Cost-Effectiveness of Novel Oral Anticoagulants for Stroke Prevention in Non-Valvular Atrial Fibrillation

Employing Real-World Evidence for the Economic Evaluation of Non-Vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation in Thailand

BACKGROUND

This study aimed to assess the cost-effectiveness of non-vitamin K antagonist oral anticoagulants (NOACs) in comparison with warfarin using data from real practice based on the perspective of the health care system in Thailand.

METHODS

A four-state Markov model encompassing well-controlled atrial fibrillation (AF), stroke and systemic embolism, major bleeding and death was utilised to forecast clinical and economic outcomes. Transitional probabilities, direct medical costs and utilities were derived from the real-world data of the 'COOL-AF Thailand' registry, Thailand's largest nationwide registry spanning 27 hospitals. The cohort comprised AF patients. The primary outcomes assessed were total costs, life years, quality-adjusted life years (QALYs) and the incremental cost-effectiveness ratio. All costs and outcomes were subject to an annual discount rate of 3.0%. A spectrum of sensitivity analyses was conducted.

RESULTS

The mean age of the cohort was 68.8 ± 10.7 years. The NOACs group incurred a marginally lower total lifetime cost than the warfarin group (247,857 Thai baht [THB] vs 253,654 THB or 7137 USD vs 7304 USD) and experienced gains of 0.045 life years and 0.043 QALYs over the warfarin group. Given the lower cost and higher benefits associated with NOACs, this implies that NOAC treatment is a dominant strategy compared to warfarin for AF patients. At a ceiling ratio of 160,000 THB (4607 USD) per QALY, NOACs presented a 61.2% probability of being cost effective.

CONCLUSIONS

Non-vitamin K antagonist oral anticoagulants represent a cost-saving alternative to warfarin in the real clinical practice. However, with a probability of being cost effective below 65%, it suggests some parameter uncertainty regarding their overall cost effectiveness compared to warfarin.

Patient satisfaction after conversion from warfarin to direct oral anticoagulants for patients on extended duration of anticoagulation for venous thromboembolism - The SWAN Study

Background

Warfarin is an anticoagulant medication proven effective in the initial treatment and secondary prevention of venous thromboembolism. Anti-Xa direct oral anticoagulants are alternatives to warfarin; however there is limited data assessing satisfaction after switching from warfarin to an anti-Xa direct oral anticoagulant in patients for treatment of venous thromboembolism.

Objectives

To assess medication satisfaction in patients requiring anticoagulation for venous thromboembolism after conversion from warfarin to an anti-Xa direct oral anticoagulant.

Methods

A retrospective cohort study with prospective assessment of satisfaction and review of adverse events following anti-Xa direct oral anticoagulant replacement of warfarin for treatment of venous thromboembolism. Out of 165 patients who had switched from warfarin to rivaroxaban or apixaban from an outpatient haematology practice, 126 patients consented for a survey of patient’s relative satisfaction of anti-Xa direct oral anticoagulant therapy compared with previous warfarin therapy using the Anti-Clot Burden and Benefits Treatment Scale and SWAN Score.

Results

The mean Anti-Clot Burden and Benefits and SWAN Score was 93% (56/60) and 83% (24.8/30) respectively reflecting high satisfaction with anti-Xa direct oral anticoagulants. 120 patients stated preference for anti-Xa direct oral anticoagulants over warfarin. Leading perceptions driving this was the reduction in frequency of medical contact and fewer bleeding side effects. Thirteen patients (10.3%) experienced an adverse event after the anti-Xa direct oral anticoagulant switch (majority were non-major bleeding) but most remained on anti-Xa direct oral anticoagulant treatment after management options were implemented with continued high satisfaction scores.

Conclusions

Patient satisfaction with anti-Xa direct oral anticoagulant therapy for the treatment and prevention of venous thromboembolism after switching from warfarin in routine clinical practice appeared high. Improved patient convenience including reduced frequency of medical contact and fewer unpredictable side effects were perceived as significant advantages of anti-Xa direct oral anticoagulants compared to warfarin.

Cost-effectiveness Evaluations Among the Direct Oral Anticoagulants for the Prevention and Treatment of Venous Thromboembolism: Systematic Review

Venous thromboembolism (VTE) is associated with high recurrence, mortality, and cost burden. Direct oral anticoagulants (DOACs) are currently used for VTE treatment, and they offer more benefits over warfarin, despite being more expensive. There is no consensus on the most cost-effective DOAC agent, especially in VTE. This systematic review aims to summarize the comparative cost-effectiveness studies and their impact among DOACs in the treatment of VTE. Literature systematic review of PubMed, Embase, and EconLit was conducted in February 2018 to identify all cost-effectiveness studies of DOAC for the treatment and prevention of VTE. Two independent investigators systematically collected search results and assessed the quality of the studies. The search identified 7 articles, all of which had dabigatran and rivaroxaban as comparators, 6 of which also included apixaban, and 2 of which also had edoxaban. Results of 3 articles concluded that apixaban is a dominant strategy compared to other DOACs in terms of Incremental Cost-Effectiveness Ratio (ICER) in the treatment and prevention of recurrent VTE. One article compared rivaroxaban and dabigatran, with the latter dominating rivaroxaban in terms of ICER. Compared to other DOACs, 2 articles reported apixaban being associated with highest annual total medical cost avoidance of US$4244 and US$4440 per patient-year (ppy), respectively. One article reported that apixaban had the highest annual total medical cost differences of US$918 ppy compared to other DOACs. This systematic review demonstrates that apixaban is considered a cost-effective strategy for VTE treatment and prevention of recurrent VTE.

Time-driven activity-based cost analysis for outpatient anticoagulation therapy: direct costs in a primary care setting with optimal performance

OBJECTIVES

To determine how overall cost of anticoagulation therapy for warfarin compares with that of Novel Oral Anticoagulants (NOACs). Also, to demonstrate a scientific, comprehensive, and an analytical approach to estimate direct costs involved in monitoring and management of anticoagulation therapy for outpatients in an academic primary care clinic setting, post-initiation of therapy.

METHODS

A population-based cross-sectional study was conducted in conjunction with observations of patient care processes between August 2014 and January 2015. The study was conducted in an academic primary care outpatient setting at Mayo Clinic's warfarin anticoagulation clinic, Rochester, MN. The anticoagulation clinic serves patients 18 years of age or older in Warfarin therapy management, for any indication, after referral from the patient's primary care provider. The study included anticoagulation clinic enrollment data on a population of 5,526 patients. Time-Driven Activity-Based Costing (TDABC) technique was applied. Detailed process flow maps which showed process steps for all the anticoagulation program components and care continuum phases were created. Staff roles associated with each of the process steps were identified and displayed on the maps. Process times and costs were captured and analyzed. The main outcome was direct cost of monitoring and management of anticoagulation therapy, post-initiation of therapy.

RESULTS

The cost of warfarin management for patients who display unstable International Normalized Ratio (INR) is more than three times those who display stable INR over time. (Comparator to distinguish stability: Frequency of point-of-care visits needed by patients.) For complex anticoagulation patients, total cost of medication and monitoring for warfarin anticoagulation therapy is similar to that for NOACs.

CONCLUSION

Despite warfarin being significantly less expensive to purchase than NOACs, overall warfarin management incurs higher costs due to laboratory monitoring and provider time than NOACs. NOAC treatment, therefore, may not be more expensive than warfarin therapy management for complex anticoagulation patients.

Health Care Costs and Utilization of Dabigatran Compared With Warfarin for Secondary Stroke Prevention in Patients With Nonvalvular Atrial Fibrillation: A Retrospective Population Study

BACKGROUND

It remains unclear whether the use of new oral anticoagulants, compared with warfarin, is economically beneficial in Asian countries.

OBJECTIVE

The objective of this study is to compare the health care costs and utilization between dabigatran and warfarin in a real-world nonvalvular atrial fibrillation (NVAF) population.

RESEARCH DESIGN

Data were obtained from the Taiwan National Health Insurance Database, and patients with an NVAF diagnosis between June 1, 2012, and May 31, 2014, were identified using the International Classification of Diseases, Ninth Revision code of 427.31. The patients in the dabigatran cohort were matched 1:2 to those in the warfarin cohort by sex, age, residential region, and a propensity score that incorporated a major bleeding history, CHADS2 score, and Charlson Comorbidity Index. The all-cause health care utilization and associated costs of the 2 treatment groups were compared at 3 and 12 months.

RESULTS

A total of 1149 patients taking dabigatran were identified and matched with 2298 warfarin users. During the 3-month observation period, the likelihood of having at least 1 hospitalization among dabigatran users was significantly lower than that of warfarin users (odds ratio=0.78; P=0.001). Patients in the dabigatran group incurred lower mean emergency department costs ($2383.1 vs. $3033.6), mean ischemic stroke-related hospitalization costs ($8869.5 vs. $13,990.5), and mean all-cause hospitalization costs ($32,402.2 vs. $50,669.9) at 3 months. However, both the mean and median outpatient costs of warfarin users were consistently lower than those of dabigatran users ($17,161.2 vs. $24,931.4 and $10,509.0 vs. $20,671.5, respectively). Similar trends were observed at 12 months, except that the 2 groups had comparable total health care costs.

CONCLUSIONS

The use of dabigatran is associated with lower emergency department and all-cause hospitalization costs but greater outpatient costs in a real-world, NVAF patient population compared with warfarin.

Characteristics of patients with thromboembolic disorders on warfarin therapy in resource limited settings

Background

Warfarin is a drug with narrow therapeutic index used in the management of thromboembolic disorders. Several factors affect its plasma concentrations with a resultant risk of toxicity. We examined the database of patients on warfarin therapy in order to establish the factors that affect the stability of INR and correlated them to clinical outcomes in resource limited settings.

Methods

We analysed retrospective data of patients admitted to adult medical wards at Moi Teaching and Referral Hospital (MTRH) in 2015. Inclusion criteria were patients with thromboembolic and related disorders and on warfarin treatment. Derived data included demographics, indications for warfarin use, co-prescribed drugs, co-morbidities, INR measurements, duration of hospital stay and clinical outcomes. Descriptive statistics were used to summarize the data. Pearson’s correlation coefficient was used to assess relationships between duration of hospitalization and number of INR tests. Regression splines were used to capture INR trends during the follow up period. Data was analysed using R v. 3.3.1.

Results

A total of 310 patients had thromboembolic disorders, out of which 63 met the study criteria.

The median age was 48 years, while the mean number of INR measurements was once every four days. Majority of patients did not achieve stable INR values, with only two having consecutive INR values within therapeutic goal. Patients who died had high INR levels. The median duration of hospital stay was 9 days (IQR: 7.0, 16.5). There was a significant correlation between length of stay in hospital and the number of times that INR were measured (Corr = 0.667, p < 0.001). The two most common indications for warfarin were DVT (64.4%) and atrial fibrillation (24.7%). All the patients had one or more comorbid conditions except for 11 with DVT alone, with cardiovascular diseases and infections being the most frequent, and on concomitant medications, majority of which are known to interact with warfarin.

Conclusions

It was difficult to achieve stable INR under the prevailing conditions despite the frequent tests.

The potential factors that may have contributed to the fluctuations include drug-drug interactions, frequency of INR tests, comorbidities and the short duration of hospital stay.

Approaches to Direct Oral Anticoagulant Selection in Practice

Direct oral anticoagulants (DOACs) carry many advantages over warfarin and are now considered first line or an alternative for mnay thromboembolic disorders. With the emergence of 5 DOAC agents to the market as well as the accumulating evidence gathered from head-to-head comparisons between the agents, we attempt to provide direction for clinicians when selecting the most appropriate DOAC agent. Important aspects such as efficacy, safety, cost effectiveness, approved indications, and other drug-related factors will be addressed to highlight the major similarities and diversities among the DOACs. When considering the safety profile of DOACs, evidence points toward apixaban as the safest followed by dabigatran and then rivaroxaban. On the other hand, dabigatran currently has the only approved antidote, idarucizumab. According to the approved DOAC indications, rivaroxaban may be favorable in European countries given its additional indication for secondary prevention of myocardial infarction. Following rivaroxaban, dabigatran and apixaban have the largest number of approved indications and lastly comes edoxaban and then betrixaban. For patients with renal impairment, betrixaban is the safest option, followed by apixaban and edoxaban, then rivaroxaban and lastly dabigatran. When considering DOAC dosing, rivaroxaban, edoxaban, and betrixaban are mainly dosed once daily compared to dabigatran and apixaban, which are dosed twice daily. However, rivaroxaban and betrixaban must be administered with food, which adds another level of complexity to the DOAC dosing. Lastly, taking into consideration drug interactions, dabigatran, edoxaban, and betrixaban have the least amount of interactions compared to apixaban and rivaroxaban. Each DOAC has its own set of features that makes it better suited than others based on the exact clinical situation. Therefore, no conclusion can be drawn to the most superior DOAC based on the aspects discussed in this review.

Exploring indications for the Use of direct oral anticoagulants and the associated risks of major bleeding

Thrombosis is a leading cause of morbidity and mortality in the United States. Arterial and venous thromboses are implicated in the pathogenesis of major disorders, including myocardial infarction, ischemic stroke, and venous thromboembolism. Over the past decade, direct oral anticoagulants (DOACs) (eg, direct thrombin inhibitor and factor Xa [FXa] inhibitors) have been adopted as alternatives to warfarin due to their clinical advantages and efficacy for the treatment of thrombosis. As with all anticoagulants, treatment with DOACs is associated with a risk of major bleeding, including life-threatening gastrointestinal bleeds and intracranial hemorrhages (ICHs). In turn, the burden of bleeding associated with DOAC treatment is itself associated with substantial healthcare costs that are amplified by an increased risk of thromboembolic events and mortality following major bleeding events, especially in patients with ICHs. Given the rapid adoption of the DOACs and projected usage in the large patient population affected by thromboembolic conditions, clinicians are increasingly likely to encounter patients with major bleeding events due to DOAC therapy. Unlike warfarin, effective strategies to manage these bleeds are limited. There is an unmet need for reversal agents for use in the management of patients who receive FXa inhibitors and experience life-threatening bleeding or need emergency surgery. Andexanet alfa and ciraparantag are being evaluated as potential antidotes for both direct and indirect FXa inhibitors.

Direct-Acting Oral Anticoagulants: Practical Considerations for Emergency Medicine Physicians

Nonvalvular atrial fibrillation- (NVAF-) related stroke and venous thromboembolism (VTE) are cardiovascular diseases associated with significant morbidity and economic burden. The historical standard treatment of VTE has been the administration of parenteral heparinoid until oral warfarin therapy attains a therapeutic international normalized ratio. Warfarin has been the most common medication for stroke prevention in NVAF. Warfarin use is complicated by a narrow therapeutic window, unpredictable dose response, numerous food and drug interactions, and requirements for frequent monitoring. To overcome these disadvantages, direct-acting oral anticoagulants (DOACs)—dabigatran, rivaroxaban, apixaban, and edoxaban—have been developed for the prevention of stroke or systemic embolic events (SEE) in patients with NVAF and for the treatment of VTE. Advantages of DOACs include predictable pharmacokinetics, few drug-drug interactions, and low monitoring requirements. In clinical studies, DOACs are noninferior to warfarin for the prevention of NVAF-related stroke and the treatment and prevention of VTE as well as postoperative knee and hip surgery VTE prophylaxis, with decreased bleeding risks. This review addresses the practical considerations for the emergency physician in DOAC use, including dosing recommendations, laboratory monitoring, anticoagulation reversal, and cost-effectiveness. The challenges of DOACs, such as the lack of specific laboratory measurements and antidotes, are also discussed.

Underuse of anticoagulation in patients with atrial fibrillation

Atrial fibrillation (AF) is a major risk factor for ischemic stroke. Guidelines recommend anticoagulation for patients with intermediate and high stroke risk (CHA2DS2-VASc score ≥ 2). Underuse of anticoagulants among eligible patients remains a persistent problem. Evidence demonstrates that the psychology of the fear of causing harm (omission bias) results in physicians' hesitancy to initiate anticoagulation and an inaccurate estimation of stroke risk. The American Heart Association (AHA) initiated the Get With The Guidelines-AFIB (GWTG-AFIB) module in June 2013 to enhance guideline adherence for treatment and management of AF. Better quality of care for AF patients can be provided by increasing adherence to anticoagulation guidelines and improving patient compliance with anticoagulation therapy through education and established protocols. Nonvitamin K antagonist oral anticoagulants may facilitate better patient adherence due to ease of administration and reduced monitoring burden. In this review, we discuss the reasons for underuse, omission bias contributing to underuse, and different strategies to address this issue.

Cost-effectiveness of apixaban vs. other new oral anticoagulants for the prevention of stroke: an analysis on patients with non-valvular atrial fibrillation in the Greek healthcare setting

BACKGROUND AND OBJECTIVES

Three new oral anticoagulants (NOACs) are currently approved for stroke prevention and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). The objective of this analysis was to assess the cost effectiveness of apixaban against other NOACs for the prevention of stroke in patients with NVAF in Greece.

METHODS

A Markov model that evaluated clinical events, quality-adjusted life expectancy, and costs for patients treated with apixaban or other NOACs formed the basis of the analysis. Clinical events were modeled for a lifetime horizon, based on clinical efficacy data from an indirect comparison, using the ARISTOTLE, ROCKET-AF, and RE-LY clinical trials. Resource use associated with patient monitoring was elicited via a panel of experts (cardiologists and internists). Cost calculations reflect the local clinical setting and followed a third-party payer perspective (Euros, discounted at 3 %).

RESULTS

Apixaban was projected to reduce the occurrence of clinical events and increase quality-adjusted life expectancy and incremental costs of treatment compared with other NOACs. Taking into account costs of medications, patient monitoring, and management of events, the incremental cost-effectiveness ratios for apixaban 5 mg twice daily vs. dabigatran 110 mg twice daily, dabigatran 150 mg twice daily, and rivaroxaban 20 mg once daily were estimated at €9907/quality-adjusted life-year (QALY), €13,727/QALY, and €6936/QALY gained, respectively. Extensive sensitivity analyses indicated that results were robust over a wide range of inputs.

CONCLUSIONS

Based on the results of this analysis, apixaban can be a cost-effective alternative to other NOACs for the prevention of stroke in patients with NVAF in Greece.