Feb. 10 2020

Biostatistics Chair Embraces Complexity

Answering a research question often isn’t as simple as it first appears—particularly in studies that take place over many years. Take the question of how long-term exposure to air pollution impedes lung function in young people. Without accounting for growth spurts during puberty when lung capacity accelerates, the findings could underestimate the potential damage.

Kiros T. Berhane, the new chair of biostatistics at Columbia University Mailman School of Public Health, has identified and addressed these kinds of research complexities throughout his career by employing quantitative reasoning. Innovative methods like the one he developed to account for growth spurts have helped shape government policies to limit exposures to environmental pollutants. And they continue to be influential, applied by researchers to examine health challenges from asthma to obesity.

Growing up in Ethiopia, Berhane had broad interests and aptitude but was drawn to numbers. He was the first in his family to go to college (his younger brother soon followed in his footsteps and is now a biostatistician at Drexel). Scoring among the top in the country on his entrance exams, the elder Berhane defied expectations that he would pursue engineering or medicine and instead elected to pursue mathematics. In statistics, he found a branch of mathematics that allowed him to apply his quantitative skills to solving real-world problems. An interest in the life sciences took him to biostatistics.


“Kiros [Berhane] has led or contributed to some of the most important work on the impact of air pollution on human health that has been conducted over the past ten years.”
—Andrea Baccarelli, chair of environmental health sciences

He earned a PhD in biostatistics at the University of Toronto and completed a post-doc at Johns Hopkins where he began a career-spanning specialization in statistics for environmental health. On the faculty of the University of Southern California for the last 22 years, he was lead biostatistician on one of the country’s first longitudinal studies looking at the long-term effects of exposure to air pollution on children’ health (a similar longitudinal study is housed at the Columbia Center for Children’s Environmental Health at Columbia Mailman School).

In the study of air pollution’s effects on lung growth, Berhane and his collaborators found that children living in polluted communities and closer to motor vehicle traffic were more likely to experience large deficits in lung growth. Results were published in the New England Journal of Medicine and The Lancet. The team has produced a large body of original research that has firmly established the evidence for significant cardio-respiratory health effects of long-term exposure to air pollution. This led the U.S. Environmental Protection Agency, which funded some of this research, to invite Berhane to serve as a member of its science advisory board. His research was cited each time the agency considered air pollution regulations. When follow-up papers recently appeared in the New England Journal of Medicine and JAMA, they pointed to some good news: improvements in air quality due to regulations resulted in healthier lung growth and reductions in asthma-like symptoms.

“Kiros has led or contributed to some of the most important work on the impact of air pollution on human health that has been conducted over the past ten years,” notes Columbia Mailman Environmental Health Sciences Chair Andrea Baccarelli, who led the search committee for the biostatistics chair. “His innovative research methods have allowed for insights that have informed the policy debate on air pollution regulations.”

The statistical method Berhane developed for the lung function study would also go on to have applications for a range of studies, for instance, looking at the relationship between childhood obesity and the built environment, including the availability of green spaces and physical activity. This wasn’t the only instance of his methods having an extended life. For a separate study of cancer risk among uranium miners, Berhane developed a method to account for latency—the length of time it takes cancer to develop after both short and long exposures. Again, his method was later applied to other research questions such as Vietnam Veteran’s exposures to Agent Orange. (Berhane was invited to serve on National Academies of Sciences committees looking at Agent Orange.) “One of the good things about biostatistics is that you can develop a method for one study which can be applied to a host of other research questions,” he says.

In his new role as chair of biostatistics, Berhane intends to build on the department’s strengths while charting a course to a future for the field—not least of all by fostering diversity. He was co-director of a new program at USC called LA’s Biostatistics Education Summer Training program at USC (LA’s BEST@USC). Several of its inaugural graduates are currently considering doctoral degrees as a result of their experience in the program—exactly the goal the program is intended for. (The USC program is modeled on the Columbia Mailman School’s Biostatistics and Epidemiology Summer Training program, initiated by students in 2007 to support minority and first-generation college students. Several of its graduates are currently training for doctoral degrees or have already earned PhDs.) A highly regarded teacher and mentor both in the United States and abroad, Berhane has led workshops in biostatistics globally—most recently in Nigeria for 72 trainees from across West Africa. He was also the 2016-2017 recipient of the prestigious Fulbright Scholar Award in the Teaching/Research category.

Another priority is strengthening the department’s research and educational capacity in data science. Speaking at the recent Columbia Mailman Data Science in Public Health Summit, Berhane, who is also the Cynthia and Robert Citron-Roslyn and Leslie Goldstein Professor of Biostatistics, noted that students are eager to acquire skills in data science. At USC, he co-led the launch of an MS degree in Health Data Science. In a similar fashion, he plans to expand learning opportunities in data science for Columbia Mailman students at all levels—including through collaborations with the Columbia University Data Science Institute. Yet while data science offers powerful tools to public health scientists, its algorithms are a “black box” in the sense that they aren’t tied to causal mechanisms. Traditional biostatistics offers an important complement, says Berhane, by providing insights into study design, hidden biases, and the interpretation of results.

“Biostatistics is in an exciting state,” says Berhane. “Things are changing very fast. More than ever, we have the opportunity to make a positive difference for human health.”