Measurement of D-dimer concentrationsmay help clinicians predict who isat high risk of recurrent venous thromboembolism(VTE) after stopping anticoagulanttherapy. Recurrent VTE occursin as many as 30% of patients whodiscontinue therapy. Those at highestrisk include patients who are male, areobese (>30 kg/m2), and had a proximal(vs distal) deep vein thrombosis. Arecent prospective study of 608 patientsevaluated the rate of recurrenceafter 3 months of oral anticoagulanttherapy. Therapy was stopped after 3months, then D-dimer levels weremeasured a month later. Patients withnormal levels (n = 385) did not resumetherapy. Patients with high levels (n =223) were randomized to resume therapyor remain off anticoagulants. Afteran average of 1.4 years of follow-up,recurrence rates were 6.2% in thegroup with normal levels, 1.9% in thegroup that resumed therapy, and 15%in the group with high levels whoremained off therapy. The authors concludedthat high D-dimer levels predicthigh risk of recurrent VTE, and this riskcan be minimized by restarting warfarintherapy.
Long-term therapy with anticoagulantslowers recurrent VTE risk but isassociated with a 1% to 3% risk ofmajor bleeding. Identifying patientswith a low risk of recurrence is importantin order to safely discontinuetherapy as soon as possible. Currentrecommendations for a first episode ofunprovoked VTE call for 6 to 12 monthsof therapy. The results of this study suggestthat use of the D-dimer test mayprovide an alternate approach to therapy,although further evaluation is necessaryto confirm safety and efficacy.
Dr. Garrett is a clinical pharmacistpractitioner at Cornerstone HealthCare in High Point, NC.