Paper
Condition-family stock and rate split sharply here: OTHER and Oncology dominate on count, while Healthy volunteers are the clearest rate outlier.
Which condition families carry the most older CT.gov 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 using one condition-family label per study. 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 large condition families. The broad OTHER bucket led the stock table at 3,366 studies, followed by Oncology at 2,619, Healthy volunteers at 2,516, and Cardiovascular at 1,798. Healthy volunteers had the highest large-family description-black-box rate at 17.8 percent, far above renal and urology at 8.5 percent and metabolic at 8.3 percent. The condition-family black-box view mixes diffuse registry stock with a very sharp healthy-volunteer blackout pattern that is more severe than ordinary no-results counts alone. Condition families are keyword-derived registry groupings, not formal disease ontologies or diagnoses.