Paper
Country-linked stock and rate tell different stories: the United States dominates on volume, while Japan and South Korea are sharper on rate.
Which country-linked CT.gov portfolios carry the most older studies that are overdue, unlinked, and missing both detailed description and primary outcome description? We analysed 249,507 eligible older closed interventional studies from the March 29, 2026 full-registry snapshot and exploded country links. We defined a description black-box study as one with a two-year results gap, no linked publication, no detailed description, and no primary outcome description, then ranked country-linked portfolios with at least 500 linked studies. The United States led the country-linked stock table at 5,833 studies, followed by France at 1,353, Germany at 1,262, and Canada at 1,036. Japan had the highest large-country description-black-box rate at 10.7 percent, while South Korea reached 9.1 percent and Germany 8.4 percent. Country-linked black-box tables show where the strictest narrative opacity remains concentrated after studies failed results and linkage tests. Country-linked rows are non-exclusive because multinational studies can contribute to more than one national portfolio in the registry for readers.