The long-term clinical course of acute deep venous thrombosis

Background: In patients who have symptomatic deep venous thrombosis, the long-term risk for recurrent venous thromboembolism and the incidence and severity of post-thrombotic sequelae have not been well documented. Objective: To determine the clinical course of patients during the 8 years after their first episode of symptomatic deep venous thrombosis. Design: Prospective cohort study. Setting: University outpatient thrombosis clinic. Patients: 355 consecutive patients with a first episode of symptomatic deep venous thrombosis. Measurements: Recurrent venous thromboembolism, the post-thrombotic syndrome, and death. Potential risk factors for these outcomes were also evaluated. Results: The cumulative incidence of recurrent venous thromboembolism was 17.5% after 2 years of follow-up (95% CI, 13.6% to 22.2%), 24.6% after 5 years (CI, 19.6% to 29.7%), and 30.3% after 8 years (CI, 23.6% to 37.0%). The presence of cancer and of impaired coagulation inhibition increased the risk for recurrent venous thromboembolism (hazard ratios, 1.72 [CI, 1.31 to 2.25] and 1.44 [CI, 1.02 to 2.01], respectively). In contrast, surgery and recent trauma or fracture were associated with a decreased risk for recurrent venous thromboembolism (hazard ratios, 0.36 [CI, 0.21 to 0.62] and 0.51 [CI, 0.32 to 0.87], respectively). The cumulative incidence of the post-thrombotic syndrome was 22.8% after 2 years (CI, 18.0% to 27.5%), 28.0% after 5 years (CI, 22.7% to 33.3%), and 29.1% after 8 years (CI, 23.4% to 34.7%). The development of ipsilateral recurrent deep venous thrombosis was strongly associated with the risk for the post-thrombotic syndrome (hazard ratio, 6.4; CI, 3.1 to 13.3). Survival after 8 years was 70.2% (CI, 64.7% to 75.6%). The presence of cancer increased the risk for death (hazard ratio, 8.1; CI, 3.6 to 18.1). Conclusion: Patients with symptomatic deep venous thrombosis, especially those without transient risk factors for deep venous thrombosis, have a high risk for recurrent venous thromboembolism that persists for many years. The post-thrombotic syndrome occurs in almost one third of these patients and is strongly related to ipsilateral recurrent deep venous thrombosis. These findings challenge the widely adopted use of short-course anticoagulation therapy in patients with symptomatic deep venous thrombosis.