Clinical Trial

A clinical trial is a study that uses human volunteers to answer a specific research question. An important epidemiological tool, clinical trials consist of two subtypes: observational trials and interventional trials. Observational trials consist of collecting data and inferring results after surveillance of a population in its natural environment. Interventional trials examine whether a new treatment is safe and effective in humans.

A group of physicians, nurses, medical researchers, and other healthcare professionals oversee a clinical trial. They coordinate the study and the study participants, manage and interpret the results, and publish findings. People choose to participate in clinical trials for several reasons, including earlier access to new treatments and the advancement of medical research; however, they must meet the study's specific inclusion criteria, which are characteristics that the study investigators determine a priori. Inclusion criteria can include age; the extent, or stage, of the disease; prior treatments, and others. In addition, exclusion criteria are determined to prohibit certain people who cannot participate in the clinical trial. Once the study participants have been selected, they must provide informed consent. This process consists of explaining the purpose, risks and benefits, duration, and any required procedures of the trial. After informed consent and the gathering of participants, the clinical trial can begin.

Successful clinical trials incorporate frequent contact between the study participant and the research team as well as strict adherence to the study protocol, a detailed methodology on the execution of the study. During a clinical trial, the clinical research team will assess the participant's baseline health, provide the intervention or treatment that is being studied, monitor the participant's response to the intervention through laboratory tests or imaging, and record results. Sometimes, a clinical trial may find that the treatment is causing harm. The research team may choose to stop the clinical trial; however, if a treatment is shown to benefit the study participants, this signifies that the treatment may be ready for mass distribution.

Clinical trials have four different phases. Phase I trials evaluate the safety of the new treatment, determine a safe dosage, and identify side effects in a small group of people (usually 20 to 100 people). Phase II trials are an expansion of Phase I trials and use 100 to 300 people to evaluate safety. Phase III trials confirm the effectiveness of the new treatment, further elucidate the safety profile of the treatment, including monitoring side effects, and compare the new treatment to ones already available. These trials usually consist of 1,000 to 3,000 people. Lastly, Phase IV trials occur after the treatment is on the market by monitoring the intervention's safety.

Funding for clinical trials comes from many sources. These include hospitals, medical schools, research foundations, pharmaceutical companies, and federal agencies, including the National Institutes of Health and the Centers for Disease Control and Prevention.