Published online by Cambridge University Press: 04 March 2015
Venous thromboembolism (VTE) is difficult to diagnose yet potentially life threatening. A low-risk pretest probability (PTP) assessment combined with a negative Ddimer can rule out VTE in two-thirds of outpatients, reducing the need for imaging. Real-life implementation of this strategy is associated with several challenges.
We evaluated the impact of introducing a standardized diagnostic algorithm including a mandatory PTP assessment and D-dimer on radiologic test use for VTE in our emergency department (ED). A retrospective review of all ED visits for suspected VTE in the year prior to and following the introduction of this algorithm was conducted. VTE diagnosis was based on imaging. Guideline compliance was also assessed.
ED visits were investigated for suspected VTE in the pre- and postintervention periods (n 5 1,785). Most D-dimers (95%) ordered were associated with a PTP assessment, and 50% of visits assigned a low PTP had a negative D-dimer. The proportion of imaging tests ordered for VTE in all ED visits was unchanged postintervention (1.9% v. 2.0%). The proportion of patients with suspected VTE in whom VTE was confirmed on imaging decreased postintervention (10.2% v. 14.1%).
In spite of excellent compliance with our algorithm, we were unable to reduce imaging for VTE. Thismay be due to a lower threshold for suspecting VTE and an increase in investigation for VTE combined with a high false positive rate of our D-dimer assay in low–pretest probability patients. This study highlights two common real-life challenges with adopting this strategy for VTE investigation.