SUMMARY
Background
While numerous studies have shown associations between neighborhood quality and chronic disease outcomes, such correlations are potentially confounded by selection of different types of people into different neighborhood environments. We sought to identify the causal effects of neighborhood deprivation on type 2 diabetes risk, by comparing refugees to Sweden who were actively dispersed by government policy to low-, moderate-, or high-deprivation neighborhoods.
Methods
We studied national register data on N=61,386 refugees who arrived in Sweden at age 25–50 during 1987–1991, a period of quasi-random dispersal of refugees to Swedish neighborhoods varying in poverty, unemployment levels, schooling, and social welfare participation. Individuals in our sample were assigned to one of 4,833 neighborhoods, categorized as high-deprivation” (≥1 SD above the mean), “moderate deprivation” (within 1 SD of the mean), or “low-deprivation” (≥1 SD below the mean). The primary outcome was diagnosis with type 2 diabetes measured through 2010. We used multivariate logistic and linear regressions to assess the effects of neighborhood deprivation on diabetes risk, controlling for potential confounders affecting neighborhood assignment and assessing effects of cumulative exposure to different neighborhood conditions.
Findings
Being assigned to an area deemed high-deprivation versus low-deprivation was associated with an increased risk of diabetes among refugees (OR 1·22, 95% CI: 1·07, 1·38; p=0·001). In analyses that included fixed effects for assigned municipality, the increased diabetes risk was estimated to be 0·85 percentage points (−0·030, 1·728; p=0·058). Neighborhood effects grew over time, such that 5 years of additional exposure to high-deprivation versus low-deprivation neighborhoods was associated with a 9% increase in diabetes risk.
Interpretation
This study leverages a natural experiment to show that neighborhood deprivation increased the risk of diabetes among refugees to Sweden. This finding has heightened significance in the context of the current refugee crisis in Europe.
Funding
U.S. National Heart, Lung, and Blood Institute, U.S. National Center for Advancing Translational Sciences, U.S. National Institute on Minority Health and Health Disparities, Swedish Research Council.