Event studies
Line up protocol changes with market reactions using the date each version was posted publicly, not just when it was submitted.
“All enquiry and all learning is but recollection.”
Every protocol amendment ever posted to ClinicalTrials.gov, compiled into relational tables with one row per trial version. A snapshot tells you where a trial ended up. The history shows how it got there.
Release v2026.09.26, reflecting the ClinicalTrials.gov release of 2026-09-25.
ClinicalTrials.gov keeps every version of every trial, but shows them one trial at a time. Bulk downloads and public mirrors carry only the current version, so the amendments before it (a delayed completion date, a cut to enrollment, a quiet status change) are out of reach for any analysis across many trials.
Anamnesis Data compiles every version of every trial into relational tables. There are no per-trial lookups: a single query covers the whole registry, with the date each change became public.
A latest-snapshot mirror shows only the end: terminated, 63 enrolled. The history shows a 900-patient plan unwinding over nearly three years, and in Anamnesis Data it sits in the same table as every other trial.
Line up protocol changes with market reactions using the date each version was posted publicly, not just when it was submitted.
Measure how often and by how much completion dates move, across sponsors, phases, and therapeutic areas.
Trace paths from recruiting to suspended, terminated, or completed, and the stated reasons for stopping.
Compare anticipated with actual enrollment, and track targets as they are revised over a trial's life.
Build features from how a trial has changed so far, not only from where it stands today.
See when drugs, devices, and procedures were added to or dropped from a trial's registered interventions.
Download every table as Parquet and load it into pandas, Polars, DuckDB, Spark, or your own data warehouse. Each release is versioned, so an analysis can be pinned to an exact snapshot.
Query every version of every trial with SQL, with nothing to download or set up. Connect from any SQL client, BI tool, or notebook, and join the history to your own data.
Every version of every trial, with:
Field-level changes between consecutive versions, plus per-version outcomes, locations, sponsors and collaborators, and posted results.
Every primary-completion slip across the whole registry, in one query. The same SQL runs on the hosted database or on the downloaded files.
WITH v AS (
SELECT nct_id, nct_version,
last_update_post_date,
primary_completion_date AS pcd,
LAG(primary_completion_date) OVER (
PARTITION BY nct_id
ORDER BY nct_version
) AS prev_pcd
FROM trial_versions
)
SELECT *,
pcd - prev_pcd AS slip_days
FROM v
WHERE pcd > prev_pcd;
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These terms cover this compiled dataset only. The underlying trial records are available from ClinicalTrials.gov at no charge, and nothing here restricts data you obtain from ClinicalTrials.gov directly.
Questions about the data, a use case, or a license? We'd like to hear from you.