The Missing Data  -  Increasing diversity in clinical trials… A must!

Updated: 3 days ago

Precision medicine is one of the next big things, if not the next big thing in the medical world.

However, its current prospects are hampered by a lack of data, in particular, by a curious imbalance of said data with respect to ethnicity.


An article by Trianon Scientific Communication from the point where science meets social issues.




There is a lack of diversity in the human genomic data base.


Precision medicine is the idea that it is possible to tailor the treatment of a disease to every single individual.


It is already used to treat certain forms of cancer, and it will probably revolutionise the pain treatment industry, as it seems now possible to target your treatment according to your individual circumstances.


In medical terms, it is the individualisation of posology, i.e. the study of how to dose medicines.



Precision medicine


Looking beyond this immediate application, the idea is that the information in our genome could transform healthcare as we know it for everyone.


As the former POTUS Barack Obama so aptly put it:


“The promise of precision medicine is to deliver the right treatment at the right time to the right person, every time.”

Barack Obama


In order to fulfil this great promise, a database of human genomes is required and such databases do of course, exist, however, the dataset reflects the economic realities of this world:

  • 70% of the data stored in the Genome wide Association study Catalogue (GWAS) are from people of European ancestry;

  • 30% are from people of Asian descent.[1]



Picture from the Irish Times


Considering that “Caucasian” people do not constitute the majority of our planet’s population, this is bad science.


Even worse, the so-called Human Reference Genome [2] used by scientists all over the world was derived from volunteers of European descent, and thus cannot be representative of all humans.


The genome of people of African descent differs by about 10% from that “reference genome”.[3]


By comparison, Caucasian DNA differs by only ~ 1% from the “reference genome”.


This under-representation of ethnically diverse populations makes it difficult to fully comprehend the genetic architecture of human disease and exacerbates health disparities.


Furthermore, since human genomic studies lack ethnic diversity, our ability to translate genetic research into clinical practice or public health policy may be dangerously incomplete, or worse, incorrect.


When lack of diversity leads to misdiagnosis


Hypertrophic cardiomyopathy (abnormally thick heart muscle) is the most common genetic heart disease in the United States, affecting approximately one in every 500 people worldwide.



Hypertrophic cardiomyopathy


The presence of specific DNA variations may be used to diagnose the condition.


In 2016, it was discovered that African Americans were being misdiagnosed at a disproportionately high rate.


Further analysis showed that 5 genetic variations associated with hypertrophic cardiomyopathy present in the genome of African Americans were in fact harmless.[4]


Diversity in clinical trials is key


It is as important to have people from different sex and ethnicity in clinical trials.



Clinical trials


Many diseases lack efficient treatment, and many researchers around the world are trying to meet these unsatisfied requirements.


Clinical trials are the foundation of new drug approvals, and this process would not be possible without the volunteers who participate in clinical trials.


Clinical trials, on the other hand, consistently fail to represent the demographic diversity of the populations that the drugs in development are intended to serve.


Lack of women in drug trials


Women have been excluded from clinical drug trials for decades, in part due to unfounded fears that female hormone fluctuations make women difficult to study.


Women were barred from participating in clinical trials in part due to thethalidomide tragedy, where thousands of pregnant women who used the drug gave birth to babies with horrific limb deformities.



Baby born to a mother who had taken thalidomide while pregnant



You can have more information by reading our previous article below here.

The NIH and FDA wanted to keep defects from investigational drugs to a minimum.


The decision to exclude all women, not just pregnant ones, reflects a long-held scientific belief that males represent the “normal” or “default” biological situation, while females are “complex”.


These organizations didn’t seem to realize that concentrating solely on men would leave them with useless information.


According to new research from the University of California, Berkeley, and the University of Chicago, women are more likely than men to experience adverse side effects from medications because drug dosages have historically been based on clinical trials conducted on men.[5]


Zolpidem, the popular sleep medication marketed as Ambien, lingers longer in women’s blood than in men’s, causing next-morning drowsiness, significant cognitive impairment, and an increase in traffic accidents. For these reasons, the FDA cut the recommended dosage for women in half in 2013.



Ambien (Zolpidem tablets)


Lack of diverse ethnicities in clinical trials

A study on the process of the FDA approvals of anti-cancer drugs between 1994 and 2014 has shown that the median percentage of:

  • African and African American participants per trial ranged from 1.8–3.5%.

  • Asian participants, the range was 0–7%,

  • any group unspecified or not described as white, Black, or Asian, was 1.4–3.4%.[6]


Diversity in clinical trials will ensure that the outcomes for the trial are valid for all groups when the drug is available and that the health system and society are also marked with access and equity.


And Covid-19?


Thanks to statistics compiled in the US, it is now known that Covid 19 has a colour, as it is more deadly for indigenous and black people than for the rest of the population.


This is in part due to genetic factors, however, social factors such as the quality of medical care available to the average black person compared to that available to the average white person play an important role as well.[7]



2020 Mortality Rate: U.S. COVID-19 Deaths per 100,000, By Ethnicity


Because responses may differ across patient groups, it is critical for clinical trial participants to represent the patients who will use the medical products.


In general, vaccine studies should include non-Caucasian people in percentages reflecting their population representation.


But since the COVID-19 pandemic has affected them disproportionately, scientists think that they should even be over-represented to a degree exceeding the proportion of the general society in the relevant research, and in the clinical trials in particular.[8]


Is it what is happening?


See for yourself:



Ethnicity of Participants in Pfizer-BioNTech and Moderna COVID-19 Vaccine Clinical Trials


Although people of colour are still under-represented in the clinical trials for the two initial COVID-19 vaccines when compared to their population share, the trials included more people from diverse racial/ethnic backgrounds and are more diverse than some trials have historically been.[9]


A step in the right direction.


Most people say that the reason they participated in a clinical trial is because they were asked.
If we have patients coming through our front door, and they at least get asked, diversity could be increased just from that alone. — Nadine Barrett.

— Nadine Barrett, Associate director of community engagement and stakeholder strategy at Duke Cancer Institute.




[1] https://www.ebi.ac.uk/gwas/ [Last accessed on March 21st, 2021]

[2] https://en.wikipedia.org/wiki/Reference_genome [Last accessed on March 21st, 2021]

[3] https://www.nature.com/articles/s41588-018-0273-y [Last accessed on March 21st, 2021]

[4] https://www.nih.gov/news-events/nih-research-matters/genetic-misdiagnoses-heart-condition-black-americans [Last accessed on March 21st, 2021]

[5] https://www.sciencedaily.com/releases/2020/08/200812161318.htm [Last accessed on March 21st, 2021]

[6] https://www.nature.com/articles/d41586-018-05049-5 [Last accessed on March 21st, 2021]

[7] https://www.apmresearchlab.org/covid/deaths-2020-review [Last accessed on March 21st, 2021]

[8] https://www.kff.org/racial-equity-and-health-policy/issue-brief/racial-diversity-within-covid-19-vaccine-clinical-trials-key-questions-and-answers/ [Last accessed on March 21st, 2021]

[9] https://www.kff.org/racial-equity-and-health-policy/issue-brief/racial-diversity-within-covid-19-vaccine-clinical-trials-key-questions-and-answers/ [Last accessed on March 21st, 2021]

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