Post-doc research fellow Sam Harper (left) and Professor John Lynch found that, while improving, the gap in life expectancy between whites and blacks in the U.S. is still exists.
Owen Egan

The story behind the numbers

By Neale McDevitt | These are heady times for the number crunchers in the Population Health group in the Department of Epidemiology, Biostatistics and Occupational Health. While the McGill community is used to seeing its researchers in the spotlight, an epidemiological study that checked in on the historic difference in mortality rates among blacks and whites in the United States has been grabbing headlines worldwide lately.

Poring over some 46 million death certificates spanning 20 years from the database of the U.S. National Cancer Institute, the study's authors, epidemiology post-doctoral research fellow Sam Harper and Professor John Lynch, came up with the proverbial "good news, bad news" results. While the long-standing gap in mortality rates between blacks and whites has narrowed to historically low levels, the discrepancy is still significant—the life expectancy of black males in the U.S. is six-and-a-half years shorter than that of whites, four-and-a-half years shorter for women.

"Our job is to work back up the causal tree to determine why things have changed," said Lynch. "Instead of waving our flashlight around wildly saying 'things are better,' we shine the light on specific spots and say 'things got better there, there and there.'"

The study showed that the narrowing gap resulted from lower mortality rates over the past decade in just a few areas, including homicide, HIV and cardiovascular disease. Despite the finding that the gap still exists, Harper suggests that the study demonstrates that it is possible to improve the situation. "We found that cardiovascular disease explained about 30 percent of the existing gap for men and about 40 percent for women. Our study suggests applying what we already know about cardiovascular disease to try and remedy this gap."

Breaking new ground

For Lynch, studies like this offer further proof that epidemiologists must think in terms of reinventing their field in order to become "more policy relevant" by providing politicians and other decision-makers with the tools to make informed choices. One of the population health group's recent papers was recognized as a "conceptual breakthrough" and was nominated as one of the "Papers of the Year" by the prestigious medical journal, The Lancet. That study used a novel methodology to look at how rates of cardiovascular disease are affected by socioeconomic factors.

Working with Statistics Canada, Lynch's group is looking to develop a micro-simulation model that would forecast possible outcomes to a variety of health-related scenarios similar to the models used by economists to predict things like the impact a drop in the marginal tax rate would have on unemployment. "Using the same modeling techniques, we want to be able to say 'If we apply the various interventions for heart disease, it would further reduce the gap by this much,'" he said.

"We are hoping to set up a national network across the country of groups in health and health care who are interested in trying to use these models and techniques. It's very much in its infancy but it is a promising direction in which to go because it will give policy makers realistic options rather than just putting out the same old 'the risk associated with such and such exposure is threefold.'"

Small group leaves big footprint

Though small in numbers, the Population Health group, or "our little shop," as Lynch calls it, is spreading its tendrils throughout the campus and around the world. An interdisciplinary enhancement grant from Canadian Institutes of Health Research has paved the way for collaborations with McGill researchers doing work in everything from genetics and psychiatry to sociology, bioinformatics, and family policy. The group is also working on a variety of projects with researchers in Australia, the U.K., Denmark, Sweden, Finland and Brazil. "It's great to be able to overlay our diverse work within McGill with these broader international collaborations," says Lynch. "I like to expose students to these new ideas and then it's up to them to pick it up and run with it. This is their life, their career," says Lynch.

"These are exciting times for our group because we're all changing directions and that's a good thing to do. As academics, that's our job, isn't it?"