PB0428 - Post-thrombotic syndrome in patients with venous thromboembolism treated with rivaroxaban – Results from the FIRST Registry

Background: Post-thrombotic syndrome (PTS) is a common complication of deep vein thrombosis (DVT) and affects 20-50% of patients. Recent studies have reported that rivaroxaban may reduce the risk of PTS compared with warfarin. Data reporting the incidence and severity of PTS after treatment with rivaroxaban in routine practice are limited.

Aims: To report the incidence and severity of PTS in patients managed with rivaroxaban for DVT enrolled in the FIRST registry assessed using the patient-reported Villalta scale (PRV).

Methods: The FIRST registry was a UK only, non-interventional prospective multicentre study, investigating the incidence of long-term complications of VTE in patients treated with rivaroxaban. (Clinicaltrials.gov NCT02248610). Participants with a diagnosis of DVT were sent the PRV by mail. The PRV is a validated adaptation of the Villalta scale. Questionnaire data were entered locally onto the web-based registry database. The presence of PTS was reported as a PRV score >4 and categorised according to severity. Data were analysed with descriptive statistics. Comparison between subgroups was made using a Mann-Whitney test for continuous data or the chi square or Fisher’s exact test for categorical data.

Results: 934 (74%) of participants were enrolled in the FIRST registry with a lower limb DVT. 628/934 remained in follow-up on the 7/1/20 when the questionnaires were sent to local sites. In total, 215 (34%) were returned. 44.7% of participants were reported to have PTS. Participants with proximal index events were more likely to report PTS (p <.05) (Table 1.) Post thrombotic syndrome was severe in 9.8% of cases (Table 2.)

Conclusion(s): In this cross-sectional sub study from the FIRST registry, PTS was reported at a higher frequency in participants treated with rivaroxaban in routine clinical practice to that reported in post hoc phase III analyses, but at a comparable frequency to emerging real world data.