Use of novel oral anticoagulants for patients with atrial fibrillation: systematic review and clinical implications

Identifying outcome measures for atrial fibrillation value-based contracting using the Delphi method

BACKGROUND

Value-based contracts that tie payments for pharmaceuticals to predefined outcomes aim to promote value through shared risk and aligned incentives between manufacturers and payers.

METHODS

We conducted a Delphi study among diverse stakeholders (patients, providers, payers, pharmacy benefits managers, pharmaceutical company representatives) to identify top meaningful outcomes for inclusion in value-based contracts for atrial fibrillation medications. The final panel (n = 55) rated the importance of each outcome on a 5-point Likert scale and selected their top 3 most meaningful outcomes. Non-patient participants rated the feasibility of collecting each outcome on a 5-point Likert scale. Consensus was defined as ≥75% agreement (Likert scores ≥4/5 or selection of an outcome as most meaningful). Differences between stakeholder groups were examined using Fisher's Exact Test.

RESULTS

Consensus was achieved for importance of 10 outcomes (Likert scale), where "preventing stroke or mini-stroke" reached 100% agreement (55/55). Eighty-one percent (44/54) of participants selected "preventing stroke or mini-stroke" as the most meaningful outcome (rank order question). The measures rated as most feasibly collected were "reducing hospitalizations" (97%, 36/37) followed by "preventing stroke or mini-stroke" and "reducing emergency department visits" (both 92%, 34/37). There were statistically significant differences between patients and non-patients [0% (0/17) vs 22% (8/37), P = 0.047] and patients and providers [0% (0/17) vs 39% (7/18), P = 0.008] in selection of "improving health-related quality of life" as a most meaningful outcome.

CONCLUSIONS

These findings will inform the design of atrial fibrillation value-based pharmaceutical contracts and provide additional insight into preferences for outcomes which could be used to improve the quality of atrial fibrillation care.

Algorithm for the Choice of Anticoagulant for Patients with Atrial Fibrillation

Aim. To evaluate the effectiveness of the anticoagulant choice algorithm in the prevention of complications of atrial fibrillation (AF).

Material and methods. Patients with AF (n=98) were included into observational prospective study. The level of adherence to treatment, risk of food interactions and presence of CYP2C9 and VKORC1 genes mutations were determined at the initial examination. These indicators were necessary to specify an eligible anticoagulant according to the evaluated algorithm. Therapy was prescribed by the attending physician. Hemorrhagic and thromboembolic complications were assessed at the next examination after 24 weeks.

Results. Hemorrhagic complications were observed in 31.6% of patients during the follow-up. Their number was comparable in individuals taking antiplatelet agents and direct oral anticoagulants (DOACs) (χ2=1.44; p<0.49, Pearson) and significantly more in individuals taking warfarin (as compared to DOACs: χ2=25.08; p<0.000, Pearson; and antiplatelet agents: χ2=34.32; p<0.000, Pearson). Thromboembolic complications were reported in 8.16% of patients. Their number was more in patients taking DOACs than warfarin (χ2=7.03; p<0.03, Pearson). Patients who had to take DOACs according to the algorithm, but in the study took warfarin, demonstrated significantly greater number of thromboembolic complications, with a comparable number of hemorrhagic complications. Patients who could take warfarin according to the algorithm, but in the study took DOACs, had significantly greater number of thromboembolic complications, with a comparable number of hemorrhagic complications.

Conclusion. The results of the study demonstrated the potential for reduction in complications, especially thromboembolic, in the choice of anticoagulant using the algorithm; and reduction in complications of therapy, primarily with warfarin, due to the initial prescription of DOACs. The proposed approach, which consists in using the quantitative assessment of adherence to treatment, and only if necessary supplemented by the assessment of food preferences and/or pharmacogenetic studies, contributes to the treatment optimization.

Inequality in oral anticoagulation use and clinical outcomes in atrial fibrillation: a Danish nationwide perspective

Aim

To explore the potential of small-area variation analysis as a tool for identifying unwarranted variation in oral anticoagulation (OAC) use and clinical outcomes in patients with atrial fibrillation (AF) and thereby identify locations with opportunity for improvement in AF care.

Methods and results

Based on Danish health care registries, we conducted a nationwide historical cohort study including first-time AF patients with a CHA2DS2-VASc (congestive heart failure, hypertension, age ≥ 75, diabetes, thromboembolism, vascular disease, age 65-74, and sex category) score ≥ 2 between 2007 and 2014 (n = 94 482). For each administrative region and municipality, we assessed OAC initiation and persistence as well as the risk of ischaemic stroke, haemorrhagic stroke, and other major bleeding, respectively. In addition, potential temporal changes were examined for all outcomes. Initiation of OAC varied among regions from 49.5% to 62.4%. In patients initiating OAC, the proportion of patients still receiving OAC after 1 year varied from 73.9% to 79.3%. Oral anticoagulation use increased in all regions during the study period, particularly after 2010, but regional variation in OAC initiation persisted. Generally, the regions and municipalities with the highest initiation of OAC also had the highest OAC persistence. The risk of ischaemic stroke and other major bleeding was lower in these regions and municipalities. We found no significant difference between regions in risk of haemorrhagic stroke.

Conclusion

Substantial geographical variation in OAC use and clinical outcomes occurs in Denmark demonstrating the potential of small-area variation analysis as a tool for identifying unwarranted variation in AF care and clinical outcomes. Our findings demonstrate the need for additional initiatives to ensure uniform high-quality care for AF patients.

In vitro toxicity assessment of rivaroxaban degradation products and kinetic evaluation to decay process

Degradation kinetics of oral anticoagulant rivaroxaban (RIV) was assessed in acid and alkaline media and while exposed to UVC radiation. Among all stress conditions tested, kinetic degradation process was better described by a zero-order model. A stability indicating method was validated for the analysis of the anticoagulant RIV in tablets by high-performance liquid chromatography. Robustness was evaluated with a two-level Plackett-Burman experimental design. The effect of acute exposition of the human hepatoblastoma HepG2 cell line to RIV stressed samples (100 and 500 µM) was assessed through in vitro toxicity tests. MTT reduction, neutral red uptake, mitochondrial membrane potential, and low molecular weight DNA diffusion assays were employed for cytotoxicity evaluation (5×10⁴ cells/well). The genotoxic potential was assessed by comet assay (2×10⁴ cells/well). Acute toxicity to HepG2 cells was assessed after 24 h incubation with sample solutions, for each test. A direct relationship between the increased amount of alkaline degradation products and higher cytotoxic potential was found. Results obtained by viability assay investigations support the concerns on risks associated with acute toxicity and genotoxicity of pharmaceutical samples containing degradation products as impurities.

Better clinical outcome with direct oral anticoagulants in hospitalized heart failure patients with atrial fibrillation

Background

Atrial fibrillation (AF) is common in patients with heart failure and is associated with higher mortality. Although previous studies have reported that direct oral anticoagulants (DOACs) reduce the risk of cardiovascular events in out-patients with AF, it remains unclear whether DOACs reduce mortality in hospitalized heart failure (HHF) patients with AF. Therefore, we examined the impact of DOACs on mortality in this group of patients.

Methods

Consecutive 497 HHF patients with AF were retrospectively registered and divided into three groups on the basis of the presence of anticoagulant therapy: non-anticoagulant group (Non, n = 90), Vit K antagonists (VKAs) group (n = 257) and DOACs group (n = 150). We followed up all the patients for mortality.

Results

In the Kaplan-Meier analysis (mean follow-up of 1093 days), all-cause mortality was significantly lower in the VKAs and DOACs groups than in the Non group (31.1% and 15.3% vs. 43.3%, log-rank P < 0.001). In the multivariable Cox proportional hazard analysis after adjusting for other potential confounding factors, usage of DOACs and VKAs were independently associated with lower mortality in HHF patients AF (DOACs, HR 0.356, P = 0.001; VKAs, HR 0.472, P = 0.002). Furthermore, the propensity-matched 1:1 cohort was assessed based on the propensity score (DOACs, n = 114 and VKAs, n = 114). All-cause mortality was significantly lower in the DOACs group than in the VKAs group in the post-matched cohort (12.3% vs. 35.1%, log-rank P = 0.038). In the Cox proportional hazard analysis, the use of DOACs was associated with lower mortality in the post-matched cohort (HR 0.526, P = 0.041).

Conclusion

Appropriate use of anticoagulants in HHF patients with AF is important, and DOACs potentially improve all-cause mortality in such patients.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0746-z) contains supplementary material, which is available to authorized users.

Clinical Prediction Model for Time in Therapeutic Range While on Warfarin in Newly Diagnosed Atrial Fibrillation

Background

Though warfarin has historically been the primary oral anticoagulant for stroke prevention in newly diagnosed atrial fibrillation (AF), several new direct oral anticoagulants may be preferred when anticoagulation control with warfarin is expected to be poor. This study developed a prediction model for time in therapeutic range (TTR) among newly diagnosed AF patients on newly initiated warfarin as a tool to assist decision making between warfarin and direct oral anticoagulants.

Methods and Results

This electronic medical record–based, retrospective study included newly diagnosed, nonvalvular AF patients with no recent warfarin exposure receiving primary care services through a large healthcare system in rural Pennsylvania. TTR was estimated as the percentage of time international normalized ratio measurements were between 2.0 and 3.0 during the first year following warfarin initiation. Candidate predictors of TTR were chosen from data elements collected during usual clinical care. A TTR prediction model was developed and temporally validated and its predictive performance was compared with the SAMe‐TT₂R₂ score (sex, age, medical history, treatment, tobacco, race) using R² and c‐statistics. A total of 7877 newly diagnosed AF patients met study inclusion criteria. Median (interquartile range) TTR within the first year of starting warfarin was 51% (32, 67). Of 85 candidate predictors evaluated, 15 were included in the final validated model with an R² of 15.4%. The proposed model showed better predictive performance than the SAMe‐TT₂R₂ score (R²=3.0%).

Conclusions

The proposed prediction model may assist decision making on the proper mode of oral anticoagulant among newly diagnosed AF patients. However, predicting TTR on warfarin remains challenging.

Acute lower gastrointestinal haemorrhage: outcomes and risk factors for intervention in 949 emergency cases

PURPOSE

Outcomes of acute lower gastrointestinal haemorrhage (ALGIH) are mostly derived from studies performed in the sub-acute/elective rather than the emergency department (ED) setting. The aims of this study were to determine the incidence and outcomes of patients presenting to a tertiary hospital ED with ALGIH and to identify associated clinicopathological risk factors.

METHOD

A retrospective observational cohort study of consecutive patients presenting with ALGIH to a tertiary hospital ED was performed. Primary outcome measures included mortality and hospital (including high dependency [HDU]) admission. Secondary outcome measures included rates of (i) blood transfusion, (ii) radiological/endoscopic investigation(s) and (iii) therapeutic intervention.

RESULTS

ALGIH accounted for 949 (512 M, mean age 62.3 years) of 130,262 (0.73%) ED presentations, of which 285 patients (30.1%) were on anti-platelet/coagulant therapy. There were five deaths (0.5%). Hospital admission was required in 498 patients (52.5%), of which 19 (3.8%) required HDU monitoring. Hospital admission was twice as likely in males and four times more likely in patients >75 years old and those taking multiple anti-platelet/coagulant therapy (P < 0.05). Blood product transfusion was required in 172 patients (34.5%), specialist investigations in 230 (46.2%) and therapeutic intervention in 51 (10.2%) (surgery in 24 [4.8%]; endoscopic haemostasis in 20 [4.0%] and angiographic embolisation in 9 [1.8%] patients).

CONCLUSION

ALGIH accounts for 1% of all ED presentations, with half requiring hospital admission. Mortality and surgical intervention rates are low and although most patients can be managed supportively, access to interventional radiology/endoscopy is important.

Costs of major intracranial, gastrointestinal and other bleeding events in patients with atrial fibrillation - a nationwide cohort study

Background

Use of oral anticoagulation therapy in patients with atrial fibrillation (AF) involves a trade-off between a reduced risk of ischemic stroke and an increased risk of bleeding events. Different anticoagulation therapies have different safety profiles and data on the societal costs of both ischemic stroke and bleeding events are necessary for assessing the cost-effectiveness and budgetary impact of different treatment options. To our knowledge, no previous studies have estimated the societal costs of bleeding events in patients with AF.

The objective of this study was to estimate the 3-years societal costs of first-incident intracranial, gastrointestinal and other major bleeding events in Danish patients with AF.

Methods

The study was an incidence-based cost-of-illness study carried out from a societal perspective and based on data from national Danish registries covering the period 2002-2012. Costs were estimated using a propensity score matching and multivariable regression analysis (first difference OLS) in a cohort design.

Results

Average 3-years societal costs attributable to intracranial, gastrointestinal and other major bleeding events were 27,627, 17,868, and 12,384 EUR per patient, respectively (2015 prices). Existing evidence shows that the corresponding costs of ischemic stroke were 24,084 EUR per patient (2012 prices). The average costs of bleeding events did not differ between patients with AF who were on oral anticoagulation therapy prior to the event and patients who were not.

Conclusions

The societal costs attributable to major bleeding events in patients with AF are significant. Intracranial haemorrhages are most costly to society with average costs of similar magnitude as the costs of ischemic stroke. The average costs of gastrointestinal and other major bleeding events are lower than the costs of intracranial haemorrhages, but still substantial. Knowledge about the relative size of the costs of bleeding events compared to ischemic stroke in patients with AF constitutes valuable evidence for decisions-makers in Denmark as well as in other countries.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-017-2331-z) contains supplementary material, which is available to authorized users.

No Decline in the Risk of Stroke Following Incident Atrial Fibrillation Since 2000 in the Community: A Concerning Trend

Background

While atrial fibrillation is a recognized risk factor for stroke, contemporary data on trends in stroke incidence after the diagnosis of atrial fibrillation are scarce.

Methods and Results

Olmsted County, MN residents with incident atrial fibrillation or atrial flutter (collectively referred to as AF) from 2000 to 2010 were identified. Cox regression determined associations of year of AF diagnosis with ischemic stroke and transient ischemic attack (TIA) occurring through 2013. Among 3247 AF patients, 321 (10%) had an ischemic stroke/TIA over a mean of 4.6 years (incidence rate [95% CI] per 100 person‐years: 2.14 [1.91–2.38]). Two hundred thirty‐nine (7%) of 3265 AF patients experienced an ischemic stroke (incidence rate: 1.54 [1.35–1.75]). The risk of both outcomes remained unchanged over time after adjusting for demographics and comorbidities (hazard ratio [95% CI] per year of AF diagnosis: 1.00 [0.96–1.04] for ischemic stroke/TIA; 1.01 [0.96–1.06] for ischemic stroke only). In analyses restricted to patients with prescription information, the rates of anticoagulation use did not change over time, reaching 50.8% at 1 year after AF diagnosis. Further adjustment for anticoagulation use did not alter the temporal trends in stroke incidence (hazard ratio [95% CI] per year of AF diagnosis: 1.06 [0.97–1.15] for ischemic stroke/TIA; 1.08 [0.98–1.20] for ischemic stroke only).

Conclusions

Strokes/TIAs are frequent after AF, occurring in 10% of patients after 5 years of follow‐up. The occurrence of stroke/TIA did not decline over the last decade, which may be influenced by a leveling off of anticoagulation use. This concerning trend has major public health implications.

Preclinical and translational evaluation of coagulation factor IXa as a novel therapeutic target

The benefits of novel oral anticoagulants are hampered by bleeding. Since coagulation factor IX (fIX) lies upstream of fX in the coagulation cascade, and intermediate levels have been associated with reduced incidence of thrombotic events, we evaluated the viability of fIXa as an antithrombotic target. We applied translational pharmacokinetics/pharmacodynamics (PK/PD) principles to predict the therapeutic window (TW) associated with a selective small molecule inhibitor (SMi) of fIXa, compound 1 (CPD1, rat fIXa inhibition constant (Ki, 21 nmol/L) relative to clinically relevant exposures of apixaban (rat fXa Ki 4.3 nmol/L). Concentrations encompassing the minimal clinical plasma concentration (C min) of the 5 mg twice daily (BID) dose of apixaban were tested in rat arteriovenous shunt (AVS/thrombosis) and cuticle bleeding time (CBT) models. An I max and a linear model were used to fit clot weight (CW) and CBT. The following differences in biology were observed: (1) antithrombotic activity and bleeding increased in parallel for apixaban, but to a lesser extent for CPD1 and (2) antithrombotic activity occurred at high (>99%) enzyme occupancy (EO) for fXa or moderate (>65% EO) for fIXa. translational PK/PD analysis indicated that noninferiority was observed for concentrations of CPD1 that provided between 86% and 96% EO and that superior TW existed between 86% and 90% EO. These findings were confirmed in a study comparing short interfering (si)RNA-mediated knockdown (KD) modulation of fIX and fX mRNA. In summary, using principles of translational biology to relate preclinical markers of efficacy and safety to clinical doses of apixaban, we found that modulation of fIXa can be superior to apixaban.

Heart Failure and Mortality in Patients With Nonvalvular Atrial Fibrillation Started on Novel Oral Anticoagulant Therapy: A Single-Center Experience

Heart failure (HF) is the leading cause of in-hospital morbidity and mortality in the elderly population. Coexistence of HF and atrial fibrillation (AF) increases the risk of thromboembolic events. Oral anticoagulant therapy reduces the risk of thromboembolic events in patients with AF. Novel oral anticoagulants (NOACs) have been introduced as an alternative drug for prevention from thromboembolic events in patients with nonvalvular AF. The primary aim of this study is to investigate the clinical effects of warfarin, dabigatran, and rivaroxaban in patients with nonvalvular AF. The secondary aim of this study is to reveal the predictors of all-cause mortality in patients with nonvalvular AF undergoing NOACs therapy. The study population consisted of 171 patients with nonvalvular AF. Patients were divided into 3 groups according to the usage of oral anticoagulant therapy including coumadin (51 patients), dabigatran (52 patients), and rivaroxaban (68 patients). Although CHA2DS2-VASc score was similar between groups, HAS-BLED score was significantly higher in patients using rivaroxaban. Dyspepsia and itching were more common in patients using dabigatran. Heart failure and vascular disease were more common in the nonsurviving group (10 patients) than in the surviving group (110 patients) in patients using NOACs. Among age, sex, HF, hypertension, vascular disease, and CHA2DS2-VASc, which were included in the regression model, only the presence of HF was an independent predictor of all-cause mortality in patients using NOACs. In conclusion, the mortality rate is significantly higher in patients with HF using NOACs. Moreover, HF is an independent predictor of all-cause mortality in patients using NOACs.

Non-vitamin K antagonist oral anticoagulants in atrial fibrillation and venous thromboembolism: where are we now?

Four non-vitamin-K antagonist oral anticoagulants (NOACs) are now available and are variously approved for stroke prevention in atrial fibrillation and the management of venous thromboembolism. On the whole, these drugs offer clear benefits over warfarin, overcoming problems with unpredictable individual responses and avoiding the need for frequent and resource-intensive monitoring. Sufficient data are now available to recommend the use of particular NOACs in defined settings. As a group these drugs offer a real alternative to warfarin; their more widespread use for stroke prevention in atrial fibrillation, in the management of venous thromboembolism, and perhaps in other settings promises to bring real clinical gains for at-risk populations worldwide. This review highlights the growing importance of effective anticoagulation therapy at a time when cardiovascular risk profiles are evolving, discusses the relative merits of the NOACs over warfarin, and describes the use of specific agents in specific patient populations.