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About 40 percent of Americans belong to a racial or ethnic minority. But the people who participate in clinical trials are much more homogeneous. These trials are the studies that test whether drugs work and inform doctors' decisions about how to treat their patients. As NPR's Rae Ellen Bichell reports, that mismatch can have big health consequences.
RAE ELLEN BICHELL, BYLINE: Here's the gist of an article this week in the journal PLOS Medicine - clinical trials in biomedical research are too white.
SAM OH: Yeesh (laughter) it's a little jarring to hear it that way.
BICHELL: But that's the reality. Sam Oh is an epidemiologist at UC San Francisco. He was one of a group of 14 researchers who found that diversity in biomedical research does not reflect the American population.
OH: Only 2 percent of cancer studies and less than 5 percent of pulmonary studies have studied enough minorities to provide useful information.
BICHELL: When subjects in clinical trials don't look like the patients who could end up taking the medications, that can be problematic.
OH: And we've known for years that certain drugs don't work on parts of our population.
BICHELL: The blood thinner clopidogrel, or Plavix, doesn't work in most Pacific Islanders. Their bodies don't produce the enzymes required to activate the drug, so taking the medication is like taking a placebo. People with epilepsy who are of Asian descent have to get genetic testing before being prescribed the seizure medication carbamazepine because the drug can severely damage the skin and internal organs of patients with a certain gene variant.
OH: African-Americans and Puerto Ricans don't respond as well to some of the most common asthma controller medications. And that's really a tragedy since these two groups are also the most affected by asthma in the United States.
BICHELL: Coming across disparities like the asthma example, Oh says...
OH: You begin to wonder, well, why is this the case? And part of that reason might be because our studies in the past have not recruited as heavily in those populations.
BICHELL: There are a lot of reasons why minorities are underrepresented in biomedical research, from limited access to the specialty care centers where patients are often recruited to trials to fears of exploitation in medical research based on trials in the past like Tuskegee where researchers crossed serious ethical lines with minority subjects. Dr. Michael Lauer oversees grant applications at the National Institutes of Health.
MICHAEL LAUER: There have been some bad experiences, some very bad experiences which have appropriately led people from minority communities to have less trust in the research environment than they otherwise might have.
BICHELL: But Lauer says the importance of increasing diversity among study subjects has been on NIH radar for almost 30 years. And things are starting to look up.
LAUER: For example, between 2010 and 2014, the proportion of participants in clinical trials who are black has increased from 10 percent to 23 percent.
BICHELL: The review boards that decide which studies will get funding, however, remain mostly white. The community of researchers applying for grants also skews white. That's one of the things Oh and his colleagues say needs to change because people are more likely to sign up for a clinical trial if the recruiter looks like them or at least speaks their language.
OH: So it's really important when you want to do science in diverse communities you have a scientific team and a scientific staff that is also diverse.
BICHELL: As the U.S. becomes more diverse, Oh says, these gaps are more important to fill, and filling them might help make a dent in the estimated $300 billion lost each year to health disparities. Rae Ellen Bichell, NPR News. Transcript provided by NPR, Copyright NPR.