A clinical trial is a research study that looks at how well a new treatment works in people.  This is called “efficacy.”  The treatment may be a drug, medical procedure, medical device, or even a lifestyle change.  A clinical trial also makes sure the new treatment is safe, well-tolerated, and does not cause harm or serious side effects in most people. 

For example, a clinical trial may look at whether a new exercise routine helps people lose weight.  Or it may look at whether a new drug helps lower blood pressure in people with high blood pressure.

In short, a clinical trial helps to answer two important questions:

  • Does the new treatment work in humans?  If so, how well does it work? Is it better or the same as treatments that are currently available?  If it is the same, does it have fewer side effects than other treatments?  Does it help people who have not responded to other treatments?

  • Is the new treatment safe?  No treatment is completely safe for everyone; however, a clinical trial helps make sure the benefits outweigh the possible risks for most people.

Who conducts clinical trials?

Each clinical trial is led by a principal investigator, who is usually a medical doctor. In addition, there is often a team of doctors, nurses, social workers, and other health professionals who will work directly with you and provide your medical care.  To cover the costs involved, a study must also have financial support (funding).  This funding may come from a drug company (pharmaceutical), university medical center, government agency, or other organization.  The group that provides funding is usually referred to as the “sponsor.”

Why are clinical trials needed?

Clinical trials try to find better ways to prevent, screen for, diagnose, or treat diseases and other health problems. Without them, we would not have new treatments or other advances in health and medicine.

What is a study protocol?

Clinical studies in the United States are regulated by a government agency called the “Food and Drug Administration (FDA).”  Each study is reviewed, approved, and watched over by the FDA.  Before a clinical trial can begin, it must receive approval from the FDA.  It must also have an action plan (called a “protocol”).  The action plan describes what will be done in the study, how it will be conducted, and why each part of the study is needed.  This helps make sure the study will answer certain questions about the treatment while trying to make sure the people taking part are kept as safe as possible.  Among other things, a protocol describes:

  • The reason for conducting the study

  • Who may participate (“eligibility”)

  • How many participants are needed

  • What tests and procedures will be done during the study and how often

  • Information about the drugs that will be used, including the name and dosage

  • The phase of the study (phase I – phase IV)

  • How long the study will last

Actual study protocols can be very long (over 100 pages) and very technical.  They are not written with patients in mind, so they can be hard for most patients to understand. Clinical trials must also have guidelines about who can be in them, and this information can be helpful if you are trying to decide whether you want to participate.

Clinical studies in the United States are regulated by a government agency called the “Food and Drug Administration (FDA).” Each study is reviewed, approved, and watched over by an independent panel of qualified doctors, researchers, and members of the community called an “Institutional Review Board (IRB).” This review board makes sure your rights, safety, and welfare is protected, and that the study itself is being done for honest and ethical reasons. It also makes sure that the health risks involved are reasonable compared to the possible benefits. Remember, no treatment is completely safe for everyone; however, a clinical trial helps make sure the benefits outweigh the possible risks for most people.

Before a new treatment can be tested in humans, it goes through years of research in laboratories, followed by testing in animals such as mice or rats. After each phase of research, the clinical trial team submits an “Investigation New Drug” application (IND) to the FDA. Along with an independent ethics committee, the FDA reviews the results and decides whether the study can continue to the next phase. Once approved for human testing, the new treatment is studied in a very small group of people (usually 20-100). These studies are called “Phase I” studies. Gradually, the number of people involved will be increased until the testing reaches Phase III studies. After completing Phase III, the trial team submits a “New Drug Application” (NDA) to the FDA for approval. If the new treatment receives FDA approval, it can be put on the market for public use. In some cases, Phase IV trials might be conducted as well.

Why are clinical studies divided into phases?

Because each phase has a different goal or certain questions it is trying to answer.  Knowing which phase a trial is in can be helpful, especially if you are trying to decide whether to participate.  In general, phase I studies have the most potential risk, but they can also be very helpful, especially if you need access to a new treatment that is not yet available for public use.

  • Phase I studies are meant to find the best dosage that can be given without serious side effects.  The first few people in the study will often get a low dose of the treatment and are watched very closely.  If there are only minor side effects, the next few participants will get a higher dose. This continues until researchers find the dose that works best and with the fewest side effects.

  • Phase II studies are generally intended to study the new treatment in a much larger number of people (usually 100 to 300).  The main objective is to see if it works and is well-tolerated in many people. 

  • Phase III studies compare the new treatment to what’s currently available.  Does the treatment work better—or as well—as treatments that are currently on the market?  If it does not work as well, does it have fewer side effects?  Do some people improve with this new treatment who did not improve with treatments that are currently on the market? Phase III studies involve large numbers of patients (300 to 3,000 or more) and are aimed at being the definitive assessment of how well the new treatment works in comparison with current 'gold standard' treatment.

  • Phase IV studies take place after the Food and Drug Administration (FDA) has approved a treatment for use by the public.  Phase IV studies might look at the safety of a treatment in special populations, or over a longer period of time, or to address certain aspects that weren’t included in the original studies.  For example, a phase IV study might want to find out if an FDA-approved blood pressure drug can also slow the loss of kidney function in people with kidney disease.