Comparison of the clinical history of symptomatic isolated distal deep-vein thrombosis vs. proximal deep vein thrombosis in 11 086 patients

Background: The clinical significance of symptomatic isolated distal deep vein thrombosis (DVT) is uncertain. Consequently, this leads to important disparities in its management. Objective: To examine the clinical history of isolated distal DVT and to compare it with that of proximal DVT. Methods: Using data from the international, prospective, RIETE registry on patients with confirmed symptomatic venous thromboembolism (VTE), we compared the risk factors and 3-month outcome in patients with isolated distal DVT vs. proximal DVT. Results: Eleven thousand and eighty-six patients with symptomatic DVT, but without pulmonary embolism, were included between 2001 and 2008; 1921 (17.3%) exhibited isolated distal DVT. Anticoagulant treatment was received by 89.1% (1680/1885) of isolated distal DVT and 91.8% (7911/8613) of proximal DVT patients for the entire follow-up period. Isolated distal DVTs were more associated with transient risk factors (i.e. recent travel, hospitalization, recent surgery), whereas proximal DVTs were more associated with chronic states (i.e. >= 75 years or with active cancer). At 3 months, major bleeding rate was lower in patients with isolated distal DVT (1.0% vs. 2.2%, P < 0.01), whereas VTE recurrence rate was equivalent (2.0% vs. 2.7%, P = 0.07). The mortality rate was lower in patients with isolated distal DVT (2.7% vs. 7.5%; P < 0.001); this was mainly due to a lower rate of non-VTE-related deaths (2.2% vs. 6.3%; P < 0.001). Active cancer was the main predictive factor of death in patients with isolated distal DVT. Conclusions: Proximal and isolated distal DVT patients differ in terms of risk factors and clinical outcomes, suggesting different populations. In the short term, the life expectancy of patients with isolated distal DVT depended chiefly on their cancer status.