Esteban González Burchard, MD, MPH, grew up as a Mexican American in California, raised by a single mother. Because he had lighter skin than his mother, he was often faced with the complexities of identifying as “Hispanic.”
“That always perplexed and challenged me,” says Burchard, a physician-scientist and professor at the University of California, San Francisco. “[My mother] wasn’t Black, although she looked Black, and she wasn’t White — she was in this in-between zone.”
His personal experiences led him to a research career focused on understanding how genetic ancestry — as well as the social determinants of health connected to race and ethnicity — impact the health of people who are minoritized.
One barrier he and other researchers in his field have faced is the lack of detailed ancestry data. This has been particularly challenging when studying health in Hispanic communities because of the vast genetic, cultural, and socioeconomic diversity in a population grouped together primarily because of a shared language. Hispanic people are also often grouped together under the term “Latino,” which refers to anyone descended from people in Central and South America, including Portuguese-speaking Brazilians.
“Although Latinos have been considered to be first and foremost an ethnic group, they represent a heterogeneous mix of Native American, European, and African ancestries,” Burchard and his co-authors wrote in an article published in the American Journal of Public Health. “Therefore, they can self-identify as any race or of mixed race as defined by the 2000 U.S. Census.”
The U.S. Department of Health and Human Services requires health care providers to report demographic data about the race and ethnicity of patients, but hospitals frequently fall short of employing best practices when it comes to collecting and applying detailed demographic data — including self-identification of countries of ancestry, according to a report by the Agency for Healthcare Research and Quality.
When detailed, disaggregated demographic data are not collected and analyzed, this can hide health disparities that impact subgroups of Hispanic and/or Latino people differently, explains Luisa N. Borrell, DDS, PhD, a 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 the aggregation, because when they put all the Hispanics together … we look like we have better or similar outcomes to non-Hispanic Whites,” Borrell says. “We cannot just rely on the broad categories. We have to dive deeper into the currently used racial/ethnic categories if we are serious about solving health inequities.”
The Hispanic paradox
The phenomenon Borrell references is known as the “Hispanic epidemiological paradox,” a term coined by sociologist Kyriakos S. Markides, PhD, in 1986 to describe the relatively good health documented among Hispanic people in the southwestern United States, in spite of socioeconomic and systemic challenges that might otherwise portend poorer health.
At the time, Hispanic people had similar rates of infant mortality, cardiovascular disease, cancer, and other diseases as White people despite having higher rates of poverty. And in 2020, people 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” could range from genetic resilience to cultural influences to selective migration (meaning healthier people are more likely to immigrate) — but epidemiologists who study race and ethnicity have suggested that grouping all Hispanics and Latinos together might be responsible for creating a false picture.
For example, in 1997, the CDC released a study that found that Hispanic people were dying from asthma at higher rates than White or Black people. Burchard, a lung specialist, looked at the data and realized that the higher death rates were almost exclusively in the Northeast United States, where there is a robust Puerto Rican community. When the data were separated 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 prompted Burchard to study how genetic ancestry impacted asthma in Hispanic and African American children. Burchard and his team analyzed the participants’ genomes and were able to identify genetic variants that might explain why common asthma drugs are less effective for people of Puerto Rican or African descent.
“Race, socioeconomic status, environmental factors — those are all social constructs that are dynamic. They change over time,” Burchard says. “What we consider as race in 2022 is not what Jim Crow considered race in 1930. The science has advanced so much in the last 22 years since the completion of the human genome project. We can now precisely measure an individual’s genetic ancestry regardless of what race” they describe themselves as.
Genes as risk indicators
Having a more accurate understanding of genetic ancestry can 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 ancestry data from patients across the country with glioma, a deadly type of tumor that occurs in the brain and spinal cord, and found that, although Hispanic and/or Latino people in general have lower rates of glioma than 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 those of Caribbean descent are more likely to have a higher percentage of European ancestry than those from Central America, who tend to have more Indigenous ancestry, says Kyle Walsh, PhD, an associate professor in the Department of Neurosurgery at Duke and the lead author of the study.
“In a proportion of Hispanic individuals’ genomes, the more European there was, the more likely they were to be a glioma patient,” Walsh explains. “Each 10% increase in 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 every state is required by law to keep a registry of brain tumor patients, which is then collected in the Central Brain Tumor Registry of the United States. They also were able to obtain census-level demographic data for almost all brain tumor diagnoses in the country — a granularity that is not available for most other diseases.
“In general, the medical field is moving more away from race and ethnicity classifiers,” Walsh says, referring to recent efforts to remove “race corrections” from algorithms that estimate kidney function and need for a C-section. “At the same time, those indicators do [show] real things about the person: representative aspects of their genetic background, environmental background, foods, lifestyle, cultural differences.”
Walsh says that asking patients to self-identify their ancestry is likely the best and most practical way to get a full and accurate picture of their health, especially when genetic testing is not feasible.
“[Patients tend] to know a lot about their background, who they are, and where they’re from,” he says. “They’re reporting pretty valid, robust data. It seems to be important to give them the opportunity to provide that.”
Social and environmental factors
While genes certainly influence health, Borrell cautions against an over-reliance on genetics to explain health inequities in the United States.
“Rather than relying on the risk in genetics, we need to look at the interaction between genetics and the social environment,” she says.
Ideally, data collection from patients should go beyond race, ethnicity, and even ancestry. It would also ask questions about socioeconomic position, whether the patient was born in the United States or another country, how old they were when they immigrated and how long they have been in the United States, and what kinds of environmental and social health risks they might have encountered or been exposed to over their life course, Borrell says.
“They should include as much information as they can for the social context in which people interact, live, and work,” she says.
Having better data and context for patients of varying racial and ethnic backgrounds will help in identifying treatments and cures for diverse populations, Burchard says.
In the United States, as much as 90% of clinical trial participants identify as White, and fewer than half of clinical trials report race and ethnicity at all.
Burchard believes the first step to changing this is for medical schools and teaching hospitals to commit to diversifying the people working in the medical field.
“We need more scientists and physicians from diverse populations because it’s 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 want medical students to challenge the system.”
