Association Between Ambulance Diversion and Survival Among Patients with Acute Myocardial Infarction

For a patient suffering from an acute myocardial infarction (AMI), the best choice for care is the nearest hospital emergency department (ED). That care, however, is not available when ambulances are diverted from an ED—either because of shortages of staff or inpatient beds, or major equipment failures. Patients then have to travel further to an ED and possibly wait longer for care.

To find the effect of ambulance diversion on patient outcomes, researchers looked at Medicare data for four California counties that account for 63 percent of the state’s population. They obtained daily diversion logs from local agencies and excluded diversions that would not affect the admission of AMI patients.

The researchers categorized 13,860 patients from 502 zip codes into groups based on length of ED diversion on the day of their AMI:

  • No diversion (41% of patients)
  • Less than six hours (25%)
  • Six to 12 hours (19%)
  • Twelve or more hours (15%)

Patients in the first three groups had comparable mortality rates regardless of time horizon. Patients in the fourth category had higher one-year mortality rates and a greater likelihood of being African-American.

Ambulance diversion is an indicator of a larger health care access problem.