New “HAS-BLED” Tool Identifies Those with Atrial Fibrillation at Risk for Bleeding From Coumadin or Warfarin
April 22, 2010 7:11 AM CT
By Peggy Noonan and Mellanie True Hills
Doctors have developed a new tool that will help fine-tune one treatment for atrial fibrillation.
If you have atrial fibrillation, you are at risk for a stroke, but anticoagulant drugs, such as Coumadin or warfarin, can decrease that risk. Also called blood-thinners, they help prevent the blood clots that cause strokes.
Doctors use the CHADS2 scoring system to determine who should be on warfarin. But in some patients, managing it becomes a finely-tuned balancing act that is not always easy. One potential risk is bleeding. Now a new tool may help doctors walk this tightrope.
Previous such tools, called schemas, that helped doctors figure out the bleeding risks of oral anticoagulant drugs for atrial fibrillation patients, had limitations—they didn’t focus specifically on those with atrial fibrillation, or focused on a specific subgroup who had atrial fibrillation, or included other risk factors. And being based on past cases meant that they didn’t take into account advancements such as monitoring.
Now a team of researchers led by Dr. Gregory YH Lip in the United Kingdom (University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham) has developed a new schema, called HAS-BLED, that outperformed existing schema in assessing the one-year risk of major bleeding in atrial fibrillation patients.
Real world risk factors
“Despite extensive use of oral anticoagulation (OAC) in patients with atrial fibrillation (AF) and the increased bleeding risk associated with such OAC use, no handy quantification tool of assessing this risk exists,” Dr. Lip explains. “We aimed to develop a practical risk score…in a cohort of ‘real world’ AF patients.”
Just having atrial fibrillation puts a person at higher risk of stroke. That risk is even greater in people who have atrial fibrillation combined with other conditions, such as heart failure, hypertension (high blood pressure), diabetes, or a history of previous blood clots, referred to as thromboembolisms. The HAS-BLED schema takes into account those “comorbidities” (related health problems). It also takes into account the fact that people who have atrial fibrillation are more likely to be taking oral anticoagulant medications, like Coumadin, and are more likely to be elderly. It also notes that among elderly patients the risk of major hemorrhage “can be similar” for both Coumadin and aspirin, which is surprising since aspirin is often considered more benign.
Dr. Lip’s team used data on 3,978 adults who were 18 or older and were part of the EuroHeart Survey on Atrial Fibrillation. All had confirmed atrial fibrillation and complete follow-up data. Their risk of “major bleeding” was defined as any bleeding that was not a hemorrhagic (bleeding) stroke and that was serious enough to require hospitalization or blood transfusion or both.
New scoring tool
“We propose a novel bleeding risk score, HAS-BLED, which provides an easy, practical tool to assess the individual bleeding risk of AF patients, potentially supporting clinical decision-making regarding antithrombotic [anti-clotting] therapy for stroke prevention,” the researchers conclude.
HAS-BLED is an acronym of the major factors the system takes into account, using the first letter of each:
- Hypertension: 1 point for uncontrolled high blood pressure, with a systolic (top number) reading of 160 or higher
- Abnormal kidney and/or liver function: 1 point for impaired kidney or liver function, and 2 points for both
- Stroke: 1 point for previous history of stroke, especially deep brain (lacunar) stroke
- Bleeding: 1 point for previous history of bleeding, anemia or having predisposition to bleeding
- Labile INR: 1 point for unstable or high INRs, or poor time (less than 60%) in the therapeutic time range
- Elderly: 1 point for age 65 or older
- Drugs and/or alcohol: 1 point for taking antiplatelet drugs (like aspirin or Plavix) and 1 point for consuming 8 or more alcoholic drinks per week, or 2 points for both
When they analyzed the data, they concluded that using both the CHADS2 and HAS-BLED tools could have prevented bleeding in patients who were on oral anticoagulants as well as strokes in patients who were not. “Assessment of both stroke and bleeding risk using the CHADS2 and HAS-BLED schemas, respectively, in the EuroHeart Survey on AF population would have resulted in withholding OAC therapy in 12% of the patients who suffered a major bleeding within one year and the initiation of OAC in 95% of the patients at high risk for stroke who were discharged without OAC and had suffered a stroke within one year,” the researchers said.
Balancing on the Coumadin tightrope
And, although it seems the opposite of what should be true, they add, “Indeed, the patients at highest stroke and thromboembolic [blood clot] risk are – paradoxically – more likely to sustain bleeding complications. This may lead to confusion when trying to decide on the most appropriate antithrombotic regimen, to balance the risks of bleeding against the risk of stroke, thereby limiting the applicability of such schemas.”
Using both tools will help doctors walk that tightrope balancing between the risk of blood clots and the risk of bleeds for each patient. As the study authors note, “The ‘trade off’ in terms of the benefits and risks of OAC using the CHADS2 index and HAS-BLED score demonstrates that in the vast majority of AF patients who require OAC (CHADS2 index ≥ 2) the risk of bleeding outweighs the potential benefit of OAC if the HAS-BLED bleed score exceeds the individual CHADS2 index.”
Considering the recent results of the RE-LY trial, the researchers note that people whose HAS-BLED scores show they’re at higher bleeding risk could be prescribed the lower dose (110 mg twice a day) of dabigatran, “which demonstrated a significant reduction in major bleeding compared to warfarin, with a similar stroke risk.” And for people whose bleeding risk is lower, dabigatran could be prescribed at 150 mg, “which offers superior efficacy but with a similar major bleeding risk to warfarin.”
They also indicated that HAS-BLED scores could be used to identify those who may need a device to occlude or block the left atrial appendage instead of taking warfarin. That might include patients who are simultaneously at high risk of ischemic stroke and of bleeding.
When compared against a previously proposed schema, HAS-BLED was found to be more accurate in predicting bleeding risk and is also simpler and easier for doctors to remember and use. It will help doctors make better decisions, with greater confidence, as to whether to recommend that those living with atrial fibrillation be on medications, such as Coumadin or dabigatran, or receive occlusion devices for the left atrial appendage.
The HAS-BLED score has been validated in a cohort of 7,000 patients “where it outperformed existing bleeding schema,” Dr. Lip reports.
The researchers indicated that the schema needs to be validated in at least one other large study before it is ready for widespread use. In addition, the impact of thyroid disease, which is a risk factor for afib and commonly accompanies it, needs to be considered in further studies.
Comments: So what does this research mean to you? Every day we hear from those with atrial fibrillation who don’t want to start Coumadin, or want to get off of it. There are many others who don’t know whether or not they should be on it. If you determine from your results using the CHADS2 and HAS-BLED scoring systems that you should be doing something differently, please print out a copy of this information and discuss it with your doctor.
To learn more, see:
- A novel user-friendly score (HAS-BLED) to assess one-year risk of major bleeding in atrial fibrillation patients: The Euro Heart Survey, Chest, the official publication of the American College of Chest Physicians, prepublished online February 26, 2010
- New Stroke Risk Factors for Those with Atrial Fibrillation: Female Gender, Heart Disease, and Age — this research, from the same researchers who created HAS-BLED, proposed the CHA2DS2-VASc Scoring System, which provides additional criteria beyond CHADS2 for evaluating the need for Coumadin
Peggy Noonan specializes in writing about health for consumers and medical professionals. She writes for leading national magazines and consumer publications as well as StopAfib.org.
Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.