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Patient Evidence Summary
Doctor, my D-dimer test was negative. Does this mean I don’t have a deep vein thrombosis?
This study found that a negative D-dimer blood test can safely rule out deep vein thrombosis (DVT) in patients who present to the emergency department with symptoms suggestive of a DVT and whose clinical assessment suggests that DVT is not likely. For patients below the age of 50, a conventional D-dimer cutoff of 500 μg/L was used. For patients 50 years or older, a negative result was defined as a D-dimer level lower than the person’s age multiplied by 10, also known as an “age-adjusted D-dimer”. In this study, patients with a negative age-adjusted D-dimer had a very low chance of developing venous thromboembolism (VTE) during the 3-month follow-up period.
Study highlights
Among patients 50 years or older who had symptoms suggestive of a DVT, whose clinical assessment suggested that DVT was unlikely and whose D-dimer level was above 500 μg/L but below their age-adjusted cutoff, none developed venous thromboembolism during the 3-month follow-up period. Using the age-adjusted D-dimer cutoff allowed doctors to safely rule out DVT in 7 more patients out of every 100 in whose clinical assessment suggested DVT was not likely, compared with using the standard cutoff of 500 μg/L. This means fewer patients needed an ultrasound to assess for a blood clot.
Understanding the problem
DVT can be difficult to diagnose because symptoms such as leg pain and swelling may occur with many other medical conditions. Doctors often use a blood test called a D-dimer to help rule out a blood clot. For many patients, a negative D-dimer result means that a blood clot is unlikely, and further investigation with an ultrasound of the leg is unnecessary. However, D-dimer levels naturally increase with age, such that many older adults without DVT have D-dimer levels above the usual cutoff of 500 μg/L, meaning that the test is less useful to rule out DVT in this age group.
To address this, the authors of this study tested a higher "age-adjusted" D-dimer cutoff in patients 50 years or older, calculated as the patient’s age multiplied by 10. Age-adjusted D-dimer cutoffs have previously been shown to safely rule out blood clots in the lungs (pulmonary embolism), but prior to this study, it was unknown whether age-adjusted D-dimer could be used to rule out DVT specifically. The researchers of this study wanted to know if an age-adjusted D-dimer cutoff could safely rule out DVT in patients over the age of 50.
Who? The study included 3205 adults (median age 59) across 4 countries (Belgium, Canada, France and Switzerland) with symptoms suggestive of DVT. Of the 3205 patients, about two thirds (68%) had a non-high/unlikely DVT probability probability of DVT based on commonly used clinical scoring tool called the Wells score. Of these patients, 161 (7.4%) had a D-dimer level between 500 and their age-adjusted cutoff.
Patients who were younger than 18 years old, pregnant, already receiving blood thinners, who had symptoms of PE, had a life expectancy less than 3 months, or who were unable to consent to the study or not available for follow-up, were excluded from the study.
What? The study assessed whether an age-adjusted D-dimer cutoff could safely rule out DVT in patients 50 years or older whose clinical assessment suggested that DVT was unlikely.
Outcomes at 3 month follow-up among patients whose clinical assessment suggested that DVT was not likely
| Group | Number of patients | VTE during 3 months follow-up |
|---|---|---|
| D-dimer below 500 μg/L | 531 | 2 patients, less than 1 in 100 |
| D-dimer between 500 μg/L and the age-adjusted cutoff | 161 | 0 patients |
| All people with a negative age-adjusted D-dimer | 692 | 2 people, less than 1 in 100 |
In summary, this study found that an age-adjusted D-dimer cutoff can safely increase the number of people in whom DVT can be ruled out without ultrasound. This approach should be used only as part of a diagnostic strategy that includes clinical assessment, such as the Wells score. It should not be used to rule out DVT in people whose clinical assessment suggests that DVT is likely.
This Evidence Summary is based on the following article:
Le Gal G, Robert-Ebadi H, Thiruganasambandamoorthy V, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Deep Vein Thrombosis. JAMA. 2026 Feb 3;335(5):416-424. doi: 10.1001/jama.2025.21561. PubMed
Isidora Rovic, MD
Isidora Rovic is a PGY-3 Internal Medicine resident at McMaster University with a strong interest in hematology. She is passionate about medical education for early trainees and has a particular interest in translating complex medical topics into clear, patient-friendly language to support informed decision-making and improve patient care.
Siraj Mithoowani, MD, MHPE, FRCPC, FACP
Siraj Mithoowani is an Assistant Professor in the Department of Medicine, McMaster University, and is a clinical hematologist at St. Joseph's Healthcare, Hamilton. He specializes in the care of non-malignant and thrombotic blood disorders. His research interests are in venous thromboembolism and postgraduate medical education.
Published: Tuesday, July 28, 2026
Please note that the information contained herein is not to be interpreted as an alternative to medical advice from a professional healthcare provider. If you have any questions about any medical matter, you should consult your professional healthcare providers, and should never delay seeking medical advice, disregard medical advice or discontinue medication based on information provided here.
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This Evidence Summary was printed from the CLOT+ website on 2026/08/16. To view other Evidence Summaries or to register to receive email notifications about new Evidence Summaries, please visit us at https://plus.mcmaster.ca/ClotPlus/Articles/EvidenceSummaries |
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, McMaster University