Are Cost Benefits of Anticoagulation for Stroke Prevention in Atrial Fibrillation Underestimated?

Neurointerventional Therapies for Stroke in Atrial Fibrillation: Illustrated Cases

Approximately 800,000 strokes occur in the United States every year, resulting in 200,000 deaths. Strokes may be ischemic (80%) or hemorrhagic (20%). Strokes caused by atrial fibrillation (AF) are thromboembolic, and AF is the leading cause of ischemic stroke. Rapid distinction between these forms of strokes is critical because approaches to treatment are different. The goal for acute ischemic stroke is reperfusion of ischemic brain tissue, whereas the treatment of hemorrhagic stroke is supportive therapy and correction of the underlying conditions. The treatment of acute ischemic strokes is similar to treatment of acute myocardial infarction, which requires timely reperfusion for optimal results.

The economic burden to medicare of stroke events in atrial fibrillation populations with and without thromboprophylaxis

Some 3 million people in the United States have atrial fibrillation (AF). Without thromboprophylaxis, AF increases overall stroke risk 5-fold. Prevention is paramount as AF-related strokes tend to be severe. Thromboprophylaxis reduces the annual incidence of stroke in AF patients by 22%-62%. However, antithrombotics are prescribed for only about half of appropriate AF patients. The study team estimates the economic implications for Medicare of fewer stroke events resulting from increased thromboprophylaxis among moderate- to high-risk AF patients. The decision model used considers both reduced stroke and increased bleeding risk from thromboprophylaxis for a hypothetical cohort on no thromboprophylaxis (45%), antiplatelets (10%), and anticoagulation (45%). AF prevalence, stroke risk, and stroke risk reduction are adjusted for age, comorbidities, and anticoagulation/antiplatelet status. Health care costs are literature based. At baseline, an estimated 24,677 ischemic strokes, 9127 hemorrhagic strokes, and 9550 bleeding events generate approximately $2.63 billion in annual event-related health care costs to Medicare for every million AF patients eligible for thromboprophylaxis. A 10% increase in anticoagulant use in the untreated population would reduce stroke events by 9%, reduce stroke fatalities by 9%, increase bleed events by 5%, and reduce annual stroke/bleed-related costs to Medicare by about $187 million (7.1%) for every million eligible AF patients. A modest 10% increase in the use of thromboprophylaxis would reduce event-related costs to Medicare by 7.1%, suggesting a compelling economic motivation to improve rates of appropriate thromboprophylaxis. New oral anticoagulants offering better balance between the risks of stroke and major bleeding events may improve these clinical and economic outcomes.

Review of economics and cost-effectiveness analyses of anticoagulant therapy for stroke prevention in atrial fibrillation in the US

OBJECTIVE

To summarize the available evidence on the issues in health economics related to oral anticoagulation for stroke prevention in atrial fibrillation (AF) in the US.

DATA SOURCES

A literature review was performed using PubMed, EMBASE, Cochrane Library, and International Pharmaceutical Abstracts, as well as the websites of professional organizations.

STUDY SELECTION AND DATA EXTRACTION

The search was conducted according to a prespecified protocol, limiting articles to those published in English from 2001 to October 2012 and focused on the economics associated with AF and AF-related stroke in the US. Data from 27 studies were extracted and included in the review.

DATA SYNTHESIS

Strokes in patients with AF are more debilitating and have higher recurrence rates and mortality compared with strokes unrelated to AF. However, data describing the long-term cost of AF-related stroke and stroke subtypes remain limited. The costs of major gastrointestinal (GI) bleeding and intracranial bleeding related to warfarin are significant, whereas the costs of the more frequent minor GI bleeding are relatively low. Overall, the cost-effectiveness of warfarin versus aspirin or no treatment in patients with at least 1 risk factor for stroke is well established. Economic evaluations based on results from randomized controlled clinical trials generally found that new anticoagulants were a cost-effective alternative to warfarin for stroke prevention in AF. However, these cost-effectiveness results are highly sensitive to how well optimal international normalized ratio control is maintained (within target of 2.0-3.0) for warfarin and the time horizon used for analysis. Time in therapeutic range for warfarin in routine clinical practice was lower than in clinical trials, as shown by previous studies.

CONCLUSIONS

This review identified several areas of uncertainty regarding the economic benefit of anticoagulants. The generalizability of cost-effectiveness results of anticoagulant therapy in AF based on clinical trial data must be confirmed by comparative effectiveness research conducted in the real-world setting.

Long-Term Costs of Ischemic Stroke and Major Bleeding Events among Medicare Patients with Nonvalvular Atrial Fibrillation

Purpose. Acute healthcare utilization of stroke and bleeding has been previously examined among patients with nonvalvular atrial fibrillation (NVAF). The long-term cost of such outcomes over several years is not well understood. Methods. Using 1999–2009 Medicare medical and enrollment data, we identified incident NVAF patients without history of stroke or bleeding. Patients were followed from the first occurrence of ischemic stroke, major bleeding, or intracranial hemorrhage (ICH) resulting in hospitalization. Those with events were matched with 1–5 NVAF patients without events. Total incremental costs of events were calculated as the difference between costs for patients with events and matched controls for up to 3 years. Results. Among the 25,465 patients who experienced events, 94.5% were successfully matched. In the first year after event, average incremental costs were $32,900 for ischemic stroke, $23,414 for major bleeding, and $47,640 for ICH. At 3 years after these events, costs remained elevated by $3,156–$5,400 per annum. Conclusion. While the costs of stroke and bleeding among patients with NVAF are most dramatic in the first year, utilization remained elevated at 3 years. Cost consequences extend beyond the initial year after these events and should be accounted for when assessing the cost-effectiveness of treatment regimens for stroke prevention.

Gender differences in emergency stroke care and hospital outcome in acute ischemic stroke: a multicenter observational study

BACKGROUND

We aimed to investigate the effect of gender difference on the accessibility to emergency care, hospital mortality and disability in acute stroke care.

METHODS

This study was performed on a single-tiered basic emergency medical service with a comprehensive national health insurance. Demographic variables, risk factors, elapsed time intervals, performing diagnosis and treatment options, hospital mortality, and modified Rankin Scale of acute ischemic stroke during 2008 were collected. We modeled the multivariate regression analysis for gender differences on the accessibility, hospital mortality, and disability. The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated adjusting for potential risk factors.

RESULTS

The total number of patients was 6635. The time from symptom onset to emergency department (ED) arrival and to computed tomography or magnetic resonance imaging scan and from ED arrival to computed tomography or magnetic resonance imaging scan was significantly longer in women. No significant difference was found in either the time to intravenous thrombolysis or in the number of patients who received intravenous thrombolysis, anti-platelet therapy, anti-coagulation, or operation. The hospital mortality rate was higher in women (3.9%) than in men (2.9%) (P = .03). The increased disability was significantly higher in women (67.8%) than in men (65.1%) (P = .02). The hospital mortality and increased disability showed a non-significant difference between the 2 genders in the adjusted model (OR, 1.10; 95% CI, 0.74-1.64) and (OR, 1.11; 95% CI, 0.96-1.28), respectively.

CONCLUSION

The adjusted model for risk factors showed no significant difference on hospital mortality and disability between the 2 genders for stroke patients.

Cost-effectiveness of dabigatran for stroke prevention in non-valvular atrial fibrillation in Spain

INTRODUCTION AND OBJECTIVES

Assessment of the cost-effectiveness of dabigatran for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation in Spain, from the perspective of the National Health System.

METHODS

Adaptation of a Markov chain model that simulates the natural history of the disease over the lifetime of a cohort of 10,000 patients with non-valvular atrial fibrillation. Model comparators were warfarin in a first scenario, and a real world prescribing pattern in a second scenario, in which 60% of the patients were treated with vitamin K antagonists, 30% with acetylsalicylic acid, and 10% received no treatment. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

Dabigatran reduced the occurrence of clinical events in both scenarios, providing gains in quantity and quality of life. The incremental cost-effectiveness ratio for dabigatran compared to warfarin was 17,581 euros/quality-adjusted life year gained and 14,118 euros/quality-adjusted life year gained when compared to the real world prescribing pattern. Efficiency in subgroups was demonstrated. When the social costs were incorporated into the analysis, dabigatran was found to be a dominant strategy (ie, more effective and less costly). The model proved to be robust.

CONCLUSIONS

From the perspective of the Spanish National Health System, dabigatran is an efficient strategy for the prevention of stroke in patients with non-valvular atrial fibrillation compared to warfarin and to the real-world prescribing pattern; incremental cost-effectiveness ratios were below the 30,000 euros/quality-adjusted life year threshold in both scenarios. Dabigatran would also be a dominant strategy from the societal perspective, providing society with a more effective therapy at a lower cost compared to the other 2 alternatives. Full English text available from:www.revespcardiol.org.

Cost-effectiveness of dabigatran etexilate for the prevention of stroke and systemic embolism in UK patients with atrial fibrillation

Objective

To assess the cost-effectiveness of dabigatran etexilate, a new oral anticoagulant, versus warfarin and other alternatives for the prevention of stroke and systemic embolism in UK patients with atrial fibrillation (AF).

Methods

A Markov model estimated the cost-effectiveness of dabigatran etexilate versus warfarin, aspirin or no therapy. Two patient cohorts with AF (starting age of <80 and ≥80 years) were considered separately, in line with the UK labelled indication. Modelled outcomes over a lifetime horizon included clinical events, quality-adjusted life years (QALYs), total costs and incremental cost-effectiveness ratios (ICERs).

Results

Patients treated with dabigatran etexilate experienced fewer ischaemic strokes (3.74 dabigatran etexilate vs 3.97 warfarin) and fewer combined intracranial haemorrhages and haemorrhagic strokes (0.43 dabigatran etexilate vs 0.99 warfarin) per 100 patient-years. Larger differences were observed comparing dabigatran etexilate with aspirin or no therapy. For patients initiating treatment at ages <80 and ≥80 years, the ICERs for dabigatran etexilate were £4831 and £7090/QALY gained versus warfarin with a probability of cost-effectiveness at £20 000/QALY gained of 98% and 63%, respectively. For the patient cohort starting treatment at ages <80 years, the ICER versus aspirin was £3457/QALY gained and dabigatran etexilate was dominant (ie, was less costly and more effective) compared with no therapy. These results were robust in sensitivity analyses.

Conclusions

This economic evaluation suggests that the use of dabigatran etexilate as a first-line treatment for the prevention of stroke and systemic embolism is likely to be cost-effective in eligible UK patients with AF.

Costs and clinical consequences of suboptimal atrial fibrillation management

Atrial fibrillation (AF) places a considerable burden on the US health care system, society, and individual patients due to its associated morbidity, mortality, and reduced health-related quality of life. AF increases the risk of stroke, which often results in lengthy hospital stays, increased disability, and long-term care, all of which impact medical costs. An expected increase in the prevalence of AF and incidence of AF-related stroke underscores the need for optimal management of this disorder. Although AF treatment strategies have been proven effective in clinical trials, data show that patients still receive suboptimal treatment. Adherence to AF treatment guidelines will help to optimize treatment and reduce costs due to AF-associated events; new treatments for AF show promise for future reductions in disease and cost burden due to improved tolerability profiles. Additional research is necessary to compare treatment costs and outcomes of new versus existing agents; an immediate effort to optimize treatment based on existing evidence and guidelines is critical to reducing the burden of AF.

Anticoagulation management in clinical practice: preventing stroke in patients with atrial fibrillation

Atrial fibrillation (AF) is a major and widely recognized risk factor for cardioembolic stroke. Prophylactic therapy for the prevention of stroke in patients with AF is often achieved through oral anticoagulation, specifically with warfarin, which has been used for this purpose for more than 50 years. Although warfarin therapy is effective when implemented appropriately, it is often underutilized and requires consistent monitoring to ensure both safety in avoiding bleeding and efficacy in preventing strokes. Because the burden of AF-related stroke continues to rise, healthcare professionals need to understand the strengths and limitations of current and emerging treatment options. This review outlines current practices for managing the risk of stroke with anticoagulation in patients with AF, and discusses how new oral anticoagulants may affect clinical practice.

Retrospective study of total healthcare costs associated with chronic nonvalvular atrial fibrillation and the occurrence of a first transient ischemic attack, stroke or major bleed

OBJECTIVE

To determine the direct healthcare costs associated with the onset of chronic nonvalvular atrial fibrillation (CNVAF), warfarin utilization and the occurrence of cerebrovascular events in a commercially-insured population.

RESEARCH DESIGN AND METHODS

This retrospective, observational cohort study utilized medical and pharmacy claims from a large, geographically diverse managed-care organization (N = 18.5 million) to identify continuously benefit-eligible CNVAF patients > or =45 years of age without prior valvular disease or warfarin use between January 1, 2001 and June 1, 2002. All patients were followed at least 6 months, until plan termination or the end of study follow-up. Stroke risk was assessed using the CHADS(2) (stroke-risk) index; warfarin use was defined as having filled at least one pharmacy claim. Inpatient and outpatient cost benchmarks were utilized to estimate total direct healthcare costs (pre- and post-AF index claim). For patients with transient ischemic attacks (TIA), ischemic stroke (IS) and major bleed (MB) total direct healthcare costs were also assessed. The limitations of this study included a descriptive retrospective study design without a comparison group or adjustment for baseline disease severity and drug exposure, as well as, the reliance upon administrative claims data and use of a standardized reference costing methodology.

RESULTS

The pre- and post-AF onset total direct healthcare costs (pmpm) for 3891 incidence CNVAF patients were $412 and $1235, respectively, a 200% increase. Of the 448 (12%) patients with a cerebrovascular event, pmpm costs post-AF ranged from $2235 to $3135 correlating with CHADS(2) stroke-risk status and exposure to warfarin. Total cohort pmpm costs pre and post event increased 24% from $3446.91 to $4262.12. Approximately 20% of all events occurred <2 days and 46% within 1 month after the index AF claim. Any warfarin exposure, regardless of CHADS(2) risk had an 18% to 29 % decrease in pmpm costs.

CONCLUSIONS

Post-AF total direct healthcare costs were 3 times greater than pre-AF costs. For those with a TIA, IS or MB, post-AF total direct healthcare costs increased 4.5 times from pre-AF costs; overall post-event costs in this cohort increased approximately 25% over pre-event costs. Nearly half of the events occurred within 1 month of a claim associated with an AF diagnosis. Warfarin exposure appeared to be associated with lower pmpm costs in this population.

Cost-effectiveness of warfarin: trial versus "real-world" stroke prevention in atrial fibrillation

BACKGROUND AND PURPOSE

Previous cost-effectiveness analyses analyzed warfarin for stroke prevention in randomized trial settings. Given the complexities of warfarin treatment, cost-effectiveness should be examined within a real-world setting.

METHODS

Our model followed patients with atrial fibrillation at moderate to high risk of stroke through primary and recurrent ischemic stroke, hemorrhages--intracranial and extracranial, and the resulting disability. Four scenarios were examined: (1) all patients start on warfarin with perfect control, that is, international normalized ratio (INR) values always within range; (2) all patients start on warfarin with trial-like control, where INR can fall outside the recommended range; (3) all patients start on warfarin with real-world INR control; and (4) real-world prescription (and control) of warfarin, aspirin, or neither for warfarin-eligible patients. Reported warfarin discontinuation rates were used. Main outcomes were total number of events, quality adjusted life years, and costs in a US setting.

RESULTS

The total number of primary and recurrent ischemic strokes in a 1,000-patient cohort (age 70 years, lifetime analysis) was 626, 832, 984, and 1,171 in scenarios 1 to 4, respectively. The corresponding mean quality adjusted life years per patient were 7.21, 6.92, 6.75, and 6.67 for scenarios 1 to 4, respectively. Costs per patient were $68,039, $77,764, $84,518, and $87,248 in scenarios 1 to 4, respectively. If "perfect" adherence to warfarin was assumed, except for discontinuations for clinical reasons, strokes would decrease to 503, 737, 909, and 1,120 in scenarios 1 to 4, respectively.

CONCLUSIONS

Clinical and cost outcomes are strongly dependent on the quality of anticoagulation and rates of warfarin discontinuation. Clinicians should work to improve both. Policy makers should use real-world INR control and warfarin discontinuation rates when assessing cost-effectiveness.

The effect of atrial fibrillation on stroke-related inpatient costs in Sweden: a 3-year analysis of registry incidence data from 2001

OBJECTIVE

Atrial fibrillation (AF) is an important risk factor for stroke. It is prevalent in approximately one-fourth of stroke patients, and predictive of worse outcomes. This study aimed to analyze the effect of AF on stroke-related inpatient costs among first-ever stroke patients in Sweden.

METHODS

Hospitalizations and death records were monitored for 3 years in 6611 first-ever stroke patients. For stroke as primary diagnosis, inpatient costs were calculated on the basis of length of stay at different wards. For stroke as secondary diagnosis, costs were based on diagnosis-related groups.

RESULTS

Patients with AF (24% of all patients) were older (80 years vs. 73 years), had a higher prevalence of hypertension (49% vs. 41%) and/or diabetes (22% vs. 19%), higher risk of experiencing a restroke, and higher case fatality rate (43% vs. 25%) than patients without AF. The average cost per patient over 3 years was 9004 euros, with no statistically significant difference between AF and non-AF patients. However, a multiple regression analysis showed that the presence of AF resulted in higher costs after considering a number of background factors. Among patients surviving the index event, AF patients had on average 818 euros higher inpatient costs over 3 years than non-AF patients (10,192 euros vs. 9374 euros, P < 0.01). The difference in costs was highest for patients aged <65 years, with a difference of 4412 euros (P < 0.01).

CONCLUSION

AF-related strokes are associated with higher 3-year inpatient costs than non-AF strokes when controlling for factors such as case fatality rates, other risk factors for stroke, and age.

The impact of atrial fibrillation on the cost of stroke: the berlin acute stroke study

OBJECTIVES

Atrial fibrillation (AF) is an important risk factor for stroke. The primary purpose of this study was to determine the resource use for patients admitted to hospital with acute stroke and to calculate stroke-related direct costs, stratifying the results according to the presence of AF as a risk factor.

METHODS

Data from 558 consecutive patients hospitalized with confirmed acute stroke between August 2000 and July 2001 were analyzed as part of the Berlin Acute Stroke Study. Sociodemographic variables were assessed by direct interview, while hospital data were derived from patient medical records. Patients or their carers completed a follow-up questionnaire about resource utilization and absenteeism from work during the 12-month period after hospital admission.

RESULTS

Out of the 367 patients with follow-up data and ECG findings, 71 (19%) had AF. Patients with AF were generally older, more likely to be female, and had more severe strokes compared with those without AF. Mean direct costs per patient were significantly higher in those with AF-related strokes (EURO 11,799 vs EURO 8817 for non-AF-related strokes; P < 0.001). After adjustment for confounding factors, direct costs were comparable in the two groups, except for acute hospitalization costs, which remained significantly higher in the group with AF (P < 0.05).

CONCLUSION

Medical care for stroke patients with AF is associated with higher costs compared with those without AF; this is explained mainly by confounding factors and driven essentially by a significant difference in acute hospitalization costs.

Evaluation of genetic factors for warfarin dose prediction

OBJECTIVES

Warfarin is a commonly prescribed anticoagulant drug used to prevent thromboses that may arise as a consequence of orthopedic and vascular surgery or underlying cardiovascular disease. Warfarin is associated with a notoriously narrow therapeutic window where small variations in dosing may result in hemorrhagic or thrombotic complications. To ultimately improve dosing of warfarin, we evaluated models for stable maintenance dose that incorporated both clinical and genetic factors.

METHOD

A model was constructed by evaluating the contribution to dosing variability of the following clinical factors: age, gender, body surface area, and presence or absence of prosthetic heart valves or diabetes. The model was then sequentially expanded by incorporating polymorphisms of cytochrome P450 (CYP) 2C9; vitamin K 2,3 epoxide reductase complex, subunit 1 (VKORC1); gamma carboxylase; factor VII; and apolipoprotein (Apo) E genes.

RESULTS

Of genetic factors evaluated in the model, CYP2C9 and VKORC1 each contributed substantially to dose variability, and together with clinical factors explained 56% of the individual variability in stable warfarin dose. In contrast, gamma carboxylase, factor VII and Apo E polymorphisms contributed little to dose variability.

CONCLUSION

The importance of CYP2C9 and VKORC1 to patient-specific dose of warfarin has been confirmed, while polymorphisms of gamma carboxylase, factor VII and Apo E genes did not substantially contribute to predictive models for stable warfarin dose.

Atrial fibrillation and stroke: four treatment controversies

Atrial fibrillation is an important cause of disabling ischemic stroke, and adjusted-dose warfarin is highly effective for prevention and remains the therapy of choice for high-risk patients. Ximelagatran, a novel oral anticoagulant, is clinically equivalent to warfarin for preventing stroke in patients with atrial fibrillation, but concerns about potential hepatic toxicity have precluded US Food and Drug Administration approval. Many patients with low-risk atrial fibrillation do not benefit substantially from anticoagulation, and these patients can be reliably identified using the CHADS2 stroke risk stratification scheme. A target International Normalized Ratio (INR) range of 2 to 3 is usually recommended for anticoagulation of patients with atrial fibrillation, but a lower INR target (2, range 1.6-2.5) may be a reasonable benefit/risk trade-off for primary prevention in those aged older than 75 years. Adding aspirin to adjusted-dose anticoagulation increases bleeding (including central nervous system bleeding), is of uncertain value, and should only be done after careful consideration and with vigorous efforts to control blood pressure.