Paper
The largest family is not the quietest family, which is why stock and rate have to be separated here too.
Which therapeutic areas look quietest in ClinicalTrials.gov once older closed interventional studies are grouped into comparable condition families? We analysed 249,507 eligible older studies from the March 29, 2026 full-registry snapshot and assigned each record to one dominant keyword-based family using registry condition strings and titles. Primary comparisons focused on ghost-protocol rates, two-year no-results rates, and the share with both results and publication visibility across common families. Oncology formed the largest named family at 42,344 eligible older studies, creating the biggest absolute stock of hidden evidence. Healthy-volunteer studies had the highest ghost-protocol rate among common families at 63.5 percent, while metabolic and gastrointestinal groupings also remained heavily obscured. Infectious-disease studies were relatively more visible, reaching a 20.6 percent fully visible rate despite still carrying substantial non-reporting across mapped families in this atlas. Because the classification is keyword-based and single-label, multi-topic trials can be compressed into one family and some records remain in a broad other bucket.