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

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.

Association between transportation barriers and anticoagulation control among an inner-city, low-income population: A prospective observational cohort study

Background

Anticoagulation with warfarin represents a transportation-sensitive treatment state. Transportation barrier is a common reason for not using health care services.

Objective

To assess the association between transportation barriers to anticoagulation clinic and anticoagulation control (AC) among an inner-city, low-income population.

Patients/Methods

Adults expected to be on chronic warfarin therapy were recruited from an ambulatory anticoagulation clinic. Participants completed a validated questionnaire that assessed transportation barriers to clinic, defined as self-reported trouble getting transportation to a clinic and a composite score of the presence of transportation barriers. Suboptimal AC was defined as time in therapeutic range (TTR) <60% over 6 months. Prevalence ratios with 95% confidence intervals (CIs), adjusted for age, sex, and annual household income, described the association of transportation trouble and barriers with AC.

Results

Of 133 participants, 42.9% had suboptimal AC. Mean age was 60.4 (SD, 13.6) years, and the majority of participants were women (62.2%). Participants with transportation trouble were more likely to report being disabled/unable to work (63.6%) and annual household income <$15 000 (45.5%). Mean TTR was significantly lower for participants with transportation trouble compared to those without (53.8% [SD, 24.7%] vs 64.7% [SD, 25.0%]; P = .03). Participants reporting transportation trouble or at least one transportation barrier were 1.60 (95% CI, 1.07-2.39) and 1.68 (95% CI, 1.01-2.80) times more likely, respectively, to have suboptimal AC compared to those without.

Conclusion

Inner-city, low-income individuals with transportation barriers were more likely to have suboptimal AC. Further research is warranted to evaluate the impact of alleviating patient-specific transportation barriers on anticoagulation outcomes.

Reasons for discontinuing oral anticoagulation therapy for atrial fibrillation: a systematic review

Introduction

Atrial fibrillation (AF) is the most common cardiac arrhythmia and can lead to significant comorbidities and mortality. Persistence with oral anticoagulation (OAC) is crucial to prevent stroke but rates of discontinuation are high. This systematic review explored underlying reasons for OAC discontinuation.

Methods

A systematic review was undertaken to identify studies that reported factors influencing discontinuation of OAC in AF, in 11 databases, grey literature and backwards citations from eligible studies published between 2000 and 2019. Two reviewers independently screened titles, abstracts and papers against inclusion criteria and extracted data. Study quality was appraised using Gough’s weight of evidence framework. Data were synthesised narratively.

Results

Of 6,619 sources identified, 10 full studies and 2 abstracts met the inclusion criteria. Overall, these provided moderate appropriateness to answer the review question. Four reported clinical registry data, six were retrospective reviews of patients’ medical records and two studies reported interviews and surveys. Nine studies evaluated outcomes relating to dabigatran and/or warfarin and three included rivaroxaban (n = 3), apixaban (n = 3) and edoxaban (n = 1). Bleeding complications and gastrointestinal events were the most common factors associated with discontinuation, followed by frailty and risk of falling. Patients’ perspectives were seldom specifically assessed. Influence of family carers in decisions regarding OAC discontinuation was not examined.

Conclusion

The available evidence is derived from heterogeneous studies with few relevant data for the newer direct oral anticoagulants. Reasons underpinning decision-making to discontinue OAC from the perspective of patients, family carers and clinicians is poorly understood.

Methodological considerations for investigating oral anticoagulation persistence in atrial fibrillation

Aims 

Reports of long-term oral anticoagulant (OAC) therapy for atrial fibrillation (AF) reveal highly variable, and generally suboptimal estimates of medication persistence. The objective of this review is to summarize current literature and highlight important methodological considerations for interpreting persistence research and designing studies of persistence on OAC treatment.

Methods and results 

We summarize differences in study methodology, setting, timing, treatment, and other factors associated with reports of better or worse persistence. For example, prospective compared with retrospective study designs are associated with higher reported persistence. Similarly, patient factors such as permanent AF or high stroke risk, and treatment with non-vitamin K oral antagonists relative to vitamin K antagonists are associated with higher persistence. Persistence has also been reported to be higher in Europe compared with North America and higher when the treating physician is a general practitioner compared with a specialist. We propose a framework for assessing and designing persistence studies. This framework includes aspects of patient selection, reliability and validity of measures, persistence definitions, clinical utility of measurements, follow-up periods, and analytic approaches.

Conclusions 

Differences in study design, patient selection, treatments, and factors such as the countries/regions where studies are conducted or the type of treating physician may help explain the variability in OAC persistence estimates. A framework is proposed to assess persistence studies. This may have utility to compare and interpret published studies as well as for planning of future studies.