Neighbourhoods important factor in risk of stroke for all races

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A higher neighbourhood advantage, or socioeconomic status, of where a person lives contributes to a lower risk of having a stroke no matter the person’s race, according to findings published in an online issue of Neurology, the medical journal of the American Academy of Neurology.

The report from the University of Alabama at Birmingham Reasons for Geographic and Racial Differences in Stroke study shows this effect is the same for black and white adults, both men and women.

“More blacks than whites in the United States have strokes and die from strokes,” said Virginia Howard, lead author of the study and professor in the UAB School of Public Health Department of Epidemiology. “More people who live in the Southeastern area known as the stroke belt have stroke and die from stroke compared to those who live in the rest of the United States.”

This study showed that residents in more disadvantaged neighbourhoods had greater stroke risk than those who lived in more advantaged neighbourhoods. The neighbourhood index is composed of six factors, including a higher value of housing units and higher proportion of residents employed in professional occupations. A higher score in all of these categories leads to a higher advantaged neighbourhood.

The observation was true even after adjustment for age, race, sex and region of the country. But after adjustment for other stroke risk factors, there was no association between the level of the neighbourhood advantage and stroke risk, suggesting that those living in more disadvantaged neighbourhoods are more likely to develop risk factors including hypertension, diabetes and smoking. Because of being more likely to develop these risk factors, they are at higher risk of stroke.

“These results are consistent with other evidence showing that factors associated with living in more disadvantaged neighbourhoods contribute to stroke risk. However, it is difficult to separate the influence of neighbourhood characteristics from characteristics of the individuals living in the neighbourhood,” Howard said. “Many social and behavioural risk factors, such as smoking and physical inactivity, are more prevalent in the less advantaged neighbourhoods. Greater attention needs to be paid to risk factor management strategies in disadvantaged neighbourhoods in order to make a difference in preventing stroke on an individual level.”

The current study looked at measures of the neighbourhood advantage where people live to determine whether these factors contributed to future stroke risk. Data came from the REGARDS study, a national random sample of the general population with more people selected from the stroke belt and about half black, half white.

The study involved 24,875 people with an average age of 65 who had not had a stroke at the start of the study. The participants were divided into four neighbourhood groups, ranging from lowest level of advantage to the highest. The participants were followed for an average of seven and a half years. During that time, 929 people had a stroke.

This study has advantages over other studies in that it includes individuals of low, middle, upper-middle and high individual wealth across 1,833 urban and rural counties in the United States, and a large number of both blacks and whites. Other stroke risk factors were measured prior to the stroke.

The study was supported by the National Institute of Neurological Disorders and Stroke and the National Institute on Aging. Other authors included Leslie McClure, and Ana Diez Roux, from the Dornsife School of Public Health, Drexel University, Philadelphia, Pennsylvania; Dawn Kleindorfer,  from University of Cincinnati College of Medicine, Cincinnati, Ohio; Solveig Cunningham, from Emory University, Atlanta, Georgia; Amanda Thrift, from the Monash University and Melbourne University in Australia, and George Howard, from the School of Public Health at UAB.