Age-dependent D-dimer cut-off to avoid unnecessary CT-exams for ruling-out pulmonary embolism

To evaluate the effect of an age-dependent D-Dimer cut-off in patients who underwent a computed tomography pulmonary angiogram (CTPA) for suspected pulmonary embolism (PE). Retrospective application of an age-dependent D-dimer cut-off (age/100 in patients aged over 50) in 530 consecutive patients, both in- and outpatients, aged over 18, who underwent CTPA for suspected PE according to the guidelines. The application of an age-dependent D-dimer cut-off showed a now negative test-result in 17 of 530 patients (3.2 %). The proportion was 4.1 % (17 of 418) in patients aged over 50. None of these 17 cases was diagnosed with PE in CTPA, the false-negative rate was 0 %. The effect could be seen in outpatients (14 of 377 [3.7 %]) as well as in inpatients(3 of 153 [2.0 %]) with no statistically significant difference (p > 0.05). The application of an age-dependent D-dimer cut-off as part of the guideline-based algorithm for suspected PE reduced the number of necessary CTPA in outpatients as well as in inpatients.