AJM: Physician use of CT varies greatly, even in the same ED

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Head CT use is highly variable between emergency physicians, even those within the same department. Strategies to reduce such variation, including evidence-based knowledge delivery systems at the time of ordering, may reduce cost and improve quality of care, according to a study published in the April issue of The American Journal of Medicine.

A recent study demonstrated that a head CT was performed in one out of every 14 emergency department visits, with utilization varying significantly among institutions with different characteristics. The authors of the current study, including Luciano M. Prevedello, MD, of the Center for Evidence-Based Imaging and department of radiology at Brigham and Women’s Hospital, Boston, wanted to determine the variability in head CT use between physicians within a single emergency department.

The authors performed a cross-sectional study of all emergency department visits at Brigham and Women's Hospital in 2009, looking specifically for whether a head CT was performed and testing the degree of interphysician variability for the exam.

Of the more than 55,000 emergency department patient encounters, 8.9 percent generated a head CT exam. Unadjusted ordering rates per physician ranged from 4.4 percent to 16.9 percent, and a two-fold variation remained even after controlling for pertinent variables. In patients diagnosed with traumatic headaches, head CT ordering rates varied from 21.2 percent to 60.1 percent after controlling for variables.

Patients receiving head CT were more likely to be male, older and in a more urgent emergency category. Patients with head trauma were more likely to obtain a CT, followed by patients with stroke, headache and other types of trauma. Contrary to earlier studies, the researchers found no significant correlation between physician age or gender and CT ordering.

"The variability may have been due to physician's practice style, knowledge gaps, risk tolerance, or other factors," Prevedello said in a statement. Other possible factors listed by the authors included patient insurance status and trainee participation in the ordering process, though neither was included as a variable in this study.

The authors wrote that the presence of such significant interphysician variability indicates that a department-level use measure is not an appropriate measure of quality. Efforts should be focused on measuring the appropriateness of imaging and examining the effect of computerized physician order entry with decision support.

"We are currently investigating the impact of real-time evidence-based clinical decision support (embedded in the electronic health record) on variation in test ordering behavior of physicians to improve quality of care and improve appropriateness of testing," said Prevedello.