Apr. 19 2016

Public Health, Precisely

As the nation invests in precision medicine, a Mailman faculty consider what role public health can play

In the year since President Obama announced the $214 million Precision Medicine Initiative, the world of biomedical research has been flush with excitement about how to unlock new ways to understand and treat disease. Columbia University continues to ramp up its own precision medicine effort, including the creation of the Institute for Genomic Medicine. At the same time, many at the Mailman School have wondered what role public health can—or should—play in precision medicine, when the two seem to be on opposite ends of the population health spectrum.

At a recent faculty panel discussion, Ron Bayer, professor of Sociomedical Sciences and co-author of a related commentary in the New England Journal of Medicine, argued that the overwhelming emphasis in discussions around precision medicine has been on individual treatments. He cited one example of an effort to identify smokers who are most responsive to medications that inhibit the desire to smoke—a clinical response to a problem for which there is already a public health answer: taxes and other policies that curb tobacco use on a mass scale. As shown in a recent high-profile study in JAMA, health disparities are mediated by “community interventions, not clinical interventions,” according to Bayer.

DuBois Bowman, chair of Biostatistics and moderator of the exchange, made a case that precision medicine, as conceived by the government, incorporates several pillars of public health. A National Institutes of Health summary of its own precision medicine efforts references “prevention” and positions environmental and behavioral issues right next to genetics. “Embedded in that statement, I see a critical need for public health expertise,” said Bowman.

And many in public health have already been looking at genetic susceptibility to disease, alone or in concert with exposure to chemicals, lifestyle choices, and the social environment. Ying Kuen “Ken” Cheung, professor of Biostatistics and chair of a Mailman School committee on the role of public health in precision medicine, said that as a measure of the importance of this research and its relevance to public health, genetic variation accounts for 30 percent of health on a population level, whereas 60 percent of health determinants are explained by behavioral, environmental, and socio-economic factors. 

The emerging field of epigenetics is among the most exciting ways public health intersects with precision medicine. Incoming chair of Environmental Health Sciences Andrea Baccarelli, a pioneer in in the area, said epigenetics give scientists a way to precisely account for environmental exposures. Changes to the epigenome, from air pollution, for example, are concrete evidence of harm, making a powerful case for population-wide interventions. Moreover, this damage can be passed from one generation to the next. “This is changing the way we think about not just inheritance, but about public health,” he said. 

Why Precision Medicine Needs Public Health

Precision medicine could learn from public health’s long history of studying health questions in minorities and other vulnerable groups, panelists suggested. Bowman observed that the world of genetic research is badly imbalanced. By one estimate, 96 percent of genome-wide association studies have been limited to people of European descent. Ignoring other groups, he said, will only exacerbate disparities.

By the same token, public health should be inspired by precision medicine to explore new research avenues. Ursula Staudinger, director of the Robert N. Butler Columbia Aging Center and Robert N. Butler Professor of Sociomedical Sciences, said it makes a fundamental difference whether you approach the question of precision from the perspective of therapy and cure or whether you approach it from the perspective of building health resources. “To optimize aging trajectories, we need more precision concerning which intervention to apply with which subgroup,” said Staudinger. “This precision is not preempted by genetics but needs to take into account behavioral as well as contextual variations. Such a perspective requires to not only focus on group means but to try and unravel the mechanisms that underlie the variance in a given clinical trial.” We now have longitudinal datasets and analytical tools to learn how we become more different from each other as we age, she added.

Pam Factor-Litvak, professor of Epidemiology, made a strong case that precision medicine depends on public health expertise. “People who do precision medicine work need to be able to define questions—something public health practitioners are fabulous at,” she said. To answer these questions, researchers also need to understand appropriate methodologies and tools for data collection. Moreover, providing this expertise requires a workforce trained at schools of public health.

“There needs to be a symbiotic relationship between precision medicine and public health,” she said.