News Release

Socioeconomic factors affect blood pressure

Peer-Reviewed Publication

American Heart Association

DALLAS, July 16 – Being disadvantaged in multiple areas, such as income, education, occupation – even the neighborhood in which you live – is related to an increased risk of developing high blood pressure, researchers report in today's rapid access issue of Circulation: Journal of the American Heart Association.

Previous reports have shown that low income and low educational levels are related to hypertension. This study also examined neighborhood socioeconomic levels, says lead author Ana V. Diez Roux, M.D., Ph.D., assistant professor of medicine and epidemiology at Columbia College of Physicians and Surgeons and the Mailman School of Public Health in New York.

Researchers evaluated 8,555 people with follow-up information (6,800 whites and 1,344 blacks) who participated in the Atherosclerosis Risk in Communities (ARIC) study, which evaluated participants' blood pressure and use of blood pressure medication every three years for nine years. At the beginning of the study, all had high blood pressure as defined by systolic pressure of 140 millimeters of mercury (mm Hg) or less and diastolic pressure of 90 mm Hg or less, or had used blood pressure-lowering medication in the past two weeks.

Researchers studied four socioeconomic indicators: personal income, education level, occupation and neighborhood score. Neighborhood scores were based on socioeconomic characteristics of each person's place of residence obtained from 1990 U.S. census data. This included median household income; median residence value; and percentage of households receiving interest, dividends or net rental income. It also included percentage of adults with high school or college education and percentage of adults with ranks of executive, managerial, professional specialty occupations.

Researchers found that the risk of developing hypertension was 95 percent higher for white people who scored lowest in all four socioeconomic indicators compared to white people with all four indicators in the highest category. The risk was 43 percent higher for blacks who scored lowest in three of the four indicators compared to black people with all four indicators in the highest category. There were not enough black subjects with four indicators in the lowest category to calculate a risk ratio for that group.

Whites in the lower socioeconomic categories had greater increases in systolic pressure (upper number) over time and greater decreases over time in diastolic pressure (lower number) after age 50.

Overall, the five-year increase in systolic blood pressure was 7mm Hg in white subjects who scored lowest in all four socioeconomic areas, compared to 5 mm Hg in whites who had no indicators in the lowest categories. "Although this difference might appear small, accumulated over a lifetime, it may have important health consequence," Diez Roux says.

Diastolic pressure dropped by 0.7 mm Hg in whites 50 years and older who were disadvantaged in all four areas. Those who scored high in three or four indicators experience either no change or even a slight increase in diastolic blood pressure (0.4 mmHg).

"As we age, our arteries stiffen and systolic blood pressure increases while diastolic blood pressure decreases," says co-author Donna Arnett, Ph.D., associate professor of epidemiology at the University of Minnesota in Minneapolis. "This results in a greater pulse pressure. Pulse pressure (the difference between the systolic and diastolic) is becoming recognized as an important determinant of future risk. Diastolic increases until age 55 then decreases. The healthier your arteries, the more they will stay the same."

The study suggests that the increase in pulse pressure with age is greatest among the socioeconomically disadvantaged.

Only income was inversely related to increased systolic blood pressure in black patients. Researchers noted a five-year increase of 6.6 mm Hg in the lowest income category compared to 5.5 mm Hg in the highest. Socioeconomic differences in incidence and progression were generally weaker and less consistent in blacks.

"It is likely that many environmental factors related to socioeconomic circumstances are important in the development and course of hypertension," says Diez Roux. "We need to take these environmental factors into account both in preventing and treating hypertension."

One limitation of this study is that researchers focused on middle-aged people, Diez Roux says. "It's important to look at what factors are related to changes in blood pressure from childhood onward. We've looked at this in somewhat a late stage already, so looking at how these factors might impact very early changes in blood pressure would be very important from a prevention perspective."

In the United States, blacks typically have higher blood pressure than whites and tend to develop hypertension earlier than whites, says Arnett. "It may be that we did not see socioeconomic differences in blacks because by 45 to 64 years of age many blacks have already developed hypertension and were excluded from our study."

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Co-authors of the study include: Lloyd Chambless, Ph.D.; Sharon Stein Merkin, M.H.S.; Marsha Eigenbrodt, M.D., M.P.H.; F. Javier Nieto, M.D., Ph.D.; Moyses Szklo, M.D., Dr. P.H.; and Paul Sorlie, Ph.D. The National Heart, Lung and Blood Institute funded part of the study.

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