Impact of Anticoagulation Therapy on the Risk of Pulmonary Embolism and Bleeding Events in Patients with Isolated Distal Deep-Vein Thrombosis

The efficacy of anticoagulation for isolated distal DVT (id-DVT) is still uncertain and controversial. The aim of this study was to elucidate the risk of pulmonary embolism (PE) from id-DVT and to investigate the need for anticoagulants.We identified hospitalized patients with id-DVT diagnosed by lower-extremity ultrasonography (LEUS) from January 2013 to December 2013 in our institute. The exclusion criteria were the simultaneous detection of PE, a history of PE and/or DVT, and administration of anticoagulants before DVT detection. We retrospectively investigated the patient characteristics, treatments, occurrence of PE, and bleeding events between the groups with and without anticoagulation.A total of 151 patients met the criteria. The median (IQR) age was 74 (67, 80) years old, and there were 60 (39.7%) men. The median (IQR) observation period was 571 (160, 721) days. Significant differences in patient characteristics were observed for hypertension, operation time, consultation with experts, and follow-up LEUS. During the observation period, only one patient in the no-anticoagulation group who had traumatic cerebral hemorrhaging and was bedridden developed PE (non-massive type). However, there was no statistically significant difference in the occurrence of PE between the groups (log-rank P = 0.569). Bleeding episodes were observed in 9 of 151 (6.0%) patients, and all patients with bleeding events were taking anticoagulants (log-rank P < 0.001).The present retrospective single center study suggests that anticoagulation for id-DVT in inpatients with various backgrounds has a low efficacy to prevent the occurrence of PE and may increase bleeding events.