Paper
Closed-study actual-field discipline behaves like a hard structural boundary between cleaner and quieter registry segments.
How much hiddenness is concentrated in closed CT.gov studies that still fail to use actual completion or enrollment fields? We analysed 249,507 eligible older closed interventional studies from the March 29, 2026 full-registry snapshot and tracked three closed-study actual-field indicators. The project compares two-year no-results rates, ghost-protocol rates, and status-specific missing-actual patterns across primary-completion, completion, and enrollment discipline. Missing actual enrollment corresponds to a 100.0 percent no-results rate and a 62.8 percent ghost-protocol rate. Missing actual primary completion reaches 100.0 percent no results, missing actual completion 95.3 percent, and suspended studies are worst on actual-field discipline. Closed-study actual-field discipline therefore functions as a direct structural warning sign for opacity rather than a minor metadata defect. The separation remains visible across all three fields and links directly to the stopped-study audit as well inside older registry cohorts. Actual-field flags come from registry status and date/count types, not from external audits of what sponsors truly knew or when.