ED Diversion Raises Heart Attack Mortality

Heart attack patients have a higher risk of dying within a year if the closest ED is on diversion as opposed to operating normally on the day they get sick, according to a Robert Wood Johnson-funded study that is the first of its kind.

"If you have 100 patients admitted to an emergency department with a heart attack, 29 of them are likely to die under normal operations," when the hospital was not on diversion at all that day, within the following year, says Yu-Chu Shen of the Naval Postgraduate School in Monterey, the report's principal author.

"But if [those] same 100 patients had a heart attack on a day when their closest hospital was on diversion for 12 hours or more, the number of patients who would die would go up to 32%. You're going to have an additional three deaths that are potentially avoidable if those patients had not been subject to longer diversion," Shen says.

Higher rates of 30-day, 90-day and nine-month mortality also occurred in patients whose closest hospital was on diversion, although the difference was not as large as the one-year increased mortality.

The additional deaths occurred not just in the patients who were diverted, but in other heart attack patients who went to that hospital that same day, or the other patients already undergoing treatment at the other hospitals that accepted additional diverted patients.

Presumably, the additional deaths occurred because delays in treatment resulting from busier ED staff or increased transport times equated to greater heart muscle damage, greater oxygen deprivation or other adverse consequences.

The study examined diversion and heart attack mortality in four high-density urban California counties where hospitals admitted 13,860 Medicare patients with acute myocardial infarction between 2000 and 2005. It was published early online Sunday in the June 15 issue of the Journal of the American Medical Association. It was co-authored by Renee Y. Hsia, MD, of the Department of Emergency Medicine at San Francisco General Hospital.

Shen says the report has important policy implications for emergency department managers and hospital executives.

"They should improve patient flow, and improve coordination between inpatient settings and the ED," Shen says. "But more importantly there's a broader message here. It's that when you have ambulance diversion at the ED, it's not an isolated incident, but a reflection of a larger access issue, and that you just can't take any more patients."

Hospitals with heart attack care capabilities in Los Angeles, Santa Clara, San Francisco and San Mateo counties were included in the report, about one-third of the state's population.

When the nearest ED was on diversion on the day the patient was admitted, 30-day mortality was 19%, compared with 15% mortality if the nearest hospital was not on diversion. There also was higher 90-day and nine-month mortality for patients whose nearest hospitals were on diversion 12 hours or more.

Sandra Schneider, MD, president of the American College of Emergency Physicians, says the paper makes several critically important points about the way emergency departments are run today.

"You don't see this problem just with heart attack patients, but you would see it in patients with stroke and pneumonia, where it's important to get the treatment early," says Schneider, attending physician at Strong Memorial Hospital in Rochester, N.Y. When hospitals are crowded, door to balloon time is longer, time to pain medication is longer, and time to administer an antibiotic for a pneumonia patient is longer."

Shen and Hsia noted that their data covered a period of time prior to the launch of emergency medical authority systems that direct patients to hospitals with operative and approved catheterization labs.

That may be one explanation for the difference.

Once admitted, patient treatment patterns differed in 2 dimensions, the report explains. The number of patients receiving catheterization when the nearest hospital was on diversion for 12 hours or more was 42% compared with 49% when the nearest hospital was not on diversion. The number of patients receiving percutaneous coronary intervention was 24% when the hospital was on diversion 12 hours or more, and 31% when the nearest hospital was not on diversion.

"When the closest ED was on diversion, a lower share of patients was admitted to hospitals with a catheterization laboratory (78% for those whose nearest hospital was on diversion 12 hours or greater compared with 87% for those in the no diversion category).

Diversion is a huge U.S. problem for hospital emergency departments. According to the National Center for Health Statistics, more than 500,000 ambulances a year, or one ambulance per minute, is diverted to a different hospital than the one closest to the patient's point of origin.

The researchers pointed out that emergency department diversions 12 hours or more "occurred in 25% of the daily logs. Notably, such long diversion hours are more likely to occur in winter and in densely populated metropolitan areas – both factors associated with increased ED demand."

Additionally, ambulance diversion means patients are likely to endure treatment delays because transport times are longer, and they may end up "in less desirable setting(s)," an ED without catheterization capacity for example, they wrote.

Higher heart attack mortality was seen in patients whose closest hospital was on diversion less than six hours, to less than 12 hours. Demographic and co-morbidity factors were not different except that there was a higher share of black patients in the 12 or more hours exposure category, 11%, versus 6% in the no diversion category.

Additionally, when the nearest ED is on diversion, "a lower proportion of patients is admitted to hospitals with catheterization capacity, and a higher proportion is admitted to for-profit and government hospitals," they wrote.