation interventions where effects vary between practices or practitioners.
复制标题
设计和分析评估戒烟干预措施的研究，其中效果因实践或从业者而异。
作者：
Christopher Collett Butler;Max O Bachmann
背景
在实践中分组的患者可能具有共同的特征，导致他们对干预措施有相似的反应。从这样的群体中取样意味着试验的功效小于从人群中随机选择受试者。在实践层面上的结果可能的变化的知识是必要的，以计算样本量将需要膨胀到何种程度，以保持在面对“集群效应”的统计力量。
目标
为了规划临床试验的样本量和精度要求，我们检查了初级保健戒烟试验的报告，以获得集群水平的结果信息，发现它们没有帮助。因此，我们构建了假设情景来量化这种影响的潜在重要性。
方法
情景中，大集群间的变化进行了比较，有没有在实践水平上的效果大小的差异的样本。
结果
在5%的显著性水平下，一项具有80%把握度的研究检测到20%与10%的差异，在不存在聚类效应的情况下，每组需要200例患者。由于集群之间的结果存在中度差异，研究中需要超过1000名患者才能保持这种精度。由于群集间差异较大，将需要接近4000名受试者。
结论
在缺乏之前研究的详细数据的情况下，假设模型可以深入了解可能的集群效应对研究设计和分析的统计影响。即使集群间存在适度的差异，样本量也必须大幅增加才能保持相同的统计精度。这一领域的工作者如果能在聚类水平上公布结果变化的细节，将极大地帮助那些计划未来研究的人。
BACKGROUND
Patients grouped together in practices may share characteristics that cause them to have similar responses to an intervention. Sampling from such groups means that the power of a trial is less than when subjects are selected from the population at random. Knowledge of likely variation in outcome at the practice level is necessary to calculate the extent to which sample size would need to be inflated to maintain statistical power in the face of 'cluster effects'.
OBJECTIVES
To plan sample size and precision requirements of a clinical trial, we examined reports of primary care smoking cessation trials for information on outcomes at the level of clusters, and found them unhelpful. We therefore constructed hypothetical scenarios to quantity the potential importance of this effect.
METHOD
Scenarios of moderate and large inter cluster variation were compared with a sample where there was no difference in effect size at the level of practices.
RESULTS
A study with 80% power to detect a difference of 20% versus 10% at a 5% significance level would need 200 patients in each arm in the absence of cluster effects. With moderate variation in outcome between clusters, over a thousand patients would be needed in the study to maintain this precision. With larger inter-cluster variation, close to 4000 subjects would be required.
CONCLUSIONS
In the absence of detailed data from previous studies, hypothetical models can give insight into the statistical implications of possible cluster effects on study design and analysis. With even moderate inter-cluster variation, sample size will have to be inflated considerably to maintain the same statistical precision. Workers in this field will greatly assist those planning future research if they publish details of variation in outcome at the level of clusters.
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规划在学校吸毒预防研究中进行适当的分析。
影响因子：
5.9
作者：
Murray,DM;Hannan,PJ
通讯作者：
Hannan,PJ
DOI：
--
发表时间：
1988
期刊：
JAMA
影响因子：
--
作者：
Wilson,DM;Taylor,DW;Gilbert,JR;Best,JA;Lindsay,EA;Willms,DG;Singer,J
通讯作者：
Singer,J
一项旨在增加医生吸烟干预的随机试验。
DOI：
--
发表时间：
1989
期刊：
JAMA
影响因子：
--
作者：
Kottke,TE;Brekke,ML;Solberg,LI;Hughes,JR
通讯作者：
Hughes,JR
医生实施的吸烟干预项目：短期干预能否对普通门诊人群产生长期影响？
DOI：
10.1037//0278-6133.13.3.278
发表时间：
1994
期刊：
Health psychology : official journal of the Division of Health Psychology, American Psychological Association
影响因子：
--
作者：
Ockene,JK;Kristeller,J;Pbert,L;Hebert,JR;Luippold,R;Goldberg,RJ;Landon,J;Kalan,K
通讯作者：
Kalan,K