For most ambulance calls, basic life support trumped ALS in study

By Will Boggs MD

NEW YORK (Reuters Health) - For most out-of-hospital medical emergencies, mortality among Medicare beneficiaries is higher with advanced life support (ALS) than with basic life support (BLS), according to an observational study.

"Based on our findings, pre-hospital care policy should prioritize the principles of basic life support, or the use of basic interventions coupled with rapid transport to a hospital," Dr. Prachi Sanghavi from the University of Chicago, in Illinois, told Reuters Health by email.

In the U.S., the primary out-of-hospital response by ambulance providers is ALS rather than BLS. ALS providers spend more time at the scene (and receive higher reimbursement), but whether this translates into better outcomes for the patient is controversial.

Dr. Sanghavi's team used Medicare data for 79,687 patients with major trauma, 119,989 with stroke, 114,469 with acute myocardial infarction (AMI), and 82,530 with respiratory failure to compare survival and neurologic outcomes after receiving ALS versus BLS.

They took two methodological approaches: (1) propensity score analysis balanced observed characteristics and (2) instrumental variable analysis adjusted for the likelihood that a patient would receive ALS (based on the county where the intervention took place).

In propensity score analysis, survival at 90 days was significantly higher after BLS than after ALS for patients with major trauma (82.3% versus 76.2%, respectively), stroke (77.2% versus 70.3%), and respiratory failure (56.5% versus 52.8%). After AMI, 90-day survival was one percentage point higher with ALS (70.5%) than with BLS (69.5%).

Results were similar in instrumental variable analysis, except that survival after AMI was 4.8 to 8.4 percentage points higher with BLS than with ALS at all intervals, according to the October 12 Annals of Internal Medicine online report.

Poor neurological performance was significantly less common after BLS than after ALS for all four conditions in propensity score analysis and nonsignificantly less common after BLS than after ALS for conditions except stroke in instrumental variable analysis.

"Our results are only generalizable to the Medicare population, but we do not have strong reason to believe the results would be substantially different for a younger population, given the mechanisms that are likely at play," Dr. Sanghavi explained. "We were not able to study specific mechanisms, but other work suggests a combination of delays in reaching the hospital, the out-of-hospital use of interventions like fluid resuscitation, and serious issues with the quality of delivery of interventions like endotracheal intubation may be why ALS does poorly. These mechanisms are tied to the ambulance system and are not going to be different in a younger population. Having said this, we are beginning to study the under-65 population."

Dr. Sanghavi concluded, "Decisions in our pre-hospital care system seem to be based on political and financial interests much more than on scientific evidence. I hope physicians will help make practice in emergency medical systems (EMS) consistent with scientific evidence through the various roles they play in directing/advising ambulance organizations, receiving patients in the emergency department, and shaping clinical guidelines. Our results indicate it is crucial that we fix this system to save lives."

Dr. Comilla Sasson from University of Colorado, Aurora, coauthored an editorial related to this report. She told Reuters Health by email, "The study raises some important questions about matching the level of transport to the specific type of emergency. However, we should be very cautious to change practice based on an analysis of administrative data that does not include any EMS, clinical, or financial data. There is definitely a need for a larger randomized clinical trial, which can definitively answer whether higher levels of care are needed for certain conditions."

"There is an opportunity cost for using ALS transport, when only BLS level care is needed," Dr. Sasson continued. "When an ambulance responds to an emergency, it cannot be deployed to another patient who is more ill and unstable or whose conditions deteriorate rapidly. Further research can and must be done to better understand how we can match the right level of highly valuable and scarce resources, such as ALS care, to the patients who need it the most."

"Chest pain patients were the only group in which there was a potential survival benefit associated with ALS transport," Dr. Sasson added. "It may be that ALS providers can diagnose a heart attack and/or even send patients to the catheterization lab to get life-saving treatments much more rapidly than BLS providers. This underlies the importance of continuing to educate the public about recognizing the symptoms of a potential heart attack and calling 9-1-1 quickly."

Dr. Dustin G. Mark from Kaiser Permanente, East Bay, Oakland, California, recently reported on outcomes after out-of-hospital cardiac arrest treated by BLS versus ALS. He told Reuters Health by email, "Certainly this study strengthens the existing argument for rapid and unfettered BLS pre-hospital care for trauma patients, which has been likewise supported by several previous studies as cited by the authors. I am not so certain about the other categories under study (AMI, stroke, and respiratory failure) given that they were unable to adequately control for severity of illness in reaching their conclusions, as opposed to their analysis of trauma cases, an acknowledged major limitation of their methodology."

He concluded, "The authors did a tremendous job with the data available to them and deserve to be commended, but further analyses using more granular patient level data are necessary to drive practice changes surrounding pre-hospital medical emergencies in general."

The National Science Foundation and the National Institutes of Health partially supported this research.

SOURCE: https://bit.ly/1Lrd5ef

Ann Intern Med 2015.