What are the Types of Clinical Trials?

Understanding Clinical Trial Types

Navigating clinical trial information can be a daunting task. It’s helpful to first understand different types of clinical studies.

Interventional Studies (Clinical Trials)

Interventional studies, also called treatment studies or clinical trials, test the effects of one or more treatments (like a drug, medical device, activity, or procedure) on a specific group of people. This helps researchers learn about the safety and efficacy of the treatment. Often the intervention is investigational, which means it has not been approved for use outside of a clinical trial.

Here are some examples of questions that may be asked and answered during interventional studies:

• Did Drug X help lower blood sugar in participants with diabetes?
• Did participants with lung cancer who added Drug Y to standard chemotherapy have a better outcome than participants who only had standard chemotherapy?
• Did participants with migraines who took Drug Z as a nasal spray feel more satisfied than participants who got the same drug as an injection?

The information from clinical trials helps determine if investigational treatments work, how safe they are, and if they are better than current treatments. Government regulatory agencies (such as the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), and others) use these results to decide which treatments should be approved.

Observational Studies

Observational studies are studies where researchers observe or collect information from a group of people over time without giving any treatment. The goal is to learn about the natural state of diseases, risk factors, or outcomes. An example of an observational study is the Nurses’ Health Study (NHS), which started in 1976. This study, along with NHS 2 and NHS 3, has gathered data from more than 275,000 participants. Researchers use data about their diet, physical activity, and other lifestyle habits to find out which factors might be risk factors for major chronic diseases later in life.

Medical Records Research

Sponsors can sometimes use patient medical records to study risk factors for a disease or its likely outcome. These records include a patient’s medical history, test results, doctor observations, and medicine usage. If patients agree to share their records for research, their data can be anonymized to protect their identity and then shared with researchers. For example, researchers with access to medical records of many people with migraines can see which treatments had better outcomes or more side effects.

Weighing the Evidence in Clinical Research

Randomized, controlled, double-masked interventional studies (clinical trials) are often considered the gold standard in research. They offer the strongest evidence of an investigational treatment’s efficacy and safety because they are done in a “controlled” setting. These trials have specific rules about who can join and what will be measured. A well-designed clinical trial makes sure that any differences between groups are likely to be due to the treatments themselves, not other factors.

Consider this example: A medical record review might show that patients with cancer who took Drug A had a different outcome than patients who took Drug B. However, it’s possible that people with certain risk factors were more likely to get Drug A from their doctor, so the different outcome could be due to other factors, not the drug itself. In a controlled clinical trial comparing these two drugs, researchers would make sure that the risk factors were well balanced between the two groups.

While these types of trials are considered the gold standard, observational studies and medical records research still play important roles. For rare diseases, it can be hard to find enough participants for a controlled clinical trial. In cases like these, a review of medical records and observational studies can provide valuable data and insights needed to design clinical trials of potential new treatments.

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