Overlap in meta‐reviews results from the use of multiple identical primary studies in similar reviews. It is an important area for research synthesists because overlap indicates the degree to which reviews address the same or different literatures of primary research. Current guidelines to address overlap suggest that assessing and documenting the degree of overlap in primary studies, calculated via the corrected covered area (CCA) is a promising method. Yet, the CCA is a simple percentage of overlap and current guidelines do not detail ways that reviewers can use the CCA as a diagnostic tool while also comprehensively incorporating these findings into their conclusions. Furthermore, we maintain that meta‐review teams must address non‐independence via overlap more thoroughly than by simply estimating and reporting the CCA. Instead, we recommend and elaborate five steps to take when examining overlap, illustrating these steps through the use of an empirical example of primary study overlap in a recently conducted meta‐review. This work helps to show that overlap of primary studies included in a meta‐review is not necessarily a bias but often can be a benefit. We also highlight further areas of caution in this task and potential for the development of new tools to address non‐independence issues.

中文翻译：

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检查元综述中纳入研究的重叠：使用校正覆盖面积指数的指南。

由于在类似评论中使用多项相同的主要研究，荟萃评论的重叠结果。它是研究综合的一个重要领域，因为重叠表明评论涉及初级研究的相同或不同文献的程度。当前处理重叠问题的指南建议评估和记录原始研究中的重叠程度，通过修正覆盖面积 (CCA) 计算是一种很有前途的方法。然而，CCA 只是重叠的一个简单百分比，目前的指南没有详细说明审阅者可以使用 CCA 作为诊断工具同时还将这些发现综合纳入他们的结论的方法。此外，我们认为元审查团队必须通过比简单地估计和报告 CCA 更彻底地重叠来解决非独立性问题。相反，我们建议并详细阐述了在检查重叠时要采取的五个步骤，通过在最近进行的元审查中使用主要研究重叠的经验示例来说明这些步骤。这项工作有助于表明元评价中包含的主要研究的重叠不一定是偏见，但通常可能是一种好处。