INSTALL httpfs;
LOAD httpfs;
ATTACH 'https://huggingface.co/datasets/Nason/clinicaltrials-database/resolve/main/clinicaltrials.duckdb' AS ct (READ_ONLY);

-- Trials by phase
SELECT overall_status, COUNT(*) as n
FROM ct.studies
GROUP BY overall_status
ORDER BY n DESC;

Python

import duckdb
con = duckdb.connect()
con.sql("INSTALL httpfs; LOAD httpfs;")
con.sql("""
    ATTACH 'https://huggingface.co/datasets/Nason/clinicaltrials-database/resolve/main/clinicaltrials.duckdb'
    AS ct (READ_ONLY)
""")
con.sql("SELECT * FROM ct.studies LIMIT 5").show()

DuckDB uses HTTP range requests, so only the pages needed for your query are downloaded.

Tables

Table	Description	Rows
`reported_events`	Summary of reported adverse events	11,828,940
`outcome_measurements`	Summary data for outcome measures by study group	4,927,392
`browse_conditions`	NLM-generated MeSH terms for study conditions	4,300,046
`design_outcomes`	Planned outcome measures and observations	3,683,025
`facilities`	Facility names, addresses, and recruiting status	3,480,413
`baseline_measurements`	Demographic and baseline measures by group	2,905,943
`browse_interventions`	NLM-generated MeSH terms for study interventions	2,525,611
`result_groups`	Aggregate list of group titles/descriptions for results reporting	2,182,830
`outcome_counts`	Sample sizes for each outcome by study group	1,583,371
`keywords`	Investigator-provided keywords describing the study	1,580,811
`design_group_interventions`	Cross-reference mapping design groups to interventions	1,320,148
`study_references`	Citations to publications related to the study	1,117,973
`design_groups`	Protocol-specified groups or cohorts assigned to interventions	1,088,089
`conditions`	Disease or condition names studied in each trial	1,060,832
`interventions`	Interventions or exposures: drugs, devices, procedures, vaccines	1,001,441
`sponsors`	Sponsor and collaborator names and types	945,127
`milestones`	Participant progress through each stage of the study	882,651
`countries`	Countries where the study has sites	803,708
`id_information`	Identifiers other than NCT ID (org study IDs, secondary IDs)	768,642
`outcomes`	Outcome measure descriptions and time frames	656,300
`outcome_analysis_groups`	Groups involved in each outcome analysis	623,989
`reported_event_totals`	Totals of reported adverse events by category	594,426
`drop_withdrawals`	Summary of participant withdrawals: counts and reasons	594,116
`calculated_values`	AACT-computed fields: months to report results, facilities count, etc.	592,206
`studies`	Core study record: title, status, phase, type, dates, enrollment, and regulatory info	592,206
`brief_summaries`	Brief text summary of the study protocol	591,233
`detailed_descriptions`	Detailed text description of the study protocol	591,233
`eligibilities`	Participant eligibility criteria (inclusion/exclusion, age, sex)	591,233
`designs`	Study design details: allocation, masking, assignment, purpose	587,431
`responsible_parties`	Parties responsible for submitting study information	573,757
`overall_officials`	People responsible for overall scientific leadership	528,514
`search_term_results`		506,655
`intervention_other_names`	Synonymous names for interventions	480,499
`facility_contacts`	Contact information at each study facility	415,701
`outcome_analyses`	Statistical analyses performed on outcomes	322,641
`baseline_counts`	Sample sizes at baseline for each study group	236,718
`facility_investigators`	Investigator names at each study facility	225,407
`central_contacts`	Primary and backup contacts for enrollment questions	222,655
`ipd_information_types`	Individual participant data sharing information types	92,867
`provided_documents`	Protocol, SAP, and informed consent form documents	82,967
`result_contacts`	Points of contact for scientific information about results	78,958
`result_agreements`	Agreements between sponsor and principal investigators about results	78,958
`participant_flows`	Recruitment and pre-assignment details	78,958
`links`	Web links relevant to the study	75,078
`pending_results`	Events related to submission of results for QC review	33,146
`documents`	Full study protocol and statistical analysis plan	10,804
`retractions`	Retraction notices for study results or publications	335
`search_terms`		186

Data Source

AACT (Aggregate Analysis of ClinicalTrials.gov) -- maintained by the Clinical Trials Transformation Initiative (CTTI). Updated daily from ClinicalTrials.gov. This is public domain U.S. government data.

License

Database build code: MIT. Underlying data: public domain (U.S. government work).

GitHub

Full source code, build instructions, and data dictionary: github.com/ian-nason/clinicaltrials-database

Changelog

2026-07-06 — Full refresh + data-quality audit

Rebuilt from the AACT snapshot of 2026-07-04 and repaired after an independent SQL-verified audit.

Data changes

58,046,170 rows across 48 tables; 592,206 studies (through June 2026).

Fixes

All seven studies.*_date_type columns restored: they hold ACTUAL/ESTIMATED strings and had been silently nulled by date casting. Anticipated-vs-actual analyses (reporting timeliness, FDAAA compliance) are possible again.
README example queries corrected: categorical values are AACT's UPPER_SNAKE ('COMPLETED', 'PHASE3', 'DRUG'); the phantom has_results column replaced with calculated_values.were_results_reported.
Phantom search_results table removed from metadata and the dictionary (its source file is header-only and never loads).

Known caveats (see README for the full list)

Results are posted for only ~24% of completed interventional trials.
No reliable registration time series before 2005 (ICMJE mandate cliff).
The final snapshot month is right-censored; truncate trends at May 2026.
Free text uses ~ as a newline surrogate.

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