Possible failure of novel direct-acting oral anticoagulants in management of pulmonary embolism: a case report

BACKGROUND: The relative effectiveness of vitamin K antagonists compared with novel oral anticoagulants in treating pulmonary embolism remains unclear. Recent trials comparing the efficacy of vitamin K antagonists with factor Xa inhibitors for the treatment of pulmonary emboli have been non-inferiority studies based primarily on risk reduction (such as bleeding events), rather than resolution of specific diseases such as pulmonary embolism. Consequently, there is a lack of evidence indicating which of these agents are more effective. Here, we present a case where pulmonary emboli were treated with novel oral anticoagulants followed by warfarin to discuss the potential limitations in the use of novel oral anticoagulants as prevention or treatment of thromboembolism and the continued role for warfarin in this setting. CASE PRESENTATION: A 34-year-old African American woman presented to our clinic with shortness of breath and pleuritic chest pain several months post-surgery. She was identified as having multiple bilateral pulmonary embolisms and was treated with several novel oral anticoagulants, which failed to resolve the clots. Complete resolution was achieved upon switching to warfarin. CONCLUSIONS: The patient described in this report failed to respond to novel oral anticoagulant therapy, but her emboli resolved when she was treated with warfarin. This study challenges the notion that factor Xa inhibitors are better alternatives to vitamin K anticoagulants in the treatment of pulmonary emboli based on their safety profile and ease of use alone. As a result, further post-marketing investigations into the efficacy of these agents in the management of pulmonary emboli may be warranted

System Dynamics to Model the Unintended Consequences of Denying Payment for Venous Thromboembolism after Total Knee Arthroplasty

Background: The Hospital Acquired Condition Strategy (HACS) denies payment for venous thromboembolism (VTE) after total knee arthroplasty (TKA). The intention is to reduce complications and associated costs, while improving the quality of care by mandating VTE prophylaxis. We applied a system dynamics model to estimate the impact of HACS on VTE rates, and potential unintended consequences such as increased rates of bleeding and infection and decreased access for patients who might benefit from TKA. Methods and Findings: The system dynamics model uses a series of patient stocks including the number needing TKA, deemed ineligible, receiving TKA, and harmed due to surgical complication. The flow of patients between stocks is determined by a series of causal elements such as rates of exclusion, surgery and complications. The number of patients harmed due to VTE, bleeding or exclusion were modeled by year by comparing patient stocks that results in scenarios with and without HACS. The percentage of TKA patients experiencing VTE decreased approximately 3-fold with HACS. This decrease in VTE was offset by an increased rate of bleeding and infection. Moreover, results from the model suggest HACS could exclude 1.5% or half a million patients who might benefit from knee replacement through 2020. Conclusion: System dynamics modeling indicates HACS will have the intended consequence of reducing VTE rates. However, an unintended consequence of the policy might be increased potential harm resulting from over administration of prophylaxis, as well as exclusion of a large population of patients who might benefit from TKA