THE MYTH OF THE STABLE INR PATIENT: RESULTS FROM ORBIT-AF

Thromboembolism, bleeding and vascular death in nonvalvular atrial fibrillation patients with type 2 diabetes receiving rivaroxaban or warfarin

BACKGROUND

Diabetes increases a patient's risk of developing atrial fibrillation by 49%. Patients with nonvalvular atrial fibrillation are at a fivefold increased risk of stroke and die more frequently from vascular causes. We sought to evaluate the effectiveness and safety of rivaroxaban versus warfarin in nonvalvular atrial fibrillation patients with type 2 diabetes.

METHODS

This was an analysis of Optum® De-Identified electronic health record data from 11/2010 to 12/2019. We included adults with nonvalvular atrial fibrillation and type 2 diabetes, newly started on rivaroxaban or warfarin and with ≥ 12-months of prior electronic health record activity. Patients who were pregnant, had alternative indications for oral anticoagulation or valvular heart disease were excluded. We evaluated the incidence rate (%/year) of developing the composite outcome of stroke/systemic embolism or vascular death and major or clinically relevant nonmajor bleeding as well as each endpoint individually. Hazard ratios with 95% confidence intervals were calculated using propensity score-overlap weighted proportional hazards regression.

RESULTS

We included 32,078 rivaroxaban (31% initiated on 15 mg dose) and 83,971warfarin users (time-in-therapeutic range = 47 ± 28%). Rivaroxaban was associated with a reduced risk of stroke/systemic embolism or vascular death (3.79 vs. 4.19; hazard ratio = 0.91, 95% confdience interval = 0.88-0.95), driven mostly by reductions in vascular death (2.81 vs 3.18, hazard ratio = 0.90, 95% confidence interval = 0.86-0.95) and systemic embolism (0.13 vs. 0.16; hazard ratio = 0.82, 95% confidence interval = 0.66-1.02). Major/clinically relevant nonmajor bleeding was less frequent with rivaroxaban versus warfarin (2.17 vs. 2.31; hazard ratio = 0.94, 95% confidence interval = 0.89-0.99) due to decreased critical organ bleeding (including intracranial hemorrhage) (0.35 vs. 0.54; hazard ratio = 0.63, 95% confidence interval = 0.55-0.72).

CONCLUSIONS

In nonvalvular atrial fibrillation patients with type 2 diabetes, rivaroxaban was associated with an ~ 10% relative reduction in vascular mortality and fewer bleeding-related hospitalizations versus warfarin.

Rivaroxaban real-world evidence: Validating safety and effectiveness in clinical practice

Randomised controlled trials (RCTs) are considered the gold standard of clinical research as they use rigorous methodologies, detailed protocols, pre-specified statistical analyses and well-defined patient cohorts. However, RCTs do not take into account the complexity of real-world clinical decision-making. To tackle this, real-world data are being increasingly used to evaluate the long-term safety and effectiveness of a given therapy in routine clinical practice and in patients who may not be represented in RCTs, addressing key clinical questions that may remain. Real-world evidence plays a substantial role in supporting the use of non-vitamin K antagonist (VKA) oral anticoagulants (NOACs) in clinical practice. By providing data on patient profiles and the use of anticoagulation therapies in routine clinical practice, real-world evidence expands the current awareness of NOACs, helping to ensure that clinicians are well-informed on their use to implement patient-tailored clinical decisions. There are various issues with current anticoagulation strategies, including under- or overtreatment and frequent monitoring with VKAs. Real-world studies have demonstrated that NOAC use is increasing (Dresden NOAC registry and Global Anticoagulant Registry in the FIELD-AF [GARFIELD-AF]), as well as reaffirming the safety and effectiveness of rivaroxaban previously observed in RCTs (XArelto on preveNtion of sTroke and non-central nervoUS system systemic embolism in patients with non-valvular atrial fibrillation [XANTUS] and IMS Disease Analyzer). This article will describe the latest updates in real-world evidence across a variety of methodologies, such as non-interventional studies (NIS), registries and database analyses studies. It is anticipated that these studies will provide valuable clinical insights into the management of thromboembolism, and enhance the current knowledge on anticoagulant use and outcomes for patients.

Vitamin K antagonist use: evidence of the difficulty of achieving and maintaining target INR range and subsequent consequences

Vitamin K antagonists (VKAs) are effective oral anticoagulants that are titrated to a narrow therapeutic international normalized ratio (INR) range. We reviewed published literature assessing the impact of INR stability - getting into and staying in target INR range - on outcomes including thrombotic events, major bleeding, and treatment costs, as well as key factors that impact INR stability.

A time in therapeutic range (TTR) of ≥65 % is commonly accepted as the definition of INR stability. In the real-world setting, this is seldom achieved with standard-of-care management, thus increasing the patients’ risks of thrombotic or major bleeding events. There are many factors associated with poor INR control. Being treated in community settings, newly initiated on a VKA, younger in age, or nonadherent to therapy, as well as having polymorphisms of CYP2C9 or VKORC1, or multiple physical or mental co-morbid disease states have been associated with lower TTR. Clinical prediction tools are available, though they can only explain <10 % of the variance behind poor INR control.

Clinicians caring for patients who require anticoagulation are encouraged to intensify diligence in INR management when using VKAs and to consider appropriate use of newer anticoagulants as a therapeutic option.