From 1998 to 2007, the use of CT or MRI scans in emergency departments for injury-related conditions increased about threefold without a similar increase in the prevalence of the diagnosis of certain life-threatening trauma-related conditions, says a study in the Oct. 6 issue of the Journal of the American Medical Association, or JAMA.

Injury-related conditions are among the most common reasons for visits to emergency departments in the U.S. "The widespread availability of advanced radiology and the associated diagnostic superiority in identifying significant injuries have made these tools important in the evaluation of patients presenting to emergency departments," the authors write. Advanced radiology refers to CT, or computed tomography, and MRI, or magnetic resonance imaging.

The study authors say that increased use of these tools is associated with increased health-care expenditures, increased length of stay in the emergency department, and increased exposure to ionizing radiation. Knowing whether use of these tools has increased is important because about 70 percent of injury-related visits are by patients younger than 45, who are at the greatest risk for long-term oncological effects of ionizing radiation exposure, the article says.

Dr. Frederick Kofi Korley, of Johns Hopkins University, in Baltimore, and colleagues examined the national trends in the use of advanced radiology during emergency department visits for injury-related conditions over a 10-year period ending in 2007, using data from the National Hospital Ambulatory Medical Care Survey. Sampled visits were weighted to produce estimates for the U.S.

During that period, about 325,000 emergency department visits were sampled. Of those, about 20 percent, or about 65,000 visits, were injury-related, representing an estimated average of 22.4 million visits made to emergency departments in the U.S. each year for injury-related conditions.

Visits were sampled from an average of 370 hospitals per year.

In 1998, about 6 percent of patients treated in an emergency department for injury-related conditions received CT or MRI, while by 2007 that percentage had grown to 15 percent, the article says. Analysis indicated that such patients were three times more likely in 2007 to receive a CT or MRI than in 1998. Increase in CT use accounted for the majority of the increased CT or MRI use.

"Some factors that may have contributed to this significant increase in CT use are the superiority of CT scans over X-rays for diagnosing conditions such as cervical spine fractures, the routine use of whole-body scanning for patients treated in some trauma centers, the increased availability of CT scanners, the proximity of CT scanners to the patient-care areas of most emergency departments, the speed of new-generation CT scanners leading to a decrease in the need to sedate pediatric patients, and concern about malpractice lawsuits for a missed diagnosis," the authors write.

A life-threatening condition, such as a cervical spine fracture, skull fracture, intracranial bleeding, and liver or spleen laceration, was diagnosed in 59 of 5,237 sampled visits (1.7 percent) in 1998 compared with 142 of 6,567 visits (2.0 percent) in 2007.

There was no significant change in the proportion of injury-related visits that resulted in admission to the hospital (5.9 percent in 1998 and 5.5 percent in 2007) or admission to the intensive care unit (0.62 percent in 1998 and 0.80 percent in 2007).

The researchers also found that patients ages 60 years or older were more likely to receive CT or MRI than those between the ages of 18 and 45; and patients 18 or younger were less likely to receive a CT or MRI than those between the ages of 18 and 45.

The average difference in length of stay for visits for injury-related conditions during which CT or MRI was obtained was 126 minutes longer than for similar visits in which CT or MRI scans weren't performed.

"Further work is needed to understand the patient, hospital, and physician factors responsible for this increase (in CT and MRI use) and to optimize the risk-benefit balance of advanced radiology use. The role of evidence-adoption strategies such as computerized decision support and audit and feedback in promoting adherence to decision rules for imaging needs to be further understood," the authors conclude.