Risk of stroke/systemic embolism, major bleeding and associated costs in non-valvular atrial fibrillation patients who initiated apixaban, dabigatran or rivaroxaban compared with warfarin in the United States Medicare population

To treat or not to treat: a comparative effectiveness analysis of oral anticoagulant outcomes among U.S. nursing home residents with atrial fibrillation

BACKGROUND

Nursing home residents with atrial fibrillation are at high risk for ischemic stroke, but most are not treated with anticoagulants. This study compared the effectiveness and safety between oral anticoagulant (OAC) users and non-users.

METHODS

We conducted a new-user retrospective cohort study by using Minimum Data Set 3.0 assessments linked with Medicare claims. The participants were Medicare fee-for-service beneficiaries with atrial fibrillation residing in US nursing homes between 2011 and 2016, aged ≥ 65 years. The primary outcomes were occurrence of an ischemic stroke or systemic embolism (effectiveness), occurrence of intracranial or extracranial bleeding (safety) and net clinical outcome (effectiveness or safety outcomes). Secondary outcomes included total mortality and a net clinical and mortality outcome. Cox proportional hazards and Fine and Grey models estimated multivariable adjusted hazard ratios (aHRs) and sub-distribution hazard ratios (sHRs).

RESULTS

Outcome rates were low (effectiveness: OAC: 0.86; non-users: 1.73; safety: OAC: 2.26; non-users: 1.75 (per 100 person-years)). OAC use was associated with a lower rate of the effectiveness outcome (sHR: 0.69; 95% Confidence Interval (CI): 0.61-0.77), higher rates of the safety (sHR: 1.70; 95% CI: 1.58-1.84) and net clinical outcomes (sHR: 1.20; 95% CI: 1.13-1.28) lower rate of all-cause mortality outcome (sHR: 0.60; 95% CI: 0.59-0.61), and lower rate of the net clinical and mortality outcome (sHR: 0.60; 95% CI: 0.59-0.61). Warfarin users, but not DOAC users, had a higher rate of the net clinical outcome versus OAC non-users.

CONCLUSIONS

Our results support the benefits of treatment with OACs to prevent ischemic strokes and increase longevity, while highlighting the need to weigh apparent benefits against elevated risk for bleeding. Results were consistent with net favorability of DOACs versus warfarin.

Heterogeneity after harmonisation: A retrospective cohort study of bleeding and stroke risk after the introduction of direct oral anticoagulants in four Western European countries

PURPOSE

Database heterogeneity can impact effect estimates. Harmonisation provided by common protocols and common data models (CDMs) can increase the validity of pharmacoepidemiologic research. In a case study measuring the changes in the safety and effectiveness of stroke prevention therapy after the introduction of direct oral anticoagulants (DOACs), we performed an international comparison.

METHODS

Using data from Stockholm, Denmark, Scotland and Norway, harmonised with a common protocol and CDM, two calendar-based cohorts were created: 2012 and 2017. Patients with a diagnosis code of atrial fibrillation 5 years preceding the 1-year cohort window were included. DOAC, vitamin K antagonist and aspirin treatment were assessed in the 6 months prior to the start of each year while strokes and bleeds were assessed during the year. A Poisson regression generated incidence rate ratios (IRRs) to compare outcomes from 2017 to 2012 adjusted for changes in individual-level baseline characteristics.

RESULTS

In 280 359 patients in the 2012 cohort and 356 779 in the 2017 cohort, treatment with OACs increased on average from 45% to 65%, while treatment with aspirin decreased from 30% to 10%. In all countries except Scotland, there were decreases in the risk of stroke and no changes in bleeding risk, after adjustment for changes in baseline characteristics. In Scotland, major bleeding (IRR 1.09, 95% confidence interval [CI] [1.00; 1.18]) and intracranial haemorrhage (IRR 1.31, 95% CI [1.13; 1.52]) increased from 2012 to 2017.

CONCLUSIONS

Stroke prevention therapy improved from 2012 to 2017 with a corresponding reduction in stroke risk without increasing the risk of bleeding in all countries, except Scotland. The heterogeneity that remains after methodological harmonisation can be informative of the underlying population and database.

Utilization outcomes of direct oral anticoagulants in Medicare patients

OBJECTIVE

To compare the adherence, persistence, discontinuation and switching rates of direct oral anticoagulants (DOACs) for Medicare patients with non-valvular atrial fibrillation (NVAF) or venous thromboembolism (VTE).

METHODS

This was retrospective observational cohort study design. Medicare Part D claims files were used for the study duration (2015-2018). Inclusion-exclusion criteria were applied to identify the NVAF and VTE sample using dabigatran, rivaroxaban, apixaban, edoxaban and warfarin during the identification period (2016-2017). Outcomes of adherence, persistence, time to non-persistence and time to discontinuation were assessed in those who did not switch the index drug in the follow-up period (365 days from the index date). Switching rates were assessed in those who switched the index drug at least once in the aforementioned follow-up period. Descriptive statistics were conducted for all the outcomes, and comparisons were made using t-tests, chi-square, and ANOVA. Logistic regression was conducted to compare the odds of being adherent and the odds of switching in NVAF and VTE patient cohorts.

RESULTS

Of all the DOACs, patients with NVAF or VTE were most adherent to apixaban (PDC = 76.88). Among all the DOACs, non-persistence and discontinuation rates were highest for warfarin. Majority of the switches were reported from dabigatran to other DOAC and to apixaban from other DOAC. Despite the better utilization outcomes reported for apixaban users, Medicare plans covered rivaroxaban favorably. It was associated with the lowest mean amount paid by the patient (NVAF: $76; VTE: $59), and the highest mean amount paid by the plans (NVAF: $359; VTE: $326).

CONCLUSION

Medicare plans need to consider adherence, persistence, discontinuation and switching rates of DOACs to make the coverage decisions.

Geographic variation in clinical outcomes and anticoagulation among medicare beneficiaries with non-valvular atrial fibrillation

Oral anticoagulants (OACs) have been used to prevent stroke/systemic embolism (SE) among patients with non-valvular atrial fibrillation (NVAF). To evaluate baseline clinical characteristics, incidence rates of stroke/SE and hospitalization for bleeding, and OAC use among elderly patients with NVAF in the US by geographic region. Patients with NVAF were selected from the US Centers for Medicare & Medicaid Services claims database (01JAN2013-31DEC2016). Twelve months of health plan enrollment was required before and after the NVAF diagnosis to evaluate baseline characteristics and outcomes, respectively. Each patient was assigned to a 3-digit zip code based on their primary residence, and geographic variation was visualized using ArcGIS Pro software. Over 2.8 million patients with NVAF were identified. Large geographic variation was observed in clinical characteristics, stroke/SE, hospitalization for bleeding, and OAC use among patients across the US. The zip codes with the highest mean CHA2DS2-VASc scores and frequency of prior bleeding also had the highest incidence of stroke/SE and hospitalization for bleeding. Across 3-digit zip codes, 35-63% of patients were untreated. Overall, the incidence of stroke/SE and hospitalization for bleeding were higher and OAC treatment was less frequent in zip codes located in the Southern US. Baseline clinical characteristics, incidence rates of stroke/SE and hospitalization for bleeding, and OAC usage vary considerably by 3-digit zip code in the US. The additional granularity provided in this study may help clinicians to identify small regions with high-risk of stroke/SE and hospitalization for bleeding and low use of OAC that may benefit from targeted care strategies.

Comparative outcomes associated with rivaroxaban versus warfarin use in elderly patients with atrial fibrillation or acute venous thromboembolism managed in the United States: a systematic review of observational studies

BACKGROUND

Advancing age is a risk factor for developing non-valvular atrial fibrillation (NVAF) or acute venous thromboembolism (VTE). We assessed the comparative effectiveness, safety, costs, and healthcare utilization associated with rivaroxaban versus warfarin in patients of advanced age managed in the United States (US).

METHODS

We conducted a systematic review of Medline and Embase through April 2023 to identify real-world evidence (RWE) studies of older adults (at least 65+ years of age) with either NVAF or VTE who received either rivaroxaban or warfarin in the US and reported an outcome of stroke or systemic embolism (SSE), ischemic stroke (IS), recurrent VTE, major bleeding, intracranial hemorrhage, costs, or healthcare resource utilization. We classified each outcome of interest per study as "positive" (lower risk), "negative" (higher risk), or "neutral" based upon the summary effect size of rivaroxaban versus warfarin.

RESULTS

Twenty-nine RWE studies met inclusion criteria, mostly (83%) in NVAF populations. For SSE with rivaroxaban versus warfarin, 68.8% of studies showed positive effects and 31.2% showed neutral outcome. For major bleeding, 57.7% showed neutral effects, 38.5% showed negative effects, and 3.8% of studies showed positive effects with rivaroxaban versus warfarin. Of the two studies reporting cost data, both were positive, showing lower costs for SSE for rivaroxaban versus warfarin and neutral cost for major bleeding costs.

CONCLUSIONS

This systematic review supports findings from subgroup analyses of randomized controlled trials that, compared with warfarin, rivaroxaban is associated with generally neutral or positive effects on thrombosis and a mixed picture on bleeding outcomes in older adults with either NVAF or VTE treated in the United States.

Comparative Effectiveness and Safety of Oral Anticoagulants by Dementia Status in Older Patients With Atrial Fibrillation

Importance

The development of an optimal stroke prevention strategy, including the use of oral anticoagulant (OAC) therapy, is particularly important for patients with atrial fibrillation (AF) who are living with dementia, a condition that increases the risk of adverse outcomes. However, data on the role of dementia in the safety and effectiveness of OACs are limited.

Objective

To assess the comparative safety and effectiveness of specific OACs by dementia status among older patients with AF.

Design, Setting, and Participants

This retrospective comparative effectiveness study used 1:1 propensity score matching among 1 160 462 patients 65 years or older with AF. Data were obtained from the Optum Clinformatics Data Mart (January 1, 2013, to June 30, 2021), IBM MarketScan Research Database (January 1, 2013, to December 31, 2020), and Medicare claims databases maintained by the Centers for Medicare & Medicaid Services (inpatient, outpatient, and pharmacy; January 1, 2013, to December 31, 2017). Data analysis was performed from September 1, 2021, to May 24, 2022.

Exposures

Apixaban, dabigatran, rivaroxaban, or warfarin.

Main Outcomes and Measures

Composite end point of ischemic stroke or major bleeding events over the 6-month period after OAC initiation, pooled across databases using random-effects meta-analyses.

Results

Among 1 160 462 patients with AF, the mean (SD) age was 77.4 (7.2) years; 50.2% were male, 80.5% were White, and 7.9% had dementia. Three comparative new-user cohorts were established: warfarin vs apixaban (501 990 patients; mean [SD] age, 78.1 [7.4] years; 50.2% female), dabigatran vs apixaban (126 718 patients; mean [SD] age, 76.5 [7.1] years; 52.0% male), and rivaroxaban vs apixaban (531 754 patients; mean [SD] age, 76.9 [7.2] years; 50.2% male). Among patients with dementia, compared with apixaban users, a higher rate of the composite end point was observed in warfarin users (95.7 events per 1000 person-years [PYs] vs 64.2 events per 1000 PYs; adjusted hazard ratio [aHR], 1.5; 95% CI, 1.3-1.7), dabigatran users (84.5 events per 1000 PYs vs 54.9 events per 1000 PYs; aHR, 1.5; 95% CI, 1.2-2.0), and rivaroxaban users (87.4 events per 1000 PYs vs 68.5 events per 1000 PYs; aHR, 1.3; 95% CI, 1.1-1.5). In all 3 comparisons, the magnitude of the benefits associated with apixaban was similar regardless of dementia diagnosis on the HR scale but differed substantially on the rate difference (RD) scale. The adjusted RD of the composite outcome per 1000 PYs for warfarin vs apixaban users was 29.8 (95% CI, 18.4-41.1) events in patients with dementia vs 16.0 (95% CI, 13.6-18.4) events in patients without dementia. The corresponding adjusted RD estimates of the composite outcome were 29.6 (95% CI, 11.6-47.6) events per 1000 PYs in patients with dementia vs 5.8 (95% CI, 1.1-10.4) events per 1000 PYs in patients without dementia for dabigatran vs apixaban users and 20.5 (95% CI, 9.9-31.1) events per 1000 PYs in patients with dementia vs 15.9 (95% CI, 11.4-20.3) events per 1000 PYs in patients without dementia for rivaroxaban vs apixaban users. The pattern was more distinct for major bleeding than for ischemic stroke.

Conclusions and Relevance

In this comparative effectiveness study, apixaban was associated with lower rates of major bleeding and ischemic stroke compared with other OACs. The increased absolute risks associated with other OACs compared with apixaban were greater among patients with dementia than those without dementia, particularly for major bleeding. These findings support the use of apixaban for anticoagulation therapy in patients living with dementia who have AF.

Direct Oral Anticoagulant (DOAC) Dosing in Patients with Non-valvular Atrial Fibrillation (NVAF) in the United Kingdom: A Retrospective Cohort Study Using CPRD Gold Database

INTRODUCTION

Per-label dosing of direct oral anticoagulants (DOACs) is important for the prevention of stroke and systemic embolism among patients with non-valvular atrial fibrillation (NVAF), especially those with poor renal function, advanced age, low body weight or concomitant P-glycoprotein inhibitors. The study described DOAC use and dosing patterns in patients with NVAF in the UK.

METHODS

Using Clinical Practice Research Datalink (CPRD Gold), patients' profiles were described at DOAC initiation (1 January 2016-31 March 2021) and followed for a mean [standard deviation (SD)] 2 (1) years. Patients were categorised as under-dosing: received a lower dose with no indication for a reduced dose; over-dosing: received a standard dose with an indication for a reduced dose; per-label dosing, according to Summary Product Characteristics (SmPC).

RESULTS

Forty thousand seven hundred forty-four adult patients with NVAF were identified (mean age: 75.3 (11.2) years; males: 55.4%); 22,827 (56.0%) initiated treatment with apixaban, 930 (2.3%) dabigatran, 5633 (13.8%) edoxaban and 11,354 (27.9%) rivaroxaban. Baseline Charlson comorbidity index ≥ 4 was 65.1%; CHA₂DS₂-VASc score ≥ 4 was 22.5%; HAS-BLED score ≥ 3 was 18.3%; ~ 2% had prior major bleed and 4.4% a stroke ≤ 2 years before DOAC initiation. Overall, 18.0% of patients received incorrect dosing (~ one in five). Under-dosing was highest for dabigatran (156, 16.8%) and over-dosing was highest for rivaroxaban (1084, 9.6%). Per-label dosing was highest for edoxaban (4773, 84.7%), followed by apixaban (18,756, 82.2%), rivaroxaban (9161, 80.7%) and dabigatran (732, 78.7%). Treatment persistence (no switching or discontinuation) was 79% among edoxaban users, followed by 75% for apixaban, 69% for rivaroxaban and 62% for dabigatran. About 15% of dabigatran users, 10% of rivaroxaban users, 5% of apixaban users and 4% of edoxaban users switched treatment to another DOAC during follow-up.

CONCLUSION

Although most patients received per-label dosing, ~ one in five patients was incorrectly dosed with DOAC, which may lead to serious clinical consequences and increased healthcare burden.

Risk of stroke/systemic embolism, major bleeding, and associated costs in non-valvular atrial fibrillation patients who initiated apixaban, dabigatran, or rivaroxaban compared with warfarin in the United States medicare population: updated analysis

OBJECTIVE

To provide an updated comparison of the risk and cost of stroke/systemic embolism (SE) and major bleeding between direct oral anticoagulants (DOAC: apixaban, rivaroxaban, dabigatran) and warfarin among non-valvular atrial fibrillation (NVAF) patients.

METHODS

Adults (≥65 years) initiating warfarin or DOACs between 1 January 2013 and 31 December 2014 were selected from the Medicare database and propensity scores matched 1:1 to balance baseline characteristics. Cox proportional hazards models were used to estimate the risks of stroke/SE and major bleeding of each DOAC vs. warfarin. Two-part models were used to compare the stroke/SE- and major bleeding-related medical costs in each matched cohort.

RESULTS

Of the 264,479 eligible patients, 38,740 apixaban-warfarin pairs, 76,677 rivaroxaban-warfarin pairs, and 20,955 dabigatran-warfarin pairs were matched. Apixaban (Hazard Ratio [HR] = 0.46; 95% Confidence Interval [CI] 0.38-0.56) and rivaroxaban (HR = 0.71; 95% CI 0.63-0.80) were associated with a significantly lower risk of stroke/SE compared to warfarin. Apixaban (HR = 0.57; 95% CI 0.51-0.63) and dabigatran (HR = 0.80; 95% CI 0.70-0.90) were associated with a significantly lower risk of major bleeding; rivaroxaban (HR = 1.14; 95% CI 1.07-1.21) was associated with a significantly higher risk of major bleeding compared to warfarin. Compared to warfarin, apixaban and rivaroxaban had significantly lower stroke/SE-related medical costs; and apixaban and dabigatran had significantly lower major bleeding-related medical costs.

CONCLUSIONS

This real-world analysis showed DOACs to be associated with a lower risk of stroke/SE and major bleeding, and lower medical costs compared to warfarin. Among them, only apixaban appears to be associated with a significantly lower risk of all three outcomes collectively: stroke/SE, major bleeding, and lower related medical costs compared to warfarin.

Understanding variation in the results of real-world evidence studies that seem to address the same question

OBJECTIVES

Multiple database studies on the same question, conducted by different investigators using different approaches or different data sources, can be considered sensitivity analyses for the same causal treatment effect question. We evaluated the contribution of alternative study design parameters and analysis choices to variation in estimates of the risk of major bleeding with dabigatran compared with warfarin.

STUDY DESIGN AND SETTING

We followed a 7-step process: (1) identify published studies asking the same question, (2) independently reproduce selected studies in the same data sources as the original authors, (3) contact original authors, (4) evaluate validity, (5) document critical study parameter specifications, (6) implement a designed matrix of variations in study parameters based on the original studies, and (7) evaluate contributors to variation in results.

RESULTS

Most variation remained unexplained (60-88%). Of the explained variation, two-thirds were related to data and population differences, and one-third were related to the use of alternative study design and analysis parameters. Among these, the most prominent were differences in outcome algorithms and criteria used to define follow-up.

CONCLUSION

When making policy decisions based on database study findings, it is important to evaluate the validity, consistency, and robustness of results to alternative design and analysis decisions.

Effectiveness and Safety of Apixaban in over 3.9 Million People with Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background: There is a plethora of real-world data on the safety and effectiveness of direct-acting oral anticoagulants (DOACs); however, study heterogeneity has contributed to inconsistent findings. We compared the effectiveness and safety of apixaban with those of other direct-acting oral anticoagulants (DOACs) and vitamin K antagonists (VKA e.g., warfarin). Methods: A systematic review and meta-analysis was conducted retrieving data from PubMed, SCOPUS and Web of Science from January 2009 to December 2021. Studies that evaluated apixaban (intervention) prescribed for adults (aged 18 years or older) with AF for stroke prevention compared to other DOACs or VKAs were identified. Primary outcomes included stroke/systemic embolism (SE), all-cause mortality, and major bleeding. Secondary outcomes were intracranial haemorrhage (ICH) and ischaemic stroke. Randomised controlled trials and non-randomised trials were considered for inclusion. Results: In total, 67 studies were included, and 38 studies were meta-analysed. Participants taking apixaban had significantly lower stroke/SE compared to patients taking VKAs (relative risk (RR) 0.77, 95% confidence interval (CI) 0.64–0.93, I² = 94%) and dabigatran (RR 0.84, 95% CI 0.74–0.95, I² = 66%), but not to patients administered rivaroxaban. There was no statistical difference in mortality between apixaban and VKAs or apixaban and dabigatran. Compared to patients administered rivaroxaban, participants taking apixaban had lower mortality rates (RR 0.83, 95% CI 0.71–0.96, I² = 96%). Apixaban was associated with a significantly lower risk of major bleeding compared to VKAs (RR 0.58, 95% CI 0.52–0.65, I² = 90%), dabigatran (RR 0.79, 95% CI 0.70–0.88, I² = 78%) and rivaroxaban (RR 0.61, 95% CI 0.53–0.70, I² = 87%). Conclusions: Apixaban was associated with a better overall safety and effectiveness profile compared to VKAs and other DOACs.

Relationship Amongst Vitamin K Status, Vitamin K Antagonist Use and Osteoarthritis: A Review

Vitamin K is essential for the carboxylation of the vitamin K-dependent proteins that are responsible for the suppression of matrix calcification. The use of vitamin K antagonists (VKAs) in patients with cardiovascular diseases could affect protein carboxylation and lead to the development of osteoarthritis (OA). This review aims to summarise the current evidence for the relationship between VKAs and OA. The literature search revealed that in observation studies, good vitamin K status, as reflected by the circulating level or protein carboxylation status of vitamin K, is associated positively with improved joint structural and functional indices and negatively associated with OA incidence. By contrast, in limited retrospective and prospective studies, the use of VKAs is associated positively with OA occurrence and knee/hip replacement. Pharmacological interactions between VKAs and various OA therapeutic agents exist and require careful monitoring and dosing. In conclusion, further epidemiological studies are warranted to verify the relationship between VKA use and OA to strengthen the evidence. Given that VKA use exerts potentially negative effects on joint health, intervention is required to protect the quality of life and mobility of patients.

Management of Atrial Fibrillation in Patients 75 Years and Older: JACC State-of-the-Art Review

The prevalence of atrial fibrillation (AF) is increasing as the population ages. AF treatment-related complications also increase markedly in older adults (defined as ≥75 years of age for this review). The older AF population has a high risk of stroke, bleeding, and death. Syncope and fall-related injuries are the most common reasons for nonprescription of oral anticoagulation (OAC), and are more common in older adults when OACs are used with antiarrhythmic drugs. Digoxin may be useful for rate control, but associations with increased mortality limit its use. Beyond rate and rhythm control considerations, stroke prophylaxis is critical to AF management, and the benefits of direct OACs, compared with warfarin, extend to older adults. Invasive procedures such as AF catheter ablation, pacemaker implantation/atrioventricular junction ablation, and left atrial appendage occlusion may be useful in appropriately selected cases. However, older adults have generally been under-represented in clinical trials.

Gastrointestinal Bleeding: a Cardiologist's Point of View

Oral anticoagulant therapy is widely used in different patients for the prevention and treatment of thromboembolic events: in atrial fibrillation, deep vein thrombosis/pulmonary embolism, acute coronary syndrome, in the early postoperative period after orthopedic surgery. Nowadays it is possible to use vitamin K antagonists (warfarin) as well as direct oral anticoagulants (DOAC): dabigatran, rivaroxaban, apixaban and edoxaban. The mai complication of any anticoagulant therapy is bleeding (gastrointestinal, intracranial, etc.), which seriously limits its usage. In this review the incidence of gastrointestinal bleeding (GIB) associated with oral anticoagulants intake was analyzed according to the results of both large randomized and postregistration trials. Furthermore, the effect of age on the risk of GIB development is discussed, and also aspects of the pathophysiology of gastrointestinal mucosa lesions in patients taking DOAC are considered.

Frailty and Clinical Outcomes of Direct Oral Anticoagulants Versus Warfarin in Older Adults With Atrial Fibrillation : A Cohort Study

BACKGROUND

The role of differing levels of frailty in the choice of oral anticoagulants for older adults with atrial fibrillation (AF) is unclear.

OBJECTIVE

To examine the outcomes of direct oral anticoagulants (DOACs) versus warfarin by frailty levels.

DESIGN

1:1 propensity score-matched analysis of Medicare data, 2010 to 2017.

SETTING

Community.

PATIENTS

Medicare beneficiaries with AF who initiated use of dabigatran, rivaroxaban, apixaban, or warfarin.

MEASUREMENTS

Composite end point of death, ischemic stroke, or major bleeding by frailty levels, defined by a claims-based frailty index.

RESULTS

In the dabigatran-warfarin cohort (n = 158 730; median follow-up, 72 days), the event rate per 1000 person-years was 63.5 for dabigatran initiators and 65.6 for warfarin initiators (hazard ratio [HR], 0.98 [95% CI, 0.92 to 1.05]; rate difference [RD], -2.2 [CI, -6.5 to 2.1]). For nonfrail, prefrail, and frail persons, HRs were 0.81 (CI, 0.68 to 0.97), 0.98 (CI, 0.90 to 1.08), and 1.09 (CI, 0.96 to 1.23), respectively. In the rivaroxaban-warfarin cohort (n = 275 944; median follow-up, 82 days), the event rate per 1000 person-years was 77.8 for rivaroxaban initiators and 83.7 for warfarin initiators (HR, 0.98 [CI, 0.94 to 1.02]; RD, -5.9 [CI, -9.4 to -2.4]). For nonfrail, prefrail, and frail persons, HRs were 0.88 (CI, 0.77 to 0.99), 1.04 (CI, 0.98 to 1.10), and 0.96 (CI, 0.89 to 1.04), respectively. In the apixaban-warfarin cohort (n = 218 738; median follow-up, 84 days), the event rate per 1000 person-years was 60.1 for apixaban initiators and 92.3 for warfarin initiators (HR, 0.68 [CI, 0.65 to 0.72]; RD, -32.2 [CI, -36.1 to -28.3]). For nonfrail, prefrail, and frail persons, HRs were 0.61 (CI, 0.52 to 0.71), 0.66 (CI, 0.61 to 0.70), and 0.73 (CI, 0.67 to 0.80), respectively.

LIMITATIONS

Residual confounding and lack of clinical frailty assessment.

CONCLUSION

For older adults with AF, apixaban was associated with lower rates of adverse events across all frailty levels. Dabigatran and rivaroxaban were associated with lower event rates only among nonfrail patients.

PRIMARY FUNDING SOURCE

National Institute on Aging.

Direct comparison of non-vitamin K antagonist oral anticoagulant versus warfarin for stroke prevention in non-valvular atrial fibrillation: a systematic review and meta-analysis of real-world evidences

Background

To overcome the several drawbacks of warfarin, non-vitamin K antagonist oral anticoagulants (NOACs) were developed. Even though randomized controlled trials (RCTs) provided high-quality evidence, the real-world evidence is still needed. This systematic review and meta-analysis proposed to measure the safety and efficacy profile between warfarin and NOACs in non-valvular atrial fibrillation (NVAF) patients in preventing stroke.

Results

We collected articles about the real-world studies comparing warfarin and NOACs for NVAF patients recorded in electronic scientific databases such as Embase, ProQuest, PubMed, and Cochrane. The pooled hazard ratio (HR) and 95% confidence interval (CI) were estimated using the generic inverse variance method. A total of 34 real-world studies, including 2287288 NVAF patients, were involved in this study. NOACs effectively reduced the stroke risk than warfarin (HR 0.77; 95% CI 0.69 to 0.87; p < 0.01). Moreover, NOACs effectively lowered all-cause mortality risk (HR 0.71; 95% CI 0.63 to 0.81; p < 0.01). From the safety aspect, compared to warfarin, NOACs significantly reduced major bleeding risk (HR 0.68; 95% CI 0.54 to 0.86; p < 0.01) and intracranial bleeding risk (HR 0.54; 95% CI 0.42 to 0.70; p < 0.01). However, NOACs administration failed to decrease gastrointestinal bleeding risk (HR 0.78; 95% CI 0.58 to 1.06; p = 0.12).

Conclusions

In NVAF patients, NOACs were found to be more effective than warfarin at reducing stroke risk. NOACSs also lowered the risk of all-cause mortality, cerebral hemorrhage, and severe bleeding in NVAF patients compared to warfarin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00194-1.

Comparing total medical expenditure between patients receiving direct oral anticoagulants vs warfarin for the treatment of atrial fibrillation: evidence from VA-Medicare dual enrollees

BACKGROUND: Direct oral anticoagulants (DOACs) are an alternative to warfarin for treatment of atrial fibrillation (AF). Evidence demonstrating the efficacy and safety of DOACs has primarily been from clinical trial settings. The real-world effectiveness of DOACs in specific nontrial populations that differ in age, comorbidity burden, and socioeconomic status is unclear. OBJECTIVE: To compare total downstream medical expenditure between AF patients treated with warfarin and DOACs dually enrolled in the Veterans Affairs (VA) Healthcare System and fee-for-service Medicare. METHODS: This was an exploratory treatment effectiveness study that analyzed VA administrative data and Medicare claims. We examined patients with an incident diagnosis for AF and initiated warfarin or DOAC treatment between 2012 and 2015. The primary outcome was total medical expenditure over 3 years following treatment initiation. To address potential informative censoring, we applied a multipart estimator that extends traditional 2-part models to separate differences between groups due to survival and cost accumulation effects. Inverse probability weighting was applied to address potential treatment selection bias. RESULTS: We identified 31,276 and 17,021 patients receiving warfarin and DOACs, respectively. Mean unadjusted (SD) expenditure was higher for warfarin ($56,265 [$96,666]) compared with DOAC patients ($32,736 [$52,470]). Compared with patients receiving DOACs, adjusted 3-year expenditure was $25,688 (P < 0.001) higher for patients receiving warfarin. CONCLUSIONS: VA patients with AF initiating warfarin incurred markedly higher downstream expenditure compared with similar patients receiving DOACs. The benefits of DOACs found in previous clinical trials were present in this population, suggesting that these DOACs may be the preferred option for treatment of AF in older VA patients. DISCLOSURES: This study was funded by a VA Health Services Research and Development Investigator Initiated Research Award (IIR 15-139). Support for VA/CMS data was provided by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Health Services Research and Development, VA Information Resource Center (Project Numbers SDR 02-237 and 98-004). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs, the University of Washington, Northeastern University, and Boston University. The authors declare no conflicts of interest. This research includes data obtained from the VHA Office of Performance Measurement (17API2), which resides within the Office of Analytics and Performance Integration (API), under the Office of Quality and Patient Safety (QPS; formerly known as RAPID). An oral presentation documenting a subset of the findings from this study was presented at the 2020 AcademyHealth Annual Research Meeting, delivered virtually on July 29, 2020.

Non-vitamin K oral anticoagulants and risk of fractures: a systematic review and meta-analysis

AIMS

Comparative fracture risk for non-vitamin K antagonist oral anticoagulants (NOACs) and vitamin K antagonists (VKAs) among patients with atrial fibrillation (AF) remains unclear. This study aimed to provide summary relative risk (RR) estimates for associations between NOACs vs. VKAs and fracture risk.

METHODS AND RESULTS

PubMed, EMBASE, and Cochrane Library were searched from 2010 to 26 May 2020. Observational studies investigating the association between NOACs vs. VKAs and fracture risk in patients with AF were included. The adjusted effect estimates were pooled using the DerSimonian-Laird random effects models. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Meta-analysis of Observational Studies in Epidemiological (MOOSE) guidelines were followed. Five observational studies comprising 269 922 patients and 4289 fractures were included. Non-vitamin K antagonist oral anticoagulants use was associated with a lower risk of any fractures compared to VKAs use, with moderate heterogeneity [pooled RR = 0.83, 95% confidence interval (CI): 0.75-0.92, P < 0.001, I2 = 73.0%]. When comparing individual NOAC to VKAs, a statistically significant lower risk of any fractures was found for rivaroxaban (pooled RR = 0.79, 95% CI: 0.71-0.88, P < 0.001, I2 = 55.2%) and apixaban (pooled RR = 0.75, 95% CI: 0.60-0.92, P = 0.007, I2 = 54.5%), but not dabigatran (pooled RR = 0.87, 95% CI: 0.74-1.01, P = 0.061, I2 = 74.6%). No differences were observed in all head-to-head comparisons between NOACs.

CONCLUSION

This large meta-analysis suggests that NOACs use was associated with a lower risk of fractures compared with VKAs. Fracture risks were similar between NOACs. These findings may help inform the optimal anticoagulant choice for patients with AF at high risk of fracture.

Demonstration of proof-of-concept of StrokeShield system for complete closure and occlusion of the left atrial appendage for non-valvular atrial fibrillation therapy

In the US, the most significant morbidity and mortality associated with non-valvular atrial fibrillation (NVAF) is embolic stroke, with 90% of thrombus originating from the left atrial appendage (LAA). Anticoagulation is the preferred treatment for the prevention of stroke in NVAF patients, but clinical studies have demonstrated high levels of non-compliance and increased risk of bleeding or ineligibility for anticoagulation therapy, especially in the elderly population where the incidence of NVAF is highest. Alternatively, stroke may be preventing using clinically approved surgical and catheter-based devices to exclude or occlude the LAA, but these devices continue to be plagued by peri-device leaks and thrombus formation because of residual volume. To overcome these limitations, Cor Habere (Louisville, KY) and the University of Louisville are developing a LAA closure device (StrokeShield) that completely occludes and collapses the LAA to minimize the risk of stroke. The StrokeShield device is a collapsible occluder (nitinol reinforced membrane) that completely covers the LAA orifice with an expandable conical coil anchor that attaches to the myocardium. The device is designed for catheter-based delivery and expands to completely occlude the LAA orifice and collapse the LAA. The primary advantages of the StrokeShield system are a completely sealed LAA (no peri-device flow or residual space) and smooth endothelialized connection to the left atrial wall with minimal risk of cardiac bleeding and tamponade. We tested proof-of-concept of a prototype StrokeShield device in acute (n = 2) and chronic 60-day (n = 2) healthy canine models. Acute results demonstrated that the conical coil securely attached to the myocardium (5N pull-out force) and the Nitinol umbrella fully deployed and covered the LAA ostium. Results from the chronic implants demonstrated long-term feasibility of device placement with no procedural or device-related intra- or post-operative complications, secure placement and correct positioning of the device with no device migration. The device successfully occluded the LAA ostium and collapsed the LAA with no interference with the mitral valve, circumflex coronary artery, or pulmonary veins. Necropsy demonstrated no gross signs of thrombus or end-organ damage and the device was encapsulated in the LAA. Histology demonstrated mature neointima covering the device with expected foreign body inflammatory response. These early positive results will help to guide the iterative design process for the continued development of the StrokeShield system.

Clinical and Economic Outcomes Among Nonvalvular Atrial Fibrillation Patients With Coronary Artery Disease and/or Peripheral Artery Disease

To address literature gaps on treatment with real-world evidence, this study compared effectiveness, safety, and cost outcomes in NVAF patients with coronary or peripheral artery disease (CAD, PAD) prescribed apixaban versus other oral anticoagulants. NVAF patients aged ≥65 years co-diagnosed with CAD/PAD initiating warfarin, apixaban, dabigatran, or rivaroxaban were selected from the US Medicare population (January 1, 2013 to September 30, 2015). Propensity score matching was used to match apixaban versus warfarin, dabigatran, and rivaroxaban cohorts. Cox models were used to evaluate the risk of stroke/systemic embolism (SE), major bleeding (MB), all-cause mortality, and a composite of stroke/myocardial infarction/all-cause mortality. Generalized linear and two-part models were used to compare stroke/SE, MB, and all-cause costs between cohorts. A total of 33,269 warfarin-apixaban, 9,335 dabigatran-apixaban, and 33,633 rivaroxaban-apixaban pairs were identified after matching. Compared with apixaban, stroke/SE risk was higher in warfarin (hazard ratio [HR]: 1.93; 95% confidence interval [CI]: 1.61 to 2.31), dabigatran (HR: 1.69; 95% CI: 1.18 to 2.43), and rivaroxaban (HR: 1.24; 95% CI: 1.01 to 1.51) patients. MB risk was higher in warfarin (HR: 1.67; 95% CI: 1.52 to 1.83), dabigatran (HR: 1.37; 95% CI: 1.13 to 1.68), and rivaroxaban (HR: 1.87; 95% CI: 1.71 to 2.05) patients vs apixaban. Stroke/SE- and MB-related medical costs per-patient per-month were higher in warfarin, dabigatran, and rivaroxaban patients versus apixaban. Total all-cause health care costs were higher in warfarin and rivaroxaban patients compared with apixaban patients. In conclusion, compared with apixaban, patients on dabigatran, rivaroxaban, or warfarin had a higher risk of stroke/SE, MB, and event-related costs.

Comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants and warfarin in older adults with atrial fibrillation and diabetes

OBJECTIVE

To evaluate comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants (NOACs) versus warfarin in Medicare beneficiaries with non-valvular atrial fibrillation (NVAF) and comorbid diabetes mellitus (DM).

METHODS

A retrospective cohort study using 2014-2016 5% national Medicare data was undertaken. NVAF patients with DM aged ≥65 years having at least one prescription for NOACs or warfarin between July 2014 and December 2015 were included in the study. Propensity score matching was used to balance demographic and baseline clinical characteristics of patients in two treatment groups. Cardiovascular outcomes including stroke/systemic embolism (SE) and myocardial infarction (MI) were evaluated to measure effectiveness. Assessment of safety outcomes included intracranial hemorrhage (ICH), major gastrointestinal bleeding (MGB), bleeding from other sites (OB) and all-cause mortality. Stratified Cox proportional hazards models were used to estimate hazard ratios for the outcomes in the matched cohort.

RESULTS

The matched sample consisted of 4582 patients (2291 pairs). Compared to warfarin, NOACs had a significantly lower risk of stroke/SE (hazard ratio (HR): 0.373, 95% confidence interval (CI): 0.247-0.564, p < .001) and all-cause mortality (HR: 0.783, CI: 0.656-0.873, p = .007). NOACs were found to significantly reduce the risk of ICH (HR: 0.500, CI: 0.300-0.834, p = .008) and OB (HR: 0.608, CI: 0.424-0.870, p = .007), but no difference was observed in the risk of MGB (HR: 0.862, CI: 0.640-1.160, p = .326) between NOACs and warfarin. The composite outcome demonstrated superior overall effectiveness and safety of NOAC therapy compared to warfarin therapy (HR: 0.685, CI: 0.587-0.801, p < .001).

CONCLUSION

Oral anticoagulation therapy with NOACs was found to be more effective than warfarin therapy among older adults with NVAF and comorbid DM.

Cost-Effectiveness of Direct Non-Vitamin K Oral Anticoagulants Versus Vitamin K Antagonists for the Management of Patients with Non-Valvular Atrial Fibrillation Based on Available "Real-World" Evidence: The Italian National Health System Perspective

BACKGROUND AND OBJECTIVE

The increasing availability of real-world evidence (RWE) about safety and effectiveness of direct non-vitamin K oral anticoagulants (DOACs) for the management of atrial fibrillation (AF) offers the opportunity to better understand the clinical and economic implications of DOACs versus vitamin K antagonists (VKAs). The objective of this study was to compare the economic implications of DOACs and VKAs using data from real-world evidence in patients with AF.

METHODS

A Markov model simulating the lifetime course of patients diagnosed with non-valvular AF was used to evaluate the cost-effectiveness of DOACs (i.e., rivaroxaban, dabigatran and apixaban) versus VKAs from the Italian National Health System (INHS) perspective. The model was made up of data from the literature and a meta-analysis of RWE on the incidence of stroke/systemic embolism (SE), major bleeding (MB), intracranial haemorrhage (ICH) and all-cause mortality (ACM); direct costs included drug costs, costs for drug monitoring, and management of events from official national lists. One-way and probabilistic sensitivity analyses (PSA) were used to assess the robustness of the results.

RESULTS

Results from the meta-analysis showed that apixaban had a high probability of being the most effective for stroke/SE, MB and ACM. Despite their higher acquisition costs, the cost-effectiveness analysis showed all DOACs involved a saving when compared with VKAs, with per-patient savings ranging between €4647 (rivaroxaban) to €6086 (apixaban). Moreover, all DOACs indicated a gain both in quality-adjusted life-years and life-years. According to PSA, findings related to apixaban were consistent, while for dabigatran and rivaroxaban PSA revealed a higher degree of uncertainty.

CONCLUSIONS

The beneficial effect of DOACs on containing events showed in RWE had the potential to offset drug-related costs, thus improving the sustainability of treatment for non-valvular AF in daily clinical practice.

The real world use of combined P-glycoprotein and moderate CYP3A4 inhibitors with rivaroxaban or apixaban increases bleeding

The use of direct oral anticoagulants for stroke prevention in atrial fibrillation continues to rise. Certain populations may be at higher risk for increased drug exposure and adverse events. Pharmacokinetic studies suggest increased exposure of rivaroxaban and apixaban with combined P-gp and moderate CYP3A4 inhibitors but the clinical relevance of this is unknown. This retrospective cohort study included patients receiving rivaroxaban or apixaban from January 1, 2012 to December 31, 2016 with a moderate inhibitor (amiodarone, dronedarone, diltiazem, verapamil) for at least 3 months in the drug-drug interaction (DDI) group. Propensity matching was used to identify similar control patients without the presence of the DDI. The primary outcome was a time to event analysis of any bleeding episode as defined by the International Society of Thrombosis and Hemostasis. After propensity matching, 213 patients with similar baseline characteristics were included in each group. The mean CHA2DS2-VASc score was 3.0 and median duration of follow-up was 1.45 years. The primary outcome occurred in 26.4% of patients in the DDI group and 18.4% in the control group (hazard ratio 1.8, 95% confidence interval [CI] 1.19 to 2.73; p-value = 0.006). There was no difference in bleeding rates based on type of inhibitor. Use of a combined P-gp and moderate CYP3A4 inhibitor with rivaroxaban or apixaban increased bleeding risk compared to patients without the DDI in this real world, retrospective study. Analysis in a larger patient population is needed to confirm these findings.

Prescribers' compliance with summary of product characteristics of dabigatran, rivaroxaban and apixaban-A European comparative drug utilization study

Despite a tremendous increase of direct oral anticoagulants (DOACs) prescriptions in recent years, only few data is available analysing prescribers' adherence to Summary of Product Characteristics (SmPC). We aimed to assess adherence to registered indications, contraindications, special warnings/precautions, and potential drug-drug interactions for three DOAC compounds (dabigatran, rivaroxaban, and apixaban) in six databases of five European countries (The Netherlands, United Kingdom, Spain, Denmark, and Germany). We included adult patients (≥18 years) initiating DOACs between 2008 and 2015. For several SmPC items, broad definitions were used due to ambiguous SmPC terms or lacking data in some databases. Within the study period, a DOAC was initiated in 407 576 patients (rivaroxaban: 240 985 (59.1%), dabigatran: 95 303 (23.4%), and apixaban: 71 288 (17.5%)). In 2015, non-valvular atrial fibrillation was the most common indication (>60% in most databases). For the whole study period, a substantial variation between the databases was found regarding the proportion of patients with at least one contraindication (inter-database range [IDR]: 8.2%-55.7%), with at least one special warning/precaution (IDR: 35.8%-75.2%) and with at least one potential drug-drug interaction (IDR: 22.4%-54.1%). In 2015, the most frequent contraindication was "malignant neoplasm" (IDR: 0.7%-21.3%) whereas the most frequent special warning/precaution was "prescribing to the elderly" (≥75 years; IDR: 25.0%-66.4%). The most common single compound class interaction was "concomitant use of non-steroidal anti-inflammatory drugs" (IDR: 3.0%-25.3%). Contraindications, special warnings/precautions, and potential drug-drug interactions were present in a relevant number of new DOAC users. Due to broad definitions used for some SmPC terms, overall proportions for contraindications are prone to overestimation. However, for unambiguous SmPC terms documented in the databases sufficiently, the respective estimates can be considered valid. Differences between databases might be related to "true" differences in prescription behaviour, but could also be partially due to differences in database characteristics.

Healthcare costs of NVAF patients treated with rivaroxaban and apixaban in the US

OBJECTIVES

To provide the most current assessment of real-world healthcare resource utilization (HRU) and costs among patients with non-valvular atrial fibrillation (NVAF) who newly initiated rivaroxaban and apixaban using a large US database.

MATERIAL AND METHODS

A retrospective weighted cohort design was used with healthcare insurance claims from the Optum Clinformatics Data Mart databases (January 2012-December 2018). The index date was defined as the first dispensing of rivaroxaban or apixaban. Adult NVAF patients with an index date on or after 1 January 2016, ≥ 12 months of continuous eligibility before the index date and ≥ 1 month after, and without prior use of oral anticoagulant were included. The observation period spanned from the index date to the earliest of the end of data availability, end of insurance coverage, or death. Inverse probability of treatment weighting (IPTW) was used to adjust for differences in baseline characteristics between cohorts. All-cause healthcare resource utilization (HRU), including hospitalization, emergency room, and outpatient visits, and healthcare costs, including medical and pharmacy costs, were evaluated from the payer's perspective during the observation period up to 18 and 24 months, separately.

RESULTS

In total, 23,822 rivaroxaban and 53,666 apixaban users were included. After weighting, all baseline characteristics were well balanced between cohorts (mean age: 73.8 years, female: 46.6% in both cohorts). Up to 18 months of follow-up, rivaroxaban users incurred significantly lower total healthcare costs compared to apixaban users (cost difference = -$1,121; p = 0.020), driven by significantly lower rates of outpatient hospital visits and associated costs (cost difference = -$1,579; p < 0.001). Similar results were found in the analysis conducted for up to 24 months of follow-up (total cost difference = ‒$1,111; p = 0.020).

CONCLUSIONS

In this large retrospective analysis, patients with NVAF initiated on rivaroxaban incurred significantly lower healthcare costs compared to those initiated on apixaban, which were primarily driven by significantly lower outpatient visits and costs during the 18- and 24-month follow-up periods.

Bleeding Risk in Nonvalvular Atrial Fibrillation Patients Receiving Direct Oral Anticoagulants and Warfarin: A Systematic Review and Meta-Analysis of Observational Studies

Introduction  In randomized trials in atrial fibrillation (AF) patients on direct oral anticoagulants (DOACs) have a lower risk of bleeding compared with warfarin. However, data from randomized trials may not extrapolate to general population. We aimed to determine the risk of bleeding in patients on DOACs in observational studies. Materials and Methods  Observational studies from 1990 to January 2019 were included. A pooled effect hazard ratio (HR) was calculated with a random effects model using the generic inverse variance method. Subgroup analyses according to previous anticoagulants exposure, study type, funding source, and DOAC type (direct thrombin inhibitors vs. factor Xa inhibitors) were conducted. Results  A total of 35 studies comprising 2,356,201 patients were included. The average pooled HR for observational data was 0.78 (95% confidence interval [CI] 0.71, 0.85). There were no statistically significant differences in pooled HR by previous exposure to anticoagulants, DOAC type (direct thrombin vs. factor Xa inhibitors), study type, and funding source. Among patients receiving factor Xa inhibitors, patients on apixaban had a lower risk of bleeding compared with warfarin (HR 0.60, 95% CI 0.50, 0.71, p  < 0.001) in contrast to those on rivaroxaban (HR 0.98, 95% CI 0.91, 1.06, p  = 0.60). Conclusion  In observational studies, AF patients on DOACs experience less bleeding events compared with warfarin; however, apixaban and dabigatran, but not rivaroxaban, have a lower risk of bleeding than warfarin.

Major bleeding risk associated with oral anticoagulant in real clinical practice. A multicentre 3-year period population-based prospective cohort study

AIMS

The objective was to compare major bleeding risk of direct oral anticoagulants (DOACs; per type and dose) with vitamin K antagonists (VKAs), irrespective of indication, using real-world data.

METHODS

A population-based prospective cohort study, using the French national health data system (SNIIRAM), identified 47 469 adults living within 5 well-defined geographical areas, who were new users of oral anticoagulants in the period 2013-2015: 20 205 VKA users, 19 579 rivaroxaban users, 4225 dabigatran users and 3460 apixaban users. From all emergency departments within these areas, clinical data for all adults referred for bleeding was collected and medically validated. The databases were linked for common key variables. The main outcome measure was major bleeding: intracranial haemorrhage, major gastrointestinal bleeding and other major bleeding events. Hazard ratios were derived from adjusted Cox proportional hazard models. We used propensity score weighting as a sensitivity analysis, with separate analyses according to indications (atrial fibrillation or venous thromboembolism).

RESULTS

Compared to VKAs, high and low-dose DOACs were associated with a reduced risk of intracranial haemorrhage (adjusted hazard ratio 0.55, 95% confidence interval 0.37-0.82 and 0.54, 0.26-1.12 respectively), and a reduced risk of other major bleeding events (0.41, 0.29-0.58 and 0.41, 0.22-0.79 respectively), irrespective of duration and indication. Neither DOAC dose evidenced any significant difference from VKAs in terms of risk of major gastrointestinal bleeding.

CONCLUSION

There is a clear benefit of using DOACs with regard to intracranial haemorrhage. The study provides new insight into major gastrointestinal and other major bleeding events.

Incidence Rates of Bleeding and Emergency Surgery Due to Trauma or Fracture Among Japanese Patients with Non-valvular Atrial Fibrillation Receiving Oral Anticoagulation Therapy

Introduction

In patients with nonvalvular atrial fibrillation (NVAF) receiving oral anticoagulants (OACs), reversal of coagulopathy can be achieved with specific reversal drugs such as idarucizumab, which is indicated for use in patients treated with dabigatran for cases of life-threatening or uncontrolled bleeding or during emergency procedures that may cause serious bleeding. This study examined the incidence rate (IR) of emergency surgeries and major bleeding episodes associated with fractures and trauma in Japanese patients with NVAF receiving OACs.

Methods

This retrospective, non-interventional analysis of health insurance claims was conducted using data from 62,888 OAC-naive adult patients with NVAF who initiated dabigatran, warfarin, apixaban, rivaroxaban, or edoxaban between March 2011 and June 2016. The primary endpoint was overall IR of emergency surgery or major bleeding due to fracture or trauma.

Results

Overall IR of emergency surgery or major bleeding due to fracture or trauma considering outcomes until OAC discontinuation was 0.489 per 100 patient-years (PY) (95% confidence interval [CI] 0.406–0.572). Considering first OAC exposure only, the IR was 0.483 per 100 PY (95% CI 0.394–0.573). Emergency surgery/major bleeding events due to fracture or trauma was highest in those aged ≥ 75 years (0.611 per 100 PY [95% CI 0.481–0.741]).

Conclusions

Fewer than one in 200 patients per year with NVAF receiving OACs experience emergency surgeries and major bleeding episodes associated with fractures and trauma; however, the IR of these events is markedly higher in patients of advanced age.

Trial registration

ClinicalTrials.gov 207, NCT03254147.

Patients with an abnormal heart rhythm (nonvalvular atrial fibrillation [NVAF]) have a higher risk of blood clots and stroke (which is when the blood supply to part of the brain is blocked). To reduce these risks, patients can take anticoagulants that slow or prevent the formation of blood clots. However, if the patient needs major emergency surgery or has a severe injury, the anticoagulants can increase their risk of bleeding, which can sometimes be life-threatening. There are drugs (e.g., idarucizumab) that can be used to reverse the effects of anticoagulants in this type of emergency. What we don’t know is how many NVAF patients in Japan who are on anticoagulants have emergency surgeries or major bleeding after an injury, and therefore may require a reversal drug. The authors looked at Japanese health insurance claim data from 62,888 adult patients with NVAF who started taking an anticoagulant. They found that, annually, approximately 0.5% of the patients had emergency surgery or a major bleed associated with a fracture or injury. In very elderly patients (aged at least 75 years), the annual percentage was approximately 0.6%, which was almost double the annual percentage in patients aged less than 65 years. The authors concluded that, even though the number of people requiring a reversal agent are quite small, it is important to have an effective reversal agent for patients on anticoagulants, particularly older patients.

A Real-World Observational Study of Hospitalization and Health Care Costs Among Nonvalvular Atrial Fibrillation Patients Prescribed Oral Anticoagulants in the U.S. Medicare Population

This article has been corrected. Please see J Manag Care Spec Pharm, 2020;26(5):682 BACKGROUND: Clinical trials have shown that direct oral anticoagulants (DOACs)-including dabigatran, rivaroxaban, apixaban, and edoxaban-are at least as effective and safe as warfarin for the risk of stroke/systemic embolism (SE) and major bleeding (MB) in patients with atrial fibrillation (AF). However, few studies have compared oral anticoagulants (OACs) among elderly patients.

OBJECTIVE

To compare hospitalization risks (all-cause, stroke/SE-related, and MB-related) and associated health care costs among elderly nonvalvular AF (NVAF) patients in the Medicare population who initiated warfarin, dabigatran, rivaroxaban, or apixaban.

METHODS

Patients (aged ≥ 65 years) initiating warfarin or DOACs (apixaban, rivaroxaban, and dabigatran) were selected from the Centers for Medicare & Medicaid Services database from January 1, 2013, to December 31, 2014. Patients initiating each OAC were matched 1:1 to apixaban patients using propensity score matching to balance demographic and clinical characteristics. Cox proportional hazards models were used to estimate the risk of hospitalization of each OAC versus apixaban. Generalized linear models and two-part models with bootstrapping were used to compare all-cause health care costs and stroke/SE- and MB-related medical costs between matched cohorts.

RESULTS

Of the 264,479 eligible patients, 77,480 warfarin-apixaban, 41,580 dabigatran-apixaban, and 77,640 rivaroxaban-apixaban patients were matched. The OACs were associated with a significantly higher risk of all-cause hospitalization compared with apixaban (warfarin: HR = 1.27, 95% CI = 1.23-1.31, P < 0.001; dabigatran: HR = 1.13, 95% CI = 1.08-1.18, P < 0.001; and rivaroxaban: HR = 1.22, 95% CI = 1.18-1.26, P < 0.001) and were associated with a significantly higher risk of hospitalization due to stroke/SE (warfarin: HR = 2.18, 95% CI = 1.80-2.64, P < 0.001; dabigatran: HR = 1.45, 95% CI = 1.12-1.88, P = 0.006; and rivaroxaban: HR = 1.40, 95% CI = 1.14-1.71, P = 0.001). Also, the OACs were associated with significantly higher risk of hospitalization due to MB-related conditions compared with apixaban (warfarin: HR = 1.76, 95% CI = 1.59-1.95, P < 0.001; dabigatran: HR = 1.44, 95% CI = 1.23-1.68, P < 0.001; and rivaroxaban: HR = 1.89, 95% CI = 1.71-2.09, P < 0.001). Compared with apixaban, warfarin ($3,577 vs. $3,183, P < 0.001); dabigatran ($3,217 vs. $3,060, P < 0.001); and rivaroxaban ($3,878 vs. $3,180, P < 0.001) had significantly higher all-cause total health care costs per patient per month. Patients initiating the OACs had significantly higher MB-related medical costs compared with apixaban: warfarin ($472 vs. $269; P < 0.001); dabigatran ($364 vs. $245, P < 0.001); and rivaroxaban ($493 vs. $270, P < 0.001). Warfarin was also associated with higher stroke/SE-related medical costs compared with apixaban ($124 vs. $62, P < 0.001).

CONCLUSIONS

This real-world study showed that among elderly NVAF patients in the Medicare population, apixaban was associated with significantly lower risks of all-cause, stroke/SE-related, and MB-related hospitalizations compared with warfarin, dabigatran, and rivaroxaban. Accordingly, apixaban showed significantly lower all-cause health care costs and MB-related medical costs.

DISCLOSURES

This study was funded by Bristol Myers Squibb and Pfizer. Amin is an employee of the University of California, Irvine, and was a paid consultant to Bristol Myers Squibb in connection with this study and the development of this manuscript. He has served as a consultant and/or speaker for Bristol Myers Squibb, Pfizer, and Boehringer Ingelheim. Keshishian and Zhang are employees of STATinMED Research, a paid consultant to Pfizer and Bristol Myers Squibb in connection with this study and the development of this manuscript. Trocio, Dina, Mardekian, and Liu are employees of Pfizer, with ownership of stocks in Pfizer. Le, Rosenblatt, Nadkarni, and Vo are employees of Bristol Myers Squibb. Rosenblatt and Vo have ownership of stocks in Bristol Myers Squibb. Baser has no conflicts to disclose.

Effectiveness and Safety of Oral Anticoagulants in Patients With Nonvalvular Atrial Fibrillation and Diabetes Mellitus

OBJECTIVE

To address gaps in the data comparing non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin among patients with nonvalvular atrial fibrillation (NVAF) and diabetes.

PATIENTS AND METHODS

A retrospective study was conducted on patients with NVAF and diabetes newly initiating apixaban, dabigatran, rivaroxaban, or warfarin from January 1, 2013, through September 30, 2015, with Medicare data from the US Centers for Medicare & Medicaid Services and 4 other US commercial claims databases. One-to-one propensity score matching was completed between NOACs and warfarin and between NOACs in each database, and the results were pooled. Cox proportional hazards models were used to evaluate the risk of stroke/systemic embolism (SE) and major bleeding (MB).

RESULTS

A total of 154,324 patients were included in the 6 matched cohorts, with a mean follow-up time of 6 to 8 months. Compared with warfarin, apixaban (hazard ratio [HR], 0.67; 95% CI, 0.57-0.77) and rivaroxaban (HR, 0.79; 95% CI, 0.71-0.89) were associated with a lower risk of stroke/SE; dabigatran (HR, 0.84; 95% CI, 0.67-1.07) was associated with a similar risk of stroke/SE. Apixaban (HR, 0.60; 95% CI, 0.56-0.65) and dabigatran (HR, 0.78; 95% CI, 0.69-0.88) were associated with a lower risk of MB; rivaroxaban (HR, 1.02; 95% CI, 0.94-1.10) was associated with a similar risk of MB compared with warfarin. Compared with dabigatran and rivaroxaban, apixaban was associated with a lower risk of MB. Compared with rivaroxaban, dabigatran was associated with a lower risk of MB.

CONCLUSION

This study-the largest observational study to date of patients with NVAF and diabetes taking anticoagulants-found that NOACs were associated with variable rates of stroke/SE and MB compared with warfarin.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03087487.

Effectiveness and Safety of Apixaban Compared With Rivaroxaban for Patients With Atrial Fibrillation in Routine Practice: A Cohort Study

Background

Apixaban and rivaroxaban are the most commonly prescribed direct oral anticoagulants for adults with atrial fibrillation, but head-to-head data comparing their safety and effectiveness are lacking.

Objective

To compare the safety and effectiveness of apixaban versus rivaroxaban for patients with nonvalvular atrial fibrillation.

Design

New-user, active-comparator, retrospective cohort study.

Setting

A U.S. nationwide commercial health care claims database from 28 December 2012 to 1 January 2019.

Patients

Adults newly prescribed apixaban (n = 59 172) or rivaroxaban (n = 40 706).

Measurements

The primary effectiveness outcome was a composite of ischemic stroke or systemic embolism. The primary safety outcome was a composite of intracranial hemorrhage or gastrointestinal bleeding.

Results

39 351 patients newly prescribed apixaban were propensity score matched to 39 351 patients newly prescribed rivaroxaban. Mean age was 69 years, 40% of patients were women, and mean follow-up was 288 days for new apixaban users and 291 days for new rivaroxaban users. The incidence rate of ischemic stroke or systemic embolism was 6.6 per 1000 person-years for adults prescribed apixaban compared with 8.0 per 1000 person-years for those prescribed rivaroxaban (hazard ratio [HR], 0.82 [95% CI, 0.68 to 0.98]; rate difference, 1.4 fewer events per 1000 person-years [CI, 0.0 to 2.7]). Adults prescribed apixaban also had a lower rate of gastrointestinal bleeding or intracranial hemorrhage (12.9 per 1000 person-years) compared with those prescribed rivaroxaban (21.9 per 1000 person-years), corresponding to an HR of 0.58 (CI, 0.52 to 0.66) and a rate difference of 9.0 fewer events per 1000 person-years (CI, 6.9 to 11.1).

Limitation

Unmeasured confounding, incomplete laboratory data.

Conclusion

In routine care, adults with atrial fibrillation prescribed apixaban had a lower rate of both ischemic stroke or systemic embolism and bleeding compared with those prescribed rivaroxaban.

Primary Funding Source

Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital.

Safety and effectiveness of non-vitamin K oral anticoagulants versus warfarin in real-world patients with non-valvular atrial fibrillation: a retrospective analysis of contemporary Japanese administrative claims data

Objective

To assess the safety (ie, risk of bleeding) and effectiveness (ie, risk of stroke/systemic embolism (SE)) separately for four non-vitamin K oral anticoagulants (NOACs; apixaban, dabigatran, edoxaban and rivaroxaban) versus warfarin in Japanese patients with non-valvular atrial fibrillation (NVAF), including those at high risk of bleeding and treated with reduced doses of NOACs.

Methods

We conducted a retrospective analysis of electronic health records and claims data from 372 acute care hospitals in Japan for patients with NVAF newly initiated on NOACs or warfarin. Baseline characteristics were balanced using inverse probability of treatment weighting with stabilised weights (s-IPTW). Bleeding risk and stroke/SE risk were expressed as HRs with 95% CIs. Two sensitivity analyses were conducted.

Results

A total of 73 989 patients were eligible for analysis. Notably, 52.8%-81.9% of patients received reduced doses of NOACs. After applying s-IPTW, patient characteristics were well balanced across warfarin/NOAC cohorts. The mean within-cohort age, CHADS₂ score and CHA₂DS₂-VASc score were 76 years, 2.2-2.3 and 3.8, respectively. In all age categories, the majority of the HRs for major bleeding, any bleeding and stroke/SE were equal to or below 1 for all NOACs versus warfarin. Apixaban was the only NOAC associated with a significantly lower risk of any bleeding. There was a trend towards increased risk reduction with NOACs versus warfarin in patients with body weight ≥60 kg. In patients with renal disease, the HRs for apixaban versus warfarin were below 1 for major bleeding, any bleeding and stroke/SE, with statistical significance observed for the risk reduction in stroke/SE versus warfarin. In the sensitivity analysis, there were no large differences in HRs between the two observational periods.

Conclusions

In patients with NVAF primarily treated with reduced-dose NOACs, the risks of stroke/SE and major bleeding were significantly lower with NOACs versus warfarin.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

Elderly Bleeding Risk of Direct Oral Anticoagulants in Nonvalvular Atrial Fibrillation: A Systematic Review and Meta-Analysis of Cohort Studies

Introduction

The 2014 American Heart Association (AHA)/American College of Cardiology (ACC)/Heart Rhythm Society (HRS) guidelines recommend anticoagulation to reduce clot formation and the risk of thromboembolic events in patients with atrial fibrillation but does not specify guidelines for the elderly population. Direct oral anticoagulants (DOACs) are newer US FDA-approved alternatives to warfarin and include dabigatran, rivaroxaban, apixaban and edoxaban. The efficacy of DOACs is heavily researched, but few studies have evaluated their bleeding risk.

Objectives

This systematic review and meta-analysis investigates which DOAC has the lowest bleeding risk in elderly patients with nonvalvular atrial fibrillation (NVAF).

Methods

CINAHL and MEDLINE databases were searched using specific keywords, and 244 results were identified and screened. Inclusion criteria required a major bleeding event requiring hospitalization as an outcome and excluded patients with severe renal failure. Articles that met inclusion criteria were assessed for risk of bias using the Cochrane Tool to Assess Risk of Bias in Cohort Studies. Review Manager (version 5) was used to perform the random-effects model meta-analysis. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. P < 0.05 was considered statistically significant.

Results

Six articles met inclusion criteria and encompassed 446,042 patients in total. Apixaban and dabigatran had statistically significant risk reductions compared with warfarin, whereas rivaroxaban did not (HR 0.60 [95% CI 0.52–0.69], p < 0.00001; HR 0.79 [95% CI 0.70–0.90], p = 0.0005; HR 1.03 [95% CI 0.86–1.22], p = 0.77, respectively.) Data regarding edoxaban were limited and thus not included in the analysis.

Conclusion

Apixaban and dabigatran have a significantly decreased major bleeding risk (40 and 21%, respectively) compared with warfarin. There was no statistical difference in bleeding risk between rivaroxaban and warfarin. Head-to-head prospective randomized controlled trials are required to assess the true bleeding risk of each DOAC.

Comparative clinical outcomes between direct oral anticoagulants and warfarin among elderly patients with non-valvular atrial fibrillation in the CMS medicare population

Atrial fibrillation (AF) prevalence increases with age; > 80% of US adults with AF are aged ≥ 65 years. Compare the risk of stroke/systemic embolism (SE), major bleeding (MB), net clinical outcome (NCO), and major adverse cardiac events (MACE) among elderly non-valvular AF (NVAF) Medicare patients prescribed direct oral anticoagulants (DOACs) vs warfarin. NVAF patients aged ≥ 65 years who initiated DOACs (apixaban, dabigatran, and rivaroxaban) or warfarin were selected from 01JAN2013-31DEC2015 in CMS Medicare data. Propensity score matching was used to balance DOAC and warfarin cohorts. Cox proportional hazards models estimated the risk of stroke/SE, MB, NCO, and MACE. 37,525 apixaban–warfarin, 18,131 dabigatran–warfarin, and 55,359 rivaroxaban–warfarin pairs were included. Compared to warfarin, apixaban (HR: 0.69; 95% CI 0.59–0.81) and rivaroxaban (HR: 0.82; 95% CI 0.73–0.91) had lower risk of stroke/SE, and dabigatran (HR: 0.88; 95% CI 0.72–1.07) had similar risk of stroke/SE. Apixaban (MB: HR: 0.61; 95% CI 0.57–0.67; NCO: HR: 0.64; 95% CI 0.60–0.69) and dabigatran (MB: HR: 0.79; 95% CI 0.71–0.89; NCO: HR: 0.84; 95% CI 0.76–0.93) had lower risk of MB and NCO, and rivaroxaban had higher risk of MB (HR: 1.08; 95% CI 1.02–1.14) and similar risk of NCO (HR: 1.04; 95% CI 0.99–1.09). Compared to warfarin, apixaban had a lower risk for stroke/SE, MB, and NCO; dabigatran had a lower risk of MB and NCO; and rivaroxaban had a lower risk of stroke/SE but higher risk of MB. All DOACs had lower risk of MACE compared to warfarin.

[Prehospital management of acute coronary syndrome in patients on long-term direct oral anticoagulant treatment]

BACKGROUND

Despite an increasing incidence of patients suffering from acute coronary syndrome (ACS) under simultaneous treatment with direct oral anticoagulants (DOAC), neither sufficient scientific data nor uniform guidelines for the anticoagulation treatment of these patients are currently available.

OBJECTIVE

The aim of this study was to determine the current practice of preclinical treatment of ACS in patients under DOAC treatment.

MATERIAL AND METHODS

An internet and paper-based survey of emergency physicians, specialists of internal medicine, anesthesiologists, emergency and intensive care physicians was performed concerning the prehospital treatment of ACS in patients under long-term DOAC treatment.

RESULTS

Overall, 284 questionnaires were answered. Substantial differences in the current treatment of ACS under long-term DOAC therapy were identified. While 39% of the respondents stated that they administer a combination treatment of heparin and acetylsalicylic acid (ASA), 36% renounced the administration of heparin. If a dose reduction was performed, 71% answered that they reduce the heparin dosage. Also, in cases of ST-segment elevation myocardial infarction 48% of the physicians renounced the administration of heparin.

CONCLUSION

In Germany there is currently a heterogeneous practice of emergency treatment of ACS patients under DOAC therapy with respect to the administration of heparin and ASA. Therefore, guidelines of the specialist medical societies should address the prehospital emergency anticoagulation management of ACS in patients under therapy with DOAC, which correspond to the needs of patients and emergency physicians.

Evaluation of oral anticoagulants in atrial fibrillation patients over 80 years of age with nonsevere frailty

BACKGROUND

The safety and efficacy of an oral anticoagulant (OAC) treatment and the difference between direct OACs (DOACs) and warfarin in nonsevere frail elderly patients with AF are unclear.

METHODS

This was a retrospective and observational study of 354 patients over 80 years of age with nonsevere frailty who were diagnosed with AF and treated with OACs. Nonsevere frailty was defined as a clinical frailty scale score of <7. Bleeding and thromboembolic events during the OAC treatment were followed up.

RESULTS

Of 354 patients enrolled, 273 (77.1%) received DOACs and 81 (22.9%) received warfarin. Of 273 patients receiving DOACs, there were 210 (76.9%) prescribed with appropriate doses of DOACs. Of 81 warfarin-treated patients, 53 (65.4%) were prescribed an appropriate dose of warfarin. During a follow-up of 33.1 (14.0-51.0) months, 15 patients (1.5/100 person-years) had bleeding events and 10 (1.0/100 person-years) had thromboembolic events while on an OAC treatment. The incidence ratio of bleeding events in patients receiving DOACs was lower than that in those receiving warfarin (1.0/100 person-years vs 2.9/100 person-years, hazard ratio [HR]: 0.26, 95% confidence interval [CI]: 0.07-0.91, P = .036). There was no significant difference in the incidence of thromboembolic events between the DOAC and warfarin treatment groups (0.88/100 person-years vs 1.4/100 person-years, HR: 0.63, 95% CI: 0.16-2.57, P = .52).

CONCLUSIONS

OACs are substantially safe and effective for preventing thromboembolic events in nonsevere frail patients over 80 years of age. Particularly, DOACs can be used more safely than warfarin.

Healthcare resource utilization and expenditures among newly-diagnosed elderly non-valvular atrial fibrillation patients initiating oral anticoagulants

Aims: Non-valvular atrial fibrillation (NVAF) prevalence increases with age. Hence, evaluating the economic burden among older-aged patients is vital. This study aimed to compare healthcare resource utilization (HRU) and costs among newly-diagnosed older-aged NVAF patients treated with warfarin, rivaroxaban, or apixaban vs. dabigatran.Materials and Methods: Newly-diagnosed older-aged (aged ≥65 years) NVAF patients initiating dabigatran, warfarin, rivaroxaban, or apixaban (first prescription date = index date) from 01JAN2010-31DEC2015 and with continuous enrollment for ≥12 months pre-index date were included from 100% Medicare database. Patient data were assessed until drug discontinuation/switch/dose change/death/disenrollment/study end (up to 12 months). Dabigatran initiators were 1:1 propensity score-matched (PSM) with warfarin, rivaroxaban, or apixaban initiators. Generalized linear models were used to compare all-cause HRU and costs per-patient-per-month (PPPM) between the matched cohorts.Results: After PSM with dabigatran, 70,531 warfarin, 51,673 rivaroxaban, and 25,209 apixaban patients were identified. Dabigatran patients had significantly fewer generalized-linear-model-adjusted PPPM hospitalizations (0.114 vs. 0.123; 0.111 vs. 0.121), and outpatient visits (2.864 vs. 4.201; 2.839 vs. 2.949) than warfarin and rivaroxaban patients, respectively, but had significantly more PPPM hospitalizations (0.103 vs. 0.090) and outpatient visits (2.780 vs. 2.673) than apixaban patients (all p < .0001). Dabigatran patients incurred significantly lower adjusted total PPPM costs ($3,309 vs. $3,362; $3,285 vs. $3,474) than warfarin and rivaroxaban patients, respectively (all p < .01) but higher total PPPM costs ($3,192 vs. $2,986) than apixaban patients (all p < .0001).Limitations: This study is subject to the inherent limitations of any claims dataset, including potential bias from coding errors and identification of medical conditions using diagnosis codes as opposed to clinical evidence. Medications filled over-the-counter or provided as samples by the physician are never captured in claims data.Conclusions: Newly-diagnosed older-aged NVAF patients initiating dabigatran incurred significantly lower adjusted all-cause HRU and costs than warfarin and rivaroxaban patients but higher adjusted HRU and costs than apixaban patients.

Effectiveness and Safety of Oral Anticoagulants Among Nonvalvular Atrial Fibrillation Patients

Supplemental Digital Content is available in the text.

Background and Purpose—

This ARISTOPHANES study (Anticoagulants for Reduction in Stroke: Observational Pooled Analysis on Health Outcomes and Experience of Patients) used multiple data sources to compare stroke/systemic embolism (SE) and major bleeding (MB) among a large number of nonvalvular atrial fibrillation patients on non–vitamin K antagonist oral anticoagulants (NOACs) or warfarin.

Methods—

A retrospective observational study of nonvalvular atrial fibrillation patients initiating apixaban, dabigatran, rivaroxaban, or warfarin from January 1, 2013, to September 30, 2015, was conducted pooling Centers for Medicare and Medicaid Services Medicare data and 4 US commercial claims databases. After 1:1 NOAC-warfarin and NOAC-NOAC propensity score matching in each database, the resulting patient records were pooled. Cox models were used to evaluate the risk of stroke/SE and MB across matched cohorts.

Results—

A total of 285 292 patients were included in the 6 matched cohorts: 57 929 apixaban-warfarin, 26 838 dabigatran-warfarin, 83 007 rivaroxaban-warfarin, 27 096 apixaban-dabigatran, 62 619 apixaban-rivaroxaban, and 27 538 dabigatran-rivaroxaban patient pairs. Apixaban (hazard ratio [HR], 0.61; 95% CI, 0.54–0.69), dabigatran (HR, 0.80; 95% CI, 0.68–0.94), and rivaroxaban (HR, 0.75; 95% CI, 0.69–0.82) were associated with lower rates of stroke/SE compared with warfarin. Apixaban (HR, 0.58; 95% CI, 0.54–0.62) and dabigatran (HR, 0.73; 95% CI, 0.66–0.81) had lower rates of MB, and rivaroxaban (HR, 1.07; 95% CI, 1.02–1.13) had a higher rate of MB compared with warfarin. Differences exist in rates of stroke/SE and MB across NOACs.

Conclusions—

In this largest observational study to date on NOACs and warfarin, the NOACs had lower rates of stroke/SE and variable comparative rates of MB versus warfarin. The findings from this study may help inform the discussion on benefit and risk in the shared decision-making process for stroke prevention between healthcare providers and nonvalvular atrial fibrillation patients.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT03087487.

Effectiveness and safety of direct oral anticoagulants compared to warfarin in treatment naïve non-valvular atrial fibrillation patients in the US Department of defense population

BACKGROUND

Clinical trials have demonstrated that direct oral anticoagulants (DOACs) are at least non-inferior to warfarin in reducing the risk of stroke/systemic embolism (SE) among patients with non-valvular atrial fibrillation (NVAF), but the comparative risk of major bleeding varies between DOACs and warfarin. Using US Department of Defense (DOD) data, this study compared the risk of stroke/SE and major bleeding for DOACs relative to warfarin.

METHODS

Adult patients with ≥1 pharmacy claim for apixaban, dabigatran, rivaroxaban, or warfarin from 01 Jan 2013-30 Sep 2015 were selected. Patients were required to have ≥1 medical claim for atrial fibrillation during the 12-month baseline period. Patients with a warfarin or DOAC claim during the 12-month baseline period were excluded. Each DOAC cohort was matched to the warfarin cohort using propensity score matching (PSM). Cox proportional hazards models were conducted to evaluate the risk of stroke/SE and major bleeding of each DOAC vs warfarin.

RESULTS

Of 41,001 identified patients, there were 3691 dabigatran-warfarin, 8226 rivaroxaban-warfarin, and 7607 apixaban-warfarin matched patient pairs. Apixaban was the only DOAC found to be associated with a significantly lower risk of stroke/SE (hazard ratio [HR]: 0.55; 95% confidence interval [CI]: 0.39, 0.77; p < 0.001) and major bleeding (HR: 0.65; 95% CI: 0.53, 0.80; p < 0.001) compared to warfarin. Dabigatran and rivaroxaban initiation were associated with similar risk of stroke/SE (dabigatran: HR: 0.68; 95% CI: 0.43, 1.07; p = 0.096; rivaroxaban: HR: 0.83; 95% CI: 0.64, 1.09; p = 0.187) and major bleeding (dabigatran: HR: 1.05; 95% CI: 0.79, 1.40; p = 0.730; rivaroxaban: HR: 1.07; 95% CI: 0.91, 1.27; p = 0.423) compared to warfarin.

CONCLUSION

Among NVAF patients in the US DOD population, apixaban was associated with significantly lower risk of stroke/SE and major bleeding compared to warfarin. Dabigatran and rivaroxaban were associated with similar risk of stroke/SE and major bleeding compared to warfarin.

Non-vitamin K oral anticoagulant use in the elderly: a prospective real-world study - data from the REGIstry of patients on Non-vitamin K oral Anticoagulants (REGINA)

Purpose

Numerous studies on thromboembolic prevention for non-valvular atrial fibrillation (NVAF) have shown either equal or better efficacy and safety of non-vitamin K oral anticoagulants (NOACs) compared to warfarin, even for patients aged ≥75 years. Data on elderly patients, in particular, octogenarians, are lacking. Paradoxically, this population is the one with the highest risk of bleeding and stroke with a worse prognosis. This study aims to describe safety and effectiveness of NOACs in an elderly comorbid population.

Patients and methods

REGIstry of patients on Non-vitamin K oral Anticoagulants (REGINA) is a prospective observational study enrolling consecutive NVAF patients started on NOACs and followed up to 1 year (at 1, 6, 12 months). The primary endpoint was the incidence rate of major bleeding (MB) and clinically relevant non-major bleeding (CRNMB). The secondary endpoints were the incidence of 1) stroke or systemic embolism, 2) hospitalization, 3) death, and 4) drug-related adverse events.

Results

We enrolled 227 patients aged 81.6±6.1 years (range 67–95 years; ≥80 years in 59.4%). The median CHA₂DS₂-VASc was 5 (IQR 4–5) and HAS-BLED was 4 (IQR 3–5). The estimated glomerular filtration rate was 59.27±24.12 mL/min. During follow-up, only 10 MB and 23 CRNMB occurred, with a total incidence of 4.4% (95% CI: 1.7%–7.17%) and 5.7% (95% CI: 2.68%–8.72%), respectively. There were 2 cerebral ischemic events, with a total incidence of 0.88% (95% CI: 0.84%–0.92%), 23 NOAC-related hospitalizations, no NOAC-related deaths, and 4 minor drug-related adverse effects.

Conclusion

In a population of aged and clinically complex patients, mainly octogenarians, NOACs were safe and effective.

Major bleeding with antithrombotic agents: a 2012-2015 study using the French nationwide Health Insurance database linked to emergency department records within five areas - rationale and design of SACHA study

Bleeding represents the most recognized and feared complications of antithrombotic drugs including oral anticoagulants. Previous studies showed inconsistent results on the safety profile. Among explanations, bleeding definition could vary and classification bias exists related to the lack of medical evaluation. To quantify the risk of major haemorrhagic event and event-free survival associated with antithrombotic drugs (vitamin K antagonist [VKA], non-VKA anticoagulant [NOAC], antiplatelet agent, parenteral anticoagulant) in 2012-2015, we linked the French nationwide Health Insurance database (SNIIRAM) with a local 'emergency database' (clinical and biological data collected in clinical records). In the VKA-NOAC comparison, a Cox regression analysis will be used to estimate the hazard ratio of major haemorrhagic event adjusted on gender, modified HAS-BLED score and comorbidities. A distinction on the type of major haemorrhagic event (intracranial, gastrointestinal and other haemorrhagic events) was made. We present here the study protocol and the database linkage results. Using six linkage keys, among 3 837 557 hospital visits identified in SNIIRAM, 5264 have been matched with a major haemorrhagic event identified in the 'emergency database', thus clinically confirmed. The 1090 unmatched haemorrhagic events could be explained by the fact that patients were not extracted in the SNIIRAM database (patients living in accommodation establishment with internal use of pharmacy, military people with specific insurance…). We showed the value of SNIIRAM enrichment with a clinical database, a necessary step to categorize haemorrhagic events by a clinically relevant definition and medical validation; it will allow to estimate more accuracy each type of haemorrhagic event.

A Real-World Observational Study of Hospitalization and Health Care Costs Among Nonvalvular Atrial Fibrillation Patients Prescribed Oral Anticoagulants in the U.S. Medicare Population

BACKGROUND

Clinical trials have shown that direct oral anticoagulants (DOACs)-including dabigatran, rivaroxaban, apixaban, and edoxaban-are at least as effective and safe as warfarin for the risk of stroke/systemic embolism (SE) and major bleeding (MB) in patients with atrial fibrillation (AF). However, few studies have compared oral anticoagulants (OACs) among elderly patients.

OBJECTIVE

To compare hospitalization risks (all-cause, stroke/SE-related, and MB-related) and associated health care costs among elderly nonvalvular AF (NVAF) patients in the Medicare population who initiated warfarin, dabigatran, rivaroxaban, or apixaban.

METHODS

Patients (aged ≥ 65 years) initiating warfarin or DOACs (apixaban, rivaroxaban, and dabigatran) were selected from the Centers for Medicare & Medicaid Services database from January 1, 2013, to December 31, 2014. Patients initiating each OAC were matched 1:1 to apixaban patients using propensity score matching to balance demographic and clinical characteristics. Cox proportional hazards models were used to estimate the risk of hospitalization of each OAC versus apixaban. Generalized linear models and two-part models with bootstrapping were used to compare all-cause health care costs and stroke/SE- and MB-related medical costs between matched cohorts.

RESULTS

Of the 186,132 eligible patients, 41,606 warfarin-apixaban, 30,836 dabigatran-apixaban, and 41,608 rivaroxaban-apixaban pairs were matched. The OACs were associated with a significantly higher risk of all-cause hospitalization compared with apixaban (warfarin: HR = 1.33, 95% CI = 1.27-1.38, P < 0.001; dabigatran: HR = 1.17, 95% CI = 1.11-1.23, P < 0.001; and rivaroxaban: HR = 1.27, 95% CI = 1.22-1.32, P < 0.001) and were associated with a significantly higher risk of hospitalization due to stroke/SE (warfarin: HR = 2.51, 95% CI = 1.92-3.29, P < 0.001; dabigatran: HR = 2.24, 95% CI = 1.60-3.13, P < 0.001; and rivaroxaban: HR = 1.74, 95% CI = 1.31-2.30, P < 0.001). Also, the OACs were associated with significantly higher risk of hospitalization due to MB-related conditions compared with apixaban (warfarin: HR = 1.96, 95% CI = 1.71-2.23, P < 0.001; dabigatran: HR = 1.48; 95% CI = 1.25-1.76, P < 0.001; and rivaroxaban: HR = 2.17, 95% CI = 1.91-2.48, P < 0.001). Compared with apixaban, warfarin ($3,747 vs. $3,061, P < 0.001); dabigatran ($3,230 vs. $2,951, P < 0.001); and rivaroxaban ($3,950 vs. $3,060, P < 0.001) had significantly higher all-cause total health care costs per patient per month. Patients initiating the OACs also had significantly higher stroke/SE- and MB-related medical costs compared with apixaban: warfarin (stroke/SE = $135 vs. $60, P = 0.001; MB = $537 vs. $286, P < 0.001); dabigatran (stroke/SE = $94 vs. $62, P = 0.045; MB = $373 vs. $277, P = 0.010); and rivaroxaban (stroke/SE = $91 vs. $60, P = 0.008; MB = $524 vs. $287, P < 0.001).

CONCLUSIONS

This real-world study showed that among elderly NVAF patients in the Medicare population, apixaban was associated with significantly lower risks of all-cause, stroke/SE-related, and MB-related hospitalizations compared with warfarin, dabigatran, and rivaroxaban. Accordingly, apixaban showed significantly lower all-cause health care costs and stroke/SE- and MB-related medical costs.

DISCLOSURES

This study was funded by Bristol-Myers Squibb and Pfizer. Amin is an employee of the University of California, Irvine, and was a paid consultant to Bristol-Myers Squibb in connection with this study and the development of this manuscript. Keshishian and Zhang are employees of STATinMED Research, a paid consultant to Pfizer and Bristol-Myers Squibb in connection with this study and the development of this manuscript. Trocio, Dina, Mardekian, and Liu are employees of Pfizer, with ownership of stocks in Pfizer. Le, Rosenblatt, Nadkarni, and Vo are employees of Bristol-Myers Squibb. Rosenblatt and Vo have ownership of stocks in Bristol-Myers Squibb. Baser has no conflicts to disclose.

Cost-Utility Analysis of Apixaban versus Warfarin in Atrial Fibrillation Patients with Chronic Kidney Disease

BACKGROUND

Warfarin use for stroke prevention in atrial fibrillation (AF) patients with chronic kidney disease is debated. Apixaban was shown to be safer than warfarin, with superior reduction in the risk of stroke, systemic embolism, mortality, and major bleeding irrespective of kidney function.

OBJECTIVES

To evaluate the cost-utility of apixaban compared with warfarin in AF patients at different levels of kidney function.

METHODS

A Markov model was used to estimate the cost effectiveness of apixaban compared with warfarin in AF patients at three levels of kidney function: estimated glomerular filtration rate (eGFR) of more than 80 ml/min, 50 to 80 ml/min, and 50 ml/min or less. Event rates and associated utilities were obtained from previous literature. The model adopted the US health care system perspective, with hospitalization costs extracted from the Healthcare and Utilization Project. Treatment costs were obtained from official price lists. Univariate and probabilistic sensitivity analyses were performed to evaluate the robustness of results.

RESULTS

Apixaban was a dominant treatment strategy compared with warfarin in AF patients with eGFR levels of 50 ml/min or less and 50 to 80 ml/min. In patients with an eGFR of more than 80 ml/min, apixaban was cost-effective compared with warfarin, costing $6307 per quality-adjusted life-year gained. Results were consistent assuming anticoagulant discontinuation after major bleeding events. Compared with dabigatran and rivaroxaban, apixaban was the only cost-effective anticoagulant strategy relative to warfarin in both mild and moderate renal impairment settings.

CONCLUSIONS

Apixaban is a favorably cost-effective alternative to warfarin in AF patients with normal kidney function and potentially cost-saving in those with renal impairment.

Hospital Resource Utilization and Costs Associated With Warfarin Versus Apixaban Treatment Among Patients Hospitalized for Venous Thromboembolism in the United States

A real-world US database analysis was conducted to evaluate the hospital resource utilization and costs of patients hospitalized for venous thromboembolism (VTE) treated with warfarin versus apixaban. Additionally, 1-month readmissions were evaluated. Of 28 612 patients with VTE identified from the Premier Hospital database (August 2014-May 2016), 91% (N = 26 088) received warfarin and 9% (N = 2524) received apixaban. Outcomes were assessed after controlling for key patient/hospital characteristics. For index hospitalizations, the average length of stay (LOS) was longer (3.8 vs 3.1 days, P < .001; difference: 0.7 days) and mean hospitalization cost higher (US$3224 vs US$2,740, P < .001; difference: US$484) for warfarin versus apixaban-treated patients. During the 1-month follow-up period, warfarin treatment was associated with a greater risk of all-cause readmission (odds ratio [OR]: 1.27; 95% confidence interval [CI]: 1.09-1.48, P = .003), major bleeding (MB)-related readmission (OR: 2.10; 95% CI: 1.03-4.27, P = .04), and any bleeding-related readmission (OR: 1.67; 95% CI: 1.09-2.56, P = .02) versus apixaban. The results of this real-world analysis show that compared to warfarin, apixaban treatment was associated with shorter index hospital stays, lower index hospitalization costs, and reduced risk of MB-related readmissions among hospitalized patients with VTE.

Real-World Comparative Effectiveness, Safety, and Health Care Costs of Oral Anticoagulants in Nonvalvular Atrial Fibrillation Patients in the U.S. Department of Defense Population

BACKGROUND

The ARISTOTLE trial demonstrated that apixaban had significantly lower rates of stroke/systemic embolism (SE) and major bleeding than warfarin; however, no direct clinical trials between apixaban and other direct oral anticoagulants (DOACs) are available. Few real-world studies comparing the effectiveness and safety between DOACs have been conducted.

OBJECTIVE

To compare effectiveness, safety, and health care costs among oral anticoagulants (OACs) for nonvalvular atrial fibrillation (NVAF) patients in the U.S. Department of Defense (DoD) population.

METHODS

Adult NVAF patients initiating warfarin or DOACs (apixaban, rivaroxaban, and dabigatran) were selected from U.S. DoD data from January 1, 2013, to September 30, 2015. The first OAC claim date was designated as the index date. Patients initiating another OAC were matched 1:1 to apixaban patients using propensity score matching to balance demographics and clinical characteristics. Cox proportional hazards models were used to estimate the risk of stroke/SE and major bleeding for each OAC versus apixaban. Generalized linear and two-part models with bootstrapping were used to compare all-cause health care costs and stroke/SE-related and major bleeding-related medical costs.

RESULTS

Of the 41,001 eligible patients, 7,607 warfarin-apixaban, 4,129 dabigatran-apixaban, and 11,284 rivaroxaban-apixaban pairs were matched. Warfarin (HR = 1.84; 95% CI = 1.30-2.59; P < 0.001) and rivar-oxaban (HR = 1.46; 95% CI = 1.08-1.98; P = 0.015) were associated with a significantly higher risk of stroke/SE compared with apixaban. Dabigatran (HR = 1.17; 95% CI = 0.68-2.03; P = 0.573) was associated with a numerically higher risk of stroke/SE compared with apixaban. Warfarin (HR = 1.53; 95% CI = 1.24-1.89; P < 0.001), dabigatran (HR = 1.76; 95% CI = 1.27-2.43; P < 0.001), and rivaroxaban (HR = 1.59; 95% CI = 1.34-1.89; P < 0.001) were associated with higher risks of major bleeding compared with apixaban. Compared with apixaban, patients prescribed warfarin incurred numerically higher all-cause total health care costs per patient per month (PPPM) ($2,498 vs. $2,277; P = 0.148) and significantly higher stroke/SE-related ($118 vs. $46; P = 0.012) and major bleeding-related ($166 vs. $76; P = 0.003) medical costs. Dabigatran patients incurred numerically higher all-cause total health care PPPM costs ($2,372 vs. $2,143; P = 0.150) and stroke/SE-related medical costs ($61 vs. $32; P = 0.240) but significantly higher major bleeding-related costs ($114 vs. $58; P = 0.025). Rivaroxaban patients incurred significantly higher all-cause total health care costs ($2,546 vs. $2,200; P < 0.001) and major bleeding-related medical costs PPPM ($137 vs. $69; P < 0.001) but numerically higher stroke/SE-related medical costs PPPM ($58 vs. $38; P = 0.057).

CONCLUSIONS

Among NVAF patients in the U.S. DoD population, warfarin and rivaroxaban were associated with a significantly higher risk of stroke/SE and major bleeding compared with apixaban. Dabigatran use was associated with a numerically higher risk of stroke/SE and a significantly higher risk of major bleeding compared with apixaban. Warfarin and dabigatran incurred numerically higher all-cause total health care costs compared with apixaban. Rivaroxaban was associated with significantly higher all-cause total health care costs compared with apixaban. DISCLOSURES This study was funded by Bristol-Myers Squibb and Pfizer, which were involved in the study design, as well as in the writing and revision of the manuscript. Keshishian and Zhang are paid employees of STATinMED Research, which was paid by Bristol-Myers Squibb and Pfizer to conduct this study and develop the manuscript. Gupta, Rosenblatt, Hede, and Nadkarni are paid employees of Bristol-Myers Squibb. Trocio, Dina, Mardekian, Liu, and Shank are paid employees of Pfizer.

Safety and effectiveness of apixaban in comparison to warfarin in patients with nonvalvular atrial fibrillation: a propensity-matched analysis from Japanese administrative claims data

OBJECTIVE

To investigate the risk of bleeding events and stroke/systemic embolism (SE) among Japanese patients with nonvalvular atrial fibrillation (NVAF), focusing on the initial dosage of apixaban and patient age.

METHODS

This retrospective cohort study used de-identified electronic health records based claims data from 314 acute-care hospitals in Japan. NVAF patients newly initiated on warfarin or apixaban, with no prescription during the 180-day blanking period, were eligible. Patients were allocated to receive warfarin or 5 or 2.5 mg twice daily (BID) apixaban. One-to-one propensity-score matching was used to balance patient characteristics between apixaban and warfarin.

RESULTS

Among 31,006 eligible patients, 11,972 matched pairs were identified for apixaban versus warfarin. Mean age ± standard deviation was 77.7 ± 10.0 and 77.6 ± 10.0 years and CHADS₂ score was 2.2 ± 1.4 and 2.2 ± 1.4 for warfarin and apixaban, respectively. In the apixaban cohort, 39.4% of patients received the standard dose (5 mg BID) and 60.6% received the reduced dose (2.5 mg BID). Incidence rates (events per 100 person-years) of major bleeding, any bleeding and stroke/SE were 3.7, 23.1 and 3.1, and 2.5, 18.6 and 2.0 for warfarin and apixaban cohorts, respectively. Apixaban was associated with a significantly lower risk of any bleeding (hazard ratio [HR] 0.809, 95% confidence interval [CI] 0.731-0.895; p < .001), major bleeding (HR 0.655, 95% CI 0.505-0.849; p = .001) and stroke/SE (HR 0.637, 95% CI 0.478-0.850; p = .002).

CONCLUSIONS

Our observational data from clinical practice broadly confirms the safety and efficacy results of pivotal randomized controlled trials of apixaban for stroke prevention among NVAF patients.