Racial Segregation Associated With Higher BP Among Black Adults

Reductions in Neighborhood Segregation Associated With Decreases in SBP

May 30, 2017 02:29 pm Chris Crawford

An observational study published online May 15 in JAMA Internal Medicine(jamanetwork.com) found that increases in neighborhood-level racial residential segregation were associated with small increases in systolic blood pressure (SBP).  

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The co-authors, from a handful of universities across the country, examined longitudinal data from a geographically diverse group of 2,280 black adults who were tracked during 25 years of follow-up after participation in the Coronary Artery Risk Development in Young Adults (CARDIA) study from 1985-86.

Among those living in high-segregation neighborhoods in 1985-86, later reductions in exposure to neighborhood segregation were associated with decreases in SBP of more than 1 mm Hg. However, changes in segregation levels were not associated with changes in diastolic blood pressure.

Study Details

The observational study examined the data of black participants of the CARDIA study, which was conducted in four locations (Birmingham, Ala.; Chicago; Minneapolis; and Oakland, Calif.) from 1985 to 1986, with participants examined during 25 years of follow-up. Racial segregation was assessed using a statistic that included neighborhood racial composition and the racial composition of the surrounding area.

Story highlights
  • An observational study published online May 15 in JAMA Internal Medicine found that increases in neighborhood-level racial residential segregation were associated with small increases in systolic blood pressure (SBP).
  • The co-authors examined longitudinal data from a geographically diverse group of 2,280 black adults who were tracked during 25 years of follow-up after participation in the Coronary Artery Risk Development in Young Adults study from 1985-86.
  • Among those living in high-segregation neighborhoods in 1985-86, later reductions in exposure to neighborhood segregation were associated with decreases in SBP of more than 1 mm Hg.

Among the 2,280 participants, about 43 percent were male and 57 percent female. About 82 percent were living in a high-segregation neighborhood; about 12 percent were living in a medium-segregation neighborhood; and about 6 percent were living in a low-segregation neighborhood.

Almost all participants moved at least once during the follow-up and more than half moved three or more times.

SBP increased by a mean of 0.16 mm Hg with each 1-standard deviation increase in segregation score after adjusting for time and interactions of time with age, sex and field center.

Of the 1,861 participants who lived in high-segregation neighborhoods at baseline, reductions in exposure to segregation were associated with reductions in SBP. The mean differences in SBP were -1.33 mm Hg when comparing high-segregation with medium-segregation neighborhoods and -1.19 mm Hg when comparing high-segregation with low-segregation neighborhoods after adjusting for time and interactions of time with baseline age, sex and field center.

Center for Diversity and Health Equity's Perspective

The landmark Framingham Heart Study started in 1948 and continued to collect data on the characteristics associated with cardiovascular disease of its original cohort every two years until 2014, as well as their offspring.

Similar to the Framingham study, the CARDIA study maintained a high participant-retention rate for 30 years (71 percent), said Danielle Jones, M.P.H., manager of the AAFP's Center for Diversity and Health Equity.  

"The significance of the data collected as part of the CARDIA study is that its participants were more racially/ethnically diverse than the largely white population of the Framingham study, which did not enroll a racially/ethnically diverse cohort until 1994," Jones told AAFP News.

Jones also pointed out that because CARDIA participants were recruited from four locations across the country, they were more representative, making the results applicable to the general population. Lastly, she said the CARDIA study focused specifically on younger adults, ages 18-30 -- a population for which little information was previously available.

Most importantly, Jones said this study reinforces the importance of why ZIP codes matter.

She mentioned a recent CDC Morbidity and Mortality Weekly Report (MMWR) that found younger African-Americans are more likely to live with or die from conditions such as heart disease and stroke, which typically occur at older ages in whites, because of undetected risk factors.

"Family physicians should be aware that patients living in highly segregated communities may potentially be at an elevated risk for these conditions," Jones said.

As indicated in the JAMA Internal Medicine study, residential segregation, whether by systematic discrimination or differential preferences, limits access to a range of health-promoting resources and opportunities, Jones said.

"These environments may also activate the biochemical stress response, which in turn causes an increase in the systolic blood pressure or hypertension," she added.

Family Physicians Can Help

The study authors concluded by emphasizing the need to develop strategies at the policy level that improve access to resources in these areas and provide opportunities for individuals to move into communities that are more resource rich.

"Findings from our observational study suggest that social policies that minimize segregation, such as the opening of housing markets, may have meaningful health benefits, including the reduction of blood pressure," the authors said.

"FPs can be engaged with decision-makers by applying a 'Health in all Policies'(www.phi.org) approach to the development of strategies that reduce these inequities," Jones said.

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