Management of Secondary Prevention in Venous Thromboembolism: Use of Reduced Doses of Rivaroxaban and Apixaban in Extended Therapy
Authors: Campoy Desiree , Flores Katia , Artaza Gonzalo , Velasquez César A , Canals Tania , Johansson Erik A , Peró Agustí , Sierra Jorge , Salinas Ramón , Olivera Pável E 
Published: November 2020

BACKGROUND
After a standard anticoagulation period (3-6 months), the risk of venous thromboembolism recurrence (RVTER) needs to be considered. Such risk is higher in unprovoked events and patients with persistent risk factor. The increase of D-dimer (DD) levels during the therapy seems to be strongly associated to RVTER. The use of rivaroxaban 10 mg/day and apixaban 2.5mg/12h as an extended therapy (ET) after the standard anticoagulation period has been proven to be an effective strategy to prevent recurrence without increasing bleeding events.
AIM
To assess the effectiveness and safety of reduced doses of rivaroxaban and apixaban as ET in patients with RVTER and to compare their DD levels with those of a control group on anticoagulant therapy at a standard dose.
METHODS
From April 2016 to June 2020, we included patients with venous thromboembolism (VTE) who received ET with rivaroxaban and apixaban with/at reduced doses. Dose reduction was performed following the clinical algorithm of our unit (Fig. 1). The DD values were determined using HemosIl D-Dimer HS-500 and the cut-off value was established at 500 µg/L DD levels were compared with a control group of 235 patients with VTE who received ET with standard doses of anticoagulation. DD levels were measured at the time of diagnosis (D1), initiation of treatment (D2) and 3 months after treatment (D3).
RESULTS
From a total of 116 patients (65.5% women), 77.6% (n=90) received rivaroxaban 10 mg/24h and 22.4% received apixaban 2.5 mg/12h as an ET. The mean duration of the initial anticoagulant therapy was 12 +/- 8.8 months. The mean DD value prior to the ET was 388 µg/L. In this group, 63.8% (n=74) was an unprovoked VTE and 17.2% (20) had hereditary thrombophilia. The mean of follow-up time was 6.9 +/- 8.3 months. No recurrences of VTE were observed during the follow-up and only one major bleeding event was reported in a high-bleeding risk patient.
We observed a progressive decrease of DD levels from the VTE diagnosis to the last visit, with D1, D2, and D3 values of 987 µg/L ± 324, 388 µg/L ± 134, and 288 µg/L ± 98, respectively. There were no differences in d-dimer concentrations between patients with reduce doses of rivaroxaban or apixaban and the control group with standard doses (D1: 85.6% vs 81%, p =0.22; D2: 10.2% vs 8.0%, p =0.14; and D3: 9.1% vs 9.5%, p =0.18).
CONCLUSIONS
Our data indicated that an ET strategy with reduced doses of rivaroxaban or apixaban is effective and safe. We did not observe significant differences in DD levels at follow-up compared to the control group receiving a standard dose of anticoagulation. Further studies are needed in order to select and standardize dose reduction criteria in secondary prevention.
Figure 1

Disclosures
Campoy: boehringer ingelheim: Consultancy; Daiichi Sankyo: Speakers Bureau. Sierra:Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Research Funding; Astellas: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead-Kite: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Olivera:Daiichi Sankyo: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Boehringer Ingelheim: Consultancy, Speakers Bureau; BAYER: Consultancy.