Hispanic Americans have higher levels of diabetes and less access to health care services, yet they live on average about three years longer than non-Hispanic whites and six years longer than African-Americans.
No one really knows. Hispanics are underrepresented in both clinical trials and the genome-wide association studies that have informed our understanding of the molecular foundation of health and disease, so we can only guess.
But new research is offering some insights. A study published in Genome Biology suggests that people age differently based on how their genes interact with the environment at the so-called epigenetic level. (Think of epigenetics as molecular switches that can turn genetic processes on or off.) Most of the differences in life expectancy among various ethnic and racial groups can be accounted for by faster and slower rates of aging, with ethnic characteristics serving as a proxy for the unknown underlying epigenetic factors that shape the aging process.
This is just one example of the growing body of research suggesting that we must begin to tailor medical care to individual characteristics. But one-size-fits-all medicine still predominates today, in part because most clinical trials and other studies fail to reflect the diversity of Americans, even as we enter a new era in which the principles of personalized medicine are reshaping our understanding of health care.
Most clinical research includes participants who are overwhelmingly white, non-Hispanic, and, until recently, male. More than 80 percent of genome-wide association studies have been conducted among individuals of European descent. Hispanics represent 0.54 percent of those in genome-wide association studies, not more than a rounding error.
For the most part, current medical therapies, as well as most of those in development, have been tested inadequately — or not at all — in women, children, older adults, individuals with multiple chronic conditions, low-income individuals, and racially and ethnically diverse populations.
Besides interfering with the goals of science and medicine, research that doesn’t reflect the diversity of the U.S. is also bad for the business of health. Clinical trials of “enriched populations,” meaning populations that include individuals who share particular biomarkers, may lead to faster and less-expensive clinical trials. But by themselves they won’t increase our understanding of the effectiveness and safety of therapies for the broader population. Without diversity in clinical trials, those discoveries — which may also lead to new markets — will not happen.
For decades, advocacy groups have urged the National Institutes of Health, the Food and Drug Administration, and the biopharmaceutical industry to include people of diverse racial and ethnic backgrounds, as well as women, in clinical trials. While all agree on this worthy goal, the actual results are discouraging.
The NIH Revitalization Act of 1993 requires all federally funded clinical research to prioritize the inclusion of women and underserved racial and ethnic groups. Yet between 1993 and 2013, less than 2 percent of cancer studies have included enough racial and ethnic group participants to report relevant results.
There is no single solution to the problem. But the NIH’s recently launched All of Us Research Program is a good start. Building a national cohort of 1 million or more Americans that reflects the rich diversity of the American population is a hallmark of the federal effort to accelerate research in personalized medicine.
As a next step, the NIH and FDA could develop incentives for sponsors of clinical trials to include underrepresented populations, such as rewarding the inclusion of information about demographic subgroups and the use of study designs that encourage subgroup comparisons.
The FDA should also implement a system with industry to ensure real-time tracking of inclusion in clinical trials. Reporting would cover enrollment by age, sex, race, and ethnicity, and would encourage enhanced recruitment strategies in studies where inclusion goals are not met.
The NIH and FDA, along with other public health agencies and biopharmaceutical companies, should dedicate adequate resources to community education about clinical trials through one-to-one assistance from trusted sources in minority communities. Some of the most common barriers to inclusion in clinical trials are the lack of awareness about what clinical trials are, not being asked to participate, and misconceptions about the risks. Having a trusted person to speak with and help guide research volunteers through the clinical trial process has worked in the past and will work in the future.
We need to build on the example set by All of Us, which has generated new momentum for inclusive research that can help ensure better health outcomes for all Americans.