People who suffer heart attacks or cardiac arrests in the vicinity of an ongoing major marathon are more likely to die within a month due to delays in transportation to nearby hospitals, according to newly published research from Harvard Medical School.

The delays, the researchers say, likely stem from widespread street closures during major races that can hamper transportation in an emergency.

Writing in the April 13 issue of the New England Journal of Medicine, the study authors call for citywide strategies that ensure unhampered access for medical crews in a certain radius of major races and other large public gatherings, such as sporting events or parades.

Previous studies have examined death rates among marathon runners to assess the risk of endurance training, but this is believed to be the first study to analyze the impact of such races on those living nearby due to causes that have nothing to do with the physical exertion of running a marathon.

“We have traditionally focused medical preparedness and emergency care availability to address the needs of race runners, but our study suggests that effects of a marathon may spread well beyond the course of the event and affect those who live or happen to be nearby,” said the study’s senior author, Anupam Jena, the Ruth L. Newhouse Associate Professor of Health Care Policy at Harvard Medical School.

The investigators examined 10 years’ worth of patient records analyzing death rates among older Americans, 65 years of age and over, within 30 days of having a heart attack or a cardiac arrest near a major marathon across 11 U.S. cities. Researchers compared death rates among patients hospitalized on the day of the race with those hospitalized five weeks prior or five weeks after the race. Additionally, the researchers divided patients by zip code, comparing death rates among those living near the marathon and those living in zip codes well outside of the event’s radius and unaffected by street closures.

Patients admitted to a hospital on race day were nearly 15 percent more likely to die within a month of suffering a heart attack or cardiac arrest compared with those admitted on a nonmarathon day or in a hospital outside of the marathon’s zip code(s).

That spike translated into a nearly 4 percent difference in the number of deaths. In other words, the researchers say, for every 100 patients with heart attack or cardiac arrest, three to four more people died within a month in the group admitted to a hospital on race day if they happened to go to a hospital near the race course.

The research also showed that ambulance transport was delayed by an average of 4.4 minutes on marathon days, 32 percent longer travel time compared with transports not delayed by marathons. Additionally, nearly a quarter of patients in the study got themselves to the hospital without an ambulance. While there is no record of the amount of time private transportation took, the authors suspected that many such trips would have been slow on marathon days. While the study findings do not establish cause and effect between street closures and greater mortality, the researchers point out that many studies have shown that even very small delays in getting care could make the difference between life and death.

“When it comes to treating people in the throes of a heart attack, minutes do matter. Heart muscle dies quickly during a heart attack, so current guidelines call for rapid intervention, preferably within an hour or so of diagnosing a heart attack, to salvage cardiac muscle function,” said Jena, who is also a physician at Massachusetts General Hospital.

The findings suggest that between three and four preventable deaths likely occur each year among older residents who suffer heart attacks and cardiac arrests during marathons across the eleven cities studied.