Patients with isolated distal deep-vein thrombosis (DVT) and proximal DVT have similar long-term rates of venous thromboembolism (VTE) recurrence, bleeding, and death, according to an analysis of real-world data published in the Journal of Thrombosis and Haemostasis. Treatment with direct oral anticoagulants (DOACs) was associated with lower rates of VTE recurrence, major bleeding, and mortality in these patients.
Approximately 70% of acute VTE events in the U.S. involve deep veins in the lower extremities. Lower extremity DVT is divided into two categories based on proximal extent of the thrombosis: isolated distal DVT and proximal DVT.
Currently, the management of isolated distal DVT varies across centers, given its high prevalence. In addition, there are limited data available to guide clinicians on appropriate management strategies, anticoagulation intensity, and duration of treatment for patients with this form of DVT.
To gauge the clinical outcomes of patients with isolated distal DVT versus patients with proximal DVT, Robert McBane, MD, of Mayo Clinic, and researchers evaluated rates of recurrent VTE, major and clinically relevant non-major bleeding, and death in consecutive patients with confirmed acute DVT from the Mayo Clinic Gonda Vascular Center Ultrasound and VTE Registry databases.
Patients were stratified into two groups based on DVT location:
- isolated distal DVT (n=746)
- proximal DVT (n=1,176)
Patients were also divided based on the type of anticoagulant used (low-molecular weight heparin vs. DOAC).
Average age in the isolated distal DVT and proximal DVT groups was 62.4±14.7 years and 62.8±14.1 years, respectively. Individuals in the isolated distal DVT group had thrombus at either the axial or muscular venous segments, or both. In contrast, patients with proximal DVT had acute thrombus that involved the popliteal, femoral, or iliac veins.
At baseline, a significantly higher proportion of patients in the proximal DVT group had unprovoked events (24.8% vs. 10.6%; p<0.001) and a prior history of VTE (28.1% vs. 20.2%; p<0.001).
The investigators assessed rates of VTE recurrence, major bleeding, and death within and between the DVT and anticoagulant groups.
Respectively, the average follow-up periods for the VTE Registry and Calf DVT Registry were 8.6±10.0 months and 11.1±9.4 months. Over follow-up, the rates of VTE recurrence were similar between the isolated distal DVT group (4.60 per 100 person-years) and the proximal DVT group (5.77 per 100 person-years; p=0.336).
At three months, mortality rates were significantly higher in patients with isolated distal DVT (7.2% vs. 3.9%; p=0.001), but the difference did not last beyond this period.
A total of 440 patients with isolated distal DVT and 755 patients with proximal DVT used DOACs. In this pooled subgroup, patients with isolated distal DVT had a significantly lower VTE recurrence rate (0.9% vs. 3.0%; p=0.03). Treatment with DOACs in both groups was associated with more favorable rates of VTE recurrence, major bleeding, and death.
Patients with proximal DVT were more likely to have active cancer (39.5% vs. 29.8%; p<0.001). In contrast, patients with isolated distal DVT more often had major trauma (15% vs. 6.4%; p<0.001), recent surgery (34% vs. 17.3%; p<0.001), or confinement (39% vs. 19%; p<0.001).
Multivariable modeling revealed warfarin use (vs. DOAC), increasing age, and active cancer were independent predictors of mortality.
This study is limited by its retrospective design. In addition, the inclusion of patients from only a tertiary care setting may limit the generalizability of the findings.
The authors report no relevant conflicts of interest.
Vlazny DT, Pasha AK, Kuczmik W, et al. Outcome of anticoagulation in isolated distal deep vein thrombosis compared to proximal deep venous thrombosis [published online ahead of print, 2021 Jun 1]. J Thromb Haemost. doi:10.1111/jth.15416.