Recurrent Deep Vein Thrombosis: Long-Term Incidence and Natural History

The authors, from the Department of Surgery at Stony Brook Medical Center, conducted a prospective observational study that followed 153 consecutive patients with acute, first-time deep venous thrombosis (DVT) and evaluated the 5-year recurrence of DVT, risk factors for recurrence, and the incidence of pulmonary embolism (PE) and post-thrombotic syndrome (PTS). Patients received serial examinations throughout the 5 years and underwent duplex ultrasonography (US) twice during the first year and then again any time the patient developed signs and symptoms of DVT. Anticoagulation was at the discretion of the treating physician, but patients with a proximal DVT or PE were anticoagulated for at least 6 months, whereas those with calf DVT were either anticoagulated for 3 months or underwent repeat US to look for clot extension. At 5 years, the incidence of recurrence was 26.1%. Unprovoked DVT and age>65 years were associated with a statistically significant higher incidence of recurrence (relative risk [RR] 2.9, 95% confidence interval [CI] 1.5–5.7, and RR 1.5, 95% CI 1–2.3, respectively). Having a higher thrombus burden (both proximal and distal DVT) trended toward a higher rate of recurrence, although it was not statistically significant. Thrombophilia, surgery, and trauma were not associated with increased risk of recurrence. Recurrent DVT in the ipsilateral leg was found to have a statistically significant increased severity of PTS (RR 1.6, 95% CI 1.4–2.2). Finally, PE occurred in 47 patients, 12 of whom died.