Different racial and ethnic groups experience disease and respond to treatments differently.

So, there’s a need for clinical trials for drugs and medical devices to reflect the various populations who could potentially use them.

There are, however, long-standing difficulties in recruiting and maintaining study groups that reflect society at large.

Particularly, researchers struggle to recruit minorities and people from low-income households, even in the age of nearly ubiquitous internet access.

Services like Antidote seek to connect the appropriate populations with clinical trials. Even using platforms like Facebook, recruiters have difficulty in securing a diverse population, an issue long-recognized in the clinical trial industry.

“It’s a critical issue to reach out to underserved populations,” Sarah Kerruish, chief growth officer for Antidote, told Healthline. “We know this is a major issue.”

Language barriers are one example of how it’s more difficult to recruit Hispanic people for trials, which are often fraught with technical language that’s difficult for laypeople to translate.

“There’s a huge disparity regarding trials,” Kerruish said.

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New research on recruiting

A study led by a team at Washington University School of Medicine in St. Louis found disparities in healthcare would continue unless recruiters and researchers are able to engage underrepresented groups.

In the study published in the journal Genetics in Medicine, researchers offered 967 study participants who smoked detailed information about their ancestry to help them understand smoking behavior and nicotine addiction.

While 64 percent of participants indicated they were either “very interested” or “extremely interested,” only 16 percent viewed their results online. This was after repeated attempts to get them to do so.

Among African-Americans, people from low-income households, and those with no high school diploma, the response rate was about 10 percent.

These groups are historically under-represented in medical research studies.

The study’s first author, Dr. Sarah M. Hartz, Ph.D., an assistant professor of psychiatry at Washington University, said researchers don’t know what barriers prevent these populations from participating in studies.

“We don't know whether some people don't have easy access to the internet or whether there are other factors, but this is not good news as more and more research studies move online because many of the same groups that have been underrepresented in past medical research would still be missed going forward," she said in a press release.

In the Washington University study, participants were able to have their DNA analyzed and receive reports on where their ancestors came from. Researchers followed up with multiple emails, letters in the mail, and phone calls to those who didn’t check their results online.

About 45 percent of European-Americans with high school educations and incomes above the poverty line looked at the information, while only 18 percent of African-Americans with the same credentials logged onto the site.

In 2004, a study published in JAMA found while enrollment in cancer trials was low, racial and ethnic minorities, women, and the elderly were less likely to enroll in a trial than whites, men, and younger patients. African-American participation was declining then, and continues to decline.

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Internet access doesn’t help

This is especially relevant today because of the National Institutes of Health's Precision Medicine Initiative, a project to recruit 1 million people and analyze their DNA to understand risk factors related to a variety of diseases.

As the Washington study illustrates, getting a sample reflective of the U.S. population may not be an easy task.

“Our assumption that the internet and smartphone access have equalized participation in medical research studies doesn't appear to be true,” Hartz said. “Now is the time to figure out what to do about it and how to fix it, before we get too far along in the Precision Medicine Initiative, only to learn that we're leaving some underrepresented groups of people behind.”

A study published last year found that while African-Americans comprise 12 percent of the U.S. population, they account for only 5 percent of clinical trial participants. Meanwhile, Hispanics account for 16 percent of the general population, but only 1 percent in clinical trials.

Possible explanations include higher rates of being uninsured, which limits interactions with healthcare professionals and ultimately knowledge of available clinical trials.

Also, decreased job scheduling flexibility might limit availability to participate in a trial.

Read more: Cancer trial deaths not expected to slow down research »

Unethical trials may cause distrust

Besides access, some populations are distrustful and skeptical of clinical trials because of past experiments where people were mistreated.

The most notable is the Tuskegee experiments, which lasted 40 years, ending in the 1970s.

During the trial, African-Americans from low-income households living in rural Alabama were told they were being treated for “bad blood” and would receive free healthcare from the U.S. government.

In reality, they were being denied lifesaving treatments for syphilis so researchers could study its effects by following infected people.

The Tuskegee experiments, and others like it that deny participants the necessary facts so they can give informed consent, are medically unethical.

So many clinical trials were outsourced to other countries that the U.S. Food and Drug Administration (FDA) intervened with new guidelines on accepting data from clinical trials conducted overseas.

The World Health Organization (WHO) also highlighted concerns over unethical and illegal trials being conducted on women in India hoping to conceive a child.

These are far from isolated incidents. A 2004 survey of more than 600 health researchers found nearly half of clinical trials did not undergo ethical review. Companies in the United States funded a third of those studies.

WHO and other organizations have been working to ensure countries have independent ethical review committees, and trials are conducted under their watch.

“This is a problem for many countries, not only developing countries,” Dr. Marie-Charlotte Bouësseau from WHO’s department of Ethics, Trade, Human Rights, and Health Law, said more than a decade ago. “We need to provide training to ensure that these panels are independent and able to review clinical trials without prejudice.”