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Learn the differences between RCTs and NRCTs.

New drugs, medical devices, and health advancements are always in the news. But how do these breakthroughs go from research labs to helping your patients?

Read on to understand the different types of medical research studies, with real-world examples, so you can understand how new treatments are developed.

Separate Observational and Experimental Studies

Analytic research studies fall into two main types: observational studies and experimental studies.

In observational studies, researchers monitor or record data without changing any variables. These studies help find patterns and can last for decades. For example, the Framingham Heart Study began in 1948 and continues to this day.

Observational studies can be descriptive or analytic.

Descriptive observational studies, like case studies, describe what is happening or what is observed without comparing different groups.

• A case study is a detailed description of a case, often of a single patient. It helps us learn about rare diseases or unusual medication side effects.
• A case report is a formal write-up of a single medical case and is often used interchangeably with “case study.” For example, a researcher might write a case report describing a rare surgical complication to explore ways to prevent it.
• A case series is a collection of case reports that looks at a group of patients with similar medical conditions, or patients that have had similar procedures. It helps researchers find common patterns or outcomes. For example, researchers might gather data on COVID-19 patients’ smoking histories to see if there’s a link to patient treatment outcomes.

Analytic observational studies investigate relationships between different factors by comparing different groups. The three main types are:

• A cohort study follows a group of people over time to see how different variables affect them without changing any variables. The goal is to find possible links between certain variables and the health results observed.
• A cross-sectional study looks at a group of people at a specific point in time. Researchers might collect information like age, gender, education, and health conditions (such as asthma) to understand how these factors influence disease prevalence and treatment effectiveness.
• A case-control study compares people who have a specific disease or condition (cases) with similar people who don’t (controls). Researchers look back to find clues about what might have caused the disease, especially when it’s rare.

What Are Experimental Studies?

In experimental studies, researchers change one or more variables, such as adjusting the dose of medication, and then record the effects. This type of study is good for figuring out whether one thing causes another.

A common type of experimental study is a controlled trial. These trials include a control group to compare against the treatment group. Controlled trials are separated into randomized controlled trials (RCTs) and non-randomized control trials (NRCTs).

In an RCT, participants are randomly assigned into groups to minimize selection bias and ensure the results are due to the treatment itself. RCTs help determine whether a new treatment is effective and safe before it becomes widely available.

The intervention group receives the new treatment while the control group does not. The control group may receive standard care, a placebo, or no intervention at all. Placebos help ensure that any observed effects are from the treatment itself, and not because someone believes they are getting treatment (called the placebo effect).

Examine This Back Brace RCT Example

Researchers investigated differences in quality of life between patients with adolescent idiopathic scoliosis (AIS), a sideways curvature of the spine, wearing full-time (FT) braces versus night-time (NT) braces.

Patients were randomly assigned to a brace type, with the FT group representing standard treatment worn while upright during the day and the NT group as the less intensive alternative worn at night. Over two years, researchers collected data on self-image, treatment effectiveness, and pain levels through X-rays and questionnaires. Results showed the NT group experienced less pain and a better self-image versus the FT group, showing how the choice of brace type can make a big difference in quality of life.

Non-randomized control trials (NRCTs) are like RCTs, except group assignment is not random. Instead, participants may be assigned to intervention or control groups based on factors like pre-existing health conditions, geographical location, or participant choice. NRCTs are used to compare groups where random assignment does not make sense, may be unethical, or is impractical. However, NRCTs are susceptible to bias because non-random assignment makes it harder to know if the results observed are due to the intervention.

An NRCT may involve a new treatment technique where patients who volunteer to receive it (intervention group) are compared to patients who do not participate or receive standard care (control group).

Look Into Prospective and Retrospective Studies

Prospective studies follow participants into the future, collecting new data. In contrast, retrospective studies look back at data that has already been collected. Information from retrospective studies can have limitations because it might rely on records that weren’t originally created for research.

Next month, we’ll take an in-depth look at the development pathway for drugs and medical devices with real-world examples.

Angela Halasey, BS, CPC, CCS, Contributing Writer