Among the First Studies to Find a Causal Effect of Neighborhood Deprivation on Health
Refugees who fled to Europe a generation ago are significantly more likely to have developed type 2 diabetes if they initially settled in poor neighborhoods, according to a study of 60,000 refugees who came to Sweden between 1987 and 1991.
The study, published in The Lancet Diabetes & Endocrinology, takes advantage of a natural experiment the Swedish government unwittingly created when it began dispersing refugees across the country, more or less at random, to ease labor market conditions and help new arrivals integrate more easily into Swedish society.
While many researchers have hypothesized that neighborhood environments play an important role in health, it has been difficult to prove, since unhealthy people tend to move to poor neighborhoods. The Swedish policy offered a way around the conundrum by arbitrarily placing refugees in different neighborhood environments in much the same way a scientist would randomize subjects to different experimental conditions.
The research group, which included members from UC San Francisco, Lund University in Sweden and Stanford University, found that over the course of about two decades, the people in the study who had been resettled in the most deprived neighborhoods were 15 percent more likely to develop type 2 diabetes than those in the least deprived neighborhoods.
Justin White, PhD, an assistant professor of health policy at UCSF and first author of the paper, pointed to a variety of ways that neighborhoods could have this effect, from scarce employment opportunities that leave residents with little money to buy good food, to the stress of living with few resources, to not being able to walk safely outdoors.
"Our study is highly relevant to Europe’s current refugee crisis,” White said. “It shows the decisions these governments make now will have long-lasting impacts on the lives of refugees, many of whom will remain in Europe for decades to come. Investing in their well-being today could lessen the burden on health and social support systems."
Researchers drew on data from Swedish national registers and linked it to health and prescription drug records, giving them information on more than 99 percent of Sweden’s 11.8 million people. They looked for immigrants from countries whose residents were fleeing and selected those who obtained Swedish residence permits between 1987 and 1991, the peak years of the resettlement program. Limiting their sample to those who were between 25 and 50 years old when they arrived, they came up with 61,386 people.
The Swedish policy was akin to scientific randomization, researchers said, because government officials assigned refugees to neighborhoods based only on the information in their applications, which included the languages they spoke, their educational attainment and family size.
Researchers defined the level of adversity in a given neighborhood based on how much income and education its residents had, whether they were employed and to what extent they made use of social assistance programs.
The refugees were assigned to neighborhoods in Sweden during a real estate boom, at a time when refugees had little choice of where to live. The vast majority wound up in deprived neighborhoods, with 45 percent in moderate- and 47 percent in high-deprivation areas.
The refugees were already at heightened risk for developing diabetes, both because they were refugees and because they came from regions that have the world’s highest diabetes prevalence. But the study found that the quality of the neighborhoods where they settled still influenced their long-term risk of developing the disease.
If anything, the researchers said, their study probably underestimates the effect that neighborhoods have on diabetes risk, since the refugees were free to move after the initial placement. Many did manage to find better neighborhoods between the time they settled in Sweden and the time over the next two decades that they developed diabetes, but the effects of their initial neighborhood exposures were still detectable in the data.
Other authors of the study include Rita Hamad, MD, and Sanjay Basu, PhD, of Stanford University; and Xinjun Li, MD, Henrik Ohlsson, PhD, Jan Sundquist, MD, and Kristina Sundquist, MD, of Lund University.
UC San Francisco (UCSF) is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. It includes top-ranked graduate schools of dentistry, medicine, nursing and pharmacy; a graduate division with nationally renowned programs in basic, biomedical, translational and population sciences; and a preeminent biomedical research enterprise. It also includes UCSF Health, which comprises top-ranked hospitals, UCSF Medical Center and UCSF Benioff Children’s Hospitals in San Francisco and Oakland – and other partner and affiliated hospitals and healthcare providers throughout the Bay Area.