Large-scale population study tackles Chicago's health disparities

Scientists have known for some time that a person's ethnicity is inherently linked to their health. Research has shown that some racial and ethnic sub-groups are more prone to certain diseases, such as cancer and cardiovascular disease. In Chicago, these rates of disparity are higher than other major cities, and the Chicago Multiethnic Prevention and Surveillance Study (COMPASS) at the University of Chicago Medicine Comprehensive Cancer Center aims to understand why.

Through the efforts of a multidisciplinary team, COMPASS will recruit 100,000 Chicago residents over the next five years to study the lifestyle, environmental and genetic factors that impact health. So far, more than 2,500 residents have enrolled. Eligible participants complete an in-depth interview, provide blood and urine samples for scientific analysis and agree to complete follow-up questionnaires every 2-3 years.

The study is led by Habibul Ahsan, MD, Louis Block Professor of Public Health Studies, Medicine, and Human Genetics, and associate director for population research at the Comprehensive Cancer Center. UChicago Medicine spoke with Dr. Ahsan to learn more about the importance of population research and what COMPASS will help researchers understand.

What is COMPASS?

COMPASS is a population cohort study, which simply means a study of a general population. It aims to identify and understand the causes of disease, and use this information to assess risk and identify potential prevention means. This is done by first identifying a study population and assessing each person's lifestyle, behavioral and molecular characteristics, and then following them to track any changes in health status. Linking personal characteristics with health outcomes allows us to understand what led to the development of certain diseases in certain individuals but not in others.

What makes COMPASS a unique study?

Large population studies have been done across different parts of the United States for evaluating cancer and chronic disease risk. However, most of those studies have used a more convenient way of reaching out to participants such as mass mailing or using a directory of patients, nurses, teachers, etc.

What is unique about COMPASS is that we are actually targeting the general population in the city of Chicago in randomly sampled census tracts, and then we are going to them and inviting them to participate rather than waiting for them to come to us. That way, we don't have limitations where only select individuals who are more health conscious end up participating. We're trying to learn about the whole population irrespective of their characteristics, socioeconomic status or level of health consciousness so what we learn applies to all members of the population.

What makes Chicago's population a good cohort to study?

First, other than New York and Los Angeles, Chicago has the largest urban population in the United States. In fact, this will be one of the largest urban population-based studies.

Second, the diversity of the Chicago population and their geographic distributions are a little more unique than other major cities. There have been some studies that show evidence of disparity in the health outcomes in different ethnic and socioeconomic groups in Chicago.

Does Chicago have more disparities than other large cities?

Studies suggest that Chicago has a wider gap across ethnic groups for certain diseases and outcomes, particularly for breast cancer, certain other cancers and to some extent also diabetes and cardiovascular disease as compared to other large cities.

Why is it important for people to participate in population research?

Only a small fraction of the population at large comes to a medical center when they get sick, and they spend a small fraction of their time in the hospital. So, if we conduct research studies among general populations, not just among the small fraction that come to hospital, our findings will be more robust and generalizable.

If segments of the population are not represented in biomedical research studies, we will not learn what causes disease among them and what the root cause of disparities is. So, it is important for all segments of the population, irrespective of their socioeconomic status and ethnic group, to participate in research studies. Only then, can we provide information that policy makers can use, and populations themselves can react and make changes in their lifestyles.

Why is it important to collect and study biospecimens like blood and urine?

There are many events and causes that lead to the development of disease - some are external and many are inherited. Both types of factors interplay in disease causation.

Many of the environmental causes of diseases the environmental toxins in air, in water, in food and in the settings in which we live and work are difficult to measure accurately because they change over time. Often there are what we call "biomarkers" of those environmental exposures within our blood and/or urine. And, sometimes measuring biomarkers gives a more accurate approximation of what a person has been exposed to over a long period of time. It's really important to be able to evaluate those biomarkers so that we can ascertain who has been exposed to certain contaminants that we believe might be harmful to health.

The other factor we can measure in biospecimens is our body's own defense mechanism or immune system, which provides protection or modifies the molecular processes impacted by environmental exposures or infections. Lastly, our genetic makeup that we inherit from our parents can also interact with these external factors. Understanding these inherited genetic factors through biological samples also helps identify individuals who are at high risk for certain diseases, even if it is primarily driven by environment or external factors.

Are there specific diseases you're going to focus on?

The primary focus is to find causes and new prevention approaches for cancer as well as some chronic diseases, particularly diabetes, and cardiovascular and respiratory diseases, which are the major causes of mortality and morbidity among the U.S. population - especially urban, Chicago residents. These diseases are also major sources of disparity in health status and survival across different ethnic and socioeconomic groups in the city of Chicago. Through a study like COMPASS a true population study with longitudinal evaluation we will also have the opportunity and means to evaluate other diseases down the road. It's more of a research study and resource that can tackle multiple health outcomes from a wide range of known and unknown causes.

What are your long-term goals?

Once we know and understand what leads to the development of disease and the underlying biological processes, we are in a better position to identify prevention and treatment solutions. It will take some time, but the sooner we have recruited a large number of study participants, the sooner we are able to answer the questions mentioned above. And, it might take several years.

For more information on COMPASS, visit compass.uchicago.edu and click here to enroll.