Age-adjusted versus clinical probability-adjusted D-dimer to exclude pulmonary embolism

Area of Science:

• Emergency Medicine
• Diagnostic Imaging
• Clinical Chemistry

Background:

• D-dimer testing is crucial for excluding pulmonary embolism (PE) in patients with low to intermediate clinical probability.
• However, D-dimer's nonspecificity often necessitates further imaging, even in negative cases.
• Adjusting D-dimer thresholds by age (AADD) or clinical probability (CPADD) aims to improve diagnostic accuracy.

Purpose of the Study:

• To compare the diagnostic performance of age-adjusted D-dimer (AADD) versus clinical probability-adjusted D-dimer (CPADD) in patients with suspected pulmonary embolism (PE).
• To evaluate sensitivity, specificity, and negative predictive value (NPV) of both AADD and CPADD strategies.

Main Methods:

• A retrospective analysis of 1745 patients with suspected PE (low or intermediate clinical probability) from two U.S. emergency departments was conducted.
• Patients underwent D-dimer testing and imaging for PE.
• Performance metrics including sensitivity, specificity, and NPV were calculated for AADD and CPADD.

Main Results:

• Age-adjusted D-dimer (AADD) showed higher sensitivity (96.6% vs. 87.5%) and negative predictive value (99.0% vs. 97.1%) compared to clinical probability-adjusted D-dimer (CPADD).
• CPADD exhibited slightly higher specificity (37.5% vs. 30.2%) but resulted in more negative D-dimer tests (35.4% vs. 28.0%).
• PE was confirmed in 8.3% of the analyzed cohort.

Conclusions:

• Age-adjusted D-dimer (AADD) demonstrates superior performance in terms of sensitivity and NPV for suspected PE compared to CPADD.
• While CPADD offers a marginal increase in specificity, AADD appears to be the preferable strategy for ruling out PE due to its higher NPV.
• The findings suggest AADD may reduce unnecessary imaging in suspected PE cases more effectively.