Stroke associated with discontinuation of warfarin therapy for atrial fibrillation

Evaluating the effect of inequalities in oral anti-coagulant prescribing on outcomes in people with atrial fibrillation

Aims

Whilst anti-coagulation is typically recommended for thromboprophylaxis in atrial fibrillation (AF), it is often never prescribed or prematurely discontinued. The aim of this study was to evaluate the effect of inequalities in anti-coagulant prescribing by assessing stroke/systemic embolism (SSE) and bleeding risk in people with AF who continue anti-coagulation compared with those who stop transiently, permanently, or never start.

Methods and results

This retrospective cohort study utilized linked Scottish healthcare data to identify adults diagnosed with AF between January 2010 and April 2016, with a CHA2DS2-VASC score of ≥2. They were sub-categorized based on anti-coagulant exposure: never started, continuous, discontinuous, and cessation. Inverse probability of treatment weighting-adjusted Cox regression and competing risk regression was utilized to compare SSE and bleeding risks between cohorts during 5-year follow-up. Of an overall cohort of 47 427 people, 26 277 (55.41%) were never anti-coagulated, 7934 (16.72%) received continuous anti-coagulation, 9107 (19.2%) temporarily discontinued, and 4109 (8.66%) permanently discontinued. Lower socio-economic status, elevated frailty score, and age ≥ 75 were associated with a reduced likelihood of initiation and continuation of anti-coagulation. Stroke/systemic embolism risk was significantly greater in those with discontinuous anti-coagulation, compared with continuous [subhazard ratio (SHR): 2.65; 2.39-2.94]. In the context of a major bleeding event, there was no significant difference in bleeding risk between the cessation and continuous cohorts (SHR 0.94; 0.42-2.14).

Conclusion

Our data suggest significant inequalities in anti-coagulation prescribing, with substantial opportunity to improve initiation and continuation. Decision-making should be patient-centred and must recognize that discontinuation or cessation is associated with considerable thromboembolic risk not offset by mitigated bleeding risk.

Persistence to rivaroxaban therapy for stroke prevention in clinical practice in Italy: Rationale and design of the RITMUS-AF prospective observational cohort study

Background

Non-valvular atrial fibrillation (NVAF) is a cardiac rhythm disturbance that increases the risk of stroke and is highly prevalent in Europe and Italy, increasingly with advancing age. Oral anticoagulation is a key component of stroke prevention in patients with NVAF, yet withdrawal or interruption of anticoagulation may transiently increase the risk of embolic events. Treatment persistence to anticoagulation is an important metric but one that is not well studied in patients with NVAF in Italy. The RITMUS-AF study aims to evaluate the persistence with rivaroxaban treatment for stroke prevention in patients with NVAF in Italy.

Methods

RITMUS-AF is a prospective, observational cohort study of patients with NVAF in hospital cardiology departments with a non-vitamin K antagonist oral anticoagulant surveillance program across all 20 regions of Italy. The study population comprises consecutively screened, consenting patients with NVAF naïve to and newly treated with rivaroxaban for stroke prevention in routine clinical practice. The target enrollment is 800 patients; each patient will be followed for a maximum duration of 24 months. The primary endpoint is the proportion of patients who discontinue rivaroxaban treatment. Secondary endpoints are reasons for rivaroxaban discontinuation, dose changes and reasons for changes, switches to alternative therapies and the reasons for these decisions, and self-reported adherence. Data analyses will be exploratory and descriptive.

Conclusion

RITMUS-AF will help to address the limited data in Italian clinical practice on treatment persistence and reasons for drug interruptions in patients with NVAF on rivaroxaban.

Clinical outcomes of oral anticoagulant discontinuation in atrial fibrillation: a systematic review and meta-analysis

INTRODUCTION

Oral anticoagulants (OACs) should generally be continued lifelong in patients with atrial fibrillation (AF) to ensure optimal benefits, unless contraindications arise. However, discontinuation of OACs might occur for various reasons, potentially affecting clinical outcomes. In this review, we synthesized evidence on the clinical outcomes following OAC discontinuation in patients with AF.

METHODS

We conducted a systematic review and meta-analysis using PubMed, Embase and Scopus. Cohort or case-control studies were included if data were available on clinical outcomes of OAC discontinuation, compared with continuation, in patients with AF. A random-effect meta-analyses were conducted for key outcomes of stroke, mortality, and major bleeding.

RESULTS

Eighteen observational studies having a total of 283,418 patients were included. Discontinuation significantly increased the risk of stroke (hazard ratio [HR] 1.88; 95% confidence interval [CI] 1.58-2.23), all-cause (HR 1.90; 95% CI 1.40-2.59) and cardiovascular (HR 1.83; 95% CI 1.06-3.18) mortality. The risk of major bleeding was not significantly different between the discontinued and continued groups (HR 1.04; 95% CI 0.72-1.52).

CONCLUSIONS

Discontinuation of OAC therapy was associated with an increased risk of stroke and mortality, with no difference in the risk of major bleeding. Acknowledging heterogeneity among the studies, the findings underline the need to ensure continuity of OAC therapy in patients with AF to prevent thrombotic complications and associated mortality.

PROSPERO REGISTRATION NUMBER

CRD42020186116.

Time Trends and Treatment Pathways in Prescribing Individual Oral Anticoagulants in Patients with Nonvalvular Atrial Fibrillation: An Observational Study of More than Three Million Patients from Europe and the United States

BACKGROUND

Data directly comparing trends in the use of different oral anticoagulants (OACs) among patients with atrial fibrillation (AF) from different countries are limited. We addressed this using a large-scale network cohort study in the United States (US), Belgium, France, Germany, and the United Kingdom (UK).

METHODS

We used nine databases (claims or electronic health records) that had been converted into the Observational Medical Outcomes Partnership Common Data Model with analysis performed using open-source analytical tools. We identified adults with AF and a first OAC prescription, either vitamin K antagonist (VKA) or direct oral anticoagulant (DOAC), from 2010 to 2017. We described time trends in use, continuation, and switching.

RESULTS

In 2010, 87.5%-99.8% of patients started on a VKA. By 2017, the majority started on a DOAC: 87.0% (US), 88.3% (Belgium), 93.1% (France), 88.4% (Germany), and 86.1%-86.7% (UK). In the UK, DOACs became the most common starting OAC in 2015, 2-3 years later than elsewhere. Apixaban was the most common starting OAC by 2017, 50.2%-57.8% (US), 31.4% (Belgium), 45.9% (France), 39.5% (Germany), and 49.8%-50.5% (UK), followed by rivaroxaban, 24.8%-32.5% (US), 25.7% (Belgium), 38.4% (France), 24.9% (Germany), and 30.2%-31.2% (UK). Long-term treatment was less common in the US than in Europe, especially the UK. A minority of patients switched from their index OAC in the short and long term.

CONCLUSIONS

From 2010 to 2017, VKA use had significantly declined and DOAC use had significantly increased in the US and Europe. Apixaban was the most prescribed OAC in 2017, followed by rivaroxaban.

Current status of oral anticoagulant adherence in Japanese patients with atrial fibrillation: A claims database analysis

BACKGROUND

Direct oral anticoagulants (DOACs) are widely used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). We investigated the adherence of DOACs for years known to be associated with the effectiveness in Japanese NVAF patients, using a claim database.

METHOD

We performed a retrospective evaluation of NVAF patients in a claims database in Japan, who initiated dabigatran, rivaroxaban, and apixaban between April 2011 and June 2016. Drug persistence was assessed by Kaplan-Meier method for the initially-prescribed DOAC and all DOACs including switched ones. Proportion of days covered (PDC) was also evaluated in patients with persistent prescription and compared among DOACs.

RESULTS

In the total of 671 patients, rivaroxaban (47%) was more prescribed than dabigatran (28%) and apixaban (25%). Drug persistence at 3 years was higher in rivaroxaban (69%) than dabigatran (57%) and apixaban (67%). Including switching to other DOACs, persistence of DOACs was 72% at 3 years without significant differences between index-DOACs. In multivariate Cox regression analysis, absence of hypertension, and prior history of cancer were significantly associated with the drug discontinuation of all DOACs. The mean PDC was ~ 95% and the frequency of high-adherent patients (PDC ≥0.80) was more than 90%, which similarly persisted at 3 years and showed no significant differences between index DOACs.

CONCLUSION

In a real-world Japanese claim data analysis, about 70% of patients under DOAC showed persistence with anticoagulation therapy at 3 years. High adherence to DOACs assessed by PDC (over 90%) persisted to 3 years regardless of the types of DOACs.

Discontinuation of oral anticoagulation in atrial fibrillation and risk of ischaemic stroke

OBJECTIVE

To evaluate associations between oral anticoagulant (OAC) discontinuation and risk of ischaemic stroke (IS) among patients with atrial fibrillation (AF).

METHODS

We undertook a population-based cohort study with nested case-control analysis using UK primary care electronic health records (IQVIA Medical Research Data-UK) and linked registries from the Region of Southern Denmark (RSD). Patients with AF (76 882 UK, 41 526 RSD) were followed to identify incident IS cases during 2016-2018. Incident IS cases were matched by age and sex to controls. Adjusted ORs for OAC discontinuation (vs current OAC use) were calculated using logistic regression.

RESULTS

We identified 616 incident IS cases in the UK and 643 in the RSD. ORs for IS with any OAC discontinuation were 2.99 (95% CI 2.31 to 3.86, UK) and 2.30 (95% CI 1.79 to 2.95, RSD), for vitamin K antagonist discontinuation they were 2.38 (95% CI 1.72 to 3.30, UK) and 1.83 (95% CI 1.34 to 2.49, RSD), and for non-vitamin K antagonist oral anticoagulant discontinuation they were 4.59 (95% CI 2.97 to 7.08, UK) and 3.37 (95% CI 2.35 to 4.85, RSD). ORs were unaffected by time since discontinuation and duration of use. Annually, up to 987 IS cases in the UK and 132 in Denmark could be preventable if OAC therapy is not discontinued.

CONCLUSIONS

Our results suggest that patients with AF who discontinue OAC therapy have a significant twofold to threefold higher risk of IS compared with those who continue therapy. Addressing OAC discontinuation could potentially result in a significant reduction in AF-attributed IS.

Premature permanent discontinuation of apixaban or warfarin in patients with atrial fibrillation

AIMS

The ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial randomised patients with atrial fibrillation at risk of stroke to apixaban or warfarin. We sought to describe patients from ARISTOTLE who prematurely permanently discontinued study drug.

METHODS/RESULTS

We performed a posthoc analysis of patients from ARISTOTLE who prematurely permanently discontinued study drug during the study or follow-up period. Discontinuation rates and reasons for discontinuation were described. Death, thromboembolism (stroke, transient ischaemic attack, systemic embolism), myocardial infarction and major bleeding rates were stratified by ≤30 days or >30 days after discontinuation. A total of 4063/18 140 (22.4%) patients discontinued study drug at a median of 7.3 (2.2, 15.2) months after randomisation. Patients with discontinuation were more likely to be female and had a higher prevalence of cardiovascular disease, diabetes, renal impairment and anaemia. Premature permanent discontinuation was more common in those randomised to warfarin than apixaban (23.4% vs 21.4%; p=0.002). The most common reasons for discontinuation were patient request (46.1%) and adverse event (34.9%), with no significant difference between treatment groups. The cumulative incidence of clinical events ≤30 days after premature permanent discontinuation for all-cause death, thromboembolism, myocardial infarction, and major bleeding was 5.8%, 2.6%, 0.9%, and 3.0%, respectively. No significant difference was seen between treatment groups with respect to clinical outcomes after discontinuation.

CONCLUSION

Premature permanent discontinuation of study drug in ARISTOTLE was common, less frequent in patients receiving apixaban than warfarin and was followed by high 30-day rates of death, thromboembolism and major bleeding. Initiatives are needed to reduce discontinuation of oral anticoagulation.

Patient Adherence to Novel Oral Anticoagulants (NOACs) for the Treatment of Atrial Fibrillation and Occurrence of Associated Bleeding Events: A Systematic Review and Meta-analysis

BACKGROUND

Real-world evidence from published observational studies of adherence to Novel Oral Anticoagulants (NOACs) medications and associated clinical outcome events in Atrial Fibrillation (AF) patients, was reviewed systematically.

METHODS

Observational studies assessing patient adherence to NOACs conducted on AF patients between September 2010 and June 2016 were identified by systematic searching keywords to locate eligible studies, in accordance with Cochrane guidelines. PubMed, Scopus and Google Scholar databases were searched to identify the studies. Meta-analysis was performed using a random effects model with DerSimonian-Laird weighting to obtain pooled effect sizes.

RESULTS

From 185 potentially relevant citations, 6 studies, comprising 1.6 million AF patients, were included. Among these, successful adherence to NOACs occurred in 75.6%. Adherence levels were higher in patients treated with dabigatran (72.7%) compared with those treated with apixaban (59.9%) or rivaroxaban (59.3%). However, adherence was still suboptimal (relative to an expected 80% adherence rate). Bleeding events in non-adherent patients were found to be 7.5%.

CONCLUSION

Suboptimal adherence to NOACs among AF patients was highlighted as a significant risk factor that may affect clinical outcomes, with a higher percentage of non-adherent patients having bleeding events. There is an urgent need for research on the effects of specific interventions to improve patient adherence to NOACs and to assess the related outcome factors that may be associated with adherence.

Ischemic Stroke and Transient Ischemic Attack Risk Following Vitamin K Antagonist Cessation in Newly Diagnosed Atrial Fibrillation: A Cohort Study

Background In nonvalvular atrial fibrillation (AF), oral anticoagulants prevent ischemic strokes and transient ischemic attacks (TIAs), but nonpersistence with vitamin K antagonist (VKA) oral anticoagulant therapy (20-50% at 1 year) is problematic. The precise risk of stroke/TIA after VKA cessation and its time course during extended follow-up is unknown. Methods and Results The study cohort of incident AF in patients receiving initial VKA between 2001 and 2013 was identified from the UK Clinical Practice Research Datalink (linked hospitalizations and causes of death). Using a nested case-control analysis, patients with incident stroke/TIA were matched to patients without stroke/TIA (controls). Relative risk with time since VKA cessation compared with current VKA use was approximated from conditional logistic regression. We studied 16 696 patients with incident AF and initial VKA treatment. There were 489 stroke/TIA cases matched to 2137 controls (mean CHA₂DS₂-VASc score 4.3). Compared with current VKA use, the excess incidence rate of stroke/TIA following VKA cessation in the first year after AF diagnosis was 2.29 (95% CI, 0.98-3.90) per 100 person-years of VKA cessation or 1 additional stroke/TIA per 43 patients per year discontinuing VKA, compared with 1.43 (95% CI, 0.97-1.88) per 100 person-years corresponding to 1 additional stroke/TIA per 70 patients per year, when VKA was discontinued more than 1 year after AF diagnosis. Conclusions VKA cessation is associated with a continuous excess thromboembolic stroke/TIA risk. Increasing oral anticoagulant persistence, especially in the year after AF diagnosis, should be a therapeutic target to reduce stroke/TIA in AF.

[How to maintain an adherence to oral anticoagulant in a patient with atrial fibrillation?]

Less onerous, compared with warfarin, treatment with direct oral anticoagulants (DOA) can lead to better adherence to treatment of patients with atrial fibrillation (AF). However, in a certain number of patients with AF, who were recommended by DOA, cardioembolic stroke recurs, which is largely due to the patients' failure to comply with medical recommendations. The appointment of DOA as first-line drugs does not guarantee a high adherence of patients with non-valvular AF. For elderly and old patients with AF and numerous comorbidities, the proposal of a simpler pharmacotherapy regimen is especially important. In a number of large modern studies performed in clinical practice, high adherence to rivaroxaban therapy has been established, which may be a result of taking this DOA 1 time per day, its safety and effectiveness.

Stroke and transient ischemic attacks related to antiplatelet or warfarin interruption

OBJECTIVE

Patients on anticoagulant or antiplatelet therapy are often required to discontinue these medications before and during surgical or invasive procedures. In some cases, the patient stops the treatment without medical supervision. These situations may increase stroke risk. To identify the ischemic stroke and transient ischemic attack (TIA) prevalence related to length of time of discontinuation of antiplatelet or vitamin K antagonist therapy, in a group of inpatients from a specialized neurological hospital in Brazil.

METHODS

Cross-sectional, retrospective and descriptive study of stroke inpatients for three years. Medical reports were reviewed to find study participants, stroke characteristics, risk factors, reasons and time of drug interruption.

RESULTS

In three years, there were 360 stroke and TIA inpatients, of whom 27 (7.5%) had a history of antiplatelet or vitamin K antagonist interruption correlated with the time of the event (81% ischemic stroke, 19% TIA). The median time between antiplatelet interruption and an ischemic event was five days, and 62% of events occurred within seven days after drug suspension. For vitamin K antagonists, the average time to the ischemic event was 10.4 days (SD = 5.7), and in 67% of patients, the time between drug discontinuation and the event was 7-14 days. The most frequent reason for drug suspension was patient negligence (37%), followed by planned surgery or invasive examination (26%) and side effects, including hemorrhage (18.5%).

CONCLUSION

Antiplatelet or vitamin K antagonist suspension has a temporal relationship with the occurrence of stroke and TIA. Since these events are preventable, it is crucial that healthcare professionals convince their patients that drug withdrawal can cause serious consequences.

Discontinuation and primary care visits in nonvalvular atrial fibrillation patients treated with apixaban or warfarin

Aim: Nonvalvular atrial fibrillation (NVAF) requires long-term anticoagulation treatment, which may necessitate frequent primary care visits. Materials & methods: NVAF patients initiating warfarin or apixaban in 2012–2017 were identified from linked primary (Clinical Practice Research Datalink) and secondary care (Hospital Episode Statistics) data. A propensity score matched Cox regression model compared discontinuation risk. Primary care visits were compared via negative binomial regression. Results: A total of 2695 apixaban users were matched to warfarin patients. Discontinuation risk was lower with apixaban than warfarin (hazard ratio: 0.40; 95% CI: 0.35–0.46). Apixaban patients averaged 12.2 annual primary care visits, versus 17.1 for warfarin users (p < 0.001). Conclusion: Apixaban was associated with reduced rates of discontinuation and primary care visits compared with warfarin.

Real-world adherence for direct oral anticoagulants in a newly diagnosed atrial fibrillation cohort: does the dosing interval matter?

Background

Differences in adherence may represent drug properties (e.g. dosing interval) or patient experiences while on treatment. Adherence to direct oral anticoagulants (DOACs) in nonvalvular atrial fibrillation (NVAF) is important to maintain effectiveness over the course of treatment.

Methods

This was a retrospective cohort study using 2009–2015 Truven Health MarketScan Databases. New initiators of dabigatran, rivaroxaban, and apixaban with NVAF were identified. Twelve months of continuous enrollment before treatment was required to assess demographics and medical history. Proportion of days cover (PDC) was used to measure adherence at 3, 6, 9 and 12-month. Gaps in therapy and treatment switches were also evaluated. Logistic regression was used to compare high adherence (PDC ≥0.80).

Results

A total of 14,864 dabigatran, 16,005 rivaroxaban, and 8078 apixaban users were identified. Apixaban users had the highest adherence overall, with mean PDC at 3, 6, 9, and 12-months of 0.83, 0.76, 0.72, and 0.69, while dabigatran had the lowest adherence of 0.78, 0.67, 0.61, and 0.57. Adherence to DOACs increased with increased stroke risk scores. Adherence was also higher when first days supplied was > 30 days compared to 30 days and when filled via mail order pharmacies. Switching was highest among dabigatran users. Apixaban users were the most likely to have high adherence versus dabigatran (OR = 1.73, 95% CI = 1.60–1.88) and versus rivaroxaban (OR = 1.24, 95% CI = 1.14–1.34) at 12-months.

Conclusions

Apixaban users had the highest overall adherence despite twice-daily dosing versus once-daily dosing for rivaroxaban. These findings can be useful for formulary decision-making and when assessing treatment options.

Estimating Adherence Based on Prescription or Dispensation Information: Impact on Thresholds and Outcomes. A Real-World Study With Atrial Fibrillation Patients Treated With Oral Anticoagulants in Spain

Objective: To estimate drug exposure, Proportion of Days Covered (PDC) and percentage of patients with PDC ≥ 80% from a cohort of atrial fibrillation patients initiating oral anticoagulant (OAC) treatment. We employed three different approaches to estimate PDC, using either data from prescription and dispensing (PD cohort) or two common designs based on dispensing information only, requiring at least one (D1) or at least two (D2) refills for inclusion in the cohorts. Finally, we assessed the impact of adherence on health outcomes according to each method. Methods: Population-based retrospective cohort of all patients with Non Valvular Atrial Fibrillation (NVAF), who were newly prescribed acenocoumarol, apixaban, dabigatran or rivaroxaban from November 2011 to December 2015 in the region of Valencia (Spain). Patients were followed for 12 months to assess adherence using three different approaches (PD, D1 and D2 cohorts). To analyze the relationship between adherence (PDC ≥ 80) defined according to each method of calculation and health outcomes (death for any cause, stroke or bleeding) Cox regression models were used. For the identification of clinical events patients were followed from the end of the adherence assessment period to the end of the available follow-up period. Results: PD cohort included all patients with an OAC prescription (n = 38,802), D1 cohort excluded fully non-adherent patients (n = 265) and D2 cohort also excluded patients without two refills separated by 180 days (n = 2,614). PDC ≥ 80% ranged from 94% in the PD cohort to 75% in the D1 cohort. Drug exposure among adherent (PDC ≥ 80%) and non-adherent (PDC < 80%) patients was different between cohorts. In adjusted analysis, high adherence was associated with a reduced risk of death [Hazard Ratio (HR): from 0.82 to 0.86] and (except in the PD cohort) the risk for ischemic stroke (HR: from 0.61 to 0.64) without increasing the risk of bleeding. Conclusion: Common approaches to assess adherence using measures based on days' supply exclude groups of non-adherent patients and, also, misattribute periods of doctors' discontinuation to patient non-adherence, misestimating adherence overall. Physician-initiated discontinuation is a major contributor to reduced OAC exposure. When using the PDC80 threshold, very different groups of patients may be classified as adherent or non-adherent depending on the method used for the calculation of days' supply measures. High adherence and high exposure to OAC treatment in NVAF patients is associated with better health outcomes.

[Oral anticoagulation therapy in the elderly population with atrial fibrillation. A review article]

Aging is an important risk factor for patients with atrial fibrillation. The estimated prevalence of atrial fibrillation in patients aged ≥80 years is 9-10%, and is associated with a four to five fold increased risk of embolic stroke, and with an estimated increased stroke risk of 1.45-fold per decade in aging. Older age is also associated with an increased risk of major bleeding with oral anticoagulant therapy. This review will focus on the role of oral anticoagulation with new oral anticoagulants, non-vitamin K antagonist in populations with common comorbid conditions, including age, chronic kidney disease, coronary artery disease, on multiple medication, and frailty. In patients 75 years and older, randomised trials have shown new oral anticoagulants to be as effective as warfarin, or in some cases superior, with an overall better safety profile, consistently reducing rates of intracranial haemorrhages. Prior to considering oral anticoagulant therapy in an elderly frail patient, a comprehensive assessment should be performed to include the risks and benefits, stroke risk, baseline kidney function, cognitive status, mobility and fall risk, multiple medication, nutritional status assessment, and life expectancy.

Discontinuation risk comparison among 'real-world' newly anticoagulated atrial fibrillation patients: Apixaban, warfarin, dabigatran, or rivaroxaban

Discontinuation of oral anticoagulants may expose non-valvular atrial fibrillation (NVAF) patients to an increased risk of stroke. This study describes the real-world discontinuation rates and compared the risk of drug discontinuation among NVAF patients initiating apixaban, warfarin, dabigatran, or rivaroxaban. This retrospective cohort study evaluated newly-anticoagulated NVAF patients in the MarketScan^® data population from 01/01/2012 through 12/31/2014. Discontinuation was defined as a lack of subsequent prescription of the index drug within 30 days after the last supply day of the last prescription. A Cox model was used to estimate the hazard ratio (HR) of discontinuation, adjusted for age, sex, and comorbidities. Among 45,361 eligible NVAF patients, 15,461 (34.1%) initiated warfarin; 7,438 (16.4%) apixaban; 4,661 (10.3%) dabigatran; and 17,801 (39.2%) initiated rivaroxaban treatment. Compared to warfarin, patients who initiated dabigatran (adjusted HR [aHR]: 0.84, 95% confidence interval [CI]: 0.80–0.87, P<0.001), rivaroxaban (aHR: 0.70, 95% CI: 0.68–0.73, P<0.001), or apixaban (aHR: 0.57, 95% CI: 0.55–0.60, P<0.001) were 16%, 30%, and 43% less likely to discontinue treatment, respectively. When compared to apixaban, patients who initiated dabigatran (aHR: 1.46, 95% CI: 1.38–1.54, P<0.001) or rivaroxaban (aHR: 1.23, 95% CI: 1.17–1.28, P<0.001) were more likely to discontinue treatment. Among newly-anticoagulated NVAF patients in the real-world setting, initiation on rivaroxaban, dabigatran, or apixaban was associated with a significantly lower risk of discontinuation compared to warfarin. When compared to apixaban, patients who initiated treatment with warfarin, dabigatran, or rivaroxaban were more likely to discontinue treatment.

Adherence to Rivaroxaban, Dabigatran, and Apixaban for Stroke Prevention for Newly Diagnosed and Treatment-Naive Atrial Fibrillation Patients: An Update Using 2013-2014 Data

BACKGROUND

Few studies have assessed adherence to non-vitamin K antagonist oral anticoagulants (NOACs), especially using contemporary data now that multiple NOACs are available.

OBJECTIVE

To compare adherence and treatment patterns among NOACs for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

Incident and treatment-naive NVAF patients were identified during 2013-2014 from a large claims database in this retrospective cohort study. Patients were included who initiated rivaroxaban, dabigatran, or apixaban within 30 days after diagnosis. Adherence to the index medication and adherence to any oral anticoagulant was assessed using the proportion of days covered (PDC) at 3, 6, and 9 months. The number of switches and gaps in therapy were also evaluated. Analyses were stratified by stroke risk scores, and a logistic regression model was used to control for factors that may predict high adherence.

RESULTS

Dabigatran had lower adherence (PDC = 0.76, 0.64, 0.57) compared with rivaroxaban (PDC = 0.83, 0.73, 0.66; P < 0.001) and apixaban (PDC = 0.82, 0.72, 0.66; P < 0.001) at 3, 6, and 9 months of follow-up and twice the number of switches to either other anticoagulants or antiplatelet therapy. Adherence was higher overall as stroke risk increased, and dabigatran had consistently lower adherence compared with the other NOACs. Multivariable logistic regression predicting PDC ≥ 0.80 showed rivaroxaban users with higher odds of high adherence compared with dabigatran or rivaroxaban across all time periods. Adjusted analyses showed that increasing age and comorbid hypertension and diabetes were associated with higher adherence.

CONCLUSIONS

In this real-world analysis of adherence to NOACs, rivaroxaban and apixaban had favorable unadjusted adherence profiles compared with dabigatran, while rivaroxaban users had higher odds of high adherence (PDC ≥ 0.80) among the NOACs in adjusted analyses. Clinicians and managed care organizations should consider the implications of lower adherence on clinical outcomes and quality assessment.

DISCLOSURES

This project was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through grant number UL1TR000117. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The authors have nothing to disclose. Study concept and design were contributed by Brown and Shewale. Brown and Talbert collected the data, and data analysis was performed primarily by Brown, along with Shewale and Talbert. The manuscript was written primarily by Brown, along with Shewale, and revised by all the authors.

Dabigatran etexilate: appropriate use in patients with chronic kidney disease and in the elderly patients

Dabigatran etexilate (DE) is a direct thrombin inhibitor, which has been approved for the treatment of non-valvular atrial fibrillation (AF), and for the prevention and treatment of venous thromboembolism (VTE). Despite large randomized clinical trials and independent observational studies providing robust data concerning DE safety and efficacy, some physicians still perceive mild-to-moderate renal impairment and old age as a relative contraindication to its use. In this article, we review the available scientific evidence supporting the use of DE in these clinical situations. Patients with AF and chronic kidney disease (CKD) are per se at high risk of stroke, bleeding and mortality. Although there is evidence of clinical benefit of anticoagulation in these patients, anticoagulant therapy requires caution and demands careful clinical monitoring, regardless of the drug used. In patients with no contraindication to its use, the clinical benefit of DE versus warfarin is independent of renal function. The elderly with AF are frequently undertreated because of the perception of high bleeding risk and limited clinical benefit. However, the clinical benefit of anticoagulation is independent of patient age, and age per se should not represent a contraindication to anticoagulation. DE has been extensively studied in the elderly, both in randomized clinical trials and in observational studies: DE 150 mg BID should not be used in patients 80 years of age or older, while DE 110 mg BID is as safe as warfarin. Intracranial haemorrhages reduction by DE compared with warfarin is preserved in the elderly. Therefore, mild and moderate CKD and being elderly should not deter physicians from prescribing DE. Furthermore, the availability of a specific antidote is expected to improve the safety of the use of DE in clinical practice.

Adherence to Rivaroxaban, Dabigatran, and Apixaban for Stroke Prevention in Incident, Treatment-Naïve Nonvalvular Atrial Fibrillation

BACKGROUND

Non-vitamin K antagonist oral anticoagulants (NOACs) are widely used for prevention of stroke secondary to nonvalvular atrial fibrillation (NVAF). Increased use of NOACs is partially a result of simplified regimens compared with warfarin, which has been associated with poor adherence and persistence to therapy. Few studies have assessed adherence to NOACs, especially using contemporary data now that multiple NOACs are available.

OBJECTIVE

To evaluate adherence to NOACs in a cohort of newly diagnosed NVAF patients who are commercially insured.

METHODS

Incident, treatment-naïve NVAF patients were identified in 2013 from a large claims database. Patients were included who initiated rivaroxaban, dabigatran, or apixaban within 30 days after diagnosis. Subjects were required to have 12 months of pre-index information to assess demographic and clinical characteristics (comorbidities, CHA₂ DS₂-VASc, and HAS-BLED scores). Adherence to the index medication and adherence to any oral anticoagulant was assessed using proportion of days covered (PDC) at 3, 6, and 9 months. The number of switches and gaps in therapy were also evaluated. Analyses were stratified by stroke risk scores, and a logistic regression model was used to control for factors that may predict high adherence (PDC ≥ 0.80).

RESULTS

A total of 3,455 rivaroxaban, 1,264 dabigatran, and 504 apixaban users were included with no major clinical or demographic differences between groups. At 3, 6, and 9 months of follow-up, dabigatran had lower adherence (PDC = 0.77, 0.67, and 0.62) compared with rivaroxaban (PDC = 0.84, 0.75, and 0.70; P < 0.001) and apixaban (PDC = 0.82, 0.75, and 0.71; P < 0.001), as well as nearly twice the number of switches to either other anticoagulants or antiplatelet therapy. At 9 months, 55.0% of rivaroxaban initiators had PDC ≥ 0.80, which was comparable with 56.8% for apixaban and significantly greater than 46.7% for dabigatran (P < 0.001). Adherence was higher overall as stroke risk increased and showed dabigatran had consistently lower adherence compared with the other NOACs. Overall adherence to any oral anticoagulants, allowing for switches to another NOAC or warfarin, was not dependent on the index medication (9-month PDC = 0.74, 0.71, and 0.74 for rivaroxaban, dabigatran, and apixaban initiators). Adjusted analyses showed that increasing age and comorbid hypertension and diabetes were associated with higher adherence. Compared with rivaroxaban, dabigatran initiators had nearly 30% lower odds of being adherent to their index medication, and no differences were observed between apixaban and rivaroxaban. At 9 months, there were no differences between NOACs for overall adherence to oral anticoagulants.

CONCLUSIONS

In this real-world analysis of adherence to NOACs, rivaroxaban and apixaban had favorable profiles compared with dabigatran, and rivaroxaban appeared to have higher overall adherence among the NOACs. Clinicians and managed care organizations should consider the implications of lower adherence on clinical outcomes as well as quality assessment.

DISCLOSURES

The project described was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through grant number UL1TR000117. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Brown reports receiving a training fellowship from Human and Pfizer. Study concept and design were contributed by Brown and Shewale. Talbert took the lead in data collection, along with Brown, and data interpretation was primarily performed by Brown, along with Shewale. The manuscript was written primarily by Brown, along with Shewale, and revised by all the authors.

Impact of Warfarin Persistence on Health-Care Utilization and Costs Among Patients With Atrial Fibrillation Managed in Anticoagulation Clinics in the United States

Warfarin is a recommended therapy to reduce the risk of stroke in patients with nonvalvular atrial fibrillation (NVAF). The objectives of this study were to identify potential factors associated with warfarin persistence and evaluate the impact of warfarin persistence on health-care resource utilization and costs among patients with NVAF in the United States. Patients (≥18 years) with ≥1 inpatient or ≥2 outpatient diagnoses of AF without valvular disease were identified from an electronic medical record database (January 1, 2004, to January 31, 2015). The patients with NVAF were grouped into 2 cohorts-persistent with warfarin therapy and not persistent (warfarin discontinuation in <365 days). A multivariable regression was used to identify potential predictors of warfarin persistence. Health-care costs were evaluated during a 12-month follow-up period for study cohorts. Among the study population, 52%, (n = 4086) were persistent with warfarin therapy and 48% (n = 3722) were not. Patients with NVAF with higher Charlson comorbidity index and CHADS₂ scores versus those with scores of 0 were more likely to demonstrate persistence with warfarin therapy. After adjusting for patient characteristics, patients with NVAF persistent with warfarin therapy versus those who were not were 30% less likely to be hospitalized during the follow-up period ( P < .001). Additionally, total all-cause health-care costs (US $2183, P < .001) and stroke-related costs (US $788, P < .001) were significantly lower among patients persistent with warfarin therapy versus those who were not. Patients with NVAF who have greater comorbidity and stroke risk are more likely to be persistent with warfarin therapy. Patients with NVAF who are persistent with warfarin therapy versus those who are not have lower all-cause and stroke-related health-care costs.

Overcoming global challenges in stroke prophylaxis in atrial fibrillation: The role of non-vitamin K antagonist oral anticoagulants

Atrial fibrillation is the world's most common sustained cardiac arrhythmia and is associated with a significantly increased risk of stroke. The global burden of atrial fibrillation is rising, commensurate with the ageing population. Well-controlled vitamin K antagonist-based anticoagulation has been shown to reduce the risk of stroke secondary to atrial fibrillation by two-thirds. However, patients with atrial fibrillation have frequently been denied anticoagulation because of a variety of perceived risks related to bleeding, falls, chronological age, and poor compliance. Even when vitamin K antagonists are used, maximum benefit and safety are only delivered when high quality control of therapy (TTR > 70%) is achieved, which has proven remarkably difficult in many health-care systems and amongst many patient groups. The non-vitamin K antagonist oral anticoagulants (NOACs) offer solutions to many of the challenges of achieving widespread, safe, and effective anticoagulation for stroke prophylaxis in atrial fibrillation, yet their uptake into routine clinical practice remains variable. The evidence supporting their more widespread use to overcome the challenges of stroke prophylaxis for atrial fibrillation is reviewed in this article.