The use of advanced radiology – CT or MRI imaging – during emergency department visits for injury tripled during a recent decade, according to a report in the Oct. 6 issue of JAMA.
During the same period, there was no increase in the diagnosis of life-threatening conditions or in rates of hospital admission after ED visits, suggesting that the leap in CT and MRI imaging was excessive, yielding no significant benefits to patients, said Dr. Frederick Kofi Korley of the department of emergency medicine, Johns Hopkins University, Baltimore, and his associates.
The investigators used data from the Center for Disease Control and Prevention’s National Hospital Ambulatory Medical Care Survey to perform what they described as the first study to evaluate national trends in the use of advanced radiology during ED visits for injury-related conditions. The survey details the year-by-year use of ambulatory medical services in a nationally representative sample of approximately 370 general and short-stay hospitals in all 50 states.
Between 1998 and 2007, there were more than 324,000 such visits sampled, including 65,376 (approximately 20%) in which patients had sustained injuries. “This represents an estimated average of 22.4 million visits made to EDs in the United States each year for injury-related conditions,” Dr. Korley and his colleagues said.
Compared with patients who presented to the ED with an injury-related condition in 1998, those who presented in 2007 were approximately three times more likely to undergo CT or MRI. In 1998, advanced radiology imaging was used in 5%-7% of such visits, while in 2007, it was used in 14%-17%. Most of this difference was from an increase in CT rather than MRI.
Yet the percentage of life-threatening conditions in which such imaging would be expected to yield important diagnostic information increased nonsignificantly, from 1.7% to 2.0%, during the same period. Such life-threatening conditions in which CT outperforms x-ray imaging include skull fracture, fracture of the cervical spine, intracranial hemorrhage, laceration of the liver, and laceration of the spleen, the investigators noted.
Moreover, there was no significant change during the study period in the proportion of injury-related ED visits that led to hospital admission (5.9% in 1998 and 5.5% in 2007), nor in the proportion that led to ICU admission (0.62% and 0.80%, respectively).
Patients presenting to academic hospitals were more likely to undergo advanced radiology imaging than were those presenting to nonacademic hospitals. This difference may be because academic hospitals serve more severely injured patients, have less-experienced clinicians (residents) ordering diagnostic tests, or simply have more accessible CT and MRI facilities, Dr. Korley and his associates said (JAMA 2010;304:1465-71).
In patients who underwent CT or MRI imaging, the mean length of ED stay was 126 minutes longer than that for patients who didn’t undergo advanced radiology imaging. This may reflect time spent waiting for imaging to be performed and evaluated by a radiologist, or the fact that patients referred for advanced imaging might be more seriously injured and thus require more intervention than others. Either way, excessive length of ED stay “can contribute to emergency department crowding and can increase the risk of medical error,” the researchers said.
This study was not designed to determine the reason for the large increase in CT and MRI use, but the investigators noted that the increased availability of CT scanners, the routine use of whole-body scanning at some trauma centers, the speed of new-generation CT scanners, patient demand, and concerns about malpractice lawsuits all may have contributed.
No financial conflicts of interest were reported.