Are Atrial Fibrillation Patients Receiving Warfarin in Accordance with Stroke Risk?

doi:10.1016/j.amjmed.2009.11.015

The American Journal of Medicine

Volume 123, Issue 5, May 2010, Pages 446-453

Parts of these data were presented in poster format at the Heart Rhythm Society Annual Meeting, May 13-16, 2009.

https://doi.org/10.1016/j.amjmed.2009.11.015 Get rights and content

Abstract

Background

Clinical guidelines for the management of atrial fibrillation and atrial flutter provide recommendations for anticoagulation based on patients' overall risk of stroke. To determine the real-world compliance of physicians with these recommendations, we conducted a retrospective cohort study examining the utilization of warfarin in atrial fibrillation/flutter patients by stroke risk level.

Methods

Patients with a qualifying atrial fibrillation/flutter diagnosis during ≥18 months' continuous enrollment between January 2003 and September 2007, and with ≥6 months' eligibility after the first atrial fibrillation/flutter diagnosis, were identified from the US MarketScan database (Thomson Reuters, New York, NY). Warfarin use within 30 days of the first diagnosis was assessed according to stroke risk, estimated using the Congestive heart failure, Hypertension, Age >75 years, Diabetes, Stroke (CHADS₂) score.

Results

Of 171,393 patients included in the analysis, 20.0% had a CHADS₂ score of 0 (low risk), 61.6% a score of 1-2 (moderate risk), and 18.4% a score of 3-6 (high risk). Warfarin, recommended for high stroke-risk patients, was given to only 42.1% of those with a CHADS₂ score of 3-6. A similar percentage of patients with moderate (43.5%) or low stroke risk (40.1%) received warfarin. Only 29.6% of high-risk, 33.3% of moderate-risk, and 34.1% of low-risk patients who were started on warfarin received uninterrupted therapy for 6 months following their initial prescription.

Conclusions

These data suggest that guideline recommendations that anticoagulation should be provided in accordance with stroke risk in atrial fibrillation patients are not routinely followed in clinical practice. The causes and clinical implications of under-utilization of anticoagulation in atrial fibrillation patients with high stroke risk warrant further study.

Section snippets

Study Design

This retrospective cohort study included adult patients in the US MarketScan Commercial Claims and Encounters Database and Medicare Supplemental Database from Thomson Reuters (New York, NY). These databases are derived from employer- and government-funded (Medicare) health care insurance plans and represent 21.6 million individuals covered under a variety of fee-for-service and capitated provider reimbursement schemes. Data from the MarketScan database have been used previously for a range of

Statistical Analysis

All analyses were conducted using SAS version 9 (SAS Institute Inc., Cary, NC). Continuous variables were summarized as mean ± SD and median, while binary data were summarized with percentages. The Charlson Comorbidity Index was calculated according to the method of Romano et al.³⁰ The CHADS₂ score was calculated as the sum of points allocated to each of the following stroke risk factors: congestive heart failure exacerbation (1 point), hypertension (1 point), age >75 years (1 point), diabetes

Characteristics of Overall Study Population

Of 573,519 patients in the MarketScan database with a diagnosis of atrial fibrillation/atrial flutter during the study period, 171,393 patients were included in the analysis: 51,907 (30.3%) with newly diagnosed atrial fibrillation/atrial flutter and 119,486 (69.7%) with pre-existing atrial fibrillation/atrial flutter (Figure 1). The mean (SD) duration of continuous eligibility across all patient groups was 41.0 (13.7) months. Overall, patients were of mean age 73.5 years, and 54.8% were male (

Discussion

This study demonstrated that less than half of patients with newly diagnosed or pre-existing atrial fibrillation/atrial flutter in a large US medical claims database received warfarin therapy following a diagnosis of atrial fibrillation/atrial flutter, and only a third of patients starting treatment had 6 months of uninterrupted therapy. Furthermore, the low utilization of warfarin was consistently observed across patients with high, moderate, or low stroke risk.

Despite guideline

Conclusion

This study indicates that physicians currently fail to take sufficient account of patients' overall risk of stroke when considering anticoagulant therapy, and that anticoagulation is generally underused in atrial fibrillation patients. There is a need for continued research in this area to help physicians to balance the risks and benefits of anticoagulation in atrial fibrillation patients, especially in relation to stroke risk. However, until further evidence is available, physicians should

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From January 1, 2009, to December 31, 2015, 33,539 newly-diagnosed AF patients older than 85 years old who survived more than 180 days after AF diagnosis were studied. Temporal trends regarding OAC initiation rates after incident AF were analyzed. The 1-year risks of ischemic stroke, intracranial hemorrhage, and mortality of incident AF patients diagnosed each year were compared with that of the year 2009.
Initiation rates of OACs after AF was newly diagnosed in the elderly significantly increased from 9.5% to 34.3%, mainly due to the introduction of NOACs (from 0% to 26.2%). Several clinical factors were associated with OACs underuse, including chronic obstructive pulmonary disease, abnormal renal function, anemia, and history of bleeding. Compared with year 2009 (incidence rate, 5.55%/year), the 1-year risk of ischemic stroke after AF diagnosis decreased in the era of NOACs (incidence rate, 4.20%/year; adjusted hazard ratio [aHR], 0.748 in year 2012; 4.39%/year, aHR, 0.789 in 2014; 2.75%/year; aHR, 0.513 in year 2015; all P<.01, except for year 2013, 4.80%/year [P=.07]). Also, the risks of mortality were lower in years 2012 to 2015, while the risk of ICH remained unchanged.
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Stroke remains the second leading cause of death in the world, and its prevalence is projected to rise in the United States and globally. The main driver for increased stroke prevalence is aging of the population; however, best evidenced-based strategies for stroke treatment and prevention are not always followed for older patients. Furthermore, considerable gaps in knowledge exist for stroke prevention and treatment in elderly and very elderly patients.
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Chronic anticoagulation is recommended for atrial fibrillation (AF) patients with thromboembolic risk factors regardless of AF duration/frequency. Continuous rhythm assessment with pacemakers (PMs)/implantable cardioverter-defibrillators (ICDs) and use of direct-acting oral anticoagulants (DOACs) may allow anticoagulation only around AF episodes, reducing bleeding without increasing thromboembolic risk.
The purpose of this study was to evaluate the feasibility/safety of intermittent DOAC use guided by continuous remote AF monitoring via dual-chamber PMs or ICDs.
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Among 48 patients (mean age 71.3 years; 65% male; 79% paroxysmal AF; 87% CHADS₂ score 1–2), 14,826 days of monitoring were completed. Patients used DOACs for 3763 days, representing a 74.6% reduction in anticoagulation time compared to chronic administration. Adverse events included 2 gastrointestinal bleeds (both on DOAC), 1 fatal intracerebral bleed (off DOAC), and no thromboembolic/stroke events.
Among patients with rare AF episodes and low-to-moderate stroke risk, PM/ICD-guided DOAC administration is feasible and decreased anticoagulation utilization by 75%. Few adverse events occurred, although the study was not powered to assess these outcomes. PM/ICD-guided DOAC administration may prove a viable alternative to chronic anticoagulation. Future studies are warranted.
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This study sought to identify the differences in stroke, mortality, and bleeding between men and women with atrial fibrillation (AF).
There are inconsistent data regarding the thromboembolic risk difference between men and women with AF. The authors assessed the risk of stroke, death, and bleeding in men and women with incident AF.
The authors employed a prospective historical cohort using an electronic database from a large health maintenance organization. All members with incident AF between 2004 and 2015 were included. Primary endpoints were ischemic stroke, death, and major bleeding.
The authors identified 89,213 members with incident nonvalvular atrial fibrillation (NVAF), 52.3% of whom were women. Women were older, with a higher prevalence of hypertension, whereas more men had diabetes, heart failure, and ischemic heart disease than the women did. Ischemic stroke occurred in 6.4% of the patients: 7.0% of women and 5.8% of men. Sex did not affect adjusted stroke risk (hazard ratio [HR]: 0.91; 95% confidence interval [CI]: 0.77 to 1.06; p = 0.22). However, women 75 years of age and older were at an increased risk (HR: 1.25; 95% CI: 1.17 to 1.34). Mortality rates were higher among women (33.5% vs. 32%; p < 0.001); however, women had a significantly lower adjusted mortality risk (HR: 0.78; 95% CI: 0.71 to 0.86). Women had lower risk of intracranial hemorrhage (HR: 0.81; 95% CI: 0.76 to 0.87) and major gastrointestinal bleeding (HR: 0.78; 95% CI: 0.70 to 0.87).
Men and women with AF had a similar risk of ischemic stroke, except for women 75 years of age or older, who had a higher risk. Our findings support using a similar anticoagulation strategy for prevention of stroke in men and women with a similar number of risk factors.
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The present study was to evaluate the value of CHADS2 and CHA2DS2VASC scores on predicting left atrial (LA) or left atrial appendage (LAA) thrombus in atrial fibrillation (AF) patients prior to ablation in the real world of China.
A total of 397 patients with non-valvular AF were analyzed to determine the relationship between CHADS2 and CHA2DS2VASC scores and LA/LAA thrombus identified on transesophageal echocardiography prior to radiofrequency ablation(RFA). LA/LAA thrombus was present in 38 patients (9.6%). There was a strong association between higher CHADS2 score or CHA2DS2VASC score and LA/LAA thrombus. No thrombus was identified in patients with CHA2DS2VASC score of 0 regardless of anticoagulation status. However, LA/LAA thrombus was detected in 2.9% patients with CHADS2 score of 0 without adequate anticoagulation, while no thrombus was present in the patients with CHADS2 score of 0 with adequate anticoagulation. Univariate analysis showed that heart failure (LVEF＜50%), LA≥40 mm, diabetes mellitus, previous stroke or TIA, CAD, hypertension, inadequate anticoagulation therapy, CHADS2 score of ≥2 and CHA2DS2VASC score of ≥2 were significantly associated with LA/LAA thrombus. Multivariable Cox regression analysis demonstrated that CHA2DS2VASC score of ≥2 (p = 0.02) and previous stroke or TIA (p = 0.04) were independently associated with LA/LAA thrombus regardless of anticoagulation status. ROC curve analysis showed that higher CHADS2 score and CHA2DS2VASC score could be similarly used to predict the presence of LA thrombus.
Both higher CHA2DS2VASC and CHADS2 scores were associated with LA/LAA thrombus in non-valvular AF patients prior to ablation. Although CHA2DS2VASC score and CHADS2 score had similar value to predict LA/LAA thrombus, CHA2DS2VASc score was better to identify low-risk patients for LA/LAA thrombus than CHADS2 score without anticoagulation. There will be a possibility of performing AF ablation or cardioversion in patients with a CHA2DS2VASC of 0 without TEE or anticoagulation therapy. The safety need to be verified by more multicentre randomized controlled clinical trails.
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: Funding: Financial support for the preparation of this manuscript was provided by sanofi-aventis US, Inc. This funding was used for provision of editorial support by Elizabeth Harvey, PhD and Andrew Fitton, PhD of UBC Scientific Solutions.

: Conflict of Interest: Dr. Peter Zimetbaum is a research consultant to sanofi-aventis. Dr. Jay Lin is an employee of sanofi-aventis. Hsing-Ting Yu and Matthew Emons are employees of Cerner LifeSciences, which provided consulting services to sanofi-aventis. Yan Xiong and Prajesh Kothawala were employed by Cerner LifeSciences at the time the research was conducted.

: Authorship: All authors had access to the study data, and participated in analysis or interpretation of the data (or both), and preparation of the manuscript.

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Clinical research studyAre Atrial Fibrillation Patients Receiving Warfarin in Accordance with Stroke Risk?

Abstract

Background

Methods

Results

Conclusions

Section snippets

Study Design

Statistical Analysis

Characteristics of Overall Study Population

Discussion

Conclusion

Value Health

Am J Cardiol

Lancet

J Am Coll Cardiol

Chest

Am J Cardiol

J Am Coll Cardiol

J Clin Epidemiol

Am Heart J

J Am Coll Cardiol

Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study

JAMA

Impact of atrial fibrillation on the risk of death: the Framingham Heart Study

Circulation

Impact of atrial fibrillation on mortality, stroke, and medical costs

Arch Intern Med

Atrial fibrillation as an independent risk factor for stroke: the Framingham Study

Stroke

Atrial fibrillation is associated with severe acute ischemic stroke

Neuroepidemiology

Is the hypercoagulable state in atrial fibrillation mediated by vascular endothelial growth factor?

Stroke

Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillationAnalysis of pooled data from five randomized controlled trials

Arch Intern Med

Clinical research study
Are Atrial Fibrillation Patients Receiving Warfarin in Accordance with Stroke Risk?