Probing disease disparities

Francisco Barrera

Francisco Barrera, SM ’22, delves into thorny questions about racial differences in health outcomes

May 24, 2022 – Do patients of color face higher risk of cancer after a heart transplant than white patients? Do Hispanic people who quit smoking have lower rates of cognitive decline than those who don’t quit?

These are the sorts of research questions that excite Francisco Barrera, who’s set to earn his master of science in epidemiology from Harvard T.H. Chan School of Public Health in May. He wants to uncover racial, ethnic, and gender differences in disease prevalence.

“Social injustices are particularly important to me,” said Barrera, who goes by Frank. “In this world, it appears we can have everything, but not everyone has access to the same opportunities. This is my way of creating more knowledge and awareness around issues, to show people that they exist. And hopefully this knowledge can lead to policy interventions that could eventually decrease the effects of the social injustices we face.”

An analyst at heart

Growing up in Monterrey, Mexico, Barrera was intensely observant. “I’ve always paid a lot of attention to detail and been very analytical by nature,” he said. “I like to observe things, especially people.” That inquisitiveness led him toward research while attending medical school at the University of Nuevo Leon, where he received a research fellowship and learned the basics of methodology, statistics, and scientific writing.

Over the next few years, Barrera took on every research topic that came his way, including prosthetic joints, cancer at the base of the skull, and metabolic syndrome among football players. “The opportunities where I come from are varied, and it’s difficult for a medical student to find the perfect fit,” he said. “My interest was in learning how to research. But many times I asked myself when I was going to be able to focus on something that I could be passionate about.”

He’s begun to find the topics that interest him at Harvard Chan School. Over the past year, he’s been working on a research project with Murray Mittleman, professor of epidemiology, to look at the prevalence of cancer among heart transplant recipients by race. Transplant recipients receive immunosuppressants to reduce the chances of organ rejection, but these medications can also increase the risk of many kinds of cancer, including skin cancer and malignancies in blood and bone marrow.

Using about 30 years of records from a national transplant registry—more than 60,000 in all—Barrera has examined the probability of patients both developing and dying from cancer. Preliminary results show that Black, Asian, or Hispanic recipients are less likely to be diagnosed with cancer than white patients and are more likely to die from the disease. “There are many factors that might explain these disparities, including access to high-quality medical care, insurance status, location, socioeconomic status, or even racism within the medical profession,” he said.

In order to draw conclusions from the research, Barrera said it was important to analyze the data carefully, taking into account racial differences in the development of cancer over time, rather than simply looking at an individual’s propensity to develop or die from cancer following transplant surgery.

Barrera first became aware of the subtleties of data analysis near the end of his medical training in Mexico, when he performed several meta-analyses that combined numerous studies on a particular topic. “In assessing the quality of the methods of the studies I was synthesized, I started learning about all of the different types of bias that can be created from measurement errors,” he said.

Continuing education

That experience drew him to Harvard Chan School in hopes of better learning how to perform accurate analyses of data. “The classes here have reshaped the way I see methods and research, and cleared up many misconceptions I had,” he said. For example, he has gained a much greater appreciation for the difficulties in assigning causality in observational studies. “I’ve gained a lot of humility and respect for methods, but I also feel confident with what I know now—and feel empowered to design and conduct these kinds of studies,” he said.

Barrera will remain at the School for a year as a postdoctoral researcher, working with Mittleman on a new project to examine how quitting smoking affects cognitive decline among Hispanic patients. “They have a high prevalence of smoking and a higher risk of developing dementia compared to non-Hispanic whites,” Barrera said. “This relationship has not been studied before in this population.”

At the same time, he is applying for residencies in psychiatry, pursuing his lifelong fascination with analyzing and observing human behavior. His goal is to use his training in research methods to further conduct studies that might better identify and explain differences in mental health between people in different demographic groups, to help design better individual treatment.

“There is a misconception in medicine that we can all fit in the same box,” he said. “But we are not all the same, and we do not respond the same to treatment. There are a lot of differences in gender, race, and ethnicity that can be analyzed through research in ways that may have impact on prognosis and the medical care we can provide to patients.”

Michael Blanding