Nicholas C. Ide

The ClinicalTrials.gov Results Database — Update and Key Issues

BACKGROUND The ClinicalTrials.gov trial registry was expanded in 2008 to include a database for reporting summary results. We summarize the structure and contents of the results database, provide an update of relevant policies, and show how the data can be used to gain insight into the state of clinical research. METHODS We analyzed ClinicalTrials.gov data that were publicly available between September 2009 and September 2010. RESULTS As of September 27, 2010, ClinicalTrials.gov received approximately 330 new and 2000 revised registrations each week, along with 30 new and 80 revised results submissions. We characterized the 79,413 registry and 2178 results of trial records available as of September 2010. From a sample cohort of results records, 78 of 150 (52%) had associated publications within 2 years after posting. Of results records available publicly, 20% reported more than two primary outcome measures and 5% reported more than five. Of a sample of 100 registry record outcome measures, 61% lacked specificity in describing the metric used in the planned analysis. In a sample of 700 results records, the mean number of different analysis populations per study group was 2.5 (median, 1; range, 1 to 25). Of these trials, 24% reported results for 90% or less of their participants. CONCLUSIONS ClinicalTrials.gov provides access to study results not otherwise available to the public. Although the database allows examination of various aspects of ongoing and completed clinical trials, its ultimate usefulness depends on the research community to submit accurate, informative data.

Essie: A Concept-based Search Engine for Structured Biomedical Text

This article describes the algorithms implemented in the Essie search engine that is currently serving several Web sites at the National Library of Medicine. Essie is a phrase-based search engine with term and concept query expansion and probabilistic relevancy ranking. Essies design is motivated by an observation that query terms are often conceptually related to terms in a document, without actually occurring in the document text. Essies performance was evaluated using data and standard evaluation methods from the 2003 and 2006 Text REtrieval Conference (TREC) Genomics track. Essie was the best-performing search engine in the 2003 TREC Genomics track and achieved results comparable to those of the highest-ranking systems on the 2006 TREC Genomics track task. Essie shows that a judicious combination of exploiting document structure, phrase searching, and concept based query expansion is a useful approach for information retrieval in the biomedical domain.

Chapter 9 – The Role and Importance of Clinical Trial Registries and Results Databases

Abstract This chapter describes the evolving role of clinical trial registries and results databases. The first part describes the important public health policy goals of registration and results reporting, its history, and key policies in the United States and abroad. The second part focuses on practical issues, policies, and procedures for submitting data to and using data from ClinicalTrials.gov , the largest publicly available clinical trials database in the world. The future role of systematic sharing of individual participant data also is discussed.