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Decision Support Tool Aids CTPA Appropriateness

RSNA-2010-Radiological Society of North America annual meetingCHICAGO—There is an old adage that you can lead a horse to water but that you can’t make it drink. A team of researchers from St. James Hospital in Dublin, Ireland gained first-hand experience of this maxim when they implemented a system for ordering CT pulmonary angiograms () at their facility. “With the introduction of computerized ordering systems for radiology, an opportunity has developed to introduce interactive decision systems at the time of ordering a scan,” noted Gillian Murphy, M.D., in a presentation at the RSNA on Sunday.

Her team conducted a two-part study on the development of an interactive computerized ordering system for CTPA. Their aim was to identify patients at high risk for pulmonary embolism (PE), improve the positive yield of CTPA’s, and reduce inappropriate radiation exposure. The first part of the study was a retrospective audit of CTPA use at the facility over a one-year period. They found that of the 659 patients who had undergone the procedure, 10.6 percent were diagnosed with PE. “The audit revealed that clinicians did not apply recommended Wells criteria thus, many patients underwent unnecessary CTPA’s and radiation exposure,” she reported.

The second part of the study introduced a clinical decision support system, Advisor (Cerner), which incorporated Well’s criteria for PE as well as D-dimers. (The D-dimer test is used to rule out blood clots. They are fibrin degradation products formed as a result of fibrinolysis or clot degradation by plasmin.) Following the introduction of the Advisor, 835 CTPA studies were ordered, 289/835 (35%) were subsequently canceled, and 546/835 (65%) were completed. Of those completed, 92/546 (17%) were positive, which was a significant increase (p=0.01) and 454/546 (83%) were negative, Murphy noted.

More about CTPA and clinical decision support system.

Although the introduction of the CTPA Advisor with recommended ordering guidelines enjoyed a statistically significant success—the positive rate of PE increased and inappropriate radiation exposure was reduced—Murphy observed a troubling trend. She shared that some physicians at the institution had learned to enter their CTPA order requests in such a way as to receive approval for the exam, regardless of a patient’s D-dimers or appropriateness according to Well’s criteria.


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