Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Canada.
BMC Med Res Methodol. 2010 Feb 16;10:15. doi: 10.1186/1471-2288-10-15.
Cluster randomized trials (CRTs) present unique methodological and ethical challenges. Researchers conducting systematic reviews of CRTs (e.g., addressing methodological or ethical issues) require efficient electronic search strategies (filters or hedges) to identify trials in electronic databases such as MEDLINE. According to the CONSORT statement extension to CRTs, the clustered design should be clearly identified in titles or abstracts; however, variability in terminology may make electronic identification challenging. Our objectives were to (a) evaluate sensitivity ("recall") and precision of a well-known electronic search strategy ("randomized controlled trial" as publication type) with respect to identifying CRTs, (b) evaluate the feasibility of new search strategies targeted specifically at CRTs, and (c) determine whether CRTs are appropriately identified in titles or abstracts of reports and whether there has been improvement over time.
We manually examined a wide range of health journals to identify a gold standard set of CRTs. Search strategies were evaluated against the gold standard set, as well as an independent set of CRTs included in previous systematic reviews.
The existing strategy (randomized controlled trial.pt) is sensitive (93.8%) for identifying CRTs, but has relatively low precision (9%, number needed to read 11); the number needed to read can be halved to 5 (precision 18.4%) by combining with cluster design-related terms using the Boolean operator AND; combining with the Boolean operator OR maximizes sensitivity (99.4%) but would require 28.6 citations read to identify one CRT. Only about 50% of CRTs are clearly identified as cluster randomized in titles or abstracts; approximately 25% can be identified based on the reported units of randomization but are not amenable to electronic searching; the remaining 25% cannot be identified except through manual inspection of the full-text article. The proportion of trials clearly identified has increased from 28% between the years 2000-2003, to 60% between 2004-2007 (absolute increase 32%, 95% CI 17 to 47%).
CRTs should include the phrase "cluster randomized trial" in titles or abstracts; this will facilitate more accurate indexing of the publication type by reviewers at the National Library of Medicine, and efficient textword retrieval of the subset employing cluster randomization.
整群随机试验（cluster randomized trials，CRTs）提出了独特的方法学和伦理学挑战。系统评价 CRTs（例如，处理方法学或伦理学问题）的研究人员需要有效的电子搜索策略（过滤器或 hedges）来在 MEDLINE 等电子数据库中识别试验。根据 CONSORT 声明对 CRTs 的扩展，聚类设计应在标题或摘要中明确标识；然而，术语的可变性可能使电子识别具有挑战性。我们的目标是：（a）评估一种众所周知的电子搜索策略（“randomized controlled trial”作为出版物类型）识别 CRTs 的敏感性（“召回率”）和精度；（b）评估专门针对 CRTs 的新搜索策略的可行性；（c）确定 CRTs 是否在报告的标题或摘要中得到适当标识，以及随着时间的推移是否有所改进。
我们手动检查了广泛的健康期刊，以确定 CRT 的黄金标准集。搜索策略针对黄金标准集以及先前系统评价中包含的独立 CRT 集进行了评估。
现有的策略（randomized controlled trial.pt）识别 CRTs 的敏感性（93.8%）较高，但精度相对较低（9%，阅读量为 11）；通过使用布尔运算符 AND 与与聚类设计相关的术语相结合，阅读量可以减半至 5（精度 18.4%）；通过使用布尔运算符 OR 相结合，可以最大限度地提高敏感性（99.4%），但需要阅读 28.6 篇文献才能识别出一个 CRT。只有约 50%的 CRTs在标题或摘要中明确标识为整群随机；大约 25%的 CRTs可以根据报告的随机分组单位识别，但不适用于电子搜索；其余 25%的 CRTs只能通过手动检查全文文章来识别。从 2000-2003 年的 28%到 2004-2007 年的 60%，明确标识试验的比例有所增加（绝对增加 32%，95%CI 17%至 47%）。
CRTs 应在标题或摘要中包含“cluster randomized trial”一词；这将有助于国家医学图书馆的评审员更准确地索引出版物类型，并有效地检索采用聚类随机化的子集的文本词。
