Get to Know ClinicalTrials.gov

September 2015

Rebecca J. Williams, Pharm.D., MPH

Assistant Director, ClinicalTrials.gov

National Library of Medicine

http://ClinicalTrials.gov
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Mission

The Office of Minority Health aims to promote and protect the health of 

diverse populations through research and communication of regulatory 

science that addresses health disparities.

 Goal 1- To improve and strengthen regulatory science informing the research and 

evaluation of sub-population data associations with race and ethnicity.

 Goal 2- To strengthen FDA capacity to address minority health and health disparities 

across the Agency 

 Goal 3- To promote effective communication and the dissemination of information to 

the public, particularly underserved, vulnerable populations.

March 2010 Affordable Care Act- Section 10334 mandated 

creation of OMH across all HHS divisions

Collaboration with the 

FDA Office of Minority Health
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Importance and Commitment to Diversity 

in Clinical Trials at FDA

“When a more diverse population participates in clinical trials, 

we increase the potential to know more about the extent to 

which different subgroups—males and females, young and old, 

people of various racial and ethnic backgrounds, and patients 

with differing comorbid diseases and conditions—might respond 

to a medical product. And when subgroup data are analyzed, we 

have available more information about the product that can be 

communicated to the public. The result is greater assurance in 

the safety and effectiveness of the medical products used by a 

diverse population.” 

Former FDA Commissioner Margaret Hamburg, August 2014
Outline for Presentation

• ClinicalTrials.gov Overview and Definitions

• ClinicalTrials.gov Content and Process

• Methods for Finding Trials

• ClinicalTrials.gov Results Database

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About ClinicalTrials.gov

(as of September 2015)

• Clinical studies registry and results database

– Over 199,000 studies (trials & observational studies)

– Studies with locations in all 50 states and 190 countries

– Privately and publicly funded studies involving humans

– Study information submitted by sponsors

• Web Site & registry launched in February 2000

– Results database, in September 2008

– Over 18,000 studies with results

• Database updated nightly

• Usage

– 179 million page views per month

– 61,000 visitors per day

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Why Conduct Clinical Trials?

• To obtain new and generalizable knowledge

• To provide evidence about treatments 

(benefits and risks) to inform medical decision 

making

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What is a Clinical Trial?

• A study that involves human participants to answer a 

specific research question about their health

• A protocol or research plan describes what will happen 

in the study (study visits, lab tests, etc.) 

• Participants receive an intervention such as a drug (or 

placebo) 

– The protocol determines what a participant receives

– When more than one intervention is being tested, the 

participant does not typically get to choose; assignment is 

random

• Participants are followed carefully for a period of time 

and evaluated for changes in health outcomes

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C

B

Outcomes

Outcomes

Outcomes

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A

Clinical Trial

Protocol Intervention
Example: Clinical Trial

• Effectiveness of Arginine as a Treatment 

for Sickle Cell Anemia (NCT00513617)

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Clinical Trial Example

Adapted from NCT00513617

Arms Assigned Interventions

Active Comparator

Low Dose 0.05 g/kg/day Arginine

Drug: Arginine

Depending on the weight of the child or adult, the patients took 

any where between 4-10 capsules 2 times a day. Patients weighing 

less than 45 kilograms were on the low dose active (or placebo) so 

the capsules were smaller. Patients greater than or equal to 45 kgs

were on the high dose active or placebo, so these capsules were 

larger.

Active Comparator

High Dose 0.10 g/kg/day Arginine

Drug: Arginine

Depending on the weight of the child or adult, the patients took 

any where between 4-10 capsules 2 times a day. Patients weighing 

less than 45 kilograms were on the low dose active (or placebo) so 

the capsules were smaller. Patients greater than or equal to 45 kgs

were on the high dose active or placebo, so these capsules were 

larger.

Placebo Comparator

Placebo (no Arginine)

Drug: Placebo

Depending on the weight of the child or adult, the patients took 

any where between 4-10 capsules 2 times a day. Patients weighing 

less than 45 kilograms were on the low dose active (or placebo) so 

the capsules were smaller. Patients greater than or equal to 45 kgs

were on the high dose active or placebo, so these capsules were 

larger. 10
Clinical Trials Vary in Purpose

• Wide variety of populations

– Healthy volunteers

– People with the condition in various stages of disease 

and/or treatment (early  late)

• Wide range of goals

– Assess level of toxicity, find appropriate dose, evaluate 

drug interactions

– Study the disease process 

– Evaluate if an intervention can prevent or treat disease

– Compare known treatments to each other

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Other Types of Research

• Observational studies

– A study that uses a protocol or research plan to 

evaluate a specific research question in human

participants

– Participants receive “usual medical care” (their 

treatment is not determined by the protocol)

– Participants are “observed” over time and health 

outcomes assessed

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C

B

Outcomes

Outcomes

Outcomes

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A

Observational Study

Routine Medical Care Protocol
Example: Observational Study

• Secondary Pulmonary Hypertension in Adults 

With Sickle Cell Anemia (NCT00011648)

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Observational Study Example

Adapted from NCT00011648

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• Men and women 18 years of age and older 

with sickle cell anemia

– Initial assessment (medical history, physical exam, 

blood collection, echocardiogram)

• A study nurse will contact participants two 

times a month for 2 months, then once every 

3 months for 3 years

– Telephone interview with questions about health 

and health-related events (hospitalizations or 

emergency room visits)
ClinicalTrials.gov Content and 

Process
Why Register a Study and Submit 

Results on ClinicalTrials.gov?

• Ethical and Scientific Rationale

– Responsibility to research participants, patients, 

and the public

– Research integrity

– Evidence-based medicine

• Required by various policies and laws

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Key U.S. Policies and Laws

• Journal editors require registration of clinical trials (2005)

• U.S. Federal Laws

– FDAMA 113 (1997): registration of clinical trials of investigational 

drugs for serious and life-threatening conditions

– FDAAA 801 (2007): registration & results for clinical trials of drugs 

and devices (early/Phase 1 trials excluded)

• Results reporting only required for trials of “approved” products (but 

proposed to expand to include unapproved)

• NIH encourages registration & results for all NIH-funded 

clinical trials

– Proposal issued by NIH in Nov 2014 to make this a requirement

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FDAMA 113 = Section 113 of the Food and Drug Administration Modernization Act of 1997; FDAAA 801 = Section 801 of the Food 

and Drug Administration Amendments Act of 2007 

Complete information at ClinicalTrials.gov History, Policies, and Laws: https://clinicaltrials.gov/ct2/about-site/history
350 - 450 

per week

25-30 

per week

200 - 250 

per week

>190,000

400 - 500 per week

Number of Registered Studies

Journal

Editors

FDAAA 801

Year

Studies Registered Over Time 

(as of September 2015)

2014

FDAMA
ClinicalTrials.gov Content 

(as of September 24, 2015)

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†

Includes 321 Expanded Access study records and 587 applicable device clinical trials that submitted a 

“delayed posting” under FDAAA

* Intervention types not additive; study record may include more than one type of intervention

Registration Results

Total 199,165† 18,463

Type of Trial

 Observational 37,760 (18%) 1,163 (6%)

 Interventional* 160,497 (80%) 17,300 (93%)

 - Drug or Biologic 101,366 14,116

 - Behavioral, Other 44,302 2,680

 - Surgical Procedure 17,371 890

 - Device 17,044 1,868
ClinicalTrials.gov Content 

(as of September 24, 2015)

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Registration Results

Total 199,165 18,463

Funder Type†

 Universities, foundations 97,426 3,399

 Industry 74,748 12,523

 U.S. NIH 24,482 2,241

 U.S. Federal Gov.t 4,640 589

Location

 Non-U.S. Only 91,039 (46%) --

 U.S. Only 76,066 (38%) --

 Not specified 20,360 (10%) --

 Both U.S. and Non-U.S. 11,700 (6%) --

† Funder types not additive; study record may include more than one type of funder
Content of a Study Record 

(One Record per Unique Study Protocol – Single NCT Number)

• Protocol section

– Submitted at trial start; 

updated throughout trial 

lifecycle

– Summarizes information 

from trial protocol: e.g., 

– Condition

– Interventions

– Study Design

– Includes recruitment 

information (e.g., 

eligibility, locations)

• Results section

– Submitted after trial 

completion/termination

– Summarizes trial results

– Participant flow

– Baseline 

characteristics

– Outcome measures 

(including statistical 

analyses)

– Adverse events

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Example: Observational Study

• Secondary Pulmonary Hypertension in Adults 

With Sickle Cell Anemia (NCT00011648)

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Sponsor & 

Funders

Recruitment 

Status

NCT Number

Dates

Study Title

Highlights
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Study Type: Observational ClinicalTrials.gov Identifier: NCT00011648

Estimated Enrollment: 1200

Study Start Date: February 2001

Outcome Measures: Prevalence of secondary pulmonary hypertension ...

Secondary Pulmonary Hypertension in Adults With Sickle Cell Anemia

Who can 

Participate

Who to 

Contact

Study 

Design

Highlights
ClinicalTrials.gov Process Overview

• Information submitted to ClinicalTrials.gov by Responsible 

Party of study (Sponsor or Principal Investigator)

• A record represents a single trial, even if more than 1 location

• Basic review criteria must be met before public posting

– Automated rules then manual review by ClinicalTrials.gov staff

• Each record is:

– Assigned a unique identifier (NCT Number)

– Expected to be corrected/updated throughout life cycle

– All changes tracked in public Archive site

• We add links to other useful resources about the condition 

evaluated or product studied (examples: Medline Plus; 

Genetics Home Reference; PubMed)

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Review by ClinicalTrials.gov

• Evaluate whether study information is complete 

and generally understandable

– Internal consistency and logic; complete and 

meaningful entries; formatting

• Posting of a study on ClinicalTrials.gov does not 

mean that it is endorsed by the National 

Institutes of Health (NIH)

• Choosing to participate in a study is an important 

personal decision. Talk with your doctor and 

family/friends about deciding to join a study.

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Who “Approves” a Clinical Trial?

• Clinical trials of drugs in the U.S. are reviewed, 

approved, and monitored by an ethics committee 

(known as an institutional review board or IRB)

• Purpose is to ensure that study meets ethical 

standards and that rights and welfare of 

participants are protected

– Informed consent

• Clinical trials recruiting on ClinicalTrials.gov must 

indicate that they have IRB approval

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Sample Uses of ClinicalTrials.gov

• Identify trials of potential interest for an 

individual or user community

• Track progress of a specific trial 

and availability of summary results

• Identify completed or ongoing trials for 

specific conditions/interventions

– Supplements a literature review

• Identify researchers and/or centers of 

relevance to specific conditions/interventions

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ClinicalTrials.gov Visitors by Role (2014)

Role

% Respondents

N=5,397

Patient 27%

Scientist/Researcher 19%

Family or Friend of Patient 13%

Health Care Provider (e.g., nurse, physician) 8%

Other 8%

Clinical Trial Staff 7%

Clinical Research Support (e.g. regulatory affairs) 5%

Healthy Person 4%

Student/Educator 4%

Medical Communications 3%

Librarian or Information Professional 2%

Institutional Review Board (IRB) or 

Ethics Committee Member 1%

Source: ForeSee American Customer Satisfaction Index Survey Results: 1 Jan to 31 Dec 2014
Methods for Finding Trials
Methods for Finding Trials

• Basic Search

• Advanced Search - allows for a focused search

– https://clinicaltrials.gov/ct2/search/advanced

• See Studies by Topic

– Conditions/Rare Diseases, Drugs, Dietary 

Supplements, Sponsor/Collaborators, Locations

• https://clinicaltrials.gov/ct2/search/browse

• See Studies on Map

– https://clinicaltrials.gov/ct2/search/map

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Demonstration

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Search Results Tools

• RSS Feed

– Receive automatic updates on a specific search

– https://clinicaltrials.gov/ct2/resources/rss

• Download Search Results

– Choose study fields to include

– Select file format (tab- and comma-separated 

values format is appropriate for a spreadsheet)

– https://clinicaltrials.gov/ct2/resources/download

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Other Considerations for Finding Trials

• There are many organizations that exist to 

provide support to people with a specific disease 

or condition and their families/friends

– May have resources that are more targeted for your 

needs

– Often includes ClinicalTrials.gov information

• Other organizations aim to “match” people to 

trials (and may require personal information)

– BreastCancerTrials.org

– ResearchMatch.org

– Others ...

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Possible Questions to Ask if 

Considering Participating in Research

• What is being studied?

• Why do researchers think the intervention 

may or may not be effective? Has it been 

tested before?

• What are the possible interventions that I 

might receive in trial? How will this be 

determined?

• How do the possible risks, side effects, 

benefits compare to my current treatment?

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https://clinicaltrials.gov/ct2/about-studies/learn
Possible Questions to Ask if 

Considering Participating in Research

• What tests and procedures are involved?

• How often will I have to visit hospital/clinic?

– Will an overnight stay be required?

• How long will study last?

• Who is funding the study? Who will pay costs?

• Will I received the study results?

• Who will oversee my medical care?

• What are my options if I am injured in the study?

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https://clinicaltrials.gov/ct2/about-studies/learn
ClinicalTrials.gov Results 

Database
ClinicalTrials.gov Results Database

• Current requirements for results posting:

– U.S. Law (FDAAA 801)

• Clinical trials of approved drugs, biologics, devices 

– Excluded: Phase 1 drug & small device feasibility trials

• Completed after December 2007

• Additional requirements may be coming*:

– DRAFT NIH Policy: All NIH-funded clinical trials

– Rulemaking for FDAAA: Include unapproved products

• Approximately half of studies with results on 

ClinicalTrials.gov are not yet published 

48 *http://www.nih.gov/news/health/nov2014/od-19.htm
ClinicalTrials.gov Results Database: 

Basic information – reported by arm

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• Participant Flow

– Number Started

– Number Completed

• Baseline 

Characteristics

– Number Analyzed

– Age and gender

– Other relevant measures 

(e.g., disease history)

• Primary and Secondary 

Outcome Measures

- Outcome Data

- Statistical analyses (if any)

• Serious and Other 

Adverse Events

- Total Number of Events

- Specific Events by Organ Class
Studies with Results in 

ClinicalTrials.gov

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Example of Study with Results
Participant Flow

Adapted from NCT01167023

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Placebo 5 mg Prasugrel 7.5mg Prasugrel

Started 21 41 0

Received at least 1 

dose of study drug 19 41 0

Completed 18 39 0

Not Completed 3 2 0

 Lost to Follow-up 1 1 0

 Screen Failure 1 0 0

 Sponsor Decision 1 0 0

 Withdrawal by Subject 0 1 0

Overall Study

See full study record for complete information: https://clinicaltrials.gov/ct2/show/NCT01167023
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Placebo 5 mg Prasugrel Total

Number of Participants 21 41 62

Age

[units: years]

Mean (Standard Deviation)

31.52 (8.20) 32.88 (8.60) 32.42 (8.42)

Gender

[units: participants]

Female 9 21 30

Male 12 20 32

Ethnicity (NIH/OMB)

[units: participants]

Hispanic or Latino 0 1 1

Not Hispanic or Latino 21 40 61

Unknown or Not Reported 0 0 0

Race (NIH/OMB)

[units: participants]

American Indian or Alaska Native 0 0 0

Asian 0 0 0

Native Hawaiian or Other Pacific Islander 0 0 0

Black or African American 21 40 61

White 0 1 1

More than one race 0 0 0

Unknown or Not Reported 0 0 0

Baseline Measures

Baseline Measures

Adapted from NCT01167023

See full study record for complete information: https://clinicaltrials.gov/ct2/show/NCT01167023
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Measured Values

Primary Outcome

Measure Title Percentage of Participants With Hemorrhagic Events Requiring Medical 

Intervention During the Treatment Duration

Measure 

Description

A hemorrhagic event requiring medical intervention. Medical intervention was 

defined as any medical attention resulting in therapy or further investigation 

during the 30-day treatment duration.

Time Frame Baseline through 30 days 

Placebo 5 mg Prasugrel

Number of Participants Analyzed 19 41

[units: percentage of participants] 0 0

Outcome Measures

Adapted from NCT01167023

See full study record for complete information: https://clinicaltrials.gov/ct2/show/NCT01167023
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Placebo 5 mg Prasugrel

Total Serious Adverse Events

 # participants affected/at risk 4/19 (21.05%) 8/41 (19.51%)

Blood and lymphatic system disorders

 Pancytopenia 1/19 (5.26%) 0/41 (0.00%)

Congenital, familial and genetic disorders

 Sickle cell anemia 0/19 (0.00%) 1/41 (2.44%)

 Sickle cell anemia with crisis 1/19 (5.26%) 2/41 (4.88%)

Ear and labyrinth disorders

 Vertigo 0/19 (0.00%) 1/41 (2.44%)

General Disorders

 Pain .... 1/19 (5.26%) 0/41 (0.00%)

Serious Adverse Events

Serious Adverse Events

Adapted from NCT01167023

See full study record for complete information: https://clinicaltrials.gov/ct2/show/NCT01167023
•

•

•

Linking Publications to NCT Numbers

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Clarifications about Results 

Requirements

• Summary results at the end of the trial

• Information currently targeted at readers of 

the medical literature

– “Tables” of information; “just the facts”

– No conclusions or discussion

• Results submission is not required for 

registered studies that are not subject to law 

(FDAAA 801)

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Additional Resources

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• ClinicalTrials.gov Online Training – brief animated tutorials

• http://www.nlm.nih.gov/bsd/viewlet/ct/

• Topics currently available: Basic Search, Advanced 

Search, Customize Your Display, Downloading Search 

Results, Modify a Search, RSS Feed Setup for a 

Search, Study Record Details, Using the 

ClinicalTrials.gov Results Database

• Find Studies: https://www.clinicaltrials.gov/ct2/search/index

• Learn About Clinical Studies

• https://clinicaltrials.gov/ct2/about-studies/learn

http://ClinicalTrials.gov
Thank you! 

Questions? 

Contact us at: register@clinicaltrials.gov

http://ClinicalTrials.gov