Participating in a Clinical Trial

Millions of people volunteer to take part in clinical trials every year. Their participation helps the medical community learn what works best in treating diseases. If you’re serious about volunteering, it’s important for you and your family to understand the process and your part in it.

Taking Part in a Clinical Trial

Clinical trials are medical research studies performed with the help of patients who volunteer to try new diagnostic techniques or new therapies, or to be observed as part of a group of people with a specific health issue. The doctors conducting the research seek to answer specific medical questions — ultimately to improve health and patient care.

Researchers can gather information for clinical trials using a variety of methods, including:

  • Interventional. Participants receive experimental treatment — which can include a drug, device, surgical procedure or an existing therapy used in a new way — to determine whether it's safe and effective.
  • Observational. Participants receive diagnostic or therapeutic care and researchers note the health outcome.
  • Chart review. Doctors use data from existing patient health charts to answer the research question.
  • Registry. Researchers study a specific patient population by observing participants with a particular disease, condition or exposure to something that may be affecting their health.
  • Specimen collection and research repository. Participants donate tissue for analysis, including solid tissues, cells, cell cultures or molecules derived from tissues — such as DNA, RNA and proteins — and body fluids. Participants may consent to use the samples for a particular study or for unspecified future research or testing.

Before joining a clinical trial, you must meet the specific qualifications of the study. Each study has a different set of criteria to help ensure that researchers can answer the health question they plan to investigate. Trial criteria may include age, sex, the type and stage of the disease, and previous treatment history.

Types and Phases of Clinical Trials

Clinical trials can be used for much more than testing new drugs. Types of clinical trials include:

  • Treatment trials – Test new drugs, devices, therapies or surgical techniques.
  • Prevention trials – Look for ways to prevent disease.
  • Diagnostic or screening trials – Find better tests for identifying or screening for certain health conditions.
  • Quality of life trials (or supportive care trials) – Explore ways to improve quality of life for people living with chronic disease.

Drug Trial Phases

For the study of new drugs, or of existing drugs used in new ways, clinical trials are divided into different phases, numbered from 0 to 4. The earliest phase may look at safety or side effects. A later phase may test whether a new treatment is better than existing treatments:

  • Phase 0 – An exploratory study that requires very limited human exposure to the drug, and has no therapeutic or diagnostic goals.
  • Phase 1 – Conducted with an emphasis on safety, the goal is to discover how the drug is processed, toxicity and any side effects.
  • Phase 2 – Gathers preliminary data on effectiveness — whether the drug works in participants with a certain condition, compared with participants receiving a different treatment or a placebo (a medicine that has no effect).
  • Phase 3 – Measures safety and effectiveness by examining different populations taking different dosages of the drug or in combination with other drugs.
  • Phase 4 – Occurs after the Federal Drug Administration (FDA) has approved a drug, but researchers want more information about its safety, efficacy or best use.

Medical Device Trial Phases

Clinical trials are also used to test medical devices — healthcare products that don't achieve results through chemical action or by being metabolized. A device can range from something as simple as a tongue depressor or thermometer to a complex instrument, such as a specialized heart valve or robotic surgical device.

Device trial phases include:

  • Pilot/Feasibility – May be used to answer basic research questions or provide support for a future study. It's an initial, exploratory stage to determine whether the potential benefit justifies any risk.
  • Pivotal – Evaluates the safety and effectiveness of the device for the intended use, which may require one or more studies.
  • Post-market – Assesses safety of the device after it's been used commercially, such as investigating rare adverse events or long-term effectiveness.

Research Study Funding and Leadership

The people or organizations that initiate studies are known as research sponsors. Doctors, medical institutions, foundations, voluntary groups, device and pharmaceutical companies sponsor medical studies. Federal agencies such as the National Institutes of Health (NIH), the Department of Defense (DOD) and the Department of Veterans Affairs (VA) also sponsor research. Trials can take place in hospitals, universities, doctors offices or community clinics.

Every study has a principal investigator, or lead researcher, who takes direct responsibility for completion of a clinical trial. The principle investigator directs the research and reports to the sponsor.

Informed Consent: Know Your Risks and Costs

Clinical trials aren’t always free and may include risks, even though they’re carefully controlled. Every trial is different. When it comes to cost, some studies will be fully funded, while others will be billed to your insurance company; a combination of both is also a common occurrence.

"Informed consent" is a process of learning key facts about a trial before participating. It's also a document. Once your doctors and nurses are certain you fully grasp the details — a study's purpose, procedures, risks, costs, potential benefits and how long it will take — you'll be asked to sign an informed consent document. It's not a contract and it's not binding. You may withdraw from a trial at any time.

How to Find a Clinical Trial

The Center for Information and Study on Clinical Research Participation (CISCRP) educates and informs the public, patients, medical and research communities, the media, and policymakers about clinical research and the role each party plays in the process. They offer a free search service to help you find a trial that's right for you.

To learn more about being a study participant, please contact the Clinical Research Department at