Clinical trial risk
Six-month risk ranks from public trial records
Trained on AACT through 1 March 2025. Checked against the next six months. 266,787 scored trials, 31,613 sponsors.
5,037,391 registry events. Model of record: aact11-r0-readout.
What we studied
Shortfall and termination probabilities are calibrated to within a tenth of a percentage point.
Sponsor portfolios
Expected per sponsor, vs. what happened
The model adds up the risks across a sponsor’s active trials to estimate how many will face a recruitment shortfall.
Across 400 sponsors, the model expected 1,044 shortfalls; 982 were recorded. At MD Anderson, the model underpredicted terminations: 20 were recorded against 6.5 expected.
Full sponsor comparison
| Sponsor | Active trials | Expected recruitment shortfalls | Actual | Expected terminations | Actual |
|---|---|---|---|---|---|
| Mayo Clinic | 1,574 | 28.9 | 30 | 9.1 | 14 |
| MD Anderson | 1,449 | 20.1 | 18 | 6.5 | 20 |
| Yale | 719 | 16.4 | 18 | 4.6 | 6 |
| AstraZeneca | 718 | 8.6 | 7 | 6.1 | 6 |
| Pfizer | 435 | 6.9 | 12 | 5.1 | 7 |
| University of Miami | 370 | 8.7 | 10 | — | — |
| AbbVie | 367 | 4.4 | 2 | 4.4 | 3 |
| Roche | 322 | 3.8 | 3 | 4.6 | 2 |
| Amgen | 135 | 1.6 | 0 | 2.7 | 3 |
| All 400 sponsors with 20+ active trials | 1,044 | 982 | 480 | 461 |
Expected counts are calibrated probabilities summed over the sponsor's active trials. Sponsor is the lead sponsor of record on the anchor date.
The National Cancer Institute had 23 shortfalls against 14 expected; Pfizer had 12 against 6.9.
Yale · NCT04168710
Yale’s highest recruitment-risk trial on 1 March 2025
Twelve times the average shortfall rate. Within six months, enrollment was below half the target.
Where the flags concentrate
Many top-flagged recruitment risks already have a “reason stopped” event. The shortfall is written into the public record later.
Recruitment shortfalls were concentrated in US academic medical centers, including Montefiore, Miami, Maryland, Northwell and Yale: three to four percent of active trials, five times the average. Termination risk was concentrated in large pharma, including Roche, AbbVie, Sanofi, Amgen, Pfizer and Novartis.
Review priorities
Shortfalls caught vs share of trials watched
Riskiest 20% of trials: model catches 60% of recruitment shortfalls. A screen on phase, sponsor type, size and geography catches 34%.
modelcohort screen
All outcomes and comparison details
| If you watch the riskiest | Recruitment shortfalls caught | Terminations caught | Timeline slips caught | Completions caught |
|---|---|---|---|---|
| 10% | 39% vs 20% | 46% vs 32% | 44% vs 18% | 39% vs 16% |
| 20% | 60% vs 34% | 65% vs 47% | 66% vs 31% | 58% vs 29% |
| 30% | 74% vs 45% | 76% vs 59% | 80% vs 42% | 71% vs 40% |
| 50% | 90% vs 63% | 90% vs 74% | 95% vs 61% | 88% vs 62% |
Model, with the cohort screen after "vs". The bottom 30% of the model's list holds 2 to 3% of the recruitment, termination and slip problems.
Six months, every active trial; each column uses the better of the two heads fitted for that question. The cohort screen uses 510 cells and scores each trial with the historical rate of its phase × sponsor type × size × country-count cell. Watching at random, 10% of attention catches 10% of problems. Chart: recruitment shortfall.
Recruitment target
Shortfall forecasts without mid-trial enrollment counts
Signals: record updates, date slips, stops, and the sponsor’s other trials.
ClinicalTrials.gov almost never carries accrual over time against target. Sponsors write the actual number when a trial stops, not while it runs.
Where that data lives, and what it would add
A sponsor's trial management system has enrollment by site by month; a CRO has it across sponsors. That join has not been run on this model.
The model gives six- or twelve-month probabilities of shortfall or attainment. Ranking scores are 0.80 for shortfall and 0.76 for attainment, with calibration within a tenth of a percentage point.
Rates are six-month hazards among active trials on the anchor date, so target size mostly shifts when things happen rather than whether. Lifetime attainment per trial is a different read on the same records and has not been run.
NCT04371432 · January 2026
A stopped trial changed course and completed
The registry cleared the trial’s stop reason, changed its eligibility criteria and recorded completion.
We compared predicted and recorded states across 1,192,946 transitions excluded from training, covering 116 kinds of event.
More discoveries and how surprise is measured
| Trial | When | What the registry recorded | Surprise, z |
|---|---|---|---|
| NCT00001604 | Dec 2025 | A 1999 NIH study under monthly edit waited a year after its completion bundle, far longer than such waits run | 42 |
| NCT06280833 | Sep 2025 | Completed in one bundle: enrollment and both completion dates written as actual, sites and status changed | 23 |
| NCT04371432 | Jan 2026 | A previously stopped trial cleared its stop reason, changed eligibility, and completed | 20 |
| NCT07623161 | Aug 2026 | Sites removed alongside a record verification, moving the trial far further than a site removal usually does | 17 |
After each event, we score surprise as the distance between the predicted and recorded state, standardized within each kind of event using the training period. The stopped trial’s score was 20 standard units. These scores describe recorded changes; a high score can also accompany a successful completion.
Related decks
This deck is the risk-ranking half. The scripted-action half is Trial Dynamics. Both are combined in Clinical Trial Oversight.