Computed Tomography Angiography May Be Avoidable
Patients with no risk factors unlikely to have CT angiogram positive for pulmonary embolism
WEDNESDAY, June 16 (HealthDay News) -- The risk of a computed tomography (CT) angiogram being positive for pulmonary embolism (PE) is unlikely among patients who do not present with thromboembolic risk factors, suggesting that CT angiography is unnecessary in many patients, according to research published online June 15 in Radiology.
In a retrospective analysis, Mark D. Mamlouk, M.D., of the University of California in Irvine, and colleagues evaluated the electronic medical records of 2,003 patients who underwent CT angiography for possible PE between July 2004 and February 2006 to assess thromboembolic risk factors including immobilization, malignancy, hypercoagulable state, excess estrogen state, a history of venous thromboembolism, age, and gender.
The researchers found that the angiograms were positive for PE in 9.84 percent of patients, of whom 97.46 percent had one or more thromboembolic risk factors. Of the 1,806 patients with CT angiograms that were negative for PE, 28.79 percent did not have any risk factors. The researchers also found that the sensitivity of risk factor assessment in all patients was 97.46 percent and the negative predictive value was 99.05 percent. Multivariate logistic regression analysis revealed all thromboembolic risk factors to be significant, except for gender.
"In conclusion, our study findings show that, in the setting of no thromboembolic risk factors, it is extraordinarily unlikely (0.95 percent chance) to have a CT angiogram positive for PE. Moreover, with the combination of a negative D-dimer test result, this risk is even lower. This factor suggests that, unless there is an unusual mitigating circumstance, CT angiography in these settings is likely unnecessary. This selectivity and triage step should reduce current costs and radiation exposure to patients," the authors conclude.