"Where you drop literally can determine your likelihood of having someone stop and do CPR, and it changes from one side of the street to the other," coauthor Dr. Comilla Sasson of the University of Colorado School of Medicine told Reuters Health.

Although the racial makeup of a neighborhood was a factor, "it's probably socioeconomic status that matters more than racial composition," she said.

About 300,000 people collapse from cardiac arrest each year, and other research has suggested that ethnic or socioeconomic conditions influence the chance that a bystander will start CPR.

"We've seen for many years that certain communities have a higher likelihood of a patient getting CPR," Dr. Bryan McNally of Emory University in Atlanta, another coauthor, told Reuters Health. "This is pointing out that within communities there is variation in the local or neighborhood area."

The findings, reported in the New England Journal of Medicine, are based on 14,225 cases of cardiac arrest from 29 non-rural parts of the U.S.

Using Census data, the researchers separated the sites of each collapse into two categories: high income, where the median household income was $40,000 or more, and low income. A neighborhood was given an ethnic classification if that group made up more than 80% of the population.

The overall chance of a cardiac arrest victim getting CPR from a bystander was about 29 percent.

Based on the results, if a bystander is available to help and "a person who falls down in a primarily-white higher-income neighborhood, their chance of getting CPR is 55 percent," said Sasson.

In a high-income integrated neighborhood, the chance was 49 percent, and it was 45 percent in a high-income black neighborhood.

"If that person crosses the street and goes into an African-American poor neighborhood, the percentage goes down to 35 percent," Sasson said.

She said information from focus groups suggests that one reason the rate may be lower in poorer neighborhoods is the cost of CPR training, which can be up to $250 for a class. "If you're making $20,000 a year, that's 15 percent of your monthly income. A lot of folks would love to learn it, but they can't."

FEW SURVIVE

"Once the barriers to CPR training and performance are better understood, it may be possible to design more linguistically appropriate and culturally sensitive CPR training programs that can be implemented in neighborhoods with low rates of bystander-initiated CPR," the team said.

The study "may help guide decision making about where to put our resources," McNally said in a telephone interview.

The study did not examine if a neighborhood's characteristics affected a person's chance of surviving cardiac arrest.

In this study, only 8 percent of the patients survived to be discharged from the hospital, and about half of those had some kind of brain damage.

SOURCE: bit.ly/XgOe2O New England Journal of Medicine, October 25, 2012.

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