The National Institute of Diabetes and Digestive and Kidney Diseases Central Repository provides information on studies funded by the NIDDK. Currently, data are available from 45 studies by request, including 40 sample types and over 6 million biospecimens. There are 49 ongoing studies being tracked or curated, and the Study Inventory List indicates whether samples can be shared. There are three sites which constitute this repository: Fisher BioServices, Inc. (Biosample Repository), Rutgers Lab (Genetics Repository), and RTI International (Central Data Repository). “These Repositories enable scientists not involved in the original study to test new hypotheses without any new data or biospecimen collection, and they provide the opportunity to pool data across several studies to increase the power of statistical analyses.”
Selecting PQT: Search for NIDDK Studies and Samples will result in displaying the list of search tools.
The Public Query Tools (PQT) page provides a variety of search options. The Variable Summary Tool provides users with the ability to compare studies based on selected variables by utilizing the cross study report. An example would be the selection of two variables: systolic blood pressure (sbp) and exercise. The repository search results identify two studies, The Type 1 Diabetes Control and Complications Trial (DCCT) and Epidemiology of Diabetes Interventions and Complications (EDIC). A side-by-side comparison for level 1 exercise with various ranges of systolic blood pressure readings would be:
However, in order to interpret the comparison, one should check the Variables Codebook for the definitions of the exercise values for each study, as they may not be consistent. Utilizing the Basic Search and selecting for the Condition Studied as Diabetes Type 1, the results display both links for the EDIC and DCCT studies. The Study Search Tool would be another option for locating these two studies in the repository.
The Variables Codebook link for the EDIC study is provided.
The Variables Codebook is now displayed where the different Value Labels are provided. Selecting exercise from the list indicates that four value definitions were utilized in the study.
The same process would be completed for the DCCT study with values provided for 1 and 4.
In this instance, one may still need to consult the original study publications for enhanced understanding of the Value Labels.
The repository’s Public Query Tools also offers The Navigate to Studies browsing feature, providing a way to identify research and viewing synopses with associated links. Genomic data for single nucleotide polymorphisms (SNPs) are available by selecting the DCCT/EDIC Metadata link, viewing the General Study Information and accessing the dbGaP database.
General Study Information page:
The dbGaP Database search results provide a wealth of information with links to a public download site containing release notes, manifests, documents, data dictionaries, variable summaries, and truncated analyses.
For questions, comments and inquiries, please contact Ask-A-Librarian at http://jeffline.jefferson.edu/Ask/ask.html