A clinical trial is a study that helps doctors find out if a new therapy, medicine, or device will help prevent, detect, or treat a disease. Clinical trials also help doctors find out if these new therapies and treatments are safe and if they are better than the treatments we already have.
There are 4 kinds of clinical trials:
- Treatment trials test new treatments, medicines, or surgeries.
- Prevention trials look for ways to prevent diseases using medicines, vitamins, vaccines, or lifestyle changes.
- Screening trials test ways to detect or diagnose diseases.
- Quality-of-life trials try to find ways to make life better for people living with a disease or health condition.
Clinical trials often combine a number of different aspects to make sure that the study results are without bias (the doctors did not influence the results of the study). The best clinical trials are prospective, randomized, cross-over, double-blinded studies.
- Prospective means that the patients are identified and then followed-up over time.
- Randomized means that patients are grouped by chance (usually with a computer program). The patients are usually split into a treatment group and a placebo group. The placebo group (also called the control group) receives either the current standard treatment or no treatment at all.
- Cross-over means that a patient receives both the treatment and a placebo at different times.
- Double-blinded means that neither the patient nor the researcher knows if the patient is receiving the treatment or the placebo.
Some clinical trials are called open label studies, because both the patient and the researcher know that the patient is receiving the treatment and not the placebo.
How does a clinical trial work?
Here are the basic parts of a clinical trial.
Basic Research. Before a clinical trial can start, doctors must have a theory about why a new therapy might treat a disease. It usually takes years of research to develop a theory.
Animal Studies. Doctors first test the new treatment in animals to find out if it might be helpful or harmful to people.
The Proposal. After the doctors involved in the study prove that the new treatment is safe in animals, a proposal is submitted to a group of doctors, statisticians, scientists, and people from the community who are members of an independent institutional review board (IRB). Each hospital or research center has its own IRB. It is up to the IRB to decide if the therapy is safe enough for testing in a small group of people.
Finding Patients. After getting approval from the IRB, doctors must find patients for the study. All patients who take part in a clinical trial are volunteers.
Informed Consent. Before patients can enter a clinical trial, they must sign an informed consent form. This form tells patients about the risks and benefits of the study so they can decide if they want to take part. The informed consent process does not end when you sign the form. After you enter a clinical trial, you will keep getting new information that may affect your decision about staying in the trial. The informed consent form is not a contract, and you are free to leave the clinical trial at any time. If you decide to leave the trial, you should tell the study doctor or coordinator, so they can record your reason for leaving.
Phase 1. This part of the trial is also known as the safety study, because it involves relatively few patients and lasts about 1 year. Phase 1 determines if the study is safe and if it should continue in a larger group of people.
Phase 2. This part of the trial has more patients. At this point, doctors choose a group of people who will be the control group. The control group will receive either the best available treatment or a placebo (no treatment). In most clinical trials, it is rare for patients in the control group to receive no treatment at all. Instead, they usually receive the best available treatment. Phase 2 may last many years.
Phase 3. This is the last step before a therapy is approved. Phase 3 may involve thousands of patients and can last for up to 5 years. During this phase, the patients on the new therapy are compared with those who have received other treatments or a placebo.
Phase 4 (Approval). If doctors find that the new treatment works, the Food and Drug Administration (FDA) will approve it for everyone to use. Even after approval, the treatment is still monitored. Any problems must be reported to the FDA for up to 10 years.
Who can enter a clinical trial?
Every clinical trial has guidelines about who can take part. These guidelines are made up of a list of factors called inclusion and exclusion criteria. The inclusion and exclusion criteria are what help doctors produce accurate results.
The factors that allow someone to take part in a clinical trial are called the inclusion criteria. The factors that prevent someone from taking part are called the exclusion criteria. Examples of inclusion and exclusion criteria are age, sex, the type of disease you have, your treatment history, or whether you have other medical conditions.
Before you can enter a clinical trial, you must qualify for the study. Depending on what doctors are studying, some clinical trials will need patients with certain diseases or conditions while others will need volunteers who are healthy. Depending on their overall condition, patients may only be eligible for clinical trials during certain phases of the trial.
What can I expect if I take part in a clinical trial?
It is normal to be nervous about entering a clinical trial, and feelings of being a "guinea pig" are common concerns among patients.
The exact process will depend on the type of clinical trial. You will get complete instructions about the clinical trial after you are enrolled, but here are some basics you can expect if you take part in a clinical trial.
- The clinical trial team will include doctors, nurses, social workers, and other health care professionals. You will most likely receive your care at a hospital, university, clinic, or doctor's office. You will still see your regular primary care doctor or specialist even if you are going to the doctors involved in the clinical trial.
- The clinical trial doctor will examine you before you begin the study. You may find that you need more tests and doctor visits than you normally would. These tests will help doctors follow your progress and collect the data they need for the study.
- You will need to follow the instructions for taking part in the study. For example, you may be asked to change the medicines you are currently taking or to change your diet or any activities that might affect the outcome of the study.
- You will be watched carefully during the study, and you will have to keep in touch with the clinical trial team. If at any time during the study you and your primary care doctor feel that you should leave the trial, you can.
- Even after the study is over, you will need to stay in touch with the clinical trial team for a certain amount of time.
What are the risks?
Because the treatment, medicine, or device being studied is new, doctors cannot know all of the risks and side effects at the start of a trial. The risks of a clinical trial would depend on the patient population and what is being studied.
- There may be bad or even life-threatening side effects.
- The treatment may not work.
- In randomized, double-blinded trials, neither the patient nor the doctor knows if the patient is receiving the new treatment, the standard treatment, or a placebo. In other words, you may not be getting any treatment at all. Remember, though, it is rare for any patient in a clinical trial not to receive any treatment at all.
- You may have to make many trips to the doctor, undergo a lot of testing and treatment, or even stay in the hospital.
What are the benefits?
Most people worry about the risks involved with a clinical trial, but there can be benefits as well.
- You may get a new treatment before anyone else does.
- For patients who have already tried the currently available treatment options, the clinical trial may be their last hope for a new treatment.
- Clinical trials can save lives. These studies give doctors the information they need to keep developing new procedures and treatment methods that may help others in the future.
- Your treatment costs may be lower because many of the tests and doctor visits directly related to the clinical trial are paid by the study. (In some cases, there may be a cost to you, so be sure you know about any treatment costs before you enter a clinical trial.)
- You will be getting the best care from some of the leading hospitals in the world.
How safe are clinical trials?
Many people have fears about the safety of clinical trials, and they wonder if they are gambling with their health. For this reason, the US government has set up safeguards to protect people who decide to take part in a clinical trial. Understanding the safeguards that protect patients may help to ease some of your fears about clinical trials.
During a clinical trial, doctors will closely watch you to see if the treatment is working and if you are having any side effects. All the results are carefully recorded and reviewed and must be reported at scientific meetings, to medical journals, and to the government.
Earlier, we talked about how each hospital or research center has an IRB that must review and monitor any medical research involving people. An IRB protects patients throughout the study and makes sure that the risks to the patients do not outweigh the expected benefits. IRBs also make sure that the patients are chosen fairly and that informed consent is done right.
In some studies where one treatment is compared with another or where patients are chosen randomly to receive a treatment, a Data Monitoring Committee is used. These committees are very important, especially if patients are taking part in testing for serious or life-threatening diseases. The Data Monitoring Committee can stop a study at any time if it finds that a treatment is not helping patients or that the treatment is actually harmful. If the Data Monitoring Committee finds that one treatment is much better than another, they can stop the study and give the better treatment to all patients.
Finally, the FDA always reviews the data from the doctors and inspects the clinics or other research sites involved in the study. The FDA will also do an inspection if there has been a complaint about patient safety.
How can I take part in a clinical trial?
Patients may hear about a clinical trial from their doctor, through a newspaper or the Internet, or by word of mouth.
If you are thinking about taking part in a clinical trial, you should try to learn as much as you can about the trial. Do not be afraid to ask the doctor questions. Some people find it helpful to bring a friend or relative along for support. And, because you will have so much to remember, a friend or relative can help remind you what you talked about during the meeting with the doctor.
See on other sites:
The Importance of Clinical Trials (article from MedlinePlus Magazine).
A Service of the National Institutes of Health
Clinical Trials Listing Service
Updated August 2012