Background Rivaroxaban, a direct Factor Xa inhibitor, has been shown to be more effective in preventing venous thromboembolism than enoxaparin regimens, with a similar safety profile, in patients undergoing hip or knee arthroplasty (the phase III RECORD studies). Rivaroxaban is approved for this indication worldwide.

Purpose To examine the effectiveness and safety of rivaroxaban for thromboprophylaxis in routine clinical practise and the impact of selected co-medication use on outcomes.

Materials and Methods XAMOS was a phase IV, non-interventional, open-label cohort study in patients undergoing major orthopaedic surgery in daily clinical practise. The choice of rivaroxaban or standard of care (SOC) for VTE prophylaxis was at the discretion of the attending physicians. All adverse events, including symptomatic thromboembolic and bleeding events, and pre-trial and concomitant use of medicines were reported.

Results XAMOS enrolled 17,701 patients; the safety population included 17,413 patients, of whom 8778 received rivaroxaban and 8635 received SOC (81.7% low molecular weight heparin). Baseline patient demographics and use of cytochrome P450 (CYP) 3A4 inhibitors or inducers and platelet aggregation inhibitors (PAIs) before surgery were similar between groups; these drugs were used less frequently after surgery. There was a significant reduction in the incidence of symptomatic thromboembolic events in the rivaroxaban group compared with the SOC group, with numerically but not statistically higher incidence of major bleeding events. Concomitant use of PAIs was associated with higher incidences of symptomatic thromboembolic and any bleeding events compared with non-use in both the rivaroxaban and the SOC groups (Table).

Conclusions XAMOS confirmed the results of the RECORD studies. CYP3A4 inhibitors or inducers and PAIs were used less frequently after surgery compared with before surgery. The benefit–risk profile of rivaroxaban compared with SOC was maintained in routine clinical practise in patients undergoing major orthopaedic surgery, including patients with concomitant use of PAIs.

No conflict of interest.