Effectiveness of a Diagnostic Algorithm Combining Clinical Probability, D-dimer Testing, and Computed Tomography in Patients with Suspected Pulmonary Embolism in an Emergency Department

Objective. The aim of our study was to assess the clinical effectiveness of a simplified algorithm using the Wells clinical decision rule, D-dimer testing, and computed tomography (CT) in patients with suspected pulmonary embolism (PE) in an Emergency Department (ED). Methods. Patients with clinically suspected PE from the Emergency Department were included from May 2007 through December 2008. Clinical probability was assessed using the Wells clinical decision rule and a VIDAS D-dimer assay was used to measure D-dimer concentration. Patients were categorized as “pulmonary embolism unlikely” or “pulmonary embolism likely” using the dichotomized version of the Wells clinical decision rule. Pulmonary embolism was considered excluded in patients with unlikely probability and normal D-d imer test (< 500 ng/ml). All other patients underwent CT, and pulmonary embolism was considered present or excluded based on the results. Anticoagulants were withheld from patients classified as excluded, and all patients were followed up for 3 months. Results. 241 patients were included in the study. The prevalence of PE in the entire population was 23.6%. The combination of unlikely probability using the dichotomized Wells clinical decision rule and a normal D-dimer level occurred in 23.6%, thus making CT unnecessary. During the followup period, no thromboembolic events were recorded and there were no deaths related to venous thromboembolic disease (3-month thromboembolic risk 0% [95% CI, 0%-8%]). Conclusions. In this study we have confirmed the effectiveness of a diagnostic management strategy using a simple clinical decision rule, D-dimer testing, and CT in the evaluation and management of patients with clinically suspected pulmonary embolism.