Of the total number of patients, 48.8% (n=139) had previous VBL: 20% (n=57) underwent primary prophylactic VBL and 34.7% (n=99) underwent secondary prophylaxis. Thus, 285 VBL procedures had been performed and the average number of VBL session was 2 (range 1-10)
The mean time follow up was 92.55 months (range 22-230. During the follow up period PVT was diagnosed in 41.4% of patients (n =118) of which 67.77% (n =80) had at least one previous session of VBL: 33% of patients (n =39) had performed primary prophylaxis and 34.74% (n =41) secondary. A logistic regression was conducted to assess if VBL (primary and/or secondary prophylaxis) are risk factors for PVT development. The model was significant for primary prophylaxis (p =0.002, OR 3.28, CI 1.53-7.02) resulting that the risk of PVT is increasing around 3 times after primary prophylactic VBL.
Furthermore, to our knowledge, this is the first study in the literature that focuses on this topic. More studies should be performed to evaluate and describe the relationship between VBL and the risk of PVT.