Retrospective Single‐Centre Evaluation of Alternative D‐Dimer Thresholds in the Evaluation of Suspected Acute Pulmonary Embolism

Abstract

This retrospective evaluation examined the theoretical impact of alternative D‐dimer thresholds (age‐adjusted and 1000 µg/L) in patients aged ≥ 50 years who underwent computed tomography pulmonary angiography (CTPA) after D‐dimer testing. Among 291 patients with positive D‐dimer and subsequent CTPA, the age‐adjusted threshold maintained 100% observed sensitivity (95% CI 89.7%–100%), while the 1000‐µg/L threshold missed three pulmonary emboli (sensitivity 91.2%, 95% CI 76.3%–98.1%). Applying these thresholds would have reduced CTPA use by 21.7% and 46.7%, respectively. These findings suggest that age‐adjusted D‐dimer thresholds may improve diagnostic efficiency in selected older patients; however, the absence of prospectively recorded pretest probability, verification bias and a lack of follow‐up prevents conclusions about clinical safety.