Advanced ambulance care increases mortality

Patients suffering from trauma, heart attack or stroke have a better chance at survival if they are transported by a basic life support ambulance than by an advanced life support ambulance, according to a new study involving data from nearly 400,000 patients in non-rural counties nationwide.

The study, published in the Oct. 13, 2015 issue of Annals of Internal Medicine, found that:

• For patients suffering from trauma, survival was 6.1 percentage points higher for those transported by a basic life support (BLS) ambulance than those who were transported by an advanced life support (ALS) ambulance. Patients with critical major trauma had a 12.5 percentage point greater chance of surviving for 90 days if transported by BLS.
• Patients with acute myocardial infarction (heart attack) were 5.9 percentage points more likely to survive for 90 days after their ambulance transport if they were transported in a BLS rather than ALS ambulance.
• Patients with stroke had a 4.3 percentage point greater chance of surviving for 90 days, when transported by a BLS ambulance.
• There was no survival difference between BLS and ALS ambulances for patients with respiratory failure.
• Greater use of BLS may also save money.

"We studied conditions that were representative of the major causes of death where we thought we were most likely to see a benefit from the kinds of services that ALS provides," said lead author Prachi Sanghavi, PhD, an assistant professor of public health sciences in the Biological Sciences Division at the University of Chicago and a research fellow in health care policy at Harvard Medical School.

"But we found that basic life support patients were more likely to survive. They were also more likely to have better outcomes on measures such as neurological functioning."

Prior, smaller studies from outside the United States have found similar results. A study published last year by the same team showed better survival rates following BLS transport for patients with cardiac arrest.

Advanced life support ambulances are responsible for 65 percent of emergency care for Medicare patients in the United States and are dispatched preferentially for patients with life-threatening conditions.

This study analyzed outcomes for nearly 400,000 emergency patients from a 20-percent random sample of traditional Medicare beneficiaries from non-rural counties between 2006 and 2011.

The research was conducted at Harvard Medical School with co-authors Anupam Jena, HMS associate professor of health care policy, Joseph Newhouse, John D. MacArthur Professor of health policy and management at Harvard University and Alan Zaslavsky, HMS professor of health care policy (statistics).

The authors studied survival differences between patients who received ALS in counties that use more ALS and patients who received BLS in counties that use less ALS. In order to overcome any potential selection biases that might have been inherent in either model, the researchers used two distinct statistical approaches to measuring the differences between ALS and BLS outcomes. Both approaches generally found that BLS patients for the studied conditions had better survival rates than ALS patients.

Their results also suggest that greater use of BLS could save money. Using 2011 reimbursement levels of ALS and BLS, they estimate that Medicare would have spent $322 million less on ambulance services in 2011 if all ground emergency rides had been BLS.

"This study demonstrates that in medicine costlier isn't always better; simply transporting the patient to the hospital as soon as possible appears to have a high payoff," Newhouse said.

The researchers suspect that ALS transport may delay hospital care. The ALS approach-known as "stay and play"-takes longer to deliver patients to the hospital than BLS's "scoop and run" methodology. A previous Canadian study of cardiac arrest found that ALS crews took an average of 27 minutes from arrival at the patient's side to arrival at the hospital. BLS crews took only 13 minutes.

ALS ambulances, staffed by paramedics, are equipped to perform more invasive procedures than BLS ambulances, which are staffed by emergency medical technicians. Faced with a patient in respiratory distress, for example, an ALS crew might intubate the patient; a BLS crew in the same situation would use a bag-mask respirator.