Abstract

Background:

Increasingly, risk of bias tools are used to evaluate epidemiologic studies as part of evidence synthesis (evidence integration), often involving meta-analyses. Some of these tools consider hypothetical randomized controlled trials (RCTs) as gold standards.

Methods:

We review the strengths and limitations of risk of bias assessments, in particular, for reviews of observational studies of environmental exposures, and we also comment more generally on methods of evidence synthesis.

Results:

Although RCTs may provide a useful starting point to think about bias, they do not provide a gold standard for environmental studies. Observational studies should not be considered inherently biased vs. a hypothetical RCT. Rather than a checklist approach when evaluating individual studies using risk of bias tools, we call for identifying and quantifying possible biases, their direction, and their impacts on parameter estimates. As is recognized in many guidelines, evidence synthesis requires a broader approach than simply evaluating risk of bias in individual studies followed by synthesis of studies judged unbiased, or with studies given more weight if judged less biased. It should include the use of classical considerations for judging causality in human studies, as well as triangulation and integration of animal and mechanistic data.

Conclusions:

Bias assessments are important in evidence synthesis, but we argue they can and should be improved to address the concerns we raise here. Simplistic, mechanical approaches to risk of bias assessments, which may particularly occur when these tools are used by nonexperts, can result in erroneous conclusions and sometimes may be used to dismiss important evidence. Evidence synthesis requires a broad approach that goes beyond assessing bias in individual human studies and then including a narrow range of human studies judged to be unbiased in evidence synthesis. https://doi.org/10.1289/EHP6980

中文翻译：

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环境和职业暴露观察流行病学研究的偏差评估和证据合成风险：优点和局限性。

 抽象的

 背景：

偏倚风险工具越来越多地被用来评估流行病学研究，作为证据综合（证据整合）的一部分，通常涉及荟萃分析。其中一些工具将假设的随机对照试验 (RCT) 视为黄金标准。

 方法：

我们回顾了偏倚风险评估的优点和局限性，特别是对环境暴露观察性研究的回顾，并且我们还对证据合成方法进行了更广泛的评论。

 结果：

尽管随机对照试验可能为思考偏见提供了一个有用的起点，但它们并没有为环境研究提供黄金标准。与假设的随机对照试验相比，观察性研究不应被视为存在固有偏差。在使用偏倚风险工具评估个别研究时，我们呼吁识别和量化可能的偏倚、其方向及其对参数估计的影响，而不是使用清单方法。正如许多指南所认识到的那样，证据综合需要更广泛的方法，而不是简单地评估个别研究中的偏倚风险，然后综合判断为无偏倚的研究，或者如果判断为偏倚较小的研究则给予更多权重。它应该包括使用经典的考虑因素来判断人类研究中的因果关系，以及动物和机械数据的三角测量和整合。

 结论：

偏见评估在证据合成中很重要，但我们认为可以而且应该改进它们以解决我们在此提出的担忧。过于简单化、机械化的偏倚风险评估方法（尤其是在非专家使用这些工具时可能会出现这种情况）可能会导致错误的结论，有时可能会被用来驳回重要的证据。证据合成需要一种广泛的方法，不仅仅是评估个体人类研究中的偏见，然后包括被认为在证据合成中无偏见的一小部分人类研究。 https://doi.org/10.1289/EHP6980