D-dimer levels and risk of recurrent venous thromboembolism

Context Widespread screening of patients with venous thromboembolism (VTE) for thrombophilic risk factors has become common clinical practice. Because of the increasing number of risk factors, assessing the risk of recurrence in an individual patient is intricate; therefore, a laboratory method that measures multifactorial thrombophilia is required. Objective To prospectively study the relationship between the risk of recurrent VTE and D-dimer, a global marker of coagulation activation and fibrinolysis. Design, Setting, and Participants Prospective cohort study of 610 patients older than 18 years who were treated with oral anticoagulants for at least 3 months with a first spontaneous VTE, in whom D-dimer levels were measured shortly after discontinuation of oral anticoagulation. The study was conducted at the Department of Internal Medicine I, University Hospital, Vienna, Austria. Patients entered the study at time of discontinuation of oral anticoagulants and were observed at 3-month intervals during the first year and every 6 months thereafter from July 1992 to October 2002. Main Outcome Measure Objectively documented symptomatic recurrent VTE. Results A total of 79 (13%) of 610 patients had recurrent VTE with a mean observation time of 38 months. Patients with recurrence had significantly higher D-dimer levels compared with those without recurrence (553 ng/mL vs 427 ng/mL, P=.01). Compared with patients with D-dimer levels of 750 ng/mL or higher, the relative risk (RR) of recurrence was 0.6 (95% confidence interval [CI], 0.3-1.4),0.6 (95% CI, 0.3-1.2), and 0.3 (95% CI, 0.1-0.6) in patients with D-dimer levels of 500 to 749 ng/mL, 250 to 499 ng/mL, and less than 250 ng/mL, respectively. The cumulative probability of recurrent VTE at 2 years was 3.7% (95% CI, 0.9%-6.5%) among patients with D-dimer levels of less than 250 ng/mL compared with 11.5% (95% CI, 8.0%-15.0%) among patients with higher levels (P=.001). Patients with D-dimer levels of less than 250 ng/mL had a 60% lower RR of recurrence compared with patients with higher levels (RR, 0.4; 95% CI, 0.2-0.8). Conclusion Patients with a first spontaneous VTE and a D-dimer level of less than 250 ng/mL after withdrawal of oral anticoagulation have a low risk of VTE recurrence.