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In patients with suspected deep venous thrombosis (DVT), a very low blood d-dimer concentration, in combination with low clinical probability, can rule out DVT. However, the specificity of d-dimer for DVT decreases with age, leading to more false-positive results in elders. In this retrospective study, investigators evaluated age-based d-dimer cutoffs in 1400 consecutive patients (mean age, 59) with clinically suspected DVT. Each patient underwent d-dimer measurement and leg ultrasonography. Three d-dimer cutoffs were evaluated: the conventional cutoff (500 µg/L) for all patients, age×10 µg/L for those who were older than 50, and 750 µg/L for those who were 60 or older.
About 650 patients (47%) had low probability of DVT (Wells score ≤1). DV…