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    Patent Pending

    Age-Adjusted D-dimer for Venous Thromboembolism (VTE)

    Adjusts D-dimer cutoffs by age to help rule out VTE.

    INSTRUCTIONS

    Use in patients ≥50 years old presenting to emergency department as outpatients and are being worked up for PE with low to intermediate pretest probability. Do not use in high-risk patients (i.e., those who would proceed to imaging regardless of D-dimer result).

    When to Use
    Pearls/Pitfalls
    Why Use

    • Patients ≥50 years old presenting to emergency department as outpatients who are being worked up for PE and have low to intermediate pretest probability.

    • Do not use in high-risk patients (i.e., those who would proceed to imaging regardless of D-dimer result).

    • Has been shown to significantly increase specificity in older populations with minimal reduction in sensitivity.

    • Can be used for assays that report fibrinogen equivalent units (FEU) with a D-dimer cutoff of 500 µg/L, or D-dimer units (DDU, less common) with a D-dimer cutoff of 250 µg/L. 

    • A value below age x 10 µg/L (5 µg/L for DDU assays) adequately rules out the need for further testing for PE in low- to intermediate-risk patients.

    • Note that there is currently no standard D-dimer unit of measure, and there is wide variation among labs in cutoffs reported and magnitude of unit (e.g. µg/L vs ng/mL vs µg/mL).

    • While traditional teaching previously dictated that D-dimer should only be used in low-risk patients, this was based on lower sensitivity of D-dimer assays at the time. Modern D-dimer assays (immunoturbidimetric) have sensitivities up to 100% (Knecht 1997, Righini 2014).

    • This has been proposed to increase throughput time and decrease unnecessary testing and complications in patients.

    • Accepted by ACEP and ACP as acceptable in risk-stratifying low- to intermediate-risk patients.

    years
    Optional, for comparison if you have a D-dimer result
    µg/L
    FEU (unadjusted cutoff typically ~500 or 0.50)
    DDU (unadjusted cutoff typically 230-250 or 0.23-0.25)

    Result:

    Please fill out required fields.

    Next Steps
    Evidence
    Creator Insights
    Dr. Marc P. Righini

    From the Creator

    Why did you develop the Age-Adjusted D-dimer? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?

    D-dimer measurement is a very important step in VTE diagnosis, as it allows clinicians to rule out the disease in around 30% of outpatients with suspected DVT or PE. However, the test is less useful in elderly patients (as D-dimer tests at a cutoff of 500 ng/mL are rarely truly negative). Therefore, we tried increasing the cutoff in elderly patients. Our retrospective validation suggested that an “age per 10” cutoff in patients above 50 years would be safe, and we conducted a prospective validation study, which confirmed this.

    What pearls, pitfalls and/or tips do you have for users of the Age-Adjusted D-dimer? Do you know of cases when it has been applied, interpreted, or used inappropriately?

    Some important points:

    • As with all D-dimer tests, they should be used after an assessment of clinical probability.

    • Mainly, ELISA and immunoturbidimetric tests have been used. But this represents the vast majority of tests used.

    • Limited data exist on D-dimers with cutoffs set at 250 ng/mL. Retrospective studies suggest that in this case, the age-adjusted cutoff is “age per 5”, meaning that you can rule out PE in a patient of 60 years if the result of the test is less than 300 ng/mL.

    Are there any adjustments or updates you would make to the score based on new data or practice changes?

    No. We have robust prospective validation and retrospective validation in more than 50,000 patients from everywhere in the world.

    How do you use the Age-Adjusted D-dimer in your own clinical practice? Can you give an example of a scenario in which you use it?

    We use it in every clinical practice for outpatients with suspected PE.

    Any other research in the pipeline that you’re particularly excited about?

    The prospective validation for the cutoff in patients with suspected DVT is running, which should allow in the future a one-size-fits-all cutoff for suspected PE and/or suspected DVT.

    About the Creator

    Marc P. Righini, MD, is a professor and lead researcher at the University of Geneva in Geneva, Switzerland. He is also a physician in the angiology and hemostatis division at the Geneva University Hospital. Dr. Righini’s primary research interests include diagnosis and treatment of venous thromboembolic diseases, including pulmonary embolism and deep venous thrombosis.

    To view Dr. Marc P. Righini's publications, visit PubMed

    Are you Dr. Marc P. Righini? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
    Content Contributors
    • Indira Gowda, MD
    Reviewed By
    • Colin Bell, MD
    About the Creator
    Dr. Marc P. Righini
    Are you Dr. Marc P. Righini?
    Content Contributors
    • Indira Gowda, MD
    Reviewed By
    • Colin Bell, MD