What is the sensitivity of D-dimer (D-dimer test) for diagnosing aortic dissection?

Sensitivity of D-dimer for Aortic Dissection

D-dimer has a high sensitivity of 94-98% for acute aortic dissection at the standard threshold of 0.5 μg/mL, making it a valuable initial screening test, though it cannot be used as the sole diagnostic tool due to important limitations. 1, 2, 3

Sensitivity Values and Clinical Utility

• The American College of Emergency Physicians clinical policy reports sensitivity values for D-dimer in acute aortic dissection:

  • At >0.5 μg/mL threshold: 98% sensitivity 2
  • Negative predictive value: 96-100% 2

• A pooled meta-analysis of 11 studies with 349 patients found:

  • Overall sensitivity: 94% (95% CI 91-96%) 3
  • Sensitivity remained consistent (95%) in sensitivity analyses 3

Limitations and False Negatives

Several important clinical scenarios can lead to false-negative D-dimer results in aortic dissection:

1. Time-dependent factors:

   • Significant negative correlation between D-dimer values and time from symptom onset 1
   • Testing is most reliable when performed shortly after symptom onset 2
   • D-dimer has a half-life of approximately 16 hours 2

2. Anatomical factors:

   • Thrombosed false lumens result in lower D-dimer levels 1
   • Intramural hematomas without intimal flap may produce false negatives 1
   • Short dissection length correlates with lower D-dimer values 1, 4
   • Lower extension score independently associated with negative D-dimer results 4

3. Patient factors:

   • Younger patients more likely to have false-negative results 1
   • Higher platelet count independently associated with negative D-dimer results 4

Clinical Implications

• Despite high sensitivity, D-dimer should not be used as the sole screening tool for aortic dissection 5
• A negative D-dimer result alone cannot exclude patients with potentially fatal aortic dissection conditions 4
• Even patients with negative D-dimer may require emergency surgery (44% of negative D-dimer patients had type A dissection and 33% required emergency operation due to cardiac tamponade) 4

Optimal Use in Clinical Practice

• D-dimer is most useful when combined with clinical risk stratification
• The Aortic Dissection Detection Risk Score (ADD-RS) combined with negative D-dimer has reported sensitivity of 99.9-100% 6
• CTA remains the recommended imaging modality for suspected aortic dissection with sensitivity of 99% (95% CI 91-100%) and specificity of 100% (95% CI 99-100%) 1

Important Caveats

• D-dimer lacks specificity for aortic dissection (ranges from 40-100%) 3
• Elevated in many other conditions including pulmonary embolism, myocardial infarction, pregnancy, advanced age, recent surgery, inflammatory conditions, cancer, and infections 2
• Different D-dimer assays may produce different results, and cutoff values are not transferable between methods or institutions 2

In summary, while D-dimer has high sensitivity for acute aortic dissection, clinicians must recognize its limitations and not rely solely on a negative result to exclude this potentially fatal diagnosis, particularly in patients with high clinical suspicion.