Metadata that are structured using principled schemas and that use terms from ontologies are essential to making biomedical data findable and reusable for downstream analyses. The largest source of metadata that describes the experimental protocol, funding, and scientific leadership of clinical studies is ClinicalTrials.gov. We evaluated whether values in 302,091 trial records adhere to expected data types and use terms from biomedical ontologies, whether records contain fields required by government regulations, and whether structured elements could replace free-text elements. Contact information, outcome measures, and study design are frequently missing or underspecified. Important fields for search, such as condition and intervention, are not restricted to ontologies, and almost half of the conditions are not denoted by MeSH terms, as recommended. Eligibility criteria are stored as semi-structured free text. Enforcing the presence of all required elements, requiring values for certain fields to be drawn from ontologies, and creating a structured eligibility criteria element would improve the reusability of data from ClinicalTrials.gov in systematic reviews, metanalyses, and matching of eligible patients to trials.

中文翻译：

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ClinicalTrials.gov中重复使用研究元数据的障碍

使用原则性架构进行结构化并使用本体中的术语的元数据对于使生物医学数据可发现并可用于下游分析至关重要。描述临床实验方案，经费和科学领导力的最大元数据来源是ClinicalTrials.gov。我们评估了302,091个试验记录中的值是否符合预期的数据类型和生物医学本体使用的术语，记录是否包含政府法规要求的字段以及结构化元素是否可以替代自由文本元素。联系信息，结果测量和研究设计经常丢失或指定不充分。诸如条件和干预之类的重要搜索字段不仅限于本体，而且几乎没有一半的条件用MeSH术语表示，根据建议。资格标准存储为半结构化自由文本。加强所有必需元素的存在，要求从本体论中提取某些字段的值以及创建结构化的资格标准元素将提高ClinicalTrials.gov的数据在系统评价，荟萃分析以及将符合条件的患者与试验进行匹配中的可重用性。