What is a clinical trial?

Clinical trials are research studies that look at new ways to prevent, detect, or treat disease. They are the core of medical research. The U.S. National Institute of Health defines a clinical trial as a research study in which one or more human subjects are prospectively assigned to one or more interventions to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes. The intervention may be a medication, a placebo, or another control treatment.1   


Why are clinical trials done?

Clinical trials are how doctors determine that a test, treatment, prevention technique, or behavioral approach is safe and effective. A treatment may be a new drug or new combinations of drugs, new surgical procedures or devices, or new ways to use an older treatment.


Why it is important to participate in a clinical trial?

In 1950 the average life expectancy in the United States was 68 years old. In 2022, the average life expectancy is 77 years.2 Most of the improvements in life expectancy and health have occurred because of medical research and the things that have been learned during clinical trials.


Who conducts a clinical trial?

A clinical trial is led by a “principal investigator” who is usually a medical doctor. Clinical studies also have a research team that may include doctors, nurses, pharmacists, social workers, and other health care professionals.


Who pays for the clinical trial?

The “sponsor” of the clinical trial usually pays for all research-related costs and any special testing. This includes supplying the new treatment, as well as any special testing, possible extra physician visits, and research costs involved in the clinical study. In the United States, most clinical trials are sponsored (paid for) by the federal government or the pharmaceutical industry.


Is there a charge to participate in a clinical trial?           Will I be paid for participating in the clinical trial?

There is no charge for study-related medical care provided in a clinical trial. Study-related medical care may include study visits, medications, treatments, and procedures. In some trials, transportation and other costs may be provided.


How Long Does a Clinical Trial Last?

The length of a clinical trial/study varies. It may be a single day, a few weeks, or a few years. The length of the trial should be explained during the informed consent process.


What is the clinical trial protocol?

The clinical trial protocol is a group of documents that describe the objectives, design, methodology, mathematical/statistical calculations that will be used and ensure the safety of the trial participants and the integrity of the data that is collected. It is the plan of how the trial will be conducted. 


 Can I stop being in a trial after I have started?

Taking part in a clinical trial is voluntary and you can leave the study at any time. Even if you have signed an Informed Consent Document, this is not a contract. Participants may withdraw from a study at any time, even if the study is not over.


What is informed consent?

Informed consent is the process of providing a potential participant with the key information about a research study before they decide whether or not to take part. Members of the research team explain the details of the study and provide documentation that includes details about the purpose of the study, how long it’s expected to last, tests or procedures that will be done as part of the research, and who to contact for further information. The informed consent document also explains the risks and potential benefits. You can then decide whether to sign the document.


What are a control group and a test group?

Participants in a clinical study are divided into two groups: a control group and a test group. The control group is typically not administered the intervention and may receive a placebo. The treatment group is the study participants who receive the intervention or treatment. Depending on the design of the study the participants may not be told if they are being placed in the control or treatment group. In addition, the researcher may not know.


What is the difference between an inpatient and an outpatient clinical trial?

An inpatient clinical trial means that the participant stays at the facility (usually a hospital) for the length of the study, this may include overnight stays. An outpatient clinical trial means that the participant stays at home and travels to the initial screening, study site for treatment, and follow-up visits.


Are clinical trials safe?

There are several safety mechanisms in place to ensure the safety of clinical trials. Most clinical trials in the US are approved and monitored by an independent committee called an Institutional Review Board (IRB). This group evaluates the study to ensure that the risks are minimal compared with the potential benefits of the study. Once the trial is approved by the IRB, the organizers of the study must follow a careful plan, called a protocol, that describes exactly what will happen during the study. Many trials are also monitored by a Data and Safety Monitoring Committee that is made up of experts in the disease/condition being studied who periodically look at the results as the study progresses. If they determine that the treatment is not working or is harming participants, they will stop the trial immediately.


Where can I learn more about clinical trials?

Several resources can provide more information about clinical trials:

ClinicalTrials.gov – A searchable registry and database of federally and privately supported clinical trials. https://clinicaltrials.gov/


National Institute of Health – Clinical Research Trials and You – a government website designed to help people understand the basics of clinical research.



MedNewsCenter.com – Clinical Trial Resources – Provides up-to-date patient and provider research resources. https://mednewscenter.com/



  1. National Institutes of Health (NIH). Definition of a Clinical Trial. Available: https://grants.nih.gov/policy/clinical-trials/definition.htm Accessed: April 19, 2022
  2. Centers for Disease Control and Prevention. NCHS Data Brief No. 427, December 2021. Available: https://www.cdc.gov/nchs/products/databriefs/db427.htm Accessed: April 19, 2022.



Photo by Chokniti Khongchum