Center for Evidence Synthesis in Health, Department of Health Services, Policy, and Practice (Primary), Department of Epidemiology (Secondary), Brown University School of Public Health, 121 South Main Street, Box G-S121-8, Providence, RI, 02903, USA.
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Room Str. 6.127, Utrecht, GA, 3508, Netherlands.
BMC Med Res Methodol. 2020 Feb 11;20(1):30. doi: 10.1186/s12874-020-0898-2.
There is broad recognition of the importance of evidence in informing clinical decisions. When information from all studies included in a systematic review ("review") does not contribute to a meta-analysis, decision-makers can be frustrated. Our objectives were to use the field of eyes and vision as a case study and examine the extent to which authors of Cochrane reviews conducted meta-analyses for their review's pre-specified main outcome domain and the reasons that some otherwise eligible studies were not incorporated into meta-analyses.
We examined all completed systematic reviews published by Cochrane Eyes and Vision, as of August 11, 2017. We extracted information about each review's outcomes and, using an algorithm, categorized one outcome as its "main" outcome. We calculated the percentage of included studies incorporated into meta-analyses for any outcome and for the main outcome. We examined reasons for non-inclusion of studies into the meta-analysis for the main outcome.
We identified 175 completed reviews, of which 125 reviews included two or more studies. Across these 125 reviews, the median proportions of studies incorporated into at least one meta-analysis for any outcome and for the main outcome were 74% (interquartile range [IQR] 0-100%) and 28% (IQR 0-71%), respectively. Fifty-one reviews (41%) could not conduct a meta-analysis for the main outcome, mostly because fewer than two included studies measured the outcome (21/51 reviews) or the specific measurements for the outcome were inconsistent (16/51 reviews).
Outcome choice during systematic reviews can lead to few eligible studies included in meta-analyses. Core outcome sets and improved reporting of outcomes can help solve some of these problems.
人们普遍认识到证据在为临床决策提供信息方面的重要性。当系统评价（“综述”）中包含的所有研究的信息都无法进行荟萃分析时，决策者可能会感到沮丧。我们的目的是以眼睛和视力领域为例，研究 Cochrane 综述的作者为其综述的预定主要结局领域进行荟萃分析的程度，以及为什么一些有资格的研究没有纳入荟萃分析的原因。
我们检查了截至 2017 年 8 月 11 日发表的 Cochrane Eyes and Vision 所有已完成的系统评价。我们提取了每个综述的结局信息，并使用算法将一个结局归类为其“主要”结局。我们计算了任何结局和主要结局纳入荟萃分析的研究比例。我们检查了主要结局未纳入荟萃分析的研究的原因。
我们确定了 175 项已完成的综述，其中 125 项综述包括两项或更多项研究。在这 125 项综述中，纳入至少一项荟萃分析的研究比例中位数为任何结局的 74%（四分位距[IQR]0-100%）和主要结局的 28%（IQR0-71%）。51 项综述（41%）无法对主要结局进行荟萃分析，主要原因是纳入研究少于两项（21/51 项综述）或结局的具体测量不一致（16/51 项综述）。
系统评价中结局的选择可能导致纳入荟萃分析的合格研究较少。核心结局集和对结局报告的改进可以帮助解决其中的一些问题。
