Age-Adjusted D-dimer Calculator for VTE

Helps rule out venous thromboembolism (VTE) in patients of 50 years or older with suspected pulmonary embolism (PE).

Refer to the text below the tool for more information about D-dimer testing and cut-off values.


Some of the patients of 50 years or older admitted to emergency departments with suspected pulmonary embolism and who are likely to have a low to intermediate pre-test probability may benefit from the age-adjusted D-dimer evaluation.

The method is appropriate for tests with:

  • Fibrinogen equivalent units (FEU) with a D-dimer cut-off of 500 µg/L;
  • D-dimer units (DDU, less common) with a D-dimer cut-off of 250 µg/L. 

Please note this is not appropriate for high-risk patients who are likely to proceed to imaging regardless of the D-dimer result.


D-dimer test Age-adjusted D-dimer cut-off Interpretation
Fibrinogen equivalent units (FEU) Age x 10 µg/L If test value ≤ cut-off: VTE likely, progress with CTA or V/Q scan
If test value > cut-off: VTE diagnosis unlikely
D-dimer units (DDU) Age x 5 µg/L

Patient Age (should be ≥50 yrs)
D-dimer unit type
Laboratory D-dimer level (optional)
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


 

Age-Adjusted D-dimer Testing

Some of the patients of 50 years or older admitted to emergency departments with suspected pulmonary embolism and who are likely to have a low to intermediate pre-test probability may benefit from the age-adjusted D-dimer evaluation.

The method is appropriate for tests with:

  • Fibrinogen equivalent units (FEU) with a D-dimer cut-off of 500 µg/L;
  • D-dimer units (DDU, less common) with a D-dimer cut-off of 250 µg/L.

Please note this is not appropriate for high-risk patients who are likely to proceed to imaging regardless of the D-dimer result.

D-dimer test Age-adjusted D-dimer cut-off Interpretation
Fibrinogen equivalent units (FEU) Age x 10 µg/L If test value ≤ cut-off: VTE likely, progress with CTA or V/Q scan
If test value > cut-off: VTE diagnosis unlikely
D-dimer units (DDU) Age x 5 µg/L

The age-adjusted D-dimer cut-offs were found to be more specific as the age of the patient increases, with minimal reduction in sensitivity and so can prevent unnecessary testing in low and moderate risk patients.

Modern D-dimer assays have almost perfect sensitivities. D-dimers are a by-product of fibrinogen breakage following excessive coagulation. Lower D-dimer results may indicate a lower risk of pulmonary embolism (PE) or deep venous thrombosis (DVT).

The most common D-dimer tests are:

  • Enzyme-Linked Immunosorbent Assay (ELISA);
  • Latex Agglutination Assay;
  • Whole Blood assay (Simplired);
  • Turbidimetric Assay;
  • Immunofiltration Assay.

During validation it was found that the combination of low clinical probability of DVT and use of age dependent d-dimer cut-off values for patients > 50 years is able to safely exclude DVT, compared to just comparing the conventional 500 µg/L cut-off, especially given the variability of different assay result reporting.

 

References

Original reference

Schouten HJ, Geersing GJ, Koek HL, et al. Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis. BMJ. 2013; 346:f2492.

Validation

Sharp AL, Vinson DR, Alamshaw F, Handler J, Gould MK. An Age-Adjusted D-dimer Threshold for Emergency Department Patients With Suspected Pulmonary Embolus: Accuracy and Clinical Implications. Ann Emerg Med. 2016; 67(2):249-257.

Righini M, Van Es J, Den Exter PL, et al. Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study [published correction appears in JAMA. 2014; 311(16):1694]. JAMA. 2014; 311(11):1117-1124.

Other references

Knecht MF, Heinrich F. Clinical evaluation of an immunoturbidimetric D-dimer assay in the diagnostic procedure of deep vein thrombosis and pulmonary embolism. Thromb Res. 1997; 88(5):413-417.

Tardy B, Tardy-Poncet B, Viallon A, et al. Evaluation of D-dimer ELISA test in elderly patients with suspected pulmonary embolism. Thromb Haemost. 1998; 79(1):38-41.

Douma RA, Tan M, Schutgens RE, et al. Using an age-dependent D-dimer cut-off value increases the number of older patients in whom deep vein thrombosis can be safely excluded. Haematologica. 2012; 97(10):1507-1513.


Specialty: Hematology

Year Of Study: 2013

Article By: Denise Nedea

Published On: August 11, 2020

Last Checked: August 11, 2020

Next Review: August 11, 2025