CT Pulmonary Angiography Finds more Pulmonary Embolisms with Adherence to Clinical Decision Support

Emergency department physicians were more likely to detect acute pulmonary embolism (PE) when adhering to evidence-based clinical decision support (CDS) for ordering CT pulmonary angiography, according to a study published in the journal Radiology.

Researchers from Brigham and Women’s Hospital, Harvard Medical School, and Massachusetts General Hospital, all in Boston, sought to determine the frequency of, and yield after, provider overrides of evidence-based CDS for CT pulmonary angiography in the ED.

The researchers obtained data from 2,993 CT pulmonary angiography studies from 2,655 patients who were suspected of having pulmonary embolism (PE) and who underwent CT pulmonary angiography between Jan.1, 2011, and Aug. 31, 2013. Each CT order for pulmonary angiography was exposed to CDS on the basis of the Wells criteria.

A Wells score of 4 or less for a patient results in a suggestion for d-dimer testing. Acute PE is highly unlikely in these patients if d-dimer levels are normal, the authors wrote. The yield of CT pulmonary angiography (number of positive PE diagnoses/total number of CT pulmonary angiographic examinations) was compared in patients in whom providers overrode CDS alerts by performing CT pulmonary angiography in patients with a Wells score 4 or less, and a normal d-dimer level or no d-dimer testing (override group) and those in whom providers followed Wells criteria (CT pulmonary angiography only in patients with Wells score above 4 or 4 below, with elevated d-dimer level) (adherent group).

The results showed that of the total CT pulmonary angiography studies performed, 563 examinations had a Wells score of 4 or less, but the patients did not undergo d-dimer testing. Twenty-six had a Wells score of 4 or less and had normal d-dimer levels. The yield of CT pulmonary angiography was 4.2 percent in the override group (25 of 589 studies, none with a normal d-dimer level) and 11.2 percent in the adherent group (270 of 2,404 studies).

After the researchers made adjustments for the risk factor differences between the two groups, the odds of an acute PE finding were 51.3 percent lower when providers overrode alerts than when they followed CDS guidelines. Comparison of the two groups including only patients unlikely to have PE led to similar results.

The researchers concluded that the odds of an acute PE finding in the ED when providers adhered to evidence presented in CDS were nearly double those seen when providers overrode CDS alerts. Most overrides were due to the lack of d-dimer testing in patients unlikely to have PE.