A Comparison of Stroke and Bleeding Risk Scoring Systems in Atrial Fibrillation

Dakota Thaxton Craft, Mercer University College of Pharmacy

Atrial fibrillation (AF) is a type of supraventricular tachycardia that may lead to blood clots and increase the risk of stroke. [1]  Goals of therapy include rate control or correction of rhythm disturbance and prevention of thromboembolism.  The selection of antithrombotic therapy may be based on the risk of thromboembolism due to stroke as assessed by CHADS2, or the more inclusive CHA2DS2VASC. [2]  Due to increased bleeding risks associated with antithrombotic therapy, it is recommended to stratify bleeding risks by using the HAS-BLED score (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile INR, elderly > 65 years, drugs/alcohol concomitantly). [3]  The HAS-BLED score is not applicable to all patients due to lack of available information for “labile INR” in naive patients. [4]

Comparison of HAS-BLED and HAS-BED Versus CHADS2 and CHA2DS2VASC Stroke and Bleeding Scores in Patients with Atrial Fibrillation [4]
Design Prospective, observational, cohort; N= 4,579
Objective To evaluate stroke and bleeding prediction models for risk of bleeding and assess HAS-BED score for association with bleeding risk
Study Groups N/A
Methods The Survey on anticoagulaTed pAtients RegisTer (START) register includes adults (> 18 years) who start anticoagulation therapy, the indication for therapy, the drug and dosage used.  Patient information was obtained from the START register on June 30, 2015.  High risk was defined as CHADS2 score ≥ 1 or CHA2DS2VASC ≥ 2.  Bleeding risk was evaluated using HAS-BLED or HAS-BED score, a refined version of HAS-BLED due to lack of “labile INR” values in naive patients.  High risk was defined as HAS-BLED/HAS-BED score ≥ 3.  Observation started at the beginning of follow-up and ended when patients died, stopped treatment for any reason, or experienced a major bleeding (MB) event. All variables used in the analysis were collected at baseline.  
All patients were stratified according to both CHADS2 and CHA2DS2VASC stroke scores and the HAS-BED bleeding score.  Only patients with available data for “labile INR” were stratified according to HAS-BLED bleeding score (n= 3,494).
The c statistic was used to quantify the predictive validity of the classification schemes with a scale of 0 to 1, where higher coefficients relate to better prediction of patients who will experience the outcome.
Duration N/A
Primary Outcome Measure Predictive ability of bleeding in all models
Baseline Characteristics
Men, n (%) 2,504 (54.7)
Median age, years 76
History of major bleeding, n (%) 157 (3.4)
Patients on vitamin K antagonist treatment, n (%) 3,531 (77.2)
Patients on direct oral anticoagulant, n (%) 1,048 (22.8)
Concomitant antiplatelet drugs, n (%) 755 (16.5)
Dual antiplatelet therapy, n (%) 59 (1.3)
Results
c statistic 95% CI p-value
HAS-BLED 0.59 0.539- 0.643 0.001
HAS-BED 0.52 0.468- 0.596 0.4
CHADS2 0.54 0.494- 0.596 0.1
CHA2DS2VASC 0.51 0.455- 0.561 0.8
Adverse Events Common Adverse Events: N/A
Serious Adverse Events:

Major bleed, n 115
Hemorrhage, n 13
Percentage that Discontinued due to Adverse Events: N/A
Study Author Conclusions The HAS-BLED and HAS-BED scores are useful in identifying patients at high risk for bleeding; however, the predictive ability is modest for all scoring models. Stroke stratification scores could be sufficient for tailoring antithrombotic treatment in this population.

With the increasing use of new oral anticoagulants in today’s practice, the ability to predict bleeding risk using a modified HAS-BLED score is beneficial.  Patients were scored by each system for which there was available data, allowing for full comparison of the ability of each system to predict bleeding risk.  The majority of patients included were from anticoagulation clinics that are adherent to the higher-quality recommendations of the Italian Federation of Anticoagulation Clinics, making the results less applicable to patients managed by American guidelines.

 

References

[1] American Heart Association: What is Atrial Fibrillation AFib or AF)? http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/What-is-Atrial-Fibrillation-AFib-or-AF_UCM_423748_Article.jsp#.WNRdzBiZPBI. Accessed March 23, 2017.

[2] January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the Heart Rhythm Society. Circulation. 2014;130(23):2071-104.

[3] Lane DA, Lip GY. Use of the CHA(2)DS(2)-VASc and HAS-BLED scores to aid decision making for thromboprophylaxis in nonvalvular atrial fibrillation. Circulation. 2012;126(7):860-5.

[4] Poli D, Antonucci E, Pengo V, Testa S, Palareti G. Comparison of HAS-BLED and HAS-BED Versus CHADS2 and CHA2DS2VASC Stroke and Bleeding Scores in Patients With Atrial Fibrillation. Am J Cardiol. 2017;119(7):1012-1016.

 

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