Summary

Background. D-dimer assays have a potential to rule out pulmonaryembolism in case of a normal test result. We studied the clinical utilityof incorporating the SimpliRED D-dimer test result and clinical probabilityin the routine diagnostic work-up of patients with suspectedacute pulmonary embolism. Methods. In a prospective managementstudy 245 consecutive patients, hospitalised as well as outpatients,were included. A SimpliRED D-dimer test and perfusion/(ventilation)scintigraphy were obtained in all patients, whereas clinical probabilitywas determined in the subgroup of patients with a non-diagnostic scanand normal D-dimer result. A diagnostic algorithm determined thenecessity for further testing and decisions about treatment. All patientswere followed up for 3 months. Results. In 54 patients (22%) with anormal lung scan and 50 patients (21%) with a high probability lungscan, antithrombotic therapy was withheld or started respectively, irrespectiveof the D-dimer result. A non-diagnostic lung scan was found in137 (56%) patients, of whom 70 patients had an abnormal D-dimer test,in whom further testing was ordered. Of the remaining 67 patients witha non-diagnostic lung scan and normal D-dimer test 8 patients hada high clinical probability, and the subsequent ultrasonography andpulmonary angiography yielded pulmonary emboli in 1 patient. In theremaining 66 patients, pulmonary embolism was considered to beabsent and antithrombotic treatment was stopped/withheld. Duringfollow-up of these patients only one patient experienced a possiblevenous thromboembolic event (failure rate 1,5% ; 95% CI 0-8%). TheSimpliRED D-dimer was normal in 6 of 61 patients with proven pulmonaryembolism (sensitivity 90% ; 95% CI 80-96%). Conclusion. Ourfindings suggest that it is safe to withhold anticoagulant therapy inthose patients with a non-diagnostic lung scan, a normal SimpliREDD-dimer test result, and without a high clinical probability. This resultsin a substantial decreased need for ultrasonography and pulmonaryangiography. The SimpliRED should not be used in isolation to excludepulmonary embolism.