Leveraging Open Tools to Realize the Potential of Self-Archiving: A Cohort Study in Clinical Trials

While open access (OA) is growing, many publications remain behind a paywall. This limits the impact of research and entrenches global inequalities by restricting access to knowledge to those that can afford it. Many journal policies allow researchers to make a version of their publication openly accessible through self-archiving in a repository, sometimes after an embargo period (green OA). Unpaywall and Shareyourpaper are open tools that help users find OA articles and support authors to legally self-archive their papers, respectively. This study leveraged these tools to assess the potential of green OA to increase discoverability in a cohort of clinical trial results publications from German university medical centers. Of the 1897 publications in this cohort, 46% (n = 871/1897, 95% confidence interval (CI) 44% to 48%) were neither openly accessible via a journal or a repository. Of these, 85% (n = 736/871, 95% CI 82% to 87%) had a permission to self-archive the accepted or published version in an institutional repository. Thus, most of the closed-access clinical trial results in this cohort could be made openly accessible in a repository, in line with World Health Organization (WHO) recommendations. In addition to providing further evidence of the unrealized potential of green OA, this study demonstrates the use of open tools to obtain actionable information on self-archiving at scale and empowers efforts to increase science discoverability.