Small studies are more heterogeneous than large ones: a meta-meta-analysis
Small studies are more heterogeneous than large ones: a meta-meta-analysis
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DOI：
10.1016/j.jclinepi.2015.03.017
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发表时间：
2015-08-01
影响因子：
7.2
通讯作者：
Goeman, Jelle J.
中科院分区：
文献类型：
--
作者：
IntHout, Joanna;Ioannidis, John P. A.;Goeman, Jelle J.
目的：研究间异质性在meta分析的随机效应模型中起着重要作用。大多数临床试验都是小规模的，而小规模的试验往往具有较大的效应。我们经验性地评估了试验规模和异质性（tau）之间是否也存在关系。研究设计和设置：我们选择了Cochrane数据库2009-2013年系统评价问题中每个干预评价的第一项荟萃分析，其结果为二分类（n = 2009）或连续（n = 1254）。估计的tau和试验规模之间的关联在meta分析中使用回归评估，在meta分析中使用贝叶斯方法评估。小型试验被预先定义为标准误差（SEs）超过0.2的标准化效应。结果：大多数荟萃分析基于少数试验（中位数为4）。在同一荟萃分析中，小型研究的tau(2)(S)大于大型研究的tau(2)(L)[平均比值2.11；二分分析的95%可信区间为1.05,3.87，连续荟萃分析的95%可信区间为3.11（2.00,4.78）。tau(S)的不精确性大于tau(L)：二分法的中位SE为0.39比0.20，连续小研究和大研究荟萃分析的中位SE为0.22比0.13。结论：小型研究之间的异质性大于大型研究之间的异质性。在典型的小型研究荟萃分析中，tau蛋白的估计存在很大的不精确性，这是另一个值得关注的原因，建议进行敏感性分析。(C) 2015爱思唯尔公司版权所有。
Objectives: Between-study heterogeneity plays an important role in random-effects models for meta-analysis. Most clinical trials are small, and small trials are often associated with larger effect sizes. We empirically evaluated whether there is also a relationship between trial size and heterogeneity (tau).Study Design and Setting: We selected the first meta-analysis per intervention review of the Cochrane Database of Systematic Reviews Issues 2009-2013 with a dichotomous (n = 2,009) or continuous (n = 1,254) outcome. The association between estimated tau and trial size was evaluated across meta-analyses using regression and within meta-analyses using a Bayesian approach. Small trials were predefined as those having standard errors (SEs) over 0.2 standardized effects.Results: Most meta-analyses were based on few (median 4) trials. Within the same meta-analysis, the small study tau(2)(S) was larger than the large-study tau(2)(L) [average ratio 2.11; 95% credible interval (1.05, 3.87) for dichotomous and 3.11 (2.00, 4.78) for continuous meta-analyses]. The imprecision of tau(S) was larger than of tau(L): median SE 0.39 vs. 0.20 for dichotomous and 0.22 vs. 0.13 for continuous small-study and large-study meta-analyses.Conclusion: Heterogeneity between small studies is larger than between larger studies. The large imprecision with which tau is estimated in a typical small-studies' meta-analysis is another reason for concern, and sensitivity analyses are recommended. (C) 2015 Elsevier Inc. All rights reserved.