What is the Difference Between Interventional Studies and Observational Studies?

What is the Difference Between Interventional Studies and Observational Studies?

-Enoma Okunbor

Clinicaltrials.gov, an online registry of research studies run by the United States National Library of Medicine, currently boasts 308,115 studies, with locations in all 50 states and 210 countries. Since 2000, the number of studies posted on the site has increased by a whopping 24,433%.¹

There have never been more opportunities to participate in research, but that expanded choice can make it difficult to sift through the opportunities if you’re not familiar with the terminology used by researchers.

As enrollment begins with the T1D Exchange Registry, we thought it would help from time to time to share our insights into how diabetes research studies operate. One of the first pieces of information to know about research is the difference between interventional and
observational studies. Of the hundreds of thousands of research studies registered on Clinicaltrials.gov, about 80% are interventional and 20% are observational.² Here’s what to know about the two types of studies:

Intervention Studies

Clinical trials are a great example of an intervention study. In the case of a randomized controlled trial, participants with the same disease or condition are randomly divided into two groups. One group, called the treatment arm, will be given the intervention, which may be a drug or a device. The other group, called the control arm, will not receive the intervention. The two groups are equally important to the research study, and participants are randomly divided into each group. Both groups are then followed, and their data is compared over time by researchers. With this setup, clinical trials aim to provide a controlled environment to measure the success of a drug, device, or other medical intervention.

Observational Studies

In observational studies, the researcher does not intervene and merely observes a group of participants with the same disease or condition over a period of time. This type of study allows researchers to gather information on disease trends and to characterize people affected by the disease or condition.

Our Observational Study

The recently launched T1D Exchange Registry Research study is a good example of an observational study. Specifically, it is a longitudinal cohort study, in which information about diabetes management and other important medical history is collected over time from a large number of people with type 1 diabetes.

According to Wendy Wolf, PhD, director of the T1D Exchange Registry, “this project will provide a
significant, publicly accessible way to study longer term issues, such as the effects of aging and the progression of the disease.” By joining and sharing their voices, experiences, and data, the Registry participants add to a comprehensive data set of type 1 diabetes health information in the United States, and drive meaningful treatment, care, and policy.

Some studies are easier to participate in than others, and that can impact who is able to participate. In a 2014 study, one of the main reasons cited by participants who declined to participate was logistics – many people simply don’t have the time.³

The T1D Exchange Registry is committed to addressing this concern and to making participation as user-friendly as possible. The registry platform is mobile-friendly, and participants can quickly and easily answer a questionnaire about demographic information, medical history, and diabetes management in about 15 to 20 minutes.What is the Difference Between Interventional Studies and Observational Studies?

In the U.S., all studies are required by law to ensure the confidentiality of the information of the research participants. Participants with the T1D Exchange Registry are assigned a random unique code in place of the name, email address, and phone number provided at sign-up. Any study results shared in medical journals and at scientific meetings will not include any identifying information.

The T1D Exchange Registry team is currently building an awareness campaign about the Registry. We invite you to add your voice to the growing cohort of people with type 1 diabetes by joining the Registry today.

Be heard. Support the type 1 diabetes community. Help drive research that matters. For more information, or to join, visit the T1D Exchange Registry or contact us at 617-892-6165 or Registry@T1DExchange.org.



³Newington, Lisa, and Alison Metcalfe. “Factors influencing recruitment to research: qualitative study of the experiences and perceptions of research teams.” BMC medical research methodology vol. 14 10. 23 Jan. 2014,

Photo credits: Louis Reed and Carlos Muza, respectively. 

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