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Original Investigation
July 2017

Association of Changes in Neighborhood-Level Racial Residential Segregation With Changes in Blood Pressure Among Black AdultsThe CARDIA Study

Author Affiliations
  • 1Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
  • 2Department of Epidemiology, University of North Carolina Gillings School of Public Health, Chapel Hill
  • 3Department of Nutrition, University of North Carolina Gillings School of Public Health, Chapel Hill
  • 4Institute for Social Research, University of Michigan, Ann Arbor
  • 5Department of Epidemiology, Colorado School of Public Health, Aurora
  • 6Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester
  • 7Division of Research, Kaiser Permanente Northern California, Oakland
  • 8Department of Epidemiology and Biostatistics, Drexel University Dornsife School of Public Health, Philadelphia, Pennsylvania
JAMA Intern Med. 2017;177(7):996-1002. doi:10.1001/jamainternmed.2017.1226
Key Points

Question  Are changes in exposure to neighborhood-level racial residential segregation associated with changes in blood pressure?

Findings  In this cohort study of 2280 black adults, increases in neighborhood-level racial residential segregation were associated with small but statistically significant increases in systolic blood pressure, and reductions in segregation levels were associated with more than a 1–mm Hg decrease in systolic blood pressure.

Meaning  Policies that reduce racial residential segregation may have meaningful health benefits, such as reductions in blood pressure.

Abstract

Importance  Despite cross-sectional evidence linking racial residential segregation to hypertension prevalence among non-Hispanic blacks, it remains unclear how changes in exposure to neighborhood segregation may be associated with changes in blood pressure.

Objective  To examine the association of changes in neighborhood-level racial residential segregation with changes in systolic and diastolic blood pressure over a 25-year period.

Design, Setting, and Participants  This observational study examined longitudinal data of 2280 black participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study, a prospective investigation of adults aged 18 to 30 years who underwent baseline examinations in field centers in 4 US locations from March 25, 1985, to June 7, 1986, and then were re-examined for the next 25 years. Racial residential segregation was assessed using the Getis-Ord Gi* statistic, a measure of SD between the neighborhood’s racial composition (ie, percentage of black residents) and the surrounding area’s racial composition. Segregation was categorized as high (Gi* >1.96), medium (Gi* 0-1.96), and low (Gi* <0). Fixed-effects linear regression modeling was used to estimate the associations of within-person change in exposure to segregation and within-person change in blood pressure while tightly controlling for time-invariant confounders. Data analyses were performed between August 4, 2016, and February 9, 2017.

Main Outcomes and Measures  Within-person changes in systolic and diastolic blood pressure across 6 examinations over 25 years.

Results  Of the 2280 participants at baseline, 974 (42.7%) were men and 1306 (57.3%) were women. Of these, 1861 (81.6%) were living in a high-segregation neighborhood; 278 (12.2%), a medium-segregation neighborhood; and 141 (6.2%), a low-segregation neighborhood. Systolic blood pressure increased by a mean of 0.16 (95% CI, 0.06-0.26) mm Hg with each 1-SD increase in segregation score after adjusting for interactions of time with age, sex, and field center. Of the 1861 participants (81.6%) who lived in high-segregation neighborhoods at baseline, reductions in exposure to segregation were associated with reductions in systolic blood pressure. Mean differences in systolic blood pressure were −1.33 (95% CI, −2.26 to −0.40) mm Hg when comparing high-segregation with medium-segregation neighborhoods and −1.19 (95% CI, −2.08 to −0.31) mm Hg when comparing high-segregation with low-segregation neighborhoods after adjustment for time and interactions of time with baseline age, sex, and field center. Changes in segregation were not associated with changes in diastolic blood pressure.

Conclusions and Relevance  Decreases in exposure to racial residential segregation are associated with reductions in systolic blood pressure. This study adds to the small but growing body of evidence that policies that reduce segregation may have meaningful health benefits.

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