Why Diversity in Clinical Trials is So Important

Clinical trials are essential for the development of health care products and it is increasingly recognised there is a need for increased diversity in trial participation. Teva investigates why it is vital for drug development and outlines its work in this space.

What is a clinical trial and who takes part?

These trials are controlled research studies performed by skilled clinicians with people who volunteer to evaluate the safety and efficacy of potential new drugs or medical devices. But it’s not just about testing medicines. Some clinical trials test ways to find or treat life-threatening diseases and chronic conditions.

Regulatory organizations including the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) rely on the results of clinical trials carried out by pharmaceutical companies to decide whether to approve treatments to be used in accordance with the prescribing information for each respective product.

So, who are these clinical trial participants? Mainly white people, it turns out.

Clinical trial diversity: the stats

Since the late 1990s, the number of countries contributing to the clinical-trial data used by FDA to approve drugs has almost doubled (even though 57% of the results still come from study sites in the US). But the diversity of participants taking part hasn’t changed very much. Back then, 92% of the participants in these trials were white – 20 years later that figure was 86%.

And in 2020? 75%.

In fact, in all the medications approved by the FDA in 2020, the clinical trial participants were comprised of: 75% White, 11% Hispanic, 8% Black African American, 6% Asian. Only 30% of the participants were over 65 years of age and more than half of the patients were located in the US.

Why does it matter who participates in these trials?

We depend upon the available research to know that a drug could be safe and effective, and the likelihood of it causing side effects. But the nature of those effects can vary between people of different ancestry. Some medicines may work in different ways in different population groups and in different ages, genders, etc. Trials that represent the intended patient population will better predict the results and better predict the outcomes for more people if the study population is more diverse.

For example, in one study in patients with MS, Black people's response to therapy did not last as long as White people’s response. Local anaesthetic works for a shorter time on people with red hair. It’s believed that women are more likely to suffer from some adverse side effects of medications because medicine dosages have historically been based on clinical trials conducted in men. Being able to assess how different groups respond to different medicines is key to treating conditions.

It’s recognised there is a growing need for diversity in clinical trials. In the US, the FDA published guidelines in 2020 specifically focused on improving diversity. In Europe, the EMA has a guiding Clinical Trial Regulation explicitly requiring justification of any non-representative procedures.01

But it’s not just about ethnicity.

Diversity means more than just your ethnic background – it also includes personal, physical, social and economic circumstances, everything from what you look like to where you live, from how much money you make to how you spend it, the school you go to, how you worship and the language you speak.

Bringing diversity into clinical trials means more than just increasing the pool of ethnic groups represented. It means including people from all different walks of life.

It’s clear from the statistics that ethnic groups are massively under-represented when it comes to clinical trials. And so are many other groups – ironically, often the groups who have a higher incidence of a disease and comorbidities (more than one chronic condition), who may have a higher chance of being prescribed the very medicines that treat these conditions.

Who is being excluded?

Research shows that under-represented groups in clinical trials include the old and the young, the Lesbian, Gay, Bisexual and Transgender (LGBT+) community and pregnant women or those of child-bearing age that plan to get pregnant. They include those who don’t speak the primary language of the country, who are unemployed or on low income, in alternative housing circumstances or remote locations. They also include those who are obese, have mental health conditions, learning disabilities, physical disabilities, multiple health conditions, or addictions.

These groups take disproportionately more medicines but they are largely not involved in clinical trials to assess them.

Odd, right?

So, everybody agrees that we need to have more diversity in clinical trials. Therefore, the answer is simple - recruit more people from diverse backgrounds.

Hang on. It’s not as easy as it sounds.

There are reasons why certain groups are under-represented in trials. From setting the eligibility criteria to the sites who conduct the trials, there are barriers at every step of the process. Take the trial sites for example, often located in areas that are not ethnically or socially diverse. Or the health care professionals who staff them, who may not have the language skills or appreciation for the diverse cultures represented in the local clinical population.

Or even the patients themselves. Around the world, there are people who are shut out from or have limited access to primary healthcare systems. This has its roots in the inequalities of the world we live in.

“The medical literature reflects a growing realization that structural inequalities in our healthcare system cause huge disparities in health,” says Andy Ahn MD PhD, VP Speciality Clinical Development for Headache and Pain at Teva. “This is something that the medical community is starting to look at and ask, what can we do?”

But it’s not just about being shut out from healthcare – it’s also about mistrusting the health system itself. When you look at the statistics, it’s clear that low income respondents express much greater dissatisfaction with healthcare than middle income respondents.

In the US only 59% of Black adults as opposed to 78% of White adults have been found to trust doctors. Hesitancy to take the COVID-19 vaccine is highest among Black and Bangladeshi/Pakistani populations in the UK. In Australia, the indigenous community is six times more likely than the White community to leave the hospital against medical advice. 

So what can we do?

“There are many ways we can increase diverse representation in our clinical trials,” says Melissa Grozinski-Wolff, Director Clinical Project Management and Migraine Operational Lead at Teva. “Some companies are ahead of us in this field, some are behind us.” But Teva has started the process with learnings gained from its Medication Overuse Headache (MOH) program, investigating the way in which excessive use of acute medicines can result in chronic daily headaches.

It’s known that this condition affects underserved and vulnerable populations with less access to regular medical care, who rely on self-medicating and/or use of over the counter (OTC) medications. For that reason, site recruitment for this study followed different procedures to increase diversity.

Although the trial was cancelled, the learnings from the change in approach to recruitment have been invaluable and will strengthen Teva’s future work in this area. Changes in procedures included facilitating patients with less access to healthcare as well as from a wider age range – for example, the trial group included adolescents as well as adults. A revamped site feasibility questionnaire assessed the site’s ability to recruit diverse populations and offer flexible hours and options – so that participants could attend online on weekends and in the evenings after work.

Building long-term solutions

A diversity plan is now created at the start of every trial program at Teva, indicating the percentage of minority representatives that will be included across the study. Efforts are being made to contract diversity vendors who specialize in clinical sites treating minorities so these sites can be included in our global studies.

Education is also key – as is working with local communities to build and sustain trust. Teva is currently considering a number of key tactics in this area, including educating trial sites to understand different cultures, training new investigators, providing materials in different languages and supporting patients with travel expenses.

Training patient advocacy groups is also important as is working with local communities at the early stages of trials, says Verena Ramirez Campos MD, Global Senior Medical Director.

“We are bringing these trials to the communities, implementing digital tools and building interactive materials for the communities to help build trust. Building that trust and developing relationships with the community will increase relevance and quality of our studies.”

Teva’s Medical Affairs has also recently hosted events on diversity, health equality and inclusion at the International Headache Society Congress and the World Congress of Neurology. Teva is also working closely with its Smart Planning and Big Data/AI teams to identify trial sites in underserved areas as well as countries working with more diverse trial populations.

“We want to build sustainable solutions,” says Melissa. “This is not about swooping into a community and swooping back out again at the end of the trial.”

“We have done a lot so far but we must continue to do more,” says Verena. “We can continue to improve by understanding the barriers and the technology, the insights of patients and our relationships with communities.”

“There are already things to be proud of in our clinical trial programs. Our headache clinical trial participants have included 80% women and the majority of participants in our psychiatric and asthma trials are from typically under-represented groups. But there are still many ways in which we can do better,” says Andy.

Bringing greater diversity into clinical trials is an important way to assess how different groups respond to different medicines – key to treating conditions. But it’s not just about that. Clinical trial diversity is simply the right thing to do.


  1. Back to contents.

Read more


Share this article:

You might also be interested