An ambulance in the U.S. is diverted to a different hospital every minute, on average, because of emergency department overcrowding or bed shortages, according to a study released on Monday by the National Center for Health Statistics, the Boston Herald reports. For the study, researchers classified hospital diversions as ED closures to incoming ambulances that direct traffic to other hospitals (Witlin, Boston Herald, 2/7). Researchers in 2003 collected data from 405 U.S. hospital EDs, or about 10% of all U.S. EDs. They based their findings on the amount of time hospitals reported being on diversion and the number of ambulance arrivals during those periods, the AP/Washington Post reports. The study did not measure how many times ambulance drivers said they were diverted. The study finds that about 500,000 ambulances were diverted from their original destinations because hospital EDs were too crowded or had a shortage of critical-care beds. In addition, researchers found that air and ground ambulances brought in about 14% of all ED patients, with about 16.2 million patients arriving by ambulance to all EDs. Of those patients, 70% had urgent conditions that required care within an hour. More than 60% of patients brought to EDs by ambulances were 45 or older, and about 40% were 65 or older, according to researchers.

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The study did not measure how ambulance diversions affected patients' survival, but Benjamin Sun, author of a separate study that found ambulance diversions at Los Angeles County, Calif., hospitals more than tripled between 1998 and 2004, said it likely had a negative impact. In addition, ambulance diversions can produce a chain reaction, particularly in larger cities, according to a companion study that found ambulance diversions in Los Angeles more than tripled between 1998 and 2004. Sun said, "This suggests that when a hospital decides to go on diversion, nearby hospitals subsequently go on diversion as they become overwhelmed by the increase in incoming ambulance transports." Catharine Burt, the study's lead author and a researcher with NCHS, said, "Most of the people that arrive by ambulance are older, and they have more serious medical conditions, so the fact that they're being delayed, ... whether it's two minutes or five minutes or 15, ... I can only assume that's going to have some impact" (Stobbe, AP/Washington Post, 2/7).

The study is available online.