Age-Adjusted D-dimer for Venous Thromboembolism (VTE)
Adjusts D-dimer cutoffs to help rule out VTE in patients ≥50 years old.
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).
Result:
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.
- Indira Gowda, MD