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

To determine the long-term incidence, risk factors, and associated morbidity and mortality of recurrent deep vein thrombosis (DVT). Few studies have examined the long-term natural history and impact of recurrent DVT. We conducted a prospective observational study that followed 153 consecutive patients with an acute first episode of DVT. Clinical examination and ultrasound were performed serially for at least 5 years. Location and extent of the initial DVT, recurrence, pulmonary embolism, cause of mortality, signs and symptoms of post thrombotic syndrome (PTS), and the risk factors were recorded. The incidence of recurrence at 5 years was 26.1%. Patients with both proximal and distal DVT had a higher recurrence rate than proximal (17/48 35% vs. 12/49, 24%, P = 0.27) or calf alone (11/56, 20%, P = 0.08). Unprovoked DVT and age >65 years were associated with higher recurrence rates (P < 0.001; relative risk [RR]: 2.9, 95% confidence interval [CI]: 1.5-5.7) and (P = 0.025; RR: 1.5, 95% CI: 1-2.3), respectively. Thrombophilia was not associated with increased risk of recurrence (P = 0.21). Patients with DVT due to surgery or trauma had a lower recurrence (P < 0.001). Ipsilateral recurrence was associated with increased severity of PTS (P < 0.001; RR: 1.6, 95% CI: 1.4-2.2). PE occurred 47 times, 12 (25%) of which were fatal events. Factors associated with a higher rate of recurrence included unprovoked DVT and age >65. Elevated thrombus burden had a trend towards higher risk. Patients with surgery and trauma had low recurrence rates. Ipsilateral recurrence was strongly associated with PTS. PE occurred frequently and was a common cause of death.