What are clinical trials? Clinical trials are research studies for testing the safety and effectiveness of new treatments in people. Detailed information may be found on the Resources section of the Web site.
What is ClinicalTrials.gov? The U.S. National Institutes of Health (NIH), through its National Library of Medicine (NLM), developed ClinicalTrials.gov to provide patients, family members, health professionals, and members of the public access to information on clinical research studies. For more information about this Web site, see the About section.
Which clinical trials are included in this database? ClinicalTrials.gov contains the most comprehensive central listing of clinical studies sponsored by the NIH, other Federal agencies, the pharmaceutical industry, and non-profit organizations, such as universities.
Who provides the data? Information is provided by the study sponsors. Every effort is made to ensure the quality and currency of the database.
Because of differences among these methods, your results for the same topic may vary slightly.
The Search Results page displays a list of studies in ClincialTrials.gov containing the words and phrases you provided (and their synonyms). See Working with Search Results to learn about the study records, viewing multiple studies, searching within results, and viewing details of your search.
Disease or ConditionSpecify health problems or conditions being studied.
- heart attack
Experimental TreatmentInclude drugs, devices, procedures, or vaccines used in a trial.
- vitamin e
Trial LocationSpecify a geographic location where studies are being conducted.
- Beth Israel Deaconess Medical Center
- Cleveland Clinic
- University of California San Francisco
- San Francisco
Choose a state from the menu provided.
Choose a country from the menu provided.
Additional TermsEnter any other terms that you wish to add to your search.
- pilot study
- veterans affairs medical center
- constance benson
Age GroupClick the check box to the left of each age group that you wish to include. Studies for all age groups are included when no boxes are checked.
- Children (birth-17)
- Adults (18-65)
- Senior (66+)
Study PhaseClick the check box next to each study phase you wish to include. Studies for all phases are included when no boxes are checked. The phase of a study describes the type of questions it is seeking to answer:
- Phase I: first test of a new drug or treatment in a small group to evaluate safety, determine a safe dosage range, and identify side effects.
- Phase II: study to determine effectiveness and safety of drug or treatment.
- Phase III: test of study drug or treatment to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
- Phase IV: follow-up study to evaluate risks, benefits, and optimal uses after a treatment is already available for general use.
Supported ByClick any of the boxes to specify search to specific types of organizations responsible for providing financial and other support for studies. All support categories are included when no boxes are checked.
- National Institutes of Health (NIH)
- Other Federal Agency (e.g., the Department of Veterans Affairs (VA) and the Centers for Disease Control and Prevention (CDC))
- Industry (e.g., pharmaceutical companies)
- University/Organization (e.g., community-based organizations)
Study ID NumberEnter an identification number assigned to a study.
- actg 076
The Search Results page displays a list of studies in ClincialTrials.gov containing the words and phrases you provided (and their synonyms). See Working with Search Results to learn about the study records, viewing multiple studies, searching within results, and viewing details of your search. use.
Medical terms can be difficult to remember, and often there are many names for a single concept (e.g., cancer of the colon, colonic neoplasm, colon cancer, etc.). Thus, ClinicalTrials.gov adds words related to those you entered automatically. This may increase the number of trials retrieved.
Example: When using the phrase heart attack in a search, the related phrase myocardial infarction will be added.
Synonyms added to a search can be viewed on the Query Details page.
Many medical terms are difficult to spell. When the words that you have entered are not recognized during a search, the system may suggest other words with similar spelling.
Example: A search using the word alshimer results in the message, "alshimer was not found. Select an alternative below or change your query." One word is offered: "alzheimer." To replace the original word with this one, click on the circle to the left. If you are not sure which word to use, refer to a medical dictionary.
|AND||Retrieved documents contain all words or phrases (and synonyms) connected by the AND operator||leukemia AND chemotherapy|
|OR||Retrieved documents contain either word or phrase (and synonyms) connected by the OR operator||aspirin OR ibuprofen|
|NOT||Retrieved documents do not contain the word or phrase (and synonyms) following the NOT operator||Immunodeficiency NOT AIDS|
|" "||Retrieved documents contain the exact words as specified between the quotes (and synonyms)||"heart attack"|
|[ ]||Retrieved documents contain words or phrases in a part of the document specified within the square brackets||diabetes [CONDITION]|
Notes on Operators
If you know the name of a disease or condition, use the alphabetical browse to select the first letter.
Browsing by disease heading allows you to select from a list of specific diseases categories.
To find studies sponsored by a particular organization, select one of four categories:
All studies in Browse are listed alphabetically by study title.
List of Study TitlesSearch results are displayed in a ranked ordered list based on your search criteria. The current status of the trial (e.g., recruiting), title, and conditions being studied (e.g., rheumatoid arthritis; diabetes; breast cancer) are shown for each retrieved study document.
Click on the trial title to obtain more information about the study, including:
- Location and Contact Information
- More Information
Show All TrialsSearch results may be filtered by recruitment status. When "Show all trials, including those no longer recruiting patients" box is not checked, only the following studies are displayed:
- Not yet recruiting: Participants are not yet being recruited or enrolled.
- Recruiting: Participants are currently being recruited and enrolled.
When the box is checked, trials with the following recruitment status are also displayed:
- No longer recruiting: Participants are no longer being recruited or enrolled.
- Completed: Participants are no longer being recruited; data analysis is complete.
- Suspended: Recruiting or enrolling patients has been halted temporarily; >trial is on hold due to concerns or questions regarding compliance or the >appropriateness or adequacy of the protocol.
- Terminated: Recruiting or enrolling patients has been halted permanently; >enrollment, treatment, and data collection has ceased; trial will not resume.
Displaying Multiple StudiesClick in the check box to the left of all of titles of interest on the Search Results page. After making your selections, click on the Display Selected Studies button to view the full description for all selected studies on that page.
Examining Details of the SearchTo view information related to your search, click on the Query Details button on the Search Results page. This page consists of several parts:
- Modify Your Search. Your current search is displayed in the text box. To edit your search strategy, click in the box and add or delete terms and then click the Search button.
- Table of Individual Terms and Counts. The Individual Terms column shows the words and phrases searched. Synonyms automatically included by the system are also listed (see Synonyms). The Count column indicates the total number of studies, both "Recruiting" and "No longer recruiting" (see Show All Trials), that would be retrieved if the term (and its synonyms) were searched.
- Query Suggestions. When a search may be too narrow, ClinicalTrials.gov suggests search strategies, based on your search terms, to broaden the search. All suggestions are listed in the left column of a table. If you find any of the suggestions useful, click on the "TryIt" link in the right column to view the results of the suggested search.
- Possibly Relevant MedlinePlus Topics. When possible, ClinicalTrials.gov will suggest resources at MedlinePlus that may be of interest, based on your search. MedlinePlus is a consumer health site that brings together, by health topic, authoritative information from NLM, NIH, other government, non-profit and other health-related organizations.
Search within ResultsIf many studies are retrieved initially, you may wish to add criteria to narrow your search. To search within your results, click on the Search-Within-Results button on the Search Results page. Enter words or phrases, separated by commas and select the appropriate fields to search:
- ALL-FIELDS: fields throughout the clinical trial record
- CONDITION: fields describing the diseases or conditions being studied
- TREATMENT: fields listing the drugs or interventions being studied
- LOCATION: fields with address information for participating facilities
Map of LocationsTo view a map of study locations of your search results, click on the Map of locations button on the Search Results page. Locations are displayed in two ways:
- Map of U.S. States or map of world
Click on a U.S. state to display studies with locations in that state.
Click on the world map, click on region to display studies with locations in that region.
- Location information for text browsers (displayed below the maps):
Click on a U.S. state or region to display studies with locations in that state or region.
From the list of studies limited to specific locations, click on the Return to Map of locations button to see the map of study locations of your search results.
Printing ResultsUse your Web browser's Print function to print the titles or study details.
Saving ResultsUse your Web browser's Save As... function to save information displayed on the screen to a file.
Search Results Are a Poor MatchYou may find that your search finds records that are not close to the topic you wanted. To improve your search, we suggest that you try searching again with fewer or different words. In addition, please use commas to separate words or phrases.
You may wish to view the Query Details page (see Examining Your Search) for information on the words and synonyms searched and/or query suggestions. Using Browse may also be helpful.
No Search ResultsSometimes you may find no match between the words and criteria you used to search and the trial records in the database. The Query Details page will appear with the message, "No studies were found for..."
This could be due to (1) a spelling error, (2) too many criteria in the search, or (3) there are currently no clinical trials in this database that match your search. Check your spelling with a medical dictionary or try searching again with fewer words or criteria (e.g., remove a city or state from the search).
The National Library of Medicine invites you to link from your web site to ClinicalTrials.gov.
If you link to this site, provide proper attribution to the U.S. National Library of Medicine (NLM) and ClinicalTrials.gov. It must be clear to users that data and searches are being provided by ClinicalTrials.gov. Use only real-time data provided directly by ClinicalTrials.gov to ensure that the most up-to-date and accurate information is provided to the public.
Text LinksThe text shown below should assist you in coding your html link to us. Paste the block of HTML code provided below directly into your page. Please observe the form of the ClinicalTrials.gov name, which should always include an uppercase C and T, a lowercase g, no space between "Clinical" and "Trials," and be rendered in italic letters.
ClinicalTrials.gov provides patients, family members, and members of the public easy and free access to information on clinical studies for a wide range of diseases and conditions.
<a href="http://clinicaltrials.gov/" title="Linking patients to medical research">ClinicalTrials.gov</a> provides patients, family members, and members of the public easy and free access to information on clinical studies for a wide range of diseases and conditions.
Formulating Search Requests
Links to individual search fields can be constructed, as shown below. For any multiword search terms (e.g. alzheimer disease), spaces must be replaced with a "+" character. Unusual characters must be URL encoded.
Examples:Searching for Alzheimer disease studies in ClinicalTrials.gov
http://clinicaltrials.gov/search/term=alzheimer+diseaseLinking to diabetes studies in ClinicalTrials.gov <a href="http://clinicaltrials.gov/search/condition=diabetes">Diabetes studies in ClinicalTrials.gov</a>
Linking to fluoxetine studies in ClinicalTrials.gov
<a href="http://clinicaltrials.gov/search/intervention=fluoxetine">fluoxetine studies in ClinicalTrials.gov</a>
Linking to clinical studies sponsored by NHLBI in ClinicalTrials.gov
<a href="http://clinicaltrials.gov/search/sponsor=NHLBI">Clinical studies sponsored by NHLBI in ClinicalTrials.gov</a>
You may show a specific study protocol record based on NCT number. The NCT number is NLM's unique identifier for a particular record and is found at the end of each record.
The syntax for performing complex queries requires familiarity with the search operators described previously and standard URL encoding. Any search that can be created at the ClinicalTrials.gov interface (e.g., Basic and Focused Search) may be encoded in a single link, using the template:
A left- and right-square bracket must enclose specific fields to be searched. The URL encoding for these characters is listed, in addition to the URL encoding for double quotes which can be used to limit a search to a specific phrase. Any spaces in the URL are encoded with the plus sign "+".
left square bracket
right square bracket
Source: World Wide Consortium - http://www.w3.org/
To encode the query juvenile diabetes [CONDITION] NOT transplantation [TREATMENT] as a link in a Web document:
juvenile diabetes [CONDITION]
NOT transplantation [TREATMENT]
XML FormatThe XML format of ClinicalTrials.gov protocol records may be viewed by appending a URL parameter "displayxml=true" to the end of a well-formed URL.
provides access to the XML format of study record NCT00001372.
View the DTD.
If you wish to submit comments or suggestions, please Contact Us. For more clinical trials, health, and medical information, please see Resource Information.
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