May 22, 2017Epidemiology
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. As a result, a study published on line (15 May 2017) in JAMA Internal Medicine, was performed 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.
This observational study examined longitudinal data of 2,280 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 (i.e., 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. The main outcome measures were within-person changes in systolic and diastolic blood pressure across 6 examinations over 25 years.
Results showed that of the 2,280 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, gender, and field center. Of the 1,861 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.
According to the authors, decreases in exposure to racial residential segregation are associated with reductions in systolic blood pressure, and that this study adds to the small but growing body of evidence that policies that reduce segregation may have meaningful health benefits. Living in racially segregated neighborhoods is associated with a rise in the blood pressure of black adults, while moving away from segregated areas is associated with a decrease - and significant enough to lead to reductions in heart attacks and strokes, a National Institutes of Health-funded study has found. The findings offer further evidence that policies to reduce residential racial segregation may have meaningful health benefits, especially for African-Americans, who suffer the highest rates of hypertension of any group in the United States.
Residential segregation, the separation of groups into different neighborhoods by race, has long been identified as a major cause of health disparities between blacks and whites. This is the first study to explore whether increases or decreases in residential segregation specifically affect blood pressure.