AIM: Residual thrombotic occlusion (RTO) after deep vein thrombosis (DVT) is considered as a risk factor of recurrent venous thromboembolism (VTE). We searched for risk factors associated with RTO after proximal DVT at the lower extremities. METHODS: Using compression ultrasound, we evaluated the presence of RTO at 6 months after DVT (RTO defined as a residual thrombus occupying, at maximum compressibility, >/=20% of the vein lumen before compression). RESULTS: We examined 126 Czech patients: mean age 57.5 years; 50.0% women, 68.3% femoral location of DVT (otherwise popliteal), RTO found in 45.2%. While accounting for covariates, in the whole population, RTO was significantly associated with following factors: (OR; 95% confidence limit; p value): male sex (2.01; 1.27-3.19; P=0.003), femoral location (2.76; 1.59-4.78; P=0.0003). In women, but not in men, an association was demonstrated for: concurrent pulmonary embolism (PE) (18.51; 1.85-185.7; P=0.0131), diabetes mellitus (4.62; 1.38-15.51; P=0.0133) and statin use (0.11; 0.02-0.62; P=0.0125). In contrast, in men RTO was associated with an unprovoked DVT (2.6; 1.26-5.34; P=0.0094). CONCLUSION: In the whole study population, male sex and femoral location of DVT were positively associated with RTO. In women, concurrent PE and diabetes mellitus were risk factors for RTO, while the use of statins was a protective factor. There was a positive association between RTO and unprovoked DVT in men. These findings deserve further evaluation in a larger study.

2nd Department of Internal Medicine University Hospital Faculty of Medicine Charles University Pilsen Czech Republic