Assess the safety of apixaban versus warfarin regarding ISTH major bleeding or clinically relevant non-major bleeding events in patients with NVAF (nonvalvular atrial fibrillation) and ESRD (end-stage renal disease) on hemodialysis.

Major bleeding event is defined as:Acute clinically overt bleeding (including access site related bleeding) accompanied by 1 or more of the following: Decrease in Hgb of 2g/dL or more with overt bleeding; Transfusion of 2 or more units of packed RBCs in the setting of an overt bleeding event; Bleeding within a critical site. Hemorrhagic stroke (primary or infarction with hemorrhagic conversion) were classified as major bleeds.

Non-major bleeding event is defined as: Acute or sub-acute clinically overt bleeding (including access site related bleeding) that does not meet criteria for major bleeding & results in Hospital admission for bleeding, physician guided medical or surgical treatment for bleeding, or change in antithrombotic therapy

Intent to Treat Population(ITT): Consists of all unique randomized participants regardless of their compliance with the study protocol. Participants are analyzed in the treatment group to which they were randomized.

Number of participants experiencing adjudicated stroke or systemic embolism.

Intent to Treat Population (ITT): Consists of all unique randomized participants regardless of their compliance with the study protocol. Participants are analyzed in the treatment group to which they were randomized.

Evaluate mortality rates for those participants randomized to warfarin and apixaban in patients with NVAF and ESRD on hemodialysis

Intent to Treat Population(ITT): Consists of all unique randomized participants regardless of their compliance with the study protocol. Participants are analyzed in the treatment group to which they were randomized..

Evaluate days between time from initiation to discontinuation of randomized therapy.

Consists of all unique participants who took at least one dose of the randomized study drug. Participants were analyzed as randomized.

Evaluate the pharmacokinetics of apixaban in ESRD NVAF patients on hemodialysis. The measurement was done from 0-12 hours after the dose was given on Day 1.

Participants in the Apixaban group who had a plasma sample collected. This outcome measure is not relevant to the Warfarin group.

Evaluate the pharmacokinetics of apixaban in ESRD NVAF patients on hemodialysis. The measurement was done from 0-12 hours after the dose was given on Day 1.

Participants in the Apixaban group who had a plasma sample collected. This outcome measure is not relevant to the Warfarin group.

Evaluate the pharmacokinetics of apixaban in ESRD NVAF patients on hemodialysis. The measurement was done from 0 to 12 hours after dose was given on Day 1.

Participants in the Apixaban group who had a plasma sample collected. This outcome measure is not relevant to the Warfarin group.

Evaluate the pharmacodynamics of apixaban in ESRD NVAF patients on hemodialysis

Data not collected.

Measured by self-reported days of medication compliance over the last 30 days.

Participants who reported medication compliance at month 15.

Adjudicated diagnosis of systemic arterial embolism (Non-pulmonary, non-cranial events) will require a positive clinical history consistent with an acute loss of blood flow to a peripheral artery (or arteries), which is supported by evidence of embolism/thrombosis from surgical specimens, autopsy, angiography, vascular imaging, or other objective testing.

Clinical presentation would include:

1. Abrupt development of pain, absent pulses, pallor, and/or paresis in an extremity (at least an entire digit) without previous severe claudication or findings of severe peripheral vascular disease.
2. Renal embolism will be diagnosed when sudden flank pain or a change in renal laboratory findings occurred.
3. Abdominal vascular/visceral embolism was considered definite if acute abdominal symptoms or referred symptoms developed along with a change in abdominal examination or appropriate laboratory values.

Adjudcated stroke defined as a new, non-traumatic episode of focal or global neurological dysfunction of sudden onset caused by central nervous system (CNS) vascular injury as a result of hemorrhage or infarction and not due to a readily identifiable non-vascular cause (i.e. brain tumor). CNS includes brain, spinal cord and retina. The required duration of the deficit is ≥ 24 hours.

• Events with neurologic deficit lasting for < 24 hours and an imaging modality showing evidence of an acute stroke will be counted as stroke as well.
• A retinal ischemic event (embolism, infarction) will be considered a stroke

Evaluate those experiencing stroke, systemic embolism, ISTH major bleeding, or all-cause mortality for those randomized to warfarin and apixaban in patients with NVAF and ESRD on hemodialysis

Definitions of stroke and systemic embolism are provided under the measurement description of the secondary outcomes for each individual event. Definition of major bleed is provided in outcome measurement description of the primary outcome measure.

Intent to Treat Population(ITT): Consists of all unique randomized participants regardless of their compliance with the study protocol. Participants are analyzed in the treatment group to which they were randomized.

Analysis of outcomes and treatment effect according to levels of cardiovascular biomarkers at baseline