Use of CT and MRI Scans Almost Triple in Emergency Departments

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Researchers form John Hopkins University have found the use of computed tomography (CT) and magnetic resonance imagine (MRI) scans in emergency departments has almost tripled over the past ten years.

Frederick Kofi Korley, MD, of Johns Hopkins University, and colleagues have reported their findings in the Oct. 6 issue of the Journal of the American Medical Association.

The widespread availability of advanced radiology CT and MRI scans have become widely available and are often considered the standard for evaluation of injuries in patients presenting to emergency departments.

Korley and colleagues sought to evaluate the use of CT and MRI scans during emergency department visits for injury-related conditions as approximately 70% of injury-related visits are by persons who are younger than 45 years. These younger patients are at the greatest risk for potential long-term oncological effects of ionizing radiation exposure.

The researchers analyzed data from the CDC's National Hospital Ambulatory Medical Care Survey, which collects information on outpatient (including emergency department) visits at a nationwide sample of 370 nonfederal hospitals. The data covered visits for injury related conditions in 1998 (5,237) and in 2007 (6,567).

Use of CT or MRI increased markedly over the same period, after adjusting for potential confounding variables including age, insurance status, pain severity, and the immediacy of when patients should be seen.

Analysis of the data revealed the prevalence of CT or MRI use during emergency department visits for injury-related conditions increased from 6% (257 of 5237 visits) in 1998 to 15% (981 of 6567 visits) in 2007.

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This increase use of scans greatly outpaced the increase in life-threatening conditions which only increased from 1.7% in 1998 (59 of 5237 visits) to 2.0% in 2007 (142 of 6567 visits).

The researchers found no change in prevalence of visits which resulted in the patient being admitted to the hospital (5.9% in 1998 and 5.5% in 2007) or to an intensive care unit (0.62% in 1998 and 0.80% in 2007).

Interestingly, the visits during which a CT or MRI scan was obtained lasted 126 minutes longer than those for which CT or MRI was not obtained.

Korley and colleagues comment, "Further work is needed to understand the patient, hospital, and physician factors responsible for this increase and to optimize the risk-benefit balance of advanced radiology use."

The researchers did identified certain factors associated significantly with greater likelihood of CT or MRI use. These include severe pain (1.4 increase), teaching hospital (1.52 increase), and patient age at least 60 (2.57 increase).

The increased radiation exposure relative to conventional x-rays as well as reactions and other adverse effects related to contrast agents need to be considered.

CT and MRI are better than conventional x-rays for diagnosing certain injuries, such as cervical spine fractures.

Limitations to the study, including the absence of detail on injury nature and severity, the lack of data on incidental findings that might have improved patients' overall outcomes, and the database's reliance on retrospective chart review.

Source reference:
Korley F, et al "Use of advanced radiology during visits to US emergency departments for injury-related conditions, 1998-2007" JAMA 2010; 304: 1465-1471.

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