EINSTEIN programme

Treatment of Venous Thromboembolism: the EINSTEIN Programme

The EINSTEIN clinical trial programme comprises three randomized phase III studies of rivaroxaban for the treatment of venous thromboembolism (VTE) and the long-term prevention of recurrent VTE. It is the only clinical programme that has investigated a new oral anticoagulant for the treatment of acute deep vein thrombosis (DVT) and treatment for acute pulmonary embolism (PE) in separate trials.

  • EINSTEIN DVT: rivaroxaban versus enoxaparin plus a vitamin K antagonist (VKA) in the treatment of acute DVT without symptomatic PE
  • EINSTEIN PE: rivaroxaban versus enoxaparin plus a VKA in the treatment of acute PE with or without symptomatic DVT
  • EINSTEIN EXT: rivaroxaban versus placebo in the long-term prevention of recurrent, symptomatic VTE in patients who had already received 6–12 months of anticoagulant treatment for DVT or PE

EINSTEIN DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
design

Single-drug therapy with oral rivaroxaban versus dual-drug therapy with subcutaneous subcutaneous
Introduced beneath the skin.
enoxaparin and oral VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.

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Acute DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
is a common disorder. The current standard of care is dual-drug therapy with a parenteral agent (such as unfractionated heparin, low molecular weight heparin or fondaparinux) plus a vitamin K antagonist (VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
) followed by international normalized ratio (INR INR
International normalised ratio (= INR). A system for assessing the clotting tendency of blood in patients receiving anticoagulant therapy. For patients with atrial fibrillation, the recommended target INR range is between 2 and 3. If the INR is higher than 3, patients are at risk of serious bleeding. If the INR is less than 2, patients are at risk of a blood clotting event.
)-adjusted VKA alone.1 Although short-term treatment with the current standard of care is effective, management of acute DVT with VKA therapy in the outpatient setting remains challenging. Many of these challenges relate to the limitations of VKA therapy, which include:2

  • Narrow therapeutic window
  • Requirement for regular coagulation monitoring and dose adjustment
  • Multiple food and drug interactions
  • Lifestyle limitations

Rivaroxaban, as a newer oral anticoagulant anticoagulant
Anticoagulant drugs are used to treat and prevent blood clots. Sometimes referred to as ‘blood thinners’.
, overcomes many of these limitations. It has a rapid onset of action and so does not require bridging therapy with parenteral agents. It does not require routine coagulation monitoring and has minimal interactions with commonly prescribed drugs; therefore, rivaroxaban provides a convenient, simplified treatment option for patients, with a consequent positive impact on daily life.

 
Objective

The main objective of EINSTEIN DVT was to determine whether a single-drug approach with oral rivaroxaban was at least as effective as (non-inferior to) dual-drug therapy with enoxaparin/VKA and to compare the safety of these two approaches for the treatment of patients with acute symptomatic DVT without symptomatic PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
.

 
Study design

EINSTEIN DVT was an randomized, open-label, event-driven, non-inferiority study of 3449 patients with a predefined treatment duration of 3, 6 or 12 months. The patients were randomly assigned to receive one of the following regimens:

  • Oral rivaroxaban 15 mg twice daily for 3 weeks followed by 20 mg once daily for the remaining treatment period
  • Subcutaneous Subcutaneous
    Introduced beneath the skin.
    , body weight-adjusted enoxaparin twice daily for at least 5 days plus a VKA, followed by dose-adjusted VKA only (target INR of 2.0–3.0) for the remaining treatment period
EINSTEIN DVT study design
 
Endpoints
  • The primary efficacy endpoint was symptomatic, recurrent VTE VTE
    Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
    – the composite of recurrent DVT or fatal or non-fatal PE
  • The principal safety outcome was clinically relevant bleeding, defined as the composite of major bleeding or non-major clinically relevant bleeding; major bleeding was defined as overt bleeding associated with any of the following:
    • A decrease in haemoglobin of 2 g/dl or more
    • A transfusion of two or more units of packed red blood cells or whole blood
    • Occurrence at a critical site, such as intracranial or retroperitoneal
    • Death

EINSTEIN DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
results

Efficacy and safety of rivaroxaban in the treatment of deep vein thrombosis thrombosis
Formation of a clot inside a blood vessel.

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EINSTEIN DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
met its primary efficacy endpoint and showed that a single-drug approach with oral rivaroxaban was at least as effective as (non-inferior to) conventional dual-drug therapy (subcutaneous subcutaneous
Introduced beneath the skin.
enoxaparin plus vitamin K antagonist [VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
] followed by VKA alone), with a similar safety profile, for the treatment of acute, symptomatic deep vein thrombosis thrombosis
Formation of a clot inside a blood vessel.
(DVT).

There was a significant improvement in the net clinical benefit for rivaroxaban compared with enoxaparin/VKA, achieved via a significant reduction in recurrent venous thromboembolism and a numerically lower incidence of major bleeding.

In conclusion, EINSTEIN DVT demonstrated that a fixed-dose regimen of oral rivaroxaban offers an effective and convenient single-drug alternative, with reassuring safety, to the current standard of care of dual-drug therapy for the treatment of acute DVT.

 
Patient demographics

Patients were well matched in both study arms, with similar demographic and clinical characteristics:

  • Mean age: ~56 years
  • ~57% were male
  • ~83% had a body weight of >50 to 100 kg
  • ~69% had creatinine clearance ≥80 ml/min, with a further 23% classified as having mild renal impairment (creatinine clearance 50–79 ml/min)
  • ~19% had experienced a previous venous thromboembolic event before the acute, symptomatic DVT that qualified them for inclusion in the study
 
Primary efficacy endpoint: single-drug therapy with rivaroxaban was non-inferior to dual-drug therapy with enoxaparin plus VKA for the treatment of acute DVT

The primary efficacy outcome occurred in 36/1731 (2.1%) patients treated with rivaroxaban, compared with 51/1718 (3.0%) patients treated with enoxaparin/VKA (p<0.001 for non-inferiority); there was a trend towards superiority for rivaroxaban.

einstein dvt primary effect

Source: The Einstein Investigators (2010).

efficacy outcome rivaroxaban vs enoxaparin VKA

CI, confidence interval; DVT, deep vein thrombosis; PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
, pulmonary embolism; VKA, vitamin K antagonist; VTE VTE
Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
, venous thromboembolism.

  • Composite of DVT or non-fatal or fatal PE.
 
Safety outcome: similar rates of bleeding with rivaroxaban and enoxaparin/VKA

Rivaroxaban was well-tolerated by patients in EINSTEIN DVT, and the rate of major or non-major clinically relevant bleeding was similar to that for enoxaparin plus VKA followed by VKA alone.

safety outcome hazard ratio rivaroxaban enoxaparin VKA

CI, confidence interval; PE, pulmonary embolism; VKA, vitamin K antagonist.

 
Rivaroxaban provides superior net clinical benefit

A key secondary endpoint in the study was net clinical benefit; defined as the composite of the primary efficacy endpoint and major bleeding.

  • The net clinical benefit outcome occurred in 51/1731 (2.9%) patients who received rivaroxaban compared with 73/1718 (4.2%) patients who received enoxaparin/VKA (hazard ratio 0.67; 95% confidence interval 0.47–0.95; p=0.03)
 
Adverse event rates were similar in the two treatment groups during the treatment period
adverse event rivaroxaban enoxaparin VKA

CI, confidence interval; PE, pulmonary embolism; VKA, vitamin K antagonist.

EINSTEIN PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
design

Single-drug therapy with oral rivaroxaban versus dual-drug therapy with subcutaneous subcutaneous
Introduced beneath the skin.
enoxaparin and oral VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.

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PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
is the most severe complication of DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
. It is associated with significant mortality and is often undiagnosed.1 Up to 26% of patients with untreated, clinically diagnosed PE die within 2 weeks.2 The current standard of care is initial parenteral therapy (with unfractionated heparin, low molecular weight heparin or fondaparinux) plus a VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
, followed by long-term management with INR INR
International normalised ratio (= INR). A system for assessing the clotting tendency of blood in patients receiving anticoagulant therapy. For patients with atrial fibrillation, the recommended target INR range is between 2 and 3. If the INR is higher than 3, patients are at risk of serious bleeding. If the INR is less than 2, patients are at risk of a blood clotting event.
-adjusted VKA alone.333 Short-term treatment with conventional anticoagulant anticoagulant
Anticoagulant drugs are used to treat and prevent blood clots. Sometimes referred to as ‘blood thinners’.
therapy is effective, but long-term management with VKA therapy is challenging. Many of these challenges relate to the limitations of VKA therapy, which include.5

  • Narrow therapeutic window
  • Requirement for frequent coagulation monitoring and dose adjustments
  • Multiple food and drug interactions
  • Lifestyle limitations

Rivaroxaban, as a newer oral anticoagulant, overcomes many of these limitations. It has a rapid onset of action and so does not require bridging therapy with parenteral agents. It does not require routine coagulation monitoring and has minimal interactions with commonly prescribed drugs; therefore, rivaroxaban provides a convenient, simplified treatment option for patients, with a consequent positive impact on daily life.

 
Objective

The objective of EINSTEIN PE was to determine whether a single-drug approach with oral rivaroxaban is at least as effective as (non-inferior to) dual-drug therapy with enoxaparin/VKA and to compare the safety of these two approaches in the treatment of patients with confirmed acute symptomatic PE with or without symptomatic DVT.

 
Study design

EINSTEIN PE was an randomized, open-label, event-driven, non-inferiority study of 4833 patients with a predefined treatment duration of 3, 6 or 12 months. The patients were randomly assigned to receive one of the following regimens:

  • Oral rivaroxaban 15 mg twice daily for 3 weeks followed by 20 mg once daily for the remaining treatment period
  • Subcutaneous Subcutaneous
    Introduced beneath the skin.
    body weight-adjusted enoxaparin twice daily for at least 5 days plus a VKA, followed by dose-adjusted VKA only (target INR of 2.0–3.0) for the remaining treatment period
 
Endpoints
  • The primary efficacy endpoint was symptomatic, recurrent VTE VTE
    Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
    – the composite of recurrent DVT or fatal or non-fatal PE
  • The principal safety outcome was the combination of major and non-major clinically relevant bleeding; major bleeding was defined as overt bleeding associated with any of the following:
    • A decrease in haemoglobin of 2 g/dl or more
    • A transfusion of two or more units of packed red blood cells or whole blood
    • Occurrence at a critical site, such as intracranial or retroperitoneal
    • Death
EINSTEIN DVT Study Design CO

EINSTEIN PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
results

Efficacy and safety of rivaroxaban in the treatment of pulmonary embolism

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EINSTEIN PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
demonstrated that oral rivaroxaban was at least as effective as (non-inferior to) standard dual-drug therapy with subcutaneous subcutaneous
Introduced beneath the skin.
enoxaparin plus vitamin K antagonist (VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
) followed by VKA alone for the treatment of acute, symptomatic pulmonary embolism (PE) with or without symptomatic deep vein thrombosis thrombosis
Formation of a clot inside a blood vessel.
(DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
). It also demonstrated that rivaroxaban had a similar rate of clinically relevant bleeding to standard therapy but significantly reduced the incidence of major bleeding.

In conclusion, EINSTEIN PE demonstrates that oral rivaroxaban is a simple and effective, single-drug solution for the treatment of acute PE with or without symptomatic DVT, with an improved benefit–risk profile compared with the standard of care.

 
Patient demographics

Patients were well matched in both study arms, with similar demographic and clinical characteristics:

Mean age: ~58 years

~53% were male

~83% had a body weight of >50 to 100 kg

~66% had creatinine clearance ≥80 ml/min, with a further 25% classified as having mild renal impairment (creatinine clearance 50–79 ml/min)

~24% had extensive PE (involving multiple lobes and >25% of entire pulmonary vasculature)

~25% had concurrent symptomatic DVT

~19% had experienced a previous venous thromboembolic event before the acute, symptomatic and objectively confirmed PE that qualified them for inclusion in the study

 
Primary efficacy endpoint: single-drug therapy with rivaroxaban was non-inferior to dual-drug therapy with enoxaparin plus VKA for the treatment of acute PE

The primary efficacy outcome (composite of non-fatal or fatal PE or DVT) occurred in 50/2419 (2.1%) patients treated with rivaroxaban, compared with 44/2413 (1.8%) patients treated with standard therapy (p=0.003 for non-inferiority).

EINSTEIN PE primary efficacy endpoint

Source: The EINSTEIN PE Investigators. (2012).121 VKA, vitamin K antagonist.

 
Clinical outcomes in each study group
clinical outcomes in each study group

Source: The EINSTEIN PE Investigators. (2012).121 VKA, vitamin K antagonist.

  • Composite of non-fatal or fatal PE or DVT.

CI, confidence interval; DVT, deep vein thrombosis; PE, pulmonary embolism; VKA, vitamin K antagonist; VTE VTE
Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
, venous thromboembolism.

 
Rivaroxaban had similar rates of clinically relevant bleeding compared with standard therapy but reduced major bleeding by 51%

In EINSTEIN PE, the rate of major or non-major clinically relevant bleeding in patients receiving rivaroxaban was similar to that for standard therapy. Importantly, major bleeding was significantly reduced in patients receiving rivaroxaban compared with those receiving standard therapy (p=0.003) and the rates of critical site bleeding were markedly lower for rivaroxaban.

safety outcome rivaroxaban vs enoxaparin hazard ratio

CI, confidence interval; PE, pulmonary embolism; VKA, vitamin K antagonist.

 
Rivaroxaban provides comparable net clinical benefit to standard therapy

Net clinical benefit, defined as the composite of the primary efficacy endpoint and major bleeding, was a key secondary endpoint in EINSTEIN PE.

In EINSTEIN PE, rivaroxaban had a similar net clinical benefit compared with enoxaparin plus VKA followed by VKA alone, with numerically fewer events.

  • The net clinical benefit outcome occurred in 83/2419 (3.4%) patients who received rivaroxaban compared with 96/2413 (4.0%) patients who received standard therapy (hazard ratio 0.85; 95% confidence interval 0.63–1.14; p=0.28)
 
Adverse event rates were similar in the two treatment groups during the treatment period
adverse event rivaroxaban vs enoxaparin VKA

VKA, vitamin K antagonist.

EINSTEIN EXT design

Rivaroxaban in the long-term prevention of recurrent, symptomatic VTE VTE
Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.

MORE

Effective treatment of an acute venous thromboembolic event reduces the risk of recurrence dramatically, from an estimated 25% to approximately 3% during the first 6–12 months. However, the optimal duration of anticoagulation therapy after an acute event remains a matter of debate. Treatment with VKAs beyond 1 year is associated with an annual risk of major bleeding of 1–2%,1 and clinicians must balance the long-term risks of recurrent VTE VTE
Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
if anticoagulation is halted versus the risk of bleeding with further therapy and the healthcare burden of managing this therapy. Long-term management with VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
therapy is challenging and many of these challenges relate to limitations of VKA therapy, which include:2

  • Narrow therapeutic window
  • Requirement for frequent coagulation monitoring and dose adjustments
  • Multiple food and drug interactions
  • Lifestyle limitations

Rivaroxaban, as a newer oral anticoagulant anticoagulant
Anticoagulant drugs are used to treat and prevent blood clots. Sometimes referred to as ‘blood thinners’.
, simplifies DVT DVT
Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
treatment and prevention of recurrent DVT and PE PE
Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
. It does not require routine coagulation monitoring and has minimal interactions with commonly prescribed drugs; therefore, rivaroxaban provides a convenient, simplified treatment option for patients, with a consequent positive impact on daily life.

 
Objective

The main efficacy objective of the EINSTEIN EXT study was to demonstrate that fixed-dose oral rivaroxaban (20 mg once daily) was superior to placebo in the long-term secondary prevention of recurrent VTE in patients with symptomatic DVT or PE who had already completed 6–12 months of VTE treatment with either a VKA or rivaroxaban and in whom there was clinical uncertainty as to whether to continue anticoagulation. Safety was also evaluated.

 
Study design

EINSTEIN EXT was a double-blind, randomized, placebo-controlled, event-driven superiority study of 1197 patients who were at clinical equipoise regarding the need for continued VKA therapy. Patients who had completed the EINSTEIN DVT or EINSTEIN PE studies could be recruited in to EINSTEIN EXT. In addition, patients who had not participated in these studies were also enrolled, if they had received treatment with a VKA up to randomization after an initial diagnosis of DVT or PE. The patients were randomly assigned to one of the following regimens:

  • Rivaroxaban 20 mg tablet once daily
  • Placebo once daily

In both arms, the treatment duration was either 6 or 12 months.

EINSTEIN EXT Study Design CO
 
Endpoints
  • The primary efficacy endpoint was symptomatic, recurrent VTE – the composite of recurrent DVT or fatal or non-fatal PE
  • The principal safety outcome was major bleeding, defined as overt bleeding associated with any of the following:
    • A decrease in haemoglobin of 2 g/dl or more
    • A transfusion of two or more units of packed red blood cells or whole blood
    • Occurrence at a critical site: intracranial or retroperitoneal
    • Death

EINSTEIN EXT results

Efficacy and safety of rivaroxaban for prevention of recurrent venous thromboembolism

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EINSTEIN EXT met its primary efficacy endpoint and showed that extended-duration rivaroxaban (20 mg once daily for 6–12 months) was superior – compared with placebo – for prevention of recurrent venous thromboembolism (VTE VTE
Venous thromboembolism (= VTE). A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
) in patients who had previously completed 6–12 months of treatment for VTE with either rivaroxaban or a vitamin K antagonist.

Rivaroxaban showed a favourable benefit–risk profile, as demonstrated by a significant improvement in the net clinical benefit, which was defined as the composite of the primary efficacy outcome and major bleeding.

In conclusion, EINSTEIN EXT demonstrated that rivaroxaban offers effective long-term prevention of recurrent VTE with reassuring safety.

 
Patient demographics

At study entry, patients in the rivaroxaban and placebo groups had similar demographic and clinical characteristics:

  • Mean age: ~58 years
  • ~58% were male
  • ~82% had a body weight of >50 to 100 kg
  • ~62% had creatinine clearance ≥80 ml/min, with a further 22% classified as having mild renal impairment (creatinine clearance 50–79 ml/min)
  • ~16% had experienced a previous venous thromboembolic event before the deep vein thrombosis thrombosis
    Formation of a clot inside a blood vessel.
    (DVT DVT
    Deep vein thrombosis (= DVT). A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm. Distal DVTs are found in deep veins of the calf, and are the most common type of DVT. Proximal DVTs are found in the legs above the calf muscle up to the waist.
    ) or pulmonary embolism (PE PE
    Pulmonary embolism (= PE). A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
    ) that qualified them for inclusion in the study
 
Primary efficacy endpoint: 82% relative risk reduction with rivaroxaban

The EINSTEIN EXT study included patients about whom there is clinical uncertainty whether to continue or stop anticoagulant anticoagulant
Anticoagulant drugs are used to treat and prevent blood clots. Sometimes referred to as ‘blood thinners’.
therapy after initial prophylaxis for 6–12 months with a VKA VKA
Vitamin K antagonist (= VKA). An anticoagulant that inhibits multiple steps in the blood clotting process. Administered orally, the dose varies by patient, and regular monitoring and dose adjustment are required. Vitamin K antagonists have interactions with food and other drugs. Due to the many limitations of this drug, many of those who are treated are outside of the required target INR range, which can be the cause for increased bleeding or a greater risk of stroke.
or rivaroxaban. This study showed that anticoagulation with rivaroxaban for a further 6 or 12 months was superior to placebo for the long-term prevention of recurrent symptomatic VTE. It also showed that there is still a sustained risk of recurrence in patients with symptomatic DVT or PE after the initial anticoagulant therapy for 6–12 months.

  • To prevent one venous thromboembolic event, only 15 patients need to be treated with rivaroxaban1
Relative risk reduction with rivaroxaban

Source: The EINSTEIN Investigators. (2010).

Clinical outcomes in each study group

Composite of non-fatal or fatal PE or DVT.
CI, confidence interval; DVT, deep vein thrombosis; PE, pulmonary embolism; VKA, vitamin K antagonist; VTE, venous thromboembolism.

 
Safety outcome: incidence of major bleeding was low in the rivaroxaban arm

The primary safety outcome was major bleeding, which was low and occurred in 4/598 (0.7%) patients in the rivaroxaban group and in none of the patients in the placebo group resulting in a non-significant difference (p=0.11). All cases of major bleeding in the rivaroxaban arm did not occur in a critical site, but were associated with a fall in haemoglobin of ≥2 g/dl, transfusion of ≥2 units, or both. The most common non-major clinically relevant bleeding events in the rivaroxaban arm were haematuria (9/32), epistaxis (8/32) and rectal bleeding (7/32); one event of gastrointestinal bleeding occurred (1/32).

Safety outcome: incidence of major bleeding
 
Rivaroxaban provides superior net clinical benefit

Compared with placebo, rivaroxaban provided a significantly improved net clinical benefit; a prespecified secondary endpoint defined as the composite of the primary efficacy endpoint and major bleeding. This outcome occurred in 12/602 (2.0%) patients receiving rivaroxaban and in 42/594 (7.1%) patients receiving placebo (hazard ratio 0.28; 95% CI 0.15–0.53; p<0.001).