Esteban Gonzalez Burchard, MD, MPH, grew up Mexican American in California, raised by a single mother. Because he had lighter skin than his mother, he often faced the complexities of identifying as “Hispanic”.
“It always confused and challenged me,” says Burchard, a physician scientist and professor at the University of California, San Francisco. “[My mother] it wasn’t black, although it looked black and it wasn’t white – it was in that in-between zone.
His personal experience led him to a research career focused on understanding how genetic ancestry—as well as the social determinants of health related to race and ethnicity—affect the health of people who are minorities.
One barrier he and other researchers in his field have faced is the lack of detailed provenance data. This has been particularly challenging in studying health in Hispanic communities because of the tremendous genetic, cultural, and socioeconomic diversity in a population grouped together largely because of a common language. Hispanics are also often grouped together under the term “Hispanic”, which refers to anyone descended from people in Central and South America, including Portuguese-speaking Brazilians.
“Although Hispanics are considered primarily an ethnic group, they represent a heterogeneous mixture of Native American, European, and African ancestry,” Burchard and his coauthors wrote in an article published in American Journal of Public Health. “Therefore, they may self-identify as any race or mixed race as defined by the 2000 U.S. Census.”
The U.S. Department of Health and Human Services requires healthcare providers to report demographic data on patients’ race and ethnicity, but hospitals often don’t follow best practices when it comes to collecting and applying detailed demographic data — including self-identification of countries of origin, according to a report by the Agency for Healthcare Research and Quality.
When detailed, disaggregated demographic data are not collected and analyzed, it can mask health disparities that differentially affect Hispanic and/or Hispanic subgroups, explains Luisa N. Borrell, DDS, PhD, Distinguished Professor in the Department of Epidemiology and biostatistics at the Graduate School of Public Health and Health Policy, City University of New York.
“The problem for us is aggregation, because when you put all the Hispanics together … it looks like we’re doing better or similar to non-Hispanic whites,” Borrell says. “We can’t just rely on the broad categories. We need to dive deeper into the racial/ethnic categories currently in use if we are serious about addressing health disparities.”
The Spanish Paradox
The phenomenon Borrell mentioned is known as the “Hispanic Epidemiologic Paradox,” a term coined by sociologist Kyriakos S. Markides, Ph.D., in 1986 to describe the relatively good health documented among Hispanics in the southwestern United States despite socio- the economic and systemic challenges that might otherwise portend ill health.
At the time, Hispanics had similar rates of infant mortality, cardiovascular disease, cancer, and other diseases as white people, even though they had higher rates of poverty. And in 2020, people who identified as Hispanic in the United States died at lower rates than white people, according to a Kaiser Family Foundation analysis of data from the Centers for Disease Control and Prevention (CDC).
The reasons for this “paradox” may range from genetic resilience to cultural influences to selective migration (meaning that healthier people are more likely to immigrate)—but epidemiologists who study race and ethnicity suggest that the clustering of all Hispanics and Latin Americans together may be responsible for creating a false picture.
For example, in 1997, the CDC published a study that found that Hispanics die of asthma more often than whites or blacks. Burchard, a lung specialist, looked at the data and realized that the higher death rates were almost exclusively in the northeastern United States, where there is a robust Puerto Rican community. When the data was broken down by country of origin, Burchard found that people of Mexican descent were less likely to have asthma, while people of Puerto Rican descent were much more likely to have it.
This realization led Burchard to study how genetic ancestry influenced asthma in Hispanic and African-American children. Burchard and his team analyzed the participants’ genomes and were able to identify genetic variants that could explain why common asthma medications were less effective for people of Puerto Rican or African descent.
“Race, socioeconomic status, environmental factors—these are all social constructs that are dynamic. They change over time,” says Burhardt. “What we consider race in 2022 is not what Jim Crow considered race in 1930. Science has advanced so much in the last 22 years since the completion of the Human Genome Project. We can now accurately measure an individual’s genetic ancestry, regardless of what race” they describe themselves as.
Genes as risk indicators
A more precise understanding of genetic ancestry may help identify risk factors for certain diseases — as appears to be the case with brain tumors.
Researchers at Duke University School of Medicine recently analyzed data on the origins of patients across the country with glioma, a deadly type of tumor that occurs in the brain and spinal cord, and found that although Hispanics and/or Hispanics generally have lower rates of glioma compared to white people, people of Caribbean descent had higher rates than those of Central American descent.
This may be due in part to the fact that people of Caribbean descent tend to have a higher percentage of European ancestry than those from Central America, who tend to have more Native ancestry, says Kyle Walsh, Ph.D. associate professor of neurosurgery at Duke and lead author of the study.
“In a subset of the genomes of Hispanic individuals, the more Europeans there were, the more likely they were to be glioma patients,” explains Walsh. “Every 10% increase in the genome that is European in Hispanics [resulted in] about a 1.15% increase in risk.
Walsh and his team were able to do this study because each state is required by law to maintain a registry of brain tumor patients, which is then compiled into the United States Central Brain Tumor Registry. They were also able to obtain census-level demographic data for nearly all brain tumor diagnoses in the country—a level of detail not available for most other diseases.
“In general, the medical field is moving more away from race and ethnicity classifiers,” says Walsh, referring to recent efforts to remove “race adjustments” from algorithms that assess kidney function and the need for C-sections. “At the same time, these indicators do [show] real things about man: representative aspects of his genetic background, environment, foods, lifestyle, cultural differences.
Walsh says asking patients to identify their ancestry is probably the best and most practical way to get a complete and accurate picture of their health, especially when genetic testing isn’t possible.
“[Patients tend] to know a lot about their background, who they are and where they are from,” he says. “They report pretty valid, reliable data. It seems important to give them the opportunity to provide it.”
Social and environmental factors
While genes certainly influence health, Borrell cautions against overrelying on genetics to explain health care disparities in the United States.
“Instead of relying on risk in genetics, we need to look at the interaction between genetics and the social environment,” she says.
Ideally, patient data collection should transcend race, ethnicity, and even background. He will also ask questions about socioeconomic status, whether the patient was born in the United States or in another country, how old he was when he immigrated and how long he had been in the United States, and what environmental and social risks health care they may have encountered or been exposed to throughout their lives, Borrell says.
“They should include as much information as possible about the social context in which people interact, live and work,” she says.
Having better data and context for patients of different racial and ethnic backgrounds will help identify treatments and cures for different populations, Burchard says.
In the United States, up to 90% of clinical trial participants identify as white, and less than half of clinical trials report race and ethnicity at all.
Burchard believes the first step to changing that is for medical schools and teaching hospitals to commit to diversifying the medical workforce.
“We need more scientists and doctors from diverse populations because it has been clearly shown that minority scientists tend to study minorities and [minority physicians tend to] treat minorities,” he says. “[There is] structural racism that is inherent in our biomedical and scientific communities. … I would like medical students to challenge the system.”