Better Size Diversity in Clinical Trials Could Lead to Better Outcomes for Everyone

Clinical trial research is a long, complex process. It ultimately makes new treatments available for all kinds of health conditions. But clinical research suffers from a lack of diversity in patient participation, including a lack of size diversity. The US Food and Drug Administration (FDA), National Institutes of Health (NIH), and healthcare professionals across the country all recognize this as a problem.¹

Why does size representation in clinical trials matter?

For a long time, randomized controlled trials (RCTs) were considered the gold standard in clinical research. These are trials that randomly select participants from an eligible population. RCTs were a way to capture a snapshot of a population that could then be generalized to all patients.²

But in the last few decades, research has found evidence that many groups that are underrepresented in clinical research might respond to a drug or therapy differently than other groups. This may be due to factors that range from physical and cultural to environmental and financial.²

For example, body fat does not interact with medicines the same way lean tissue like muscles, organs, and bone do. So, a drug or treatment may work differently in a person with obesity than it does in a person of average weight.¹

Despite this fact, only 30 percent of newly approved drugs mention people with obesity in their prescribing information. The FDA drug approval process also does not require information about appropriate or alternative dosing for people with obesity to be listed.³

The FDA requires dosing information for other special populations, including people with kidney or liver problems, pregnant people, and children. But the lack of a requirement for people with obesity remains despite the FDA's 2020 update to diversify clinical trial populations.^3,4

A lack of representation in clinical trials could make clinical research findings less accurate for the whole population. Better diversity in clinical trial research will produce better results for all patients.²

How do we define "obese?"

"Obese" and "overweight" are loaded terms, often applied based on opinion. When it comes to including people with obesity in research, the United States follows the guidance of the Centers for Disease Control and Prevention (CDC).³

According to the CDC, the average body mass index (BMI) in the United States is 29.6 kg/m2. About 42.4 percent of the US population has a BMI greater than 30 kg/m2, which is considered obese. Severe obesity (a BMI greater than 40 kg/m2) affects approximately 1 in 11 adults in the United States. Globally, there are more people who are obese than people who are underweight.³

What progress is being made to better include people with obesity?

Efforts to improve diverse participation in clinical trials have increased over the last few years. But there is still stigma around identifying and recruiting people with obesity.

Increasing racial diversity in clinical research may be another way to reach the same goal – to create more effective therapies for more people. This is because, for example, African Americans have a higher rate of severe obesity compared to other racial/ethnic groups. In particular, African American women have much higher rates of obesity than other groups.⁵

Groups such as the Obesity Action Coalition (OAC), Obesity Medicine Association, and the STOP Obesity Alliance are calling on the FDA to drive change. They are asking to close the gaps in the testing and approval processes for new drugs intended for people with obesity.⁶

These groups are also asking the drug companies who market these therapies to update the drug labels to include effectiveness and/or safety issues for people with obesity.⁶

Improving participation in clinical trial research is a challenge that will require change from many organizations. But the first step to improving a problem is discussing it. Advocate for yourself and others. Talk to your doctor about how you can participate in clinical trial research.