This is the current release of the guideline.

Recommendation grades (A-C) and levels of evidence (Ia-IV) are defined at the end of the "Major Recommendations" field.

Indications for Anticoagulation

Table: Indications for Oral Anticoagulation, Target International Normalised Ratio (INR) and Grade of Recommendations

*British Committee for Standards in Haematology (BCSH) 1998. Guidelines on oral anticoagulation: third edition. British Journal of Haematology, 101; 374-87.

Venous Thromboembolism (VTE)

A target INR of 2.5 is recommended for long-term oral anticoagulant (vitamin K antagonist [VKA]) therapy for secondary prevention of VTE (grade A, level 1b).

Duration of Anticoagulation

Anticoagulation for 1 month is inadequate treatment after an episode of VTE (grade A, level 1b). At least 6 weeks anticoagulation is recommended after calf vein thrombosis (grade A, level 1b) and at least 3 months after proximal deep venous thrombosis (DVT) or pulmonary embolism (PE) (grade A, level 1b). For patients with temporary risk factors and a low risk of recurrence, 3 months of treatment may be sufficient. For patients with idiopathic VTE or permanent risk factors, at least 6 months anticoagulation is recommended.

Antiphospholipid Syndrome

A target INR of 2.5 is recommended for patients with DVT or PE associated with antiphospholipid syndrome (grade A, level Ib).

Intravenous Drug Users

Treatment with low molecular weight heparin (LMWH) is an alternative to oral anticoagulation in patients with VTE secondary to intravenous drug use (grade C, level IV).

Cardioversion

A target INR of 2.5 is recommended for 3 weeks before and 4 weeks after cardioversion (grade B, level III). To minimise cardioversion cancellations due to low INRs on the day of the procedure a higher target INR, e.g. 3.0, can be used prior to the procedure.

Heart Valve Prostheses

For patients in whom valve type and location are known specific target INRs are recommended (see Table II below). Otherwise a target INR of 3.0 is recommended for valves in the aortic position and 3.5 in the mitral position.

Table II. Recommendations for Valve-Location-Specific Target INRs

Peripheral Arterial Thrombosis and Grafts

Antiplatelet drugs remain first line intervention for secondary antithrombotic prophylaxis. If long-term anticoagulation is given to patients at high risk of femoral vein graft failure a target INR of 2.5 is recommended (grade B, level IIb).

Coronary Artery Thrombosis

If oral anticoagulant therapy is prescribed a target INR of 2.5 is recommended (grade A, level I).

Paroxysmal Nocturnal Haemoglobinuria (PNH)

Long-term anticoagulation with a target INR of 2.5 is recommended for patients with large PNH clones (PNH granulocytes >50%) and a platelet count greater than 100 × 10⁹ per liter (grade B, level III). Anticoagulation can also be considered for patients with smaller clones and platelet counts less than 100 × 10⁹ per liter dependent on additional risk factors for thrombosis and bleeding (grade C, level IV).

Cancer

Warfarin is generally inferior to therapeutic LMWH for treatment of VTE in patients with cancer (grade A, level Ib).

Commencement and Discontinuation of Anticoagulation

Induction Regimens for Patients Requiring Heparin

For outpatients who do not require rapid anticoagulation a slow-loading regimen is safe and achieves therapeutic anticoagulation in the majority of patients within 3–4 weeks (grade B, level IIb). This appears to avoid over-anticoagulation and bleeding associated with rapid loading.

For patients requiring rapid initiation of oral anticoagulation regimens that start with 5 milligram (mg) doses or a single 10 mg dose followed by 5 mg doses may be preferable to regimens that start with repeated 10 mg doses in certain patient groups, e.g., the elderly (>60 years of age), those with liver disease or cardiac failure and those at high risk of bleeding (grade B, level IIb).

Discontinuation of Anticoagulation

Oral anticoagulant therapy can be discontinued abruptly when the duration of therapy is completed (grade B, level IIb).

Managing Anticoagulation in the Perioperative Period

Previous recommendations remain unchanged. Unless there is a very high risk of thromboembolism anticoagulation should be temporarily discontinued in preparation for surgery. Anticoagulation does not need to be stopped for dental extraction for patients in therapeutic range, i.e., INR <3.0.

Managing Bleeding and Excessive Anticoagulation

Reversal of anticoagulation in patients with major bleeding requires administration of a factor concentrate in preference to fresh frozen plasma, when this is available (grade B, level III), and administration of intravenous rather than oral vitamin K (grade B, level IIa).

Near-Patient Testing (NPT) and Patient Self-Management (PSM)

For either NPT or PSM programmes:

• Patients should conduct NPT, with or without PSM, within a managed programme.
• The same standards of total quality management as practiced in hospital-based clinics should be adhered to.
• Patients should be assessed for capability: only patients considered competent to follow total quality management procedures should complete training and undertake NPT, with or without PSM, as appropriate.
• NPT and PSM programmes should be reviewed and audited at regular intervals for both technical (INR measurement) and clinical utility. Controls assurance procedures should include regular review of proportion of INRs in range and the incidence of over-anticoagulation, bleeding and thrombotic adverse events.

Definitions:

Classification of Evidence Levels

Ia Evidence obtained from meta-analysis of randomised controlled trials.

Ib Evidence obtained from at least one randomised controlled trial.

IIa Evidence obtained from at least one well-designed controlled study without randomisation.

IIb Evidence obtained from at least one other type of well-designed quasi-experimental study (a situation in which implementation of an intervention is without the control of the investigators, but an opportunity exists to evaluate its effect).*

III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.

IV Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities.

*Refers to a situation in which implementation of an intervention is out with the control of the investigators, but an opportunity exists to evaluate its effect.

Classification of Grades of Recommendations

Grade A - Requires at least one randomised controlled trial as part of a body of literature of overall good quality and consistency addressing specific recommendation. (Evidence levels Ia, Ib).

Grade B - Requires the availability of well conducted clinical studies but no randomised clinical trials on the topic of recommendation. (Evidence levels IIa, IIb, III).

Grade C - Requires evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Indicates an absence of directly applicable clinical studies of good quality. (Evidence level IV).

None provided

The type of supporting evidence is identified and graded for each recommendation (see "Major Recommendations").

Not applicable: The guideline was not adapted from another source.

2006 Feb

British Committee for Standards in Haematology - Professional Association

British Committee for Standards in Haematology

Not stated

Authors: T. P. Baglin, Addenbrooke's NHS Trust, Cambridge; D. M. Keeling, Oxford Haemophilia Centre and Thrombosis Unit, Churchill Hospital, Oxford; H. G. Watson, Aberdeen Royal Infirmary, Foresterhill, Aberdeen, UK

None of the authors declared a conflict of interest.

This is the current release of the guideline.

None available

This NGC summary was completed by ECRI Institute on May 22, 2008.