The use of warfarin in veterans with atrial fibrillation

Guideline-concordant initiation of oral anticoagulant therapy for stroke prevention in older veterans with atrial fibrillation eligible for Medicare Part D

OBJECTIVE

To characterize the rate of guideline-concordant initiation of oral anticoagulation (OAC) among elderly Veterans with atrial fibrillation (AF) and high stroke risk.

DATA SOURCES/STUDY SETTING

Veterans Health Administration (VHA) Corporate Data Warehouse (CDW) linked with Medicare claims 2011-2015.

STUDY DESIGN

We identified 6619 elderly, high stroke-risk patients with a new episode of AF initially diagnosed in the VHA during fiscal years 2012-2015. We used logistic regression to estimate marginal effects of associations between patient characteristics and OAC initiation within 90 days of the first AF episode.

DATA EXTRACTION METHODS

We identified OACs using generic drug names. We calculated comorbidities and risk scores using diagnosis codes from 1 year of baseline data.

PRINCIPAL FINDINGS

Overall, 66.5% of Medicare-eligible Veterans with AF at high risk of stroke initiated an OAC within 90 days. We found lower initiation rates for patients enrolled in Medicare Part D and those ineligible for drug co-payment subsidies. OAC initiation rates increased during the study among VHA-reliant patients but not among dual VHA-Part D enrollees.

CONCLUSIONS

One-third of elderly Veterans at risk of stroke are not receiving recommended therapy. Increased coordination between Medicare and VHA providers may lead to improvements in anticoagulation quality and stroke prevention.

Oral anticoagulation use by patients with atrial fibrillation in Germany

Atrial fibrillation (AF) is the most common significant cardiac rhythm disorder. Oral anticoagulation (OAC) is recommended by guidelines in the presence of a moderate to high risk of stroke. Based on an analysis of claims-based data, the aim of this contribution is to quantify the stroke-risk dependent OAC utilisation profile of German AF patients as well as the possible causes and the associated clinical outcomes of OAC under-use. Our data set was derived from two large mandatory German medical insurance funds. Risk stratification of patients was based on the CHADS2-score and the CHA2DS2-VASc-score. Two different scenarios were constructed to deal with factors potentially disfavouring OAC use. Causes of OAC under-use and its clinical consequences were analysed using multivariate analysis. Observation year was 2008. A total of 183,448 AF patients met the inclusion criteria. This represents an AF prevalence of 2.21%. The average CHADS2-score was 2.8 (CHA2DS2-VASc-score: 4.3). On between 40.5 and 48.7% of the observed patient-days, there was no antithrombotic protection by OAC, other anticoagulants or aspirin. Older female patients with a high number of comorbidities had a higher risk of OAC under-use. Patients who had already experienced a thromboembolic event had a lower risk of OAC under-use. In the observation year, 3,367 patients experienced a stroke (incidence rate 1.8%). In our multi-level Poisson random effects estimate, OAC use decreases the stroke rate by almost 80% (IRR 0.236). In conclusion, OAC under-use is widespread in the German market. It is associated with severe clinical consequences.

Ischaemic stroke and bleeding rates in ‘real-world’ atrial fibrillation patients

Stroke prevention guidelines recommend oral anticoagulants (OAC) for atrial fibrillation (AF) patients at moderate/high risk of stroke, and antiplatelet or no therapy for those at low/moderate risk. Outcomes for AF patients receiving antiplatelet/no therapy in ‘real-life’ clinical practice were explored. This study compared clinical event rates (stroke/bleeding) for AF patients treated with OAC therapy, antiplatelets or no therapy in usual clinical practice to event rates in OAC-treated AF patients from optimally-monitored ‘real-life’ settings (anticoagulation clinics). We searched biomedical literature (1994–2010) using PubMed to identify ‘real-world’ studies of clinical event rates for AF patients receiving OAC therapy, antiplatelets, or no therapy; event rates were extracted for each treatment and setting. We identified 136 studies of thromboembolic events and 86 of bleeding events. Ischaemic stroke rates (30 studies) were higher for AF patients receiving no therapy (median: 4.45/100 person-years; range: 0.25–5.9) or antiplatelet-therapy (median: 4.45/100 person-years; range: 2.0–10) compared to OACtreated patients monitored in anticoagulation clinics (median: 1.72/100 person-years; range: 0.97–2.00), or from a non-specialized setting (median 1.66/100 person-years; range: 0–4.9). Major bleeding rates (32 studies) for patients receiving antiplatelet/no therapy were similar to OAC-treated patients from both clinical settings. As in randomised clinical trials, AF patients in ‘real-world’ clinical practice receiving antiplatelet/no therapy have higher rates of ischaemic stroke than OAC-treated patients. Antiplatelet/no therapy was associated with similar bleeding rates to OAC therapy. Increasing utilisation of anticoagulants in clinical practice could improve patient outcomes.

Left Atrial Appendage Closure with Amplatzer Cardiac Plug in Nonvalvular Atrial Fibrillation: Safety and Long-Term Outcome

Background

Atrial fibrillation (AF) is a cardiac arrhythmia with high risk for thromboembolic events, specially stroke.

Objective

To assess the safety of left atrial appendage closure (LAAC) with the Amplatzer Cardiac Plug for the prevention of thromboembolic events in patients with nonvalvular AF.

Methods

This study included 15 patients with nonvalvular AF referred for LAAC, 6 older than 75 years (mean age, 69.4 ± 9.3 years; 60% of the male sex).

Results

The mean CHADS₂ score was 3.4 ± 0.1, and mean CHA₂DS₂VASc , 4.8 ± 1.8, evidencing a high risk for thromboembolic events. All patients had a HAS-BLED score > 3 (mean, 4.5 ± 1.2) with a high risk for major bleeding within 1 year. The device was successfully implanted in all patients, with correct positioning in the first attempt in most of them (n = 11; 73.3%).

Conclusion

There was no periprocedural complication, such as device migration, pericardial tamponade, vascular complications and major bleeding. All patients had an uneventful in-hospital course, being discharged in 2 days. The echocardiographic assessments at 6 and 12 months showed neither device migration, nor thrombus formation, nor peridevice leak. On clinical assessment at 12 months, no patient had thromboembolic events or bleeding related to the device or risk factors. In this small series, LAAC with Amplatzer Cardiac Plug proved to be safe, with high procedural success rate and favorable outcome at the 12-month follow-up.

Real life anticoagulation treatment of patients with atrial fibrillation in Germany: extent and causes of anticoagulant under-use

Oral anticoagulation (OAC) with either new oral anticoagulants (NOACs) or Vitamin-K antagonists (VKAs) is recommended by guidelines for patients with atrial fibrillation (AF) and a moderate to high risk of stroke. Based on a claims-based data set the aim of this study was to quantify the stroke-risk dependent OAC utilization profile of German AF patients and possible causes of OAC under-use. Our claims-based data set was derived from two German statutory health insurance funds for the years 2007-2010. All prevalent AF-patients in the period 2007-2009 were included. The OAC-need in 2010 was assumed whenever a CHADS2- or CHA2DS2-VASC-score was >1 and no factor that disfavored OAC use existed. Causes of OAC under-use were analyzed using multivariate logistic regression. 108,632 AF-prevalent patients met the inclusion criteria. Average age was 75.43 years, average CHA2DS2-VASc-score was 4.38. OAC should have been recommended for 56.1/62.9 % of the patients (regarding factors disfavouring VKA/NOAC use). For 38.88/39.20 % of the patient-days in 2010 we could not observe any coverage by anticoagulants. Dementia of patients (OR 2.656) and general prescription patterns of the treating physician (OR 1.633) were the most important factors increasing the risk of OAC under-use. Patients who had consulted a cardiologist had a lower risk of being under-treated with OAC (OR 0.459). OAC under-use still seems to be one of the major challenges in the real-life treatment of AF patients. Our study confirms that both patient/disease characteristics and treatment environment/general prescribing behaviour of physicians may explain the OAC under-use in AF patients.

Underutilization of warfarin for stroke prophylaxis in patients with atrial fibrillation or atrial flutter in Korea

OBJECTIVE

Anticoagulation therapy with warfarin is recommended for stroke prevention in patients with atrial fibrillation (AF) or atrial flutter (AFL) whose risks for stroke are high. However, previous studies suggest that warfarin is markedly underused. This study aims to investigate the incidence and risk factors of warfarin underutilization in patients with high risk of stroke in Korea.

METHODS

This was a cross-sectional study using the data of 2009 from National Patients Sample compiled by the Health Insurance Review and Assessment Service. Patients with high risk of thromboembolism were identified with congestive heart failure, hypertension, age ≥75 years, diabetes, and prior stroke (CHADS2) score ≥2. High-risk patients of bleeding were excluded using Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) score >4. Warfarin and antithrombotic therapy underutilization were defined and estimated in high-risk patients. Any demographic and clinical factors associated with warfarin and antithrombotic therapy underutilization were explored using a logistic regression model.

RESULTS

Of the national patient sample, 15,885 patients were identified with AF or AFL. Among them, a total of 8475 patients who had an admission history, CHADS2 ≥2, and ATRIA score ≤4 were included in the analysis. From the study sample, warfarin underutilization and antithrombotic therapy underutilization were estimated to be 64.0% and 20.4%, respectively. Predictors of warfarin underutilization include female sex, age ≥80 years, lower CHADS2 score, and insurance type (Medical Aid program).

CONCLUSIONS

A high portion of AF/AFL patients with CHADS2 score ≥2 were undertreated with warfarin. As ischemic stroke is one of the leading causes of death in Korea, a more aggressive approach to prevent stroke in patients with AF/AFL is required.

Estimating Fall Risk in Veterans With Atrial Fibrillation

Using the modified Morse Fall Scale prior to hospital discharge may be a simple and productive way to help physicians determine proper anticoagulation therapy in patients with atrial fibrillation who are at risk for falls.

National trends in oral anticoagulant use in the United States, 2007 to 2011

BACKGROUND

Little is known regarding the adoption of direct thrombin inhibitors in clinical practice. We examine trends in oral anticoagulation for the prevention of thromboembolism in the United States.

METHODS AND RESULTS

We used the IMS Health National Disease and Therapeutic Index, a nationally representative audit of office-based providers, to quantify patterns of oral anticoagulant use among all subjects and stratified by clinical indication. We quantified oral anticoagulant expenditures using the IMS Health National Prescription Audit. Between 2007 and 2011, warfarin treatment visits declined from ≈2.1 million (M) quarterly visits to ≈1.6M visits. Dabigatran use increased from 0.062M quarterly visits (2010Q4) to 0.363M visits (2011Q4), reflecting its increasing share of oral anticoagulant visits from 3.1% to 18.9%. In contrast to warfarin, the majority of dabigatran visits have been for atrial fibrillation, though this proportion decreased from 92% (2010Q4) to 63% (2011Q4), with concomitant increases in dabigatran's off-label use. Among atrial fibrillation visits, warfarin use decreased from 55.8% visits (2010Q4) to 44.4% (2011Q4), whereas dabigatran use increased from 4.0% to 16.9%. Of atrial fibrillation visits, the fraction not treated with any oral anticoagulants has remained unchanged at ≈40%. Expenditures related to dabigatran increased rapidly from $16M in 2010Q4 to $166M in 2011Q4, exceeding expenditures on warfarin ($144M) in 2011Q4.

CONCLUSIONS

Dabigatran has been rapidly adopted into ambulatory practice in the United States, primarily for treatment of atrial fibrillation, but increasingly for off-label indications. We did not find evidence that it has increased overall atrial fibrillation treatment rates.

[Prevention of thromboembolism in atrial fibrillation]

Atrial fibrillation (AF) is the most prevalent chronic arrhythmia in the general population. The prognosis of AF is mainly marked by the associated thromboembolic phenomena. Of every six ischemic strokes, one is due to AF, but the proportion of ischemic strokes attributable to AF increases with age. Thromboembolic risk stratification is a key component of the clinical evaluation of the AF patient, and a clinical performance measure, and should guide the antithrombotic therapeutic strategy. Oral anticoagulation with vitamin K antagonists is effective for the prevention of ischemic stroke in nonvalvular AF but, due to several reasons, it is largely underutilized in daily clinical practice, and INR values are often sub-therapeutic. The new oral anticoagulants (thrombin inhibitors or factor Xa inhibitors) are easier to manage, and don't require laboratorial monitoring. In phase III clinical trials they have shown to be at least as effective as warfarin, but safer, particularly regarding intracranial bleeding, a complication that is responsible for 90% of warfarin-attributable deaths. These results show a potential to increase the proportion of AF patients adequately anticoagulated, which will represent a significant advance in the prevention of stroke attributable to AF.

Underuse of oral anticoagulants in atrial fibrillation: a systematic review

BACKGROUND

Atrial fibrillation is associated with substantial mortality and morbidity from stroke and thromboembolism. Despite an efficacious oral anticoagulation therapy (warfarin), atrial fibrillation patients at high risk for stroke are often under-treated. This systematic review compares current treatment practices for stroke prevention in atrial fibrillation with published guidelines.

METHODS

Literature searches (1997-2008) identified 98 studies concerning current treatment practices for stroke prevention in atrial fibrillation. The percentage of patients eligible for oral anticoagulation due to elevated stroke risk was compared with the percentage treated. Under-treatment was defined as treatment of <70% of high-risk patients.

RESULTS

Of 54 studies that reported stroke risk levels and the percentage of patients treated, most showed underuse of oral anticoagulants for high-risk patients. From 29 studies of patients with prior stroke/transient ischemic attack who should all receive oral anticoagulation according to published guidelines, 25 studies reported under-treatment, with 21 of 29 studies reporting oral anticoagulation treatment levels below 60% (range 19%-81.3%). Subjects with a CHADS(2) (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and prior stroke or transient ischemic attack) score >or=2 also were suboptimally treated, with 7 of 9 studies reporting treatment levels below 70% (range 39%-92.3%). Studies (21 of 54) using other stroke risk stratification schemes differ in the criteria they use to designate patients as "high risk," such that direct comparison is not possible.

CONCLUSIONS

This systematic review demonstrates the underuse of oral anticoagulation therapy for real-world atrial fibrillation patients with an elevated risk of stroke, highlighting the need for improved therapies for stroke prevention in atrial fibrillation.

Atrial fibrillation management: a prospective survey in ESC Member Countries

AIMS

To describe atrial fibrillation (AF) management in member countries of the European Society of Cardiology (ESC) and to verify cardiology practices against guidelines.

METHODS AND RESULTS

Among 182 hospitals in 35 countries, 5333 ambulant and hospitalized AF patients were enrolled, in 2003 and 2004. AF was primary or secondary diagnosis, and was confirmed on ECG in the preceding 12 months. Clinical type of AF was reported to be first detected in 978, paroxysmal in 1517, persistent in 1167, and permanent in 1547 patients. Concomitant diseases were present in 90% of all patients, causing risk factors for stroke to be also highly prevalent (86%). As many as 69% of patients were symptomatic at the time of the survey; among asymptomatic patients, 54% were previously experienced symptoms. Oral anticoagulation was prescribed in 67 and 49% of eligible and ineligible patients, respectively. A rhythm control strategy was applied in 67% of currently symptomatic patients and in 44% of patients who never experienced symptoms.

CONCLUSION

This survey provides a unique snapshot of current AF management in ESC member countries. Discordance between guidelines and practice was found regarding several issues on stroke prevention and antiarrhythmic therapy.