Clinical Trials and Resources

Clinical trials are human research studies that evaluate a medical, surgical or behavioral intervention. They are the primary way researchers find out if a new treatment — like a new drug, diet, type of exercise or medical device (such as a pacemaker) — is effective for people. Clinical trials have several stages. Learn more.

Phase 1 tests the safety of the intervention and is performed in a very small number of subjects to find the highest dose of the new treatment that can be given without causing severe side effects. For the treatment to enter Phase 1 testing, it has already been tested in lab and animal studies. Because of the small number of people in Phase 1 studies, rare side effects may not be seen until later phases of trials.

Phase 2 tests a larger group of patients (between 20 to 150) with the same disease, administering the experimental treatment as everyone gets in the Phase 1 study. Some Phase 2 studies randomly assign people to different treatment groups. These groups may get different doses or get the treatment in different ways to see which provides the best balance of safety and response. These studies may be done at major hospital centers, community hospitals or even at doctor’s offices.

Phase 3 clinical trials compare the safety and effectiveness of the new experimental treatment against the current standard treatment. Because health providers do not yet know which treatment is better, participants are often picked at random (called randomized) to get either the standard treatment or the new experimental treatment.

When possible, neither the doctor nor the patient knows which of the treatments the patient is getting. This type of study is called a double-blind study. Phase 3 studies are conducted in multiple sites and might even be done in different countries. They are often very large, involve hundreds of patients and take a long time for results. As with other trials, patients in phase 3 clinical trials are watched closely for side effects, and treatment is stopped if they’re too hard to manage.

Phase 4 studies look at drugs already approved by the FDA. These drugs are available for doctors to prescribe for patients. But phase 4 studies might still be needed to answer important questions. They usually involve thousands of people and look at safety over time, as well as examine other aspects of the treatment, such as quality of life or cost effectiveness. You can get the drugs used in a Phase 4 trial without being in a study.

Once all these phases of clinical trials have been completed, an application to the regulatory agency (the FDA in the U.S.) is submitted. The FDA decides whether to approve the treatment for use in patients with the illness the drug was tested on. If approved, the new treatment often becomes a standard of care, and newer drugs may be tested against it before they can be approved. If the FDA decides more evidence is needed to prove the treatment's benefits over risks, it may ask for more information or even require that more studies be done.

When considering a clinical trial, examine all options available to you and discuss with your doctor. Make sure you understand the Consent Form you are asked to sign and all the risks and benefits of participation. After enrolling, you are always free to discontinue your participation.

Having a diverse representation of genders, races, ethnicities, ages and other factors enables progress to happen faster and makes the results from the clinical trials better applicable to real life.

Always consult with your doctor before enrolling in a clinical trial. More information about clinical trials for your disease or in your geographic area can be found on clinicaltrials.gov .

If you are interested in participating in a clinical trial, once screened for eligibility, you will be allowed to review and sign the consent form. Next, your participation will begin. Some trials offer compensation for parking, time off work and travel. Such details are usually provided during the sign-up process and vary from trial to trial. Clinical trials may be sponsored by the federal government (e.g., NIH, DoD), or may be sponsored by pharmaceutical, biotechnology and device companies.