Clinical Trials Versus Clinical Studies: What’s The Difference?

As a CRO, we talk about clinical research and clinical trials, but what’s the difference? Can the two terms be used interchangeably? And why does it matter?

Every treatment on the market is the result of years of research – not just studies involving the treatment itself, but also research into the disease or condition and potential drug targets.

This is all described as clinical research – the study of human health and disease. Clinical research involves human participants in some way and aims at moving findings from bench to bedside – translating basic research into ways of helping patients. Clinical research can include direct studies involving humans, such as clinical trials, but also epidemiological studies and research on physiology, education and mental health.

There are varying opinions on what constitutes a clinical study or a clinical trial. According to Good Clinical Practice (GCP) – specifically the ICH E6 guidelines – the terms clinical trial and clinical study can be used synonymously. GCP defines a clinical trial or study as:

“Any investigation in human subjects intended to discover or verify the clinical, pharmacological, and/or other pharmacodynamic effects of an investigational product(s), and/or to identify any adverse reactions to an investigational product(s), and/or to study absorption, distribution, metabolism, and excretion of an investigational product(s) with the object of ascertaining its safety and/or efficacy.”

Others distinguish between clinical studies and clinical trials. The National Institutes of Health (NIH), for example, describes two kinds of clinical study: “A clinical study involves research using human volunteers (also called participants) that is intended to add to medical knowledge. There are two main types of clinical studies: clinical trials (also called interventional studies) and observational studies.”

Observational Versus Interventional

These two main types of clinical study – observational and interventional – describe the approaches taken in each:

• In observational studies, researchers observe study participants and record the effects of their current treatment without making any changes. Observational studies tend to be less involved for participants, who might need to complete questionnaires, for example. Participants will typically be people undergoing treatment for a medical condition, and the researchers will collect information about the results of that treatment without changing it or comparing the results to a control group.
• In interventional studies – clinical trials – an intervention is tested in a group of participants, usually compared to a control group that does not receive the intervention but a placebo in its place. A clinical trial could be testing a potential drug, procedure or device. Clinical trials have evolved over hundreds of years and have a structured framework.

Medicine authorities like the Food and Drug Administration (FDA) in the US or the European Medicines Agency (EMA) in the EU require clinical trials proving the safety and efficacy of a drug before they will allow it on the market. They often then require the company or research institute that developed an approved drug to monitor its safety and efficacy over time through observational studies.

The Clinical Trial: An Important Clinical Research Study

The clinical trial is an intervention study – a specific type of clinical research study that aims to answer a defined question about a treatment. The treatment under investigation could be a new drug, medical device or behavior, for example. The question being posed is usually around the safety or efficacy of the intervention.

A clinical trial is preceded by a long process of preclinical research. First, the intervention is studied in the lab. These tests begin in vitro and often involve toxicity screening. Then they will progress to animals, such as mice or ferrets, for further toxicity and safety testing and to gather initial efficacy results. Animals are needed at this stage, as bodies are much more complex than pure tissues grown in the lab. It’s important to understand the impact of an intervention on various biological systems, such as the nervous and circulatory systems, before the drug is tested in patients.

If an intervention still appears promising after preclinical research, it will enter the five phases of a clinical trial:

• Phase 0 – pharmacodynamics and pharmacokinetics trial on a small number of people
• Phase I – safety trial on a small number of people
• Phase II – efficacy trial with a control versus test group to determine dosage and efficacy
• Phase III – safety and efficacy trial with a large number of people (usually over 1,000)
• Phase IV – continuous monitoring through observation

Understanding Clinical Research

The distinction between types of clinical research study differs depending on who is defining them, and this is an important consideration for those undertaking clinical studies to take a treatment to market. For example, the NIH refers to interventional studies, while the FDA calls them clinical trials. This is the kind of information you can expect a CRO to know.

If you have specific questions about the research you want to undertake, or you’re looking for support with your trial, you can contact Siron Clinical.