What is a Clinical Trial?

A clinical trial or clinical study is a research study that uses human volunteers to answer a specific health question. The main goal of a clinical trial is to advance medical knowledge and to improve patient care by testing investigational treatments. Clinical trials are carefully conducted to determine whether a medical strategy, treatment or device is safe and effective for human use. It is the last step in a very long and careful research process that all began in a scientist’s lab. These investigational treatments undergo rigorous testing before they are considered for a clinical trial.

If a treatment or approach seems promising in the research lab the next step is animal testing. If the treatment is determined to be safe in animal testing, it is then moved into a clinical trial. For example, the investigators may give a treatment to participants who have a specific disease or health condition to see whether participants improve and respond to the treatment.

There are two main classes of clinical trial studies: interventional and observation. Intervention studies determine whether an experimental treatment or known therapy is effective and safe. In an observational study, the investigators are assessing health outcomes in participants according to a specific research protocol. These participants might receive interventions that include medical products, devices or procedures as a part of their care, but these participants are not specifically assigned interventions such as in a clinical trial. For instance, the investigators may observe a group of individuals to learn the effects of different lifestyle and lifestyle changes on their overall health.

Types of Clinical Trials

  • Diagnostic trials are conducted to look for better tests or procedures to diagnose a specific disease or condition.

  • Treatment trials are conducted in order to test new research medications, new treatments or better ways to approach surgery or radiation.

  • Quality of life trials, also known as “Supportive Care Trials,” are conducted to find new ways to improve the quality of life for those with chronic illness.

  • Prevention trials are conducted to look for new or better ways to prevent a disease or disorder from developing and also from returning. This can include new medications, vaccines, supplements and life-style changes.

  • Screening trials are conducted to find the best ways to screen or detect certain diseases or health conditions.

Phases of Clinical Trials

Clinical trials have four phases and each phase has a different purpose.

Phase I trials are where researchers test a new research medication or treatment in a small group of people (20-80). The purpose of this phase is to determine the safety of the new treatment or research medication, the safe dosage range and the side effects.

Phase II trials involve a larger group of people (100-300) to determine if the new research medication or treatment is effective and to once again evaluate the safety of the treatment or research medication.

Phase III trials involve a significantly larger group of people (1,000-3,000). This is to confirm how effective the new treatment or research medication is, compare it to already commonly used treatments, monitor any side effects and use this information to determine if the research medication or treatment can be used safely.

Phase IV trials involve post-marketing studies after the treatment is approved by the Food and Drug Administration (FDA). These studies give any additional information about the research medication that includes its risks, benefits and how it should be used.

Regulation of Clinical Trials

Clinical trials in the United States are regulated by the FDA, and in Canada by Health Canada, to make sure that certain standards are met due to the involvement of human volunteers. Before a clinical trial can begin the clinical study protocol, safety reporting systems and promotional materials are reviewed by independent bodies known as Institutional Review Boards (IRBs) or Independent Ethics Committees (IECs).

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