The study published in the April issue of the journal Health Services Research found that mortality risk dropped 10 percent among patients with head injury transferred from rural trauma centers in Oregon and Washington to level I trauma centers in both states.
Researchers from the Center for Policy and Research in Emergency Medicine and the Department of Surgery, OHSU School of Medicine, and the Department of Sociology at Portland State University examined data on 542 patients sent from 31 rural trauma centers – categorized as levels III, IV or V – to 15 level I and II trauma centers between 1991 and 1994. The study population included patients with everything from simple concussions to fatal traumatic brain injury, and mortality was based on death during hospitalization or within 30 days after discharge.
The team "found a small but significant improvement in mortality for head-injured patients transferred to level I centers when compared to those transferred to level II centers," said the study's lead author, K. John McConnell, Ph.D., OHSU assistant professor of emergency medicine and an economist in the Center for Policy and Research in Emergency Medicine.
OHSU and Legacy Emanuel Hospital & Health Center, both in Portland, are Oregon's only level I trauma centers. In Washington, Harborview Medical Center, located in Seattle, is the state's sole level I facility. There are six level II trauma centers serving Oregon, including one in Boise, Idaho, and two in southwest Wash., and seven serving Washington, including a hospital in Lewiston, Idaho.
Level I trauma centers provide comprehensive trauma care and are required to have trauma surgeons, anesthesiologists, nurses and all surgical subspecialties, including cardiac surgery, orthopaedics, neurosurgery, cardiology, ophthalmology, plastic surgery, gynecologic surgery, and head and neck surgery, immediately available. They also must have immediate availability of resuscitation, neuroradiology and hemodialysis technology, and they're required to annually treat 1,200 injured persons or 240 major trauma patients.
Level II trauma centers also are expected to provide comprehensive trauma care, but they have less-stringent volume performance standards and level of resources immediately available than level I centers, and they are not required to have teaching and research programs.
Despite an emphasis on regional and statewide trauma systems over the last decade nationally – Oregon has had a trauma system since 1985; Washington's began five years later – several level I trauma systems have recently closed, and 19 are threatened with closure, or may be downgraded to a level II center.
Researchers attribute many closures to the high cost of operating level I centers and, in many cases, to a high volume of uninsured patients.
"The resources should be the same between level I and II hospitals, but in reality, the training programs in Level I centers allow better 24/7 monitoring and intervention in regards to critically ill and injured patients," said study co-author Jerris Hedges, M.D., professor and chairman of emergency medicine, OHSU School of Medicine, and chief of emergency services at OHSU Hospital.
Some blame the downgrading or closing of level I centers on an assumption that level II centers offer the same level of care. "Previous studies have not shown any quantifiable differences in outcomes" between the two, McConnell said.
One problem with comparing level I and II centers is that the most severely injured patients are sent to level I centers, he said. This means patients are not transferred on a random basis, which may bias the standard analyses for such studies. Hence, earlier studies have reported patient outcomes for both types of centers as being fairly even.
OHSU researchers used detailed data and innovative statistical techniques, borrowing from the field of economics, to adjust for these differences. As a result, the researchers were able to "make the observational data look like a pseudo-randomized controlled trial," McConnell said.
"It's a novel finding," he said. "Nationally, level I centers are in danger of closing, despite having a positive effect on head-injured patients. That is, for me, one of the take-home messages."
Study co-author Craig Newgard, M.D., assistant professor of emergency medicine, OHSU School of Medicine, agreed. "Our results suggest that some of the operational and philosophical differences in the acute management of head-injured persons between level I and II centers may actually translate into improved survival among patients initially presenting to rural hospitals and transferred to level I centers versus those transferred to level II centers."
The results of the study do not suggest that all patients should be transferred to level I centers instead of level II centers, or that level II centers need to be upgraded to level I centers, McConnell emphasized.
"Instead, the policy implications are primarily that further consideration be given with respect to the closing of level I centers, and additional efforts made to delineate the specific interventions used at the Level I centers that make such a difference," he said.
The research was supported by a grant from the Centers for Disease Control and Prevention's National Center for Injury Prevention and Control.
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