D-dimer testing to determine the duration of anticoagulation therapy.
BACKGROUND
The optimal duration of oral anticoagulation in patients with idiopathic venous thromboembolism is uncertain. Testing of D-dimer levels may play a role in the assessment of the need for prolonged anticoagulation.


METHODS
We performed D-dimer testing 1 month after the discontinuation of anticoagulation in patients with a first unprovoked proximal deep-vein thrombosis or pulmonary embolism who had received a vitamin K antagonist for at least 3 months. Patients with a normal D-dimer level did not resume anticoagulation, whereas those with an abnormal D-dimer level were randomly assigned either to resume or to discontinue treatment. The study outcome was the composite of recurrent venous thromboembolism and major bleeding during an average follow-up of 1.4 years.


RESULTS
The D-dimer assay was abnormal in 223 of 608 patients (36.7%). A total of 18 events occurred among the 120 patients who stopped anticoagulation (15.0%), as compared with 3 events among the 103 patients who resumed anticoagulation (2.9%), for an adjusted hazard ratio of 4.26 (95% confidence interval [CI], 1.23 to 14.6; P=0.02). Thromboembolism recurred in 24 of 385 patients with a normal D-dimer level (6.2%). Among patients who stopped anticoagulation, the adjusted hazard ratio for recurrent thromboembolism among those with an abnormal D-dimer level, as compared with those with a normal D-dimer level, was 2.27 (95% CI, 1.15 to 4.46; P=0.02).


CONCLUSIONS
Patients with an abnormal D-dimer level 1 month after the discontinuation of anticoagulation have a significant incidence of recurrent venous thromboembolism, which is reduced by the resumption of anticoagulation. The optimal course of anticoagulation in patients with a normal D-dimer level has not been clearly established. (ClinicalTrials.gov number, NCT00264277 [ClinicalTrials.gov].).
Palareti
Gualtiero
G
Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, Bologna, Italy. palareti@tin.it
Cosmi
Benilde
B
Legnani
Cristina
C
Tosetto
Alberto
A
Brusi
Carlotta
C
Iorio
Alfonso
A
Pengo
Vittorio
V
Ghirarduzzi
Angelo
A
Pattacini
Corrado
C
Testa
Sophie
S
Lensing
Anthonie W A
AW
Tripodi
Armando
A
D000074:Acenocoumarol / Q000008:administration & dosage; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D016736:Antiphospholipid Syndrome / Q000175:diagnosis; D000991:Antithrombins / Q000172:deficiency; D004334:Drug Administration Schedule; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D012008:Recurrence; D016019:Survival Analysis; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D014812:Vitamin K / Q000037:antagonists & inhibitors; D014859:Warfarin / Q000008:administration & dosage
D000925:Anticoagulants; D000991:Antithrombins; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D014812:Vitamin K; D014859:Warfarin; D000074:Acenocoumarol