Anatomical Distribution of First VTE Event and Risk of VTE Recurrence: Long Term Follow-up and Retrospective Analysis of 346 Patients. Experience From a Single Center

Abstract 1224

Venous thromboembolism (VTE) is a chronic disease with recurrence risk that persists over the years. Predicting the chance of recurrence on an individual basis is of paramount importance for the appropriate tailoring of anticoagulant therapy. Recurrence risk is affected by thrombophilia and is lower in patients with provoked VTE than in patients with unprovoked thrombosis. Up to date there are no studies focused on the recurrence risk according to the anatomical distribution of the 1^st VTE event.

In order to evaluate the risk factors of VTE recurrence, after a review of relevant literature we set specific laboratory and clinical variables, which could be associated with VTE recurrence. Moreover, we evaluated retrospectively 346 patients of the Haemostasis Unit, who had already had an episode of VTE concerning the risk of VTE recurrence. Data statistical analysis was done with SPSS package 15.0. At first a monovariable statistical model was used with significance levels set at p= 0.05. For the multivariable statistical analysis model we used all variables with p< 0.1 from the previous model and those mentioned at recent medical literature as significantly related with VTE recurrence.

The 346 patients enrolled had already suffered a first episode of VTE and are being followed up regarding VTE recurrence. The study population, 169 (48.7%) male and 178 (51.3%) female, had a mean age at first VTE of 41.54 years. The exclusion criteria of our study were: high risk patients for VTE recurrence who received indefinite anticoagulation (n=72), patients who have suffered VTE and had a follow up period after discontinuation of anticoagulation shorter than 2 years (n=73) and patients who were lost at follow up (n=15). Among 194 patients who were enrolled 108 (55.7%) were women and 86 (44.3%) men, with a mean age at 1^st VTE of 40.10 years. 114 patients had only one VTE episode, 59 suffered two, 16 patients had tree episodes and 5 patients had >= 4 episodes.

Based on previously published data we tried to define whether the following variables are high risk factors for VTE recurrence in our population: gender, age of diagnosis, thrombophilic factors (FVLeiden, FII, HCY, VIII, AT, PrC, PrS, PAI1, Lp(a), XII), the presence of unprovoked VTE episode and VTE location (DVT, PE, CNS Thrombosis). Male gender p=0,038, FVLeiden homozygous p=0.036, the presence of unprovoked VTE p=0.029, and VTE location p= 0.05 reached statistical significance on a monovariable analysis.

Based on the previous analysis and on previously published data we applied gender, age at the time of diagnosis, presence of unprovoked VTE episode and VTE location on a multiple regression analysis in order to define independent risk factors concerning VTE recurrence (Table 1).

Concerning VTE location, CNS thrombosis has the lowest risk for VTE recurrence and Pulmonary embolism and DVT are independent risk factors compared to the first one.

Among VTE events CNS thrombosis and DVT/PE share similarities regarding the transient risk factors and the presence of predisposing thrombophilias. As far as the recurrence risk after a first VTE our study demonstrates ( in agreement with current literature) that CNS thrombosis carries recurrence risk statistically lesser than PE and the highest recurrence risk carry the patients after a first DVT event. Our study is the first observational study regarding recurrence risk after VTE coming from Greece.