The clinical course of deep-vein thrombosis. Prospective long-term follow-up of 528 symptomatic patients.

BACKGROUND AND OBJECTIVE In contrast to the extensive documentation on the short-term outcome of patients with acute deep vein thrombosis (DVT) of the lower extremities, little is known about the long-term clinical course of this disease. To determine the clinical course of patients with a first episode of symptomatic DVTn over an 8-year follow-up period. The primary aims were to assess the long-term incidence of recurrent venous thromboembolism and that of the post-thrombotic syndrome. In addition, we determined mortality and evaluated potential risk factors for all these outcomes. METHODS This was designed as a prospective cohort follow-up study. Consecutive symptomatic outpatients with a first episode of venography proven DVT were treated with an initial course of full-dose (low molecular weight) heparin, followed by at least three months of oral anticoagulants. After discharge, they were instructed to wear compression elastic stockings for at least two years. Follow-up assessments were scheduled at three and six months, and then every six months up to eight years. Diagnosis of recurrent venous thromboembolism was made according to standard criteria. The presence of post-thrombotic syndrome was evaluated using a standardized scale. RESULTS A total of 528 consecutive patients with a first episode of venography confirmed DVT were included in the study. The cumulative incidence of recurrent venous thromboembolism after two, five and eight years was 17.2, 24.3 and 29.7%, respectively. Malignancy and impaired coagulation inhibition increased the risk of recurrent venous thromboembolism (RR = 1.48 and 2.0, respectively). In contrast, surgery and recent trauma or fracture were associated with a diminished risk of recurrent venous thromboembolism (RR = 0.65 and 0.39, respectively). The cumulative incidence of post-thrombotic syndrome after two, five and eight years was 24.5, 29.6 and 29.8%, respectively. The development of ipsilateral recurrent DVT was strongly associated with the risk for post-thrombotic syndrome (risk ratio, 2.4). Survival after eight years was 69%. The presence of malignancy increased the risk of death remarkably (risk ratio, 7.1). INTERPRETATION AND CONCLUSIONS Symptomatic DVT carries a high risk for recurrent venous thromboembolism that persists for many years, especially in patients without transient risk factors for DVT. The post-thrombotic syndrome occurs in almost one-third of patients and is strongly related to recurrent ipsilateral DVT. Our findings challenge the widely adopted short course of anticoagulation in patients with symptomatic DVT.