Implementation, Clinical Benefit and Safety of a D-Dimer-Focused Pulmonary Embolism Testing Pathway in the Emergency Department

Study objective: Computed tomography pulmonary angiogram (CTPA) is overused during pulmonary embolism (PE) testing in the emergency department (ED), whereas prediction rules and D-dimer are underused. We report the adherence, clinical benefit, and safety of a D-dimer-only strategy to guide need for PE imaging in the ED. Methods: This was a prospective multicenter implementation study in 2 EDs with historical and external controls. Patients with suspected PE underwent D-dimer testing and imaging (CTPA or ventilation-perfusion scan) when D-dimer levels were 500 ng/mL or more. PE was ruled out if D-dimer was less than 500 ng/mL or with negative imaging. The primary implementation outcome was the proportion of patients tested for PE in adherence with the pathway. The primary clinical benefit outcome was the proportion of patients tested for PE who received pulmonary imaging. The primary safety outcome was diagnosis of PE in the 30 days following negative PE testing postimplementation. Results: Between January 2018 and June 2021, 16,155 patients were tested for PE, including 33.4% postimplementation, 30.7% preimplementation, and 35.9% in an external control site. Adherence with the D-dimer-only pathway was 97.6% (adjusted odds ratio (aOR) post- versus preimplementation 5.26 (95% confidence interval 1.70 to 16.26). There was no effect on the proportion undergoing PE imaging. Imaging yield increased aOR 4.89 (1.17 to 20.53). Two cases of PE (0.04%; 0.01% to 0.16%) were diagnosed within 30 days. Conclusion: In this Canadian ED study, the uptake of a D-dimer-only PE testing strategy was high. Implementation was associated with higher imaging yield and a D-dimer level of less than 500 ng/mL safely excluded PE.