The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews
The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews
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DOI：
10.1136/bmj.c365
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发表时间：
2010-02-15
影响因子：
105.7
通讯作者：
Williamson, Paula R.
中科院分区：
文献类型：
--
作者：
Kirkham, Jamie J.;Dwan, Kerry M.;Williamson, Paula R.
目的研究结果报告偏倚的发生率及其对Cochrane评价的影响。设计：建立随机试验中缺失结果数据的九点分类系统，并将其应用于Cochrane系统评价的大样本队列评价中。研究人员联系了进行试验的研究人员，并寻找了没有报告数据的原因。结果超过一半(157/283(55%))的综述没有包括所有符合条件的试验中感兴趣的综述主要结果的完整数据。由于任何原因而丢失的综述结果数据的中位数为10%，而在70篇(25%)综述中，50%或更多的潜在数据丢失。从2486个可评估试验中的155个(6%)的出版物中可以清楚地看出，研究人员已经测量和分析了综述的主要结果，但没有报告或只报告了部分结果。对于没有提到综述主要结果的报告，根据62名试验者的回答，我们关于结果报告偏差存在的分类的敏感性为88%(95%可信区间65%至100%)，特异性为80%(95%可信区间69%至90%)。三分之一的Cochrane综述(96/283(34%))包含至少一项试验，该试验高度怀疑综述的主要结果存在结果报告偏差。在对81篇综述进行的敏感性分析中，对感兴趣的主要结果进行了单一荟萃分析，其中19例(23%)的治疗效果估计减少了20%或更多。在42项仅有统计学显著结果的Meta分析中，8项(19%)在调整结果报告偏差后变得不显著，11项(26%)高估了治疗效果20%或更多。结论结果报告偏差是一个未被充分认识的问题，影响了相当大比例的Cochrane综述的结论。进行系统审查的个人需要明确解决缺少结果数据的问题，以使其审查被视为可靠的证据来源。在数据提取过程中需要格外小心，审查者应该确定何时试验报告了结果，但没有报告结果或观察到事件，并应鼓励与试验者联系。
Objective To examine the prevalence of outcome reporting bias-the selection for publication of a subset of the original recorded outcome variables on the basis of the results-and its impact on Cochrane reviews.Design A nine point classification system for missing outcome data in randomised trials was developed and applied to the trials assessed in a large, unselected cohort of Cochrane systematic reviews. Researchers who conducted the trials were contacted and the reason sought for the non-reporting of data. A sensitivity analysis was undertaken to assess the impact of outcome reporting bias on reviews that included a single meta-analysis of the review primary outcome.Results More than half (157/283 (55%)) the reviews did not include full data for the review primary outcome of interest from all eligible trials. The median amount of review outcome data missing for any reason was 10%, whereas 50% or more of the potential data were missing in 70 (25%) reviews. It was clear from the publications for 155 (6%) of the 2486 assessable trials that the researchers had measured and analysed the review primary outcome but did not report or only partially reported the results. For reports that did not mention the review primary outcome, our classification regarding the presence of outcome reporting bias was shown to have a sensitivity of 88% (95% CI 65% to 100%) and specificity of 80% (95% CI 69% to 90%) on the basis of responses from 62 trialists. A third of Cochrane reviews (96/283 (34%)) contained at least one trial with high suspicion of outcome reporting bias for the review primary outcome. In a sensitivity analysis undertaken for 81 reviews with a single meta-analysis of the primary outcome of interest, the treatment effect estimate was reduced by 20% or more in 19 (23%). Of the 42 meta-analyses with a statistically significant result only, eight (19%) became nonsignificant after adjustment for outcome reporting bias and 11 (26%) would have overestimated the treatment effect by 20% or more.Conclusions Outcome reporting bias is an under-recognised problem that affects the conclusions in a substantial proportion of Cochrane reviews. Individuals conducting systematic reviews need to address explicitly the issue of missing outcome data for their review to be considered a reliable source of evidence. Extra care is required during data extraction, reviewers should identify when a trial reports that an outcome was measured but no results were reported or events observed, and contact with trialists should be encouraged.