Simple and safe exclusion of pulmonary embolism in outpatients using quantitative D-dimer and Wells' simplified decision rule.

A safe and effective management strategy is pivotal in excluding pulmonary embolism (PE). The combination of Wells' simplified dichotomous clinical decision rule and D-dimer test is non-invasive and could be highly efficient, though its safety has not been widely studied. We evaluated safety and efficiency of this combination in excluding PE. Wells clinical decision rule was performed in 941 consecutive patients with suspected PE and, if patients had a score <or=4.0 points, a VIDAS D-dimer test followed. Patients with a normal D-dimer concentration had no further tests, PE was considered excluded, and patients did not receive anticoagulant treatment. Patients, in whom PE was excluded, were followed up for three months. Four hundred fifty patients (51.2%) had a clinical decision score =4.0 points and a normal D-dimer concentration. In 45 of these patients, during the initial diagnostic period additional objective testing, although not indicated, was performed, and PE was established in two patients. During three months of follow up no venous thromboembolic events (VTE) occurred. Therefore, the overall VTE failure rate was two of 450 (0.4% [95%CI 0-1.1]); the overall prevalence of PE was 12.3%. The diagnostic protocol could be completed and allowed a decision to be made in 90% of the study patients. This study has prospectively established the safety of a combination of a dichotomized clinical decision rule and D-dimer test in ruling out PE. The strategy proved highly efficient, since more than 50% of patients could be managed without the need for more invasive and expensive tests.