ClinicalTrials.gov

Overview

ClinicalTrials.gov is the primary international registry and results database for clinical trials, operated by the US National Library of Medicine (NLM) / NIH since 2000. It provides public access to information on privately and publicly funded clinical studies conducted around the world. Registration is mandated by the FDA Amendments Act (FDAAA 2007) for US-regulated trials, and is required by the International Committee of Medical Journal Editors (ICMJE) as a condition of publication in most major medical journals worldwide.

What ClinicalTrials.gov Provides

Registry

Each trial record includes study design, eligibility criteria, interventions, primary and secondary endpoints, sponsor and investigator contact information, recruitment status and study locations, optional protocol document uploads, and the NCT number — the universal trial identifier used in publications.

Results Database

Since 2017, FDAAA requires results submission within 12 months of primary completion for applicable clinical trials, covering participant flow and baseline characteristics, outcome measure results with statistical analyses, adverse events, and point-of-care result summaries.

In the European context, ClinicalTrials.gov is complementary to the EU Clinical Trials Register (EU CTR, https://www.clinicaltrialsregister.eu) which covers EudraCT registered trials. Under EU Clinical Trials Regulation (EU 536/2014), CTIS is replacing EudraCT for EU trials from 2023. Both registries are accepted by ICMJE.

Data Standards

ClinicalTrials.gov data is accessible via a structured API and uses controlled vocabularies for conditions (MeSH terms, ICD-10), interventions (drug names mapped to RxNorm and ChEBI), and outcomes (outcome measure terms aligned with LOINC and CDISC).

Connections

• Complements: CTIS (European registry)
• Controlled vocabularies: MeSH, ICD-10, RxNorm, ChEBI, LOINC, CDISC, MedDRA

Resources

• https://clinicaltrials.gov
• https://clinicaltrials.gov/data-api/api (REST API)
• https://www.clinicaltrialsregister.eu (EU CTR — European registry)