Effectiveness and safety of thromboprophylaxis in total hip arthroplasty – a register

Abstract

Abstract Introduction: Venous thromboembolism (VTE) is a common and potentially lethal complication after total hip arthroplasty (THA). While low molecular weight heparin (LMWH) remains the gold standard antithrombotic medication after THA in Nordic countries, recent randomized trials have demonstrated superior efficacy in new oral anticoagulants (NOAC) such as dabigatran and rivaroxaban compared to LMWH. In this register study we compared established efficacy and safety outcomes between patients who had received LMWH and NOAC as thromboprophylaxis after THA. Method: Data was collected from the Swedish Hip Arthroplasty Register (SHAR), the National Patient Register (NPR) and the Prescribed Drug Register (PDR) to form a database from which 32633 patients were selected. These included all primary THA procedures for patients with osteoarthritis. Patients who had an earlier VTE diagnosis or received a potent anticoagulant were excluded from the analysis. A binary logistic regression model adjusted for age, sex and previous antiaggregant medication was used to calculate odds ratios (OR) for VTE-incidence up till 3 months after surgery. Results: 26881 patients received LMWH and 5752 patients were treated with NOAC. The VTE-incidence in the LMWH group was 1.0% (n=264) and 0.4% (n=24) in the NOAC group. Adjusted OR for VTE was 0.42 (95% CI: 0.28-0.64, p<0.0001); deep venous thrombosis (DVT) 0.46 (95% CI: 0.28-0.76, p=0.002); pulmonary embolism (PE) 0.34 (95% CI:0.17-0.71, p=0.004); major bleeding events 0.96 (95% CI: 0.72-1.27, p=0.756); and minor bleeding events 0.75 (95% CI: 0.32-1.79, p=0.521) in the NOAC group. Conclusion: The incidence of VTE following THA was lower for patients with NOAC compared to those with LMWH as thromboprophylactic medication. There were no differences in adverse events including bleeding, reoperation and death. Similar, but less pronounced differences have been reported previously. Although, there may be residual confounding due to selection bias the magnitude of the difference warrants a call for change of practice. Abbreviations THA Total hip arthroplasty TKA Total knee arthroplasty VTE Venous thromboembolism DVT Deep venous thrombosis PE Pulmonary embolism SHAR Swedish Hip Arthroplasty Register PDR Prescribed Drug Register NPR National Patient Register LMWH Low molecular weight heparin NOAC New oral anticoagulants OR Odds ratio CI Confidence interval BMI Body mass index ASA American Society of Anesthesiologists