Anticoagulants: a guide to starting oral anticoagulants in atrial fibrillation

People with non-valvular atrial fibrillation (AF) should be treated with oral anticoagulants based on their risk of stroke. Use this tool to identify patients with non-valvular AF for whom treatment with anticoagulants is recommended, and to personalise the selection of an oral anticoagulant in 3 easy steps:

  1. Patient assessment
  2. Risk mitigation
  3. Anticoagulant selection.

Step 1: Patient assessment

Assess non-valvular AF patient’s risk of stroke using the CHADS2 score calculator.

CHADS2 score calculator
Risk factor Score
Congestive heart failure history 1
Hypertension (including well-controlled hypertension) 1
Age 75 years or older 1
Diabetes mellitus 1
Stroke or transient ischaemic attack history 2

Is the patient’s CHADS2 score ≥ 1?

Step 2: Risk mitigation

Having determined that a patient needs anticoagulation:


Use the HAS-BLED chart below to identify correctable risk factors for bleeding:

  • Hypertension (systolic blood pressure > 160 mmHg)
  • Labile INRs (< 6 in 10 INRs in the therapeutic range)
  • Drugs (antiplatelet agents, NSAIDs, or alcohol ≥ 8 units per week).


Use the HAS-BLED chart to identify people at high risk of bleeding (with three or more HAS-BLED risk factors for bleeding) who need increased clinical monitoring.
These people may also benefit from twice annual Home Medicine Reviews (HMR).

Refer people with a history of intracranial haemorrhage to a specialist.


Each HAS-BLED risk factor increases a person's bleeding risk.

  • HAS-BLED was designed to systematically assess annual risk of a major bleed in people with AF before they started warfarin.
  • Many of the risk factors in the chart are also relevant when considering the newer oral anticoagulants.

Do not

use the HAS-BLED chart to exclude people from being treated with anticoagulants. People at high risk of bleeding are also at high risk of stroke.

HAS-BLED risk factors for bleeding About HASBLED
H Hypertension (systolic blood pressure > 160 mm Hg)*
A Abnormal renal or liver function
S Stroke (history of)
B Bleeding (history of, or predisposition to bleeding)
L Labile INRs (<6 in 10 INRs in therapeutic range)*
E Elderly (e.g. age > 65 years)
D Drugs (antiplatelet agents, NSAIDs, or alcohol ≥ 8 units per week)*

*Correctable risk factors for bleeding.

Step 3: Select an anticoagulant

yes1 no1 yes2 no2 yes3 no3 yes4 ok1 ok2 no4 restart See Destination tool Medicinewise News apixaban
apixaban See Destination tool Medicinewise News dabigatran rivaroxaban

*Warfarin is contraindicated in people with severe active bleeding or with conditions associated with increased risk of severe bleeding (e.g. severe uncontrolled hypertension, recent gastrointestinal [GI] bleeding, genitourinary bleeding, active ulceration or severe thrombocytopenia as well as people with compliance problems (includes lack of access to INR monitoring as well as non adherence).