scribed these data-sharing continuums and discussed the benefits and risks of data sharing, based on the degree to which participant-level data are made available to researchers and the public.

In some trials, data are not even made available to individual researchers participating in a multicenter trial. Sometimes, data are released to researchers not associated with the study only if they show a genuine research interest in the question and a track record of research capability. In some cases, data are shared with everyone.


De-identified patient data have two major uses, observed Deborah Zarin, director of at the National Library of Medicine. They can improve transparency, helping to understand the results of an individual clinical trial, including what happened to individuals in the trial, and they can be pooled to discover new things not identified in the individual trials.

Data Sharing to Enable Independent Reanalysis

Steven Goodman, associate dean for clinical and translational research and professor of medicine and health policy and research at the Stanford University School of Medicine, discussed the former use case in the context of ensuring that a study was correctly analyzed and interpreted. Independent reanalysis of data is the basis of reproducible research and can be an extremely difficult task. An example he mentioned was a study of childhood asthma that had 72 different study forms, 109 form revisions, and almost 300,000 records in the database. The original manuscript started with 73 tables and 9 figures and underwent 40 revisions. The published manuscript contained three tables and two figures. “How do we begin from this tiny little slice that we see to begin to work backward and figure out is what they did right?” he asked. While the top tier of journals may have methodologists who can begin to check the chain of scientific custody from protocol to conduct to data to analysis to results, other journals have to rely on peer reviewers to detect problems. The authors of published studies can put additional information on the Web in the form of supplementary material and appendixes, but in reality, checking the accuracy of the results for a study like this is extremely difficult.

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