A retrospective evaluation of the age-adjusted d-dimer versus the conventional d-dimer for pulmonary embolism

摘要

The conventional d-dimer cut-off value of at least 500gFEU/l has good sensitivity but poor specificity for identifying pulmonary embolism. An elevated age-adjusted d-dimer value (age in yearsx10gFEU/l) for patients at least 50 years old has been recommended as a better cut-off with adequate sensitivity and improved specificity for identifying pulmonary embolism compared with the conventional value. We retrospectively reviewed 3117 patient encounters in which a d-dimer was ordered. The d-dimer value, age of the patient, and the computed tomography radiology report was evaluated. The sensitivity and specificity of the age-adjusted d-dimer was calculated using bootstrapping. With an assumed 99% sensitivity for the conventional d-dimer cut-off the specificity was 39.2% [95% confidence interval (CI): 37.5-41.0%]. The sensitivity of the age-adjusted d-dimer was 91.8% (95% CI: 83.8-97.2%) with a specificity of 51.0% (95% CI: 49.1-53.1%). The sensitivity of the age-adjusted d-dimer was unacceptably low compared with the conventional d-dimer cut-off.