The increasing need for anticoagulant therapy to prevent stroke in patients with atrial fibrillation

Using Machine Learning Approaches to Predict Short-Term Risk of Cardiotoxicity Among Patients with Colorectal Cancer After Starting Fluoropyrimidine-Based Chemotherapy

Cardiotoxicity is a severe side effect for colorectal cancer (CRC) patients undergoing fluoropyrimidine-based chemotherapy. To develop and compare machine learning algorithms to predict cardiotoxicity risk among nationally representative CRC patients receiving fluoropyrimidine, CRC Patients with at least one claim of fluoropyrimidine after their cancer diagnosis were included. The outcome was the 30-day cardiotoxicity from the first day of starting fluoropyrimidine. The machine learning models including extreme gradient boosting (XGBoost), random forest (RF), and logistic regression (LR) were developed using 2006-2011 SEER-Medicare data, and model performances were evaluated using 2012-2014 data. Precision, F1 score, and area under the receiver operating characteristics curve (AUC) were measured to evaluate model performances. Feature importance plots were obtained to quantify the predictor importance. Among 36,030 CRC patients, 18.74% of them developed cardiotoxicity within 30 days since the first fluoropyrimidine. The XGBoost approach had better prediction performance with higher precision (0.619) and F1 score (0.406) in predicting the 30-day cardiotoxicity, compared to the RF (precision, 0.607 and F1 score, 0.395) and LR (precision, 0.610 and F1 score, 0.398). According to the DeLong's test for AUC difference, the XGBoost significantly outperformed the RF and LR (XGBoost, 0.816 vs. RF, 0.804, P < 0.001; XGBoost vs. LR, 0.812, P = 0.003, respectively). Feature importance plots identified pre-existing cardiac conditions, surgery, older age as top significant risk factors for cardiotoxicity events among CRC patients after receiving fluoropyrimidine. In summary, the developed machine learning models can accurately predict the occurrence of 30-day cardiotoxicity among CRC patients receiving fluoropyrimidine-based chemotherapy.

Persistence with VKA treatment in newly treated atrial fibrillation patients: an analysis based on a large sample of 38,076 German patients

PURPOSE

The aim of this study was to describe persistence with vitamin K antagonist (VKA) treatment in German atrial fibrillation (AF) patients and to identify factors which may be associated with early discontinuation of VKA therapy.

METHODS

We did a retrospective cohort study based on an anonymized German claims dataset with VKA treatment-naïve AF patients, who received at least one VKA prescription. VKA therapy discontinuation was defined as a gap >180 days.

RESULTS

We identified 38,076 VKA patients who started a VKA therapy (mean age 76.13 years; 56.08% female; mean CHA₂DS₂-VASc-Score 4.49; mean Charlson Comorbidity Index (CCI) 3.91). After four quarters since start of VKA treatment, 14,889 (39.10%) of observed patients had discontinued their VKA treatment (after eight quarters: 54.61%). Mean time until treatment discontinuation was 390.55 days. Risk of VKA discontinuation increased with the diagnosis of dementia within the first two quarters of VKA treatment [HR 1.35 (95% CI 1.29-1.40)], diagnosed alcohol or drug abuse in the baseline period [HR 1.25; 95% CI 1.18-1.33)], female gender [HR 1.08; 95% CI 1.05-1.10)], higher age (HR 1.03; 95% CI 1.03-1.03), higher CCI (HR 1.05; 95% CI 1.04-1.05), any prescription of NSAID (HR 1.07; 95% CI 1.04-1.10), and number of surgeries in the first two quarters of VKA treatment (HR 1.05; 95% CI 1.04-1.05). At least one yearly visit to a cardiologist since start of VKA treatment decreased the risk of non-persistence [HR 0.90; 95% CI 0.88-0.93] and a cancer diagnosis in the baseline period (HR 0.92; 95% CI 0.89-0.96).

CONCLUSION

Non-persistence related to VKA therapy is common in AF patients. Older more comorbid female patients as well as patients who face surgeries and who do not visit a cardiologist regularly face a higher therapy discontinuation risk.

Risk of falls and major bleeds in patients on oral anticoagulation therapy

BACKGROUND

The risk of falls is the most commonly cited reason for not providing oral anticoagulation, although the risk of bleeding associated with falls on oral anticoagulants is still debated. We aimed to evaluate whether patients on oral anticoagulation with high falls risk have an increased risk of major bleeding.

METHODS

We prospectively studied consecutive adult medical patients who were discharged on oral anticoagulants. The outcome was the time to a first major bleed within a 12-month follow-up period adjusted for age, sex, alcohol abuse, number of drugs, concomitant treatment with antiplatelet agents, and history of stroke or transient ischemic attack.

RESULTS

Among the 515 enrolled patients, 35 patients had a first major bleed during follow-up (incidence rate: 7.5 per 100 patient-years). Overall, 308 patients (59.8%) were at high risk of falls, and these patients had a nonsignificantly higher crude incidence rate of major bleeding than patients at low risk of falls (8.0 vs 6.8 per 100 patient-years, P=.64). In multivariate analysis, a high falls risk was not statistically significantly associated with the risk of a major bleed (hazard ratio 1.09; 95% confidence interval, 0.54-2.21). Overall, only 3 major bleeds occurred directly after a fall (incidence rate: 0.6 per 100 patient-years).

CONCLUSIONS

In this prospective cohort, patients on oral anticoagulants at high risk of falls did not have a significantly increased risk of major bleeds. These findings suggest that being at risk of falls is not a valid reason to avoid oral anticoagulants in medical patients.

Costs and clinical consequences of suboptimal atrial fibrillation management

Atrial fibrillation (AF) places a considerable burden on the US health care system, society, and individual patients due to its associated morbidity, mortality, and reduced health-related quality of life. AF increases the risk of stroke, which often results in lengthy hospital stays, increased disability, and long-term care, all of which impact medical costs. An expected increase in the prevalence of AF and incidence of AF-related stroke underscores the need for optimal management of this disorder. Although AF treatment strategies have been proven effective in clinical trials, data show that patients still receive suboptimal treatment. Adherence to AF treatment guidelines will help to optimize treatment and reduce costs due to AF-associated events; new treatments for AF show promise for future reductions in disease and cost burden due to improved tolerability profiles. Additional research is necessary to compare treatment costs and outcomes of new versus existing agents; an immediate effort to optimize treatment based on existing evidence and guidelines is critical to reducing the burden of AF.

Principles of Anticoagulation and New Therapeutic Agents in Atrial Fibrillation

Anticoagulation is required in cardiac arrhythmias, specifically atrial fibrillation (AF) and atrial flutter, to reduce the risk of thromboembolism. Principles of anticoagulation of both AF and atrial flutter are similar because the location and nature of the arrhythmias are similar. Approximately 2 million people in the United States are affected by AF, and the prevalence is expected to exceed 10 million by the year 2050. Warfarin is known to reduce stroke risk by 68% in patients with AF and is the most effective agent for this indication, although it is not without risk. Antithrombotic therapy with antiplatelets or anticoagulants is recommended for most patients with AF. This review discusses the principles of anticoagulation and the mechanism of action, pharmacologic profile, and phase of development of the therapeutic agents used as anticoagulants.

Current issues in patient adherence and persistence: focus on anticoagulants for the treatment and prevention of thromboembolism

Warfarin therapy reduces morbidity and mortality related to thromboembolism. Yet adherence to long-term warfarin therapy remains challenging due to the risks of anticoagulant-associated complications and the burden of monitoring. The aim of this paper is to review determinants of adherence and persistence on long-term anticoagulant therapy for atrial fibrillation and venous thromboembolism. We evaluate what the current literature reveals about the impact of warfarin on quality of life, examine warfarin trial data for patterns of adherence, and summarize known risk factors for warfarin discontinuation. Studies suggest only modest adverse effects of warfarin on quality of life, but highlight the variability of individual lifestyle experiences of patients on warfarin. Interestingly, clinical trials comparing anticoagulant adherence to alternatives (such as aspirin) show that discontinuation rates on warfarin are not consistently higher than in control arms. Observational studies link a number of risk factors to warfarin non-adherence including younger age, male sex, lower stroke risk, poor cognitive function, poverty, and higher educational attainment. In addition to differentiating the relative impact of warfarin-associated complications (such as bleeding) versus the lifestyle burdens of warfarin monitoring on adherence, future investigation should focus on optimizing patient education and enhancing models of physician-patient shared-decision making around anticoagulation.

Anticoagulation in Elderly Patients Who Fall Frequently: A Therapeutic Dilemma

There is general agreement that patients with persistent atrial fibrillation, who are at risk of having a stroke, need to be anticoagulated. However, clinicians often are in a difficult dilemma when these patients also are at increased risk of falling. Falls can lead to serious injuries in anticoagulated individuals, including intracranial hemorrhages. This case study describes an 88-year-old patient with a history of falling. She received multiple injuries following a fall, including a subdural hematoma. Warfarin was among the patient's many medications. Upon admission to the hospital this patient had a supratherapeutic INR that most likely contributed to her injuries. A question facing the medical team was should she continue to receive warfarin to prevent stroke after discharge from the hospital? Much controversy exists over whether older patients receiving anticoagulation therapy are at increased risk of major hemorrhagic complications. This article discusses the relationship between anticoagulation, falling, and the risks of hemorrhagic events. It also discusses opinions on when to restart anticoagulation following resolution of the subdural hematoma. In addition, the patient was taking multiple medications that are known to contribute to falls in older people. Recommendations for lowering this patient's fall risks are presented.

Potentially Preventable Strokes in High-Risk Patients With Atrial Fibrillation Who Are Not Adequately Anticoagulated

Background and Purpose— Warfarin is the most effective stroke prevention medication for high-risk individuals with atrial fibrillation, yet it is often underused. This study examined the magnitude of this problem in a large contemporary, prospective stroke registry.

Methods— We analyzed data from the Registry of the Canadian Stroke Network, a prospective database of consecutive patients with stroke admitted to 12 designated stroke centers in Ontario (2003 to 2007). We included patients admitted with an acute ischemic stroke who (1) had a known history of atrial fibrillation; (2) were classified as high risk for systemic emboli according to published guidelines; and (3) had no known contraindications to anticoagulation. Primary end points were the use of prestroke antithrombotic medications and admission international normalized ratio.

Results— Among patients admitted with a first ischemic stroke who had known atrial fibrillation (n=597), strokes were disabling in 60% and fatal in 20%. Preadmission medications were warfarin (40%), antiplatelet therapy (30%), and no antithrombotics (29%). Of those taking warfarin, three fourths had a subtherapeutic international normalized ratio (<2.0) at the time of stroke admission. Overall, only 10% of patients with acute stroke with known atrial fibrillation were therapeutically anticoagulated (international normalized ratio ≥2.0) at admission. In stroke patients with a history of atrial fibrillation and a previous transient ischemic attack or ischemic stroke (n=323), only 18% were taking warfarin with therapeutic international normalized ratio at the time of admission for stroke, 39% were taking warfarin with subtherapeutic international normalized ratio, and 15% were on no antithrombotic therapy.

Conclusions— In high-risk patients with atrial fibrillation admitted with a stroke, and who were candidates for anticoagulation, most were either not taking warfarin or were subtherapeutic at the time of ischemic stroke. Many were on no antithrombotic therapy. These findings should encourage greater efforts to prescribe and monitor appropriate antithrombotic therapy to prevent stroke in individuals with atrial fibrillation.

Underutilization of Warfarin Therapy in Elderly Patients with Atrial Fibrillation - Fear or False Sense of Security!

Background: Under utilization of warfarin in elderly patients with atrial fibrillation (AF) has been recognized as a significant health care issue. This study examines the rate and reasons for warfarin underutilization in elderly patients with AF at the Kansas City Veterans Affairs Medical Center. Methods: Retrospective study reviewing electronic medical records of all patients aged 65 and older with the diagnosis of atrial fibrillation. Patients on warfarin were excluded. Reasons for not using warfarin were extracted by reviewing the electronic medical record. Anticoagulation indications for these patients were determined based on the ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation. Results: Warfarin was not used by 407 patients (25%) with known AF. Average age was 79+6.2 years. 60% of patients had persistent or permanent AF. Prevalence of risk factors for thromboembolism included hypertension (74%), heart failure or ejection fraction of <40% (21%), diabetes (27%) and coronary artery disease (48%). CHADS (2) scores were documented in the charts less than 1% of the times. Only 11 patients had CHADS (2) score of 0 and 70 had a score of 1. A class I or IIa indication for warfarin therapy was present in 298 (73%) of patients. Return to sinus rhythm (37%) was the most common reason for not using warfarin. In 30% of cases the reason not to use warfarin was not addressed. Other reasons not to use warfarin included fear of falls (7%), prior head or GI bleed (14%), patient refusal & noncompliance (12%). History of CVA or TIA was documented in 12% of patients. Conclusions: Underutilization of warfarin in elderly patients with atrial fibrillation remains a common problem despite their high risk for thromboembolic events. A false sense of security about the paroxysmal nature of AF, lack of proper insight about stroke risk (CHADS (2)), and fear of bleeding are the most common reasons for non use of warfarin.

Use of anticoagulation in elderly patients with atrial fibrillation who are at risk for falls

OBJECTIVE

To evaluate data addressing use of anticoagulation in elderly patients with atrial fibrillation (AF), in particular those at risk of falls.

DATA SOURCES

Primary literature was identified through PubMed MEDLINE (1966-December 2007) and EMBASE (1980-December 2007) using the search terms anticoagulation, warfarin, aspirin, elderly, falls, older persons, atrial fibrillation, bleeding, education, stroke, and use. Additional references were obtained through review of references from articles obtained.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies evaluating warfarin and aspirin efficacy in AF, as well as studies evaluating anticoagulation and falls, elderly patients, and bleeding were considered for inclusion. Selection emphasis was placed on randomized studies of AF and those evaluating anticoagulation and falls.

DATA SYNTHESIS

Uncertainties over the optimal treatment for elderly patients with AF still exist. Variance in the guidelines is reflected in current practice, as some discrepancies are present. Warfarin is underprescribed in elderly patients, with only about 50% of eligible patients receiving therapy. Falls are most often cited as the reason for not using anticoagulants in an elderly patient. Three risk-benefit analyses have been performed, and all found that despite risks associated with warfarin, its benefits outweigh its risks even in patients who fall. Warfarin should be used rather than aspirin or no therapy in elderly patients at risk of falls. Anticoagulation education has been shown to reduce the risk of bleeding in the elderly and should be a vital part of warfarin management.

CONCLUSIONS

The risk of falls alone should not automatically disqualify a person from being treated with warfarin. While falls should not dictate anticoagulant choice, assessment and management of fall risk should be an important part of anticoagulation management. Efforts should be made to minimize fall risk.

Value of Pacemaker Atrial Diagnostic Data in Patients with Paroxysmal Atrial Fibrillation: An Opportunity to Improve Rates of Warfarin Utilization

Atrial diagnostic data within implantable devices provide an opportunity to assess the frequency and quantity of atrial fibrillation (AF) episodes (AF burden) and its impact on appropriate warfarin anticoagulation. Cardiologists were given clinical scenarios to review with different types of pacemaker diagnostic data in an elderly patient with risk factors for stroke. AF specific data was associated with increased warfarin utilization, but only at intermediate rates. Potential reasons and clinical implications are discussed.

Patterns of use of antithrombotic therapy and quality of anticoagulation among patients with non-valvular atrial fibrillation in clinical practice

We conducted a retrospective cohort study of thromboprophylaxis rates and the quality of anticoagulation control among patients with atrial fibrillation (AF) using a large, geographically diverse database of electronic medical records. The study population consisted of 13,709 AF patients treated in US outpatient physician practices. Approximately two-thirds were prescribed warfarin alone or in combination with another drug. Older patients, males, and those with congestive heart failure (CHF) or prior stroke were more likely to receive antithrombotic therapy. Among 6454 patients treated with warfarin who had at least two valid prothrombin time/international normalised ratio test results, approximately half of study days were spent in target range. Female sex, CHF and residence in the Northeast were associated with more time out of range. Our study confirms that, in routine medical practice, warfarin is not prescribed for substantial numbers of eligible patients, and anticoagulation control with warfarin is suboptimal for many of those at risk for thromboembolism.

To Anticoagulate or not to Anticoagulate? A Common Dilemma for the Provider: Physicians’ Opinion Poll Based on a Case Study of an Older Long-term Care Facility Resident With Dementia and Atrial Fibrillation

OBJECTIVE

Anticoagulation therapy is an acceptable strategy for the prevention of thromboembolic events in the presence of atrial fibrillation. However, this strategy is controversial in older subjects particularly in the presence of dementia. We conducted an opinion poll regarding the decision to anticoagulate or not among physicians in practice and in various levels of training (residents and fellows) that was based on a specific, yet not unusual, case scenario in the nursing home.

SETTING

A university teaching hospital in the Bronx, NY.

METHODS

A survey questionnaire was distributed to physicians to solicit opinions on the decision to anticoagulate based on an actual case from a LTCF and the results were analyzed.

RESULTS

One hundred seven completed surveys were returned from 49 residents, 20 fellows, and 38 attending physicians. The majority (85%) felt that long-term anticoagulation therapy was not indicated in the case patient. However, most (88%) felt they would provide an antiplatelet agent, with the choice being 78% aspirin, 20% clopridogel, and 2% aspirin-dipyridamole. The most cited reasons for not providing anticoagulation were risk of falls (98%), dementia (40%), and short life expectancy (32%). However, 92% of respondents felt that the patient was a candidate for short-term anticoagulation therapy. Interestingly, the choices (yes, no, uncertain) to the questions were similar for all physicians irrespective of their level of training or years in practice (or faculty) after training.

CONCLUSIONS

Although long-term anticoagulation for thromboembolic events in atrial fibrillation is considered beneficial, recent reports suggest that warfarin is underused in older adults, especially in the long-term care setting. Our physician poll, based on a specific case scenario, is consistent with this opinion as reflected by both trainees and practicing physicians. While there are absolute and relative contraindications to the use of long-term warfarin, decisions should be individualized and based on risks, benefits, and quality of life of the resident.

New treatment options for stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia requiring treatment. Its most devastating consequence is thromboembolic stroke. Therapy with warfarin is indicated in most patients, as it has been shown conclusively to reduce the risk of stroke. Aspirin is an inferior alternative except in certain low-risk patients or for patients with an absolute contraindication to warfarin. Guidelines have been published for the administration of antithrombotic therapy in AF, but many patients who are candidates for anticoagulation do not receive this therapy. Even as this therapy is under-utilized, the indication for anticoagulation is expanding. Indefinite continuation of anticoagulation should be considered in higher-risk patients despite the appearance that sinus rhythm has been restored because asymptomatic (or silent) AF occurs frequently. Newer agents that offer substantial benefit over warfarin are being developed and would enhance compliance with anticoagulation in AF if these novel therapies prove to be safe and equivalent to warfarin in efficacy.