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Are you thinking about taking part in a clinical trial? Is a friend or family member already in a trial? Has that made you want to learn more about it? In this chapter, you will learn about the different types of trials and the risks and benefits of taking part in a trial.
What is a Clinical Trial?
A clinical trial is a research study that uses human subjects to find out if an experimental drug, therapy, medical device, lifestyle change, or test will help treat, find, or prevent a disease. A clinical trial can also find out if experimental treatments or tests are safer or more effective than those already available.
The main types of trials are treatment, screening, diagnostic, prevention, and quality of life trials.
In treatment trials, researchers may
- gather information about experimental treatments, their risks, and how well they work
- compare existing therapies to decide which one, or a combination of them, is the best treatment for a disease
- evaluate methods such as surgical techniques, psychiatric therapy, or radiotherapy.
Scientists usually do years of experiments in the laboratory and in animals before they can even consider testing an experimental medication in people. Most of this early research occurs at universities and medical centers across the country. The National Institutes of Health funds much of this basic research.
Screening trials study ways of finding a disease before symptoms occur. These methods, often called screening tests, can include
- imaging tests that produce pictures of what is inside the body
- laboratory tests that check samples of blood, urine, or other body tissues
- genetic tests that look for genes linked to some types of disease.
Diagnostic trials find new tests that could identify a disease in its early stages. Usually, trial participants must show signs of the disease or condition before they can join this type of trial.
Prevention trials study ways to reduce the risk of getting a disease or a specific medical problem. These trials find out if
- lifestyle changes, such as exercising more, getting more sleep, keeping mentally active, or eating nutritious foods, can prevent a problem
- taking certain medicines, or vitamins, or getting vaccines will prevent diseases.
Quality of life trials find ways to make life better for people living with a life threatening disease or chronic health problem. For example, they may study the role of caregivers, support groups, and various types of social interventions.
A clinical trial usually includes three phases. In some cases, four phases may be required.
A Phase I trial tests an experimental treatment on a small group of often healthy people, to judge its safety and side effects, and to find the correct drug dosage.
A Phase II trial is similar to a Phase I trial but uses more people to find out if the experimental treatment is effective and safe. This phase can last several years.
A Phase III trial is usually a large study with several hundred or more participants. This phase compares the experimental drug or procedure to a placebo or standard treatment, to make sure it is safe and works well. Some side effects that didn't show up in Phase II may show up in a Phase III trial because many more people are tested. If the U.S. Food and Drug Administration agrees that the trial results are positive, they will approve the experimental drug or device.
A Phase IV trial for drugs or devices takes place after the U.S. Food and Drug Administration approves their use. A device or drug's effectiveness and safety are monitored in large, diverse populations. Sometimes the side effects of a drug may not become clear until more people have taken it over a longer period of time.
Risks and Benefits
You may ask yourself, "Why should I join a clinical trial? Should I try something that hasn't been approved?" Asking questions is good because there are always some risks in joining a trial, but there may be benefits too.
Here are some possible benefits in joining a clinical trial.
- Your participation may help others get a better treatment for their disease in the future.
- Researchers may check your physical condition frequently, because they need data to make comparisons in a trial.
- It may be a way to get an experimental treatment for a life threatening illness before it is approved and available.
Here are some possible risks in joining a clinical trial.
- You may experience serious side effects.
- You may not get the experimental treatment, but a standard treatment or a placebo instead.
- The experimental treatment may not be better or even as good as the standard treatment for your condition.
- Even if a new procedure works for other people, it may not work for you.
Keep in mind that a few people have increased their risk of getting another condition during experimental drug trials.
For example, while testing the arthritis drug Vioxx as a treatment for polyps, researchers discovered that the drug increased the risk of heart attack and other cardiovascular problems. The drug has been taken off the market.
Another possible concern, though not a health risk, is that your health insurance or the trial may not cover all patient care costs.
Terms to Know
Here are some terms used in clinical trials.
- protocol
- inclusion and exclusion criteria
- standard treatment
- side effects
- treatment group and control group
- randomized clinical trial
- double blind study
A protocol is the detailed study plan that will be followed to answer specific research questions and protect the trial participants. It describes
- what type of people are needed in the trial
- the schedule of tests, procedures, drugs, and dosages
- how long the study will last
- how to measure the beneficial and harmful effects.
Inclusion or exclusion criteria are the set of social and medical characteristics researchers use to decide who can take part in a clinical trial. These may include
- a person's age and gender
- the type and stage of their disease
- previous treatment history
- any other medical conditions.
A placebo, sometimes called a sugar pill, is a substance that looks like the experimental drug but has no active ingredients. Researchers compare the effects of experimental treatments with placebos.
Standard treatment is a therapy that is
- effective for a specific disease or condition
- currently in wide use
- usually approved by the U.S. Food and Drug Administration
- used to compare with the newer treatment, to see which is better.
Side effects are unwanted or unexpected negative effects, such as a headache or skin irritation, caused by taking a drug or treatment. Adverse reactions are more serious side effects that can even be life threatening.
The treatment group gets the experimental treatment and the control group gets the standard treatment, a placebo, or no treatment at all. The results from the two groups are compared to determine the effectiveness of the experimental treatment.
A randomized clinical trial (RCT) is a study in which participants are randomly (that is, by chance) assigned to either the control group or the treatment group. Neither the researchers nor the participants can choose the group in which they are placed.
In a "double blind" study, the researchers and participants won't know who has been placed into the treatment group until the study is over.
For more clinical trial terms go to ClinicalTrials.gov Glossary at
http://clinicaltrials.gov/ct/info/glossary.
From the National Institute on Aging
03 January 2008
http://nihseniorhealth.gov/participatinginclinicaltrials/whatisaclinicaltrial/01.html
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