In a patient with AFib it is necessary to prescribe anticoagulation to decrease the risk of embolic events and ischemic stroke, but application of anticoagulation itself increases the risk of hemorrhagic events. Therefore in addition to risk scores for establishing a patient’s risk of ischemic events it is also necessary to assess the patient’s risk of hemorrhage, or bleeding. There are a number of risk scores to determine risk of bleeding. Figure 13 shows the point system of the HAS-BLED score (see also Hylek, Figure 10), which is used to assess risk of bleeding in patients who are anticoagulated because of AFib.[14,15] As with the CHADS scores, HAS-BLED demarcates patients into lower risk (0–1), moderate risk (2–3), and higher risk (≥4), based on their absolute percentage of having a bleeding event in a given year.

The bleeding risk factor components of HAS-BLED are similar to the stroke risk factors in the CHADS scores:

• Hypertension (systolic blood pressure >160 mm Hg) is assigned 1 point,
• Abnormal renal or hepatic function is assigned 1–2 points
• Prior stroke is assigned 1 point
• Abnormal renal or hepatic function is assigned 1–2 points.
• Bleeding or a history of anemia would be 1 point
• A labile INR level (time in therapeutic range <60%) is assigned 1 point
• Elderly (age >75 years) is assigned 1 point
• Concomitant drugs (antiplatelets [aspirin] or NSAIDs) or alcohol is assigned 1–2 points.

The result is a composite scoring system for potentially quantifying the risk of bleeding.

It is clear that there is a degree overlap between factors that predict ischemic risk and factors that predict bleeding risk, such as history of stroke and advanced age, and this makes it a challenge for physicians to find patients who are not at high risk of either ischemic stroke or bleeding.