Potential use of D-dimer measurement in patients treated with oral anticoagulant for a venous thromboembolic episode.

AIM: We compared the level of plasma D-dimer in patients with previous venous thromboembolism (VTE), receiving or not oral anticoagulant treatment (OAT) and investigated its predictive value for the risk of VTE recurrence after OAT withdrawal.

METHODS: We have studied 149 patients, 81 receiving oral anticoagulants and 68 after treatment interruption. Patients with known causes of D-dimer increase were excluded. D-dimer measurements were performed by Vidas analyzer (bioMérieux, France).

RESULTS: A significantly lower D-dimer plasma level was found in patients under OAT than in untreated patients, 197+/-134 ng/ml versus 399+/-239 ng/ml, respectively (p<0.001). This decrease was similar in the different age populations and whether the patient had thrombophilia (n=84) or not. There was no correlation between INR and D-dimer levels. During a mean follow-up of 30 months, no recurrence occurred in patients under OAT versus 7 untreated patients. Among them, 3 had a D-dimer below 500 ng/ml, and 3 others had a level above 500 ng/ml. The last patient was not tested.

CONCLUSION: The physician should be informed of the decrease of D-dimer under OAT, since the usual cut-off of 500 ng/ml used for deep vein thrombosis (DVT) exclusion is probably lower in such treated patients. It has been recently proposed that normal D-dimer level had a high negative predictive value for VTE recurrence when this dosage was performed 3 months after OAT interruption. The small number of recurrences observed in our study with an available result of D-dimer measured more than 3 months after OAT discontinuation does not allow a definite