Differences in urinary prothrombin fragment 1+2 levels after total hip replacement in relation to venous thromboembolism and bleeding events

Background: Prothrombin fragment 1 + 2 is excreted in urine (uF1 + 2) as a result of thrombin generation and, therefore, may be a useful marker of coagulation status. Objectives: To assess uF1 + 2 levels after total hip replacement (THR) in patients with venous thromboembolism (VTE) and bleeding events. Patients/methods: This study was conducted in parallel with a prospective, dose-finding study evaluating the efficacy and safety of different doses of rivaroxaban (Xarelto((R)), Bayer HealthCare AG, Wuppertal, Germany) for thromboprophylaxis, relative to enoxaparin. Deep vein thrombosis was diagnosed by mandatory venography performed 5-9 days after THR, or earlier if symptomatic. Symptomatic pulmonary embolism was diagnosed by objective testing. Bleeding complications were registered and stratified into major bleeding, clinically relevant, non-major bleeding, and minor bleeding, using predefined criteria. Results: Eighty-four patients had a VTE and 57 patients had a bleeding event (n = 722). Significantly higher median uF1 + 2 levels were observed in the VTE group on day 3 after THR (P = 0.03), compared with control. Median uF1 + 2 levels were lower in the bleeding group on day 3 after THR (P = 0.005) and on the day of venography (P = 0.36), compared with control. Comparisons between the VTE and bleeding groups showed significantly lower median uF1 + 2 levels in the bleeding group on day 3 after THR and on the day of venography (P < 0.0001 and P = 0.006, respectively). Conclusions: Measurement of uF1 + 2 could provide a simple clinical test to evaluate non-invasively the intensity of coagulation activation after THR. However, further studies are required to confirm these encouraging preliminary results.