Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

Interrupting anticoagulation in patients with nonvalvular atrial fibrillation

Three target-specific oral anticoagulants (TSOACs)-dabigatran, rivaroxaban, and apixaban-have been approved by the FDA to reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation; however, no agents are currently approved to reverse the anticoagulant effects of these TSOACs in cases of active bleeding. This review discusses the benefits and risks of these TSOACs from a clinician's perspective, with a focus on the interruption of treatment for either elective or emergent surgery, monitoring, and reversal of anticoagulation. Available coagulation assays are not ideal for monitoring the effects of TSOACs and do not provide reliable quantitative measurement of their anticoagulant effects. When necessary, activated partial thromboplastin time (aPTT) may provide qualitative information on dabigatran, and prothrombin time (PT) may provide qualitative assessment of the presence of the factor Xa inhibitors, rivaroxaban and apixaban. Current recommendations for reversal of TSOACs are based largely on limited and sometimes conflicting data from in vitro or in vivo animal models, and clinical experience with these recommendations is also limited. Methods that have been investigated for effectiveness for reversal of the pharmacodynamic effects of the TSOACs include dialysis, activated charcoal, prothrombin complex concentrate (PCC), and recombinant activated factor VII. It is important to note that even within a class of anticoagulant drugs, compounds respond differently to reversal agents; therefore, recommendations for one agent should not be extrapolated to another, even if they are from the same therapeutic class. New antidotes are being explored, including a mouse monoclonal antibody to dabigatran; andexanet alfa, a potential universal factor Xa inhibitor reversal agent; and a synthetic small molecule (PER977) that may be effective for the reversal of factor Xa inhibitors and direct thrombin inhibitors. Given the short half-lives of TSOACs, watchful waiting, rather than reversal, may be the best approach in some circumstances.

Four factor prothrombin complex concentrate (human): review of the pharmacology and clinical application for vitamin K antagonist reversal

Vitamin K antagonists (VKAs) have been used for decades for the treatment and prophylaxis of thromboembolic events. Due to their wide range of therapeutic indications, they are the most prescribed oral anticoagulant worldwide. However, they are associated with bleeding complications due to their narrow therapeutic range, variability in individual dose responses and laboratory monitoring, and overdoses. Despite off-label use of 3-factor prothrombin complex concentrates and recombinant activated factor VII, until recently, vitamin K and plasma were the only recommended therapeutic options for reversing VKAs in the USA. In 2013, a 4-factor prothrombin complex concentrate (4F-PCC) was approved in the USA for VKA reversal in patients with bleeding or requiring emergency surgery and invasive procedure. Recent randomized controlled clinical trials have shown that 4F-PCC (Kcentra™) is non-inferior for hemostatic efficacy and superior for international normalized ratio correction as compared to plasma and has a similar safety profile.

Influence of kidney function on risk of supratherapeutic international normalized ratio-related hemorrhage in warfarin users: a prospective cohort study

BACKGROUND

Anticoagulation management is difficult in chronic kidney disease, with frequent supratherapeutic international normalized ratios (INRs ≥ 4) increasing hemorrhagic risk. We evaluated whether the interaction of INR and lower estimated glomerular filtration rate (eGFR) increases hemorrhage risk and whether patients with lower eGFRs experience slower anticoagulation reversal.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Warfarin pharmacogenetics cohort (1,273 long-term warfarin users); warfarin reversal cohort (74 warfarin users admitted with INRs ≥ 4).

PREDICTOR

eGFR, INR as time-dependent covariate, and their interaction in the pharmacogenetics cohort; eGFR in the reversal cohort.

OUTCOMES & MEASUREMENTS

In the pharmacogenetics cohort, hemorrhagic (serious, life-threatening, and fatal bleeding) risk was assessed using proportional hazards regression. In the reversal cohort, anticoagulation reversal was assessed from changes in INR, warfarin and metabolite concentrations, clotting factors (II, VII, IX, and X), and PIVKA-II (protein induced by vitamin K absence or antagonist II) levels at presentation and after reversal, using linear regression and path analysis.

RESULTS

In the pharmacogenetics cohort, 454 (35.7%) had eGFRs < 60 mL/min/1.73 m(2). There were 137 hemorrhages in 119 patients over 1,802 person-years of follow-up (incidence rate, 7.6 [95% CI, 6.4-8.9]/100 person-years). Patients with lower eGFRs had a higher frequency of INR ≥ 4 (P<0.001). Risk of hemorrhage was affected significantly by eGFR-INR interaction. At INR<4, there was no difference in hemorrhage risk by eGFR (all P ≥ 0.4). At INR≥4, patients with eGFRs of 30 to 44 and < 30 mL/min/1.73 m(2) had 2.2-fold (95% CI, 0.8-6.1; P=0.1) and 5.8-fold (95% CI, 2.9-11.4; P<0.001) higher hemorrhage risks, respectively, versus those with eGFRs ≥ 60 mL/min/1.73 m(2). In the reversal cohort, 35 (47%) had eGFRs < 45 mL/min/1.73 m(2). Patients with eGFRs < 45 mL/min/1.73 m(2) experienced slower anticoagulation reversal as assessed by INR (P=0.04) and PIVKA-II level (P=0.008) than those with eGFRs ≥ 45 mL/min/1.73 m(2).

LIMITATIONS

Limited sample size in the reversal cohort, unavailability of antibiotic use and urine albumin data.

CONCLUSIONS

Patients with lower eGFRs have differentially higher hemorrhage risk at INR ≥ 4. Moreover, because the INR reversal rate is slower, hemorrhage risk is prolonged.

Anticoagulation in patients with impaired renal function and with haemodialysis. Anticoagulant effects, efficacy, safety, therapeutic options

Patients with impaired renal function are exposed to an increased risk for bleeding complications depending on the amount of the anticoagulant eliminated by the kidneys. The elimination of unfractionated heparins, vitamin K antagonists and argatroban is only minimally influenced by a reduced renal function. Low-molecular weight heparins, fondaparinux, danaparoid, hirudins and non-vitamin K antagonist oral anticoagulants (NOAC) cause a variably increased bleeding risk in renal impairment. Dose reductions are recommended for all of these anticoagulants in renal impairment, some are even contraindicated at certain levels of renal impairment. Their benefit over the conventional anticoagulants is preserved if renal dosing is employed. For end-stage renal disease patients specific treatment regimens are required.

Procoagulant therapeutics in liver disease: a critique and clinical rationale

The complex nature of haemostasis in patients with liver disease can result in bleeding and/or thrombosis. These opposing outcomes, which have multiple contributing factors, can pose diagnostic and therapeutic dilemmas for physicians. With the high rate of haemorrhagic complications in patients with cirrhosis, we examine the various procoagulants available for use in this population. In this Review, we describe the clinical and current rationale for using each of the currently available procoagulants-vitamin K, fresh frozen plasma (FFP), cryoprecipitate, platelets, recombinant factor VIIa (rFVIIa), antifibrinolytics, prothrombin concentrate complexes (PCC), desmopressin and red blood cells. By examining the evidence and use of these agents in liver disease, we provide a framework for targeted, goal-directed therapy with procoagulants.

Vitamin K: dietary intake and requirements in different clinical conditions

PURPOSE OF REVIEW

Vitamin K is an enzyme cofactor for the carboxylation of vitamin K-dependent proteins. Functions include coagulation and regulation of calcification. Different clinical conditions may alter vitamin K requirements by affecting vitamin K status and vitamin K-dependent proteins carboxylation that are reviewed here.

RECENT FINDINGS

Vitamin K consumption greater than the current usual daily requirement to maintain health is indicated for prevention of vitamin K-deficient bleeding in infants and for rescue of over-anticoagulation in patients on vitamin K-dependent oral anticoagulants. Additional vitamin K intake may be required in malabsorptive conditions such as cystic fibrosis and following bariatric surgery. Carboxylation of vitamin K-dependent proteins occurs in multiple extrahepatic tissues and has been implicated in soft tissue calcification and insulin resistance, although the exact mechanisms have yet to be determined. Contribution of colonic flora to vitamin K requirements remains controversial.

SUMMARY

With the increased incidence of vitamin K-deficient bleeding and weight-loss surgical procedures, healthcare professionals need to monitor vitamin K status in certain patient populations. Future research on the roles of vitamin K in extrahepatic tissues as they pertain to chronic disease will provide insight into the therapeutic potential of vitamin K and lead to the development of recommendations for specific clinical populations.

Prothrombin complex concentrate in trauma patients

BACKGROUND

Despite recent advances, trauma care providers nowadays face a number of coagulopathic patients. Coagulopathy in trauma patients can be secondary to the traumatic insult or therapeutic effect of the anticoagulants including the Vitamin K antagonist. The efficacy of a concentrated product of Vitamin K-dependent coagulation factors, prothrombin complex concentrate (PCC), to reverse coagulopathy has been tested mainly in nontrauma setting.

DATA SOURCES

Currently available literature on the use of PCC was identified by searches of electronic database. The indications (trauma vs nontrauma) and types of the PCC products (3 vs 4 factors) were also reviewed in each article.

CONCLUSIONS

There are small studies that show promising results regarding PCC use to reverse the Vitamin K antagonist-related coagulopathy in trauma patients. It remains unanswered whether PCC can be effective as an adjunct in patients who require massive transfusion.

A survey of nursing home physicians to determine laboratory monitoring adverse drug event alert preferences

OBJECTIVE

We conducted a survey of nursing home physicians to learn about (1) the laboratory value thresholds that clinical event monitors should use to generate alerts about potential adverse drug events (ADEs); (2) the specific information to be included in the alerts; and (3) the communication modality that should be used for communicating them.

METHODS

Nursing home physician attendees of the 2010 Conference of AMDA: The Society for Post-Acute and Long-Term Care Medicine.

RESULTS

A total of 800 surveys were distributed; 565 completed surveys were returned and seven surveys were excluded due to inability to verify that the respondents were physicians (a 70% net valid response rate). Alerting threshold preferences were identified for eight laboratory tests. For example, the majority of respondents selected thresholds of ≥5.5 mEq/L for hyperkalemia (63%) and ≤3.5 without symptoms for hypokalemia (54%). The majority of surveyed physicians thought alerts should include the complete active medication list, current vital signs, previous value of the triggering lab, medication change in the past 30 days, and medication allergies. Most surveyed physicians felt the best way to communicate an ADE alert was by direct phone/voice communication (64%), followed by email to a mobile device (59%).

CONCLUSIONS

This survey of nursing home physicians suggests that the majority prefer alerting thresholds that would generally lead to fewer alerts than if widely accepted standardized laboratory ranges were used. It also suggests a subset of information items to include in alerts, and the physicians' preferred communication modalities. This information might improve the acceptance of clinical event monitoring systems to detect ADEs in the nursing home setting.

Features of electronic health records necessary for the delivery of optimized anticoagulant therapy: consensus of the EHR Task Force of the New York State Anticoagulation Coalition

BACKGROUND

Oral anticoagulants are prescribed to millions of Americans, and consequently are among the medications most likely to contribute to emergency department visits and hospitalizations. Although guidelines and consensus statements promote systematic approaches to therapy, anticoagulation (AC) management is often suboptimal. Electronic health records (EHRs) have the potential to improve safety and quality but have not yet incorporated specialized features necessary to optimize therapy.

OBJECTIVE

To generate a comprehensive, consensus-based list of EHR features clinically necessary to deliver optimized AC management, provide a "language bridge" to accelerate incorporation of features into EHR systems, and suggest mechanisms for the objective evaluation of available EHRs.

METHODS

A multidisciplinary panel of AC specialists utilized the framework of a previously published consensus statement to map outpatient AC management and developed a comprehensive array of sequential computer logic steps using a restricted language scheme. Logic steps were then translated into narrative descriptions of potential EHR features, which were refined through multiple group evaluations. A finalized list of proposed features was ranked according to perceived clinical necessity by physician, pharmacist, and nurse panelists in a blinded manner using a 5-point Likert scale. Features receiving no more than 1 dissenting opinion were included in a finalized list of clinically necessary features.

RESULTS

The task force generated 78 recommended EHR features across 20 key discrete areas and 425 individual logic steps. All recommended features received Strongly Agree or Agree rankings regarding their perceived clinical necessity, and no feature received more than a single Disagree response.

CONCLUSION

The incorporation of key AC-related features into existing EHRs or specialized AC management systems has the potential to systematize the delivery of optimal AC care by health care professionals at the point of care. Optimized AC management has the potential to reduce adverse drug events associated with anticoagulant therapy in the outpatient setting.

Race against the clock: overcoming challenges in the management of anticoagulant-associated intracerebral hemorrhage

Patients receiving anticoagulation therapy who present with any type of intracranial hemorrhage--including subdural hematoma, epidural hematoma, subarachnoid hemorrhage, and intracerebral hemorrhage (ICH)--require urgent correction of their coagulopathy to prevent hemorrhage expansion, limit tissue damage, and facilitate surgical intervention as necessary. The focus of this review is acute ICH, but the principles of management for anticoagulation-associated ICH (AAICH) apply to patients with all types of intracranial hemorrhage, whether acute or chronic. A number of therapies--including fresh frozen plasma (FFP), intravenous vitamin K, activated and inactivated prothrombin complex concentrates (PCCs), and recombinant activated factor VII (rFVIIa)--have been used alone or in combination to treat AAICH to reverse anticoagulation, help achieve hemodynamic stability, limit hematoma expansion, and prepare the patient for possible surgical intervention. However, there is a paucity of high-quality data to direct such therapy. The use of 3-factor PCC (activated and inactivated) and rFVIIa to treat AAICH constitutes off-label use of these therapies in the United States. However, in April 2013, the US Food and Drug Administration (FDA) approved Kcentra (a 4-factor PCC) for the urgent reversal of vitamin K antagonist (VKA) anticoagulation in adults with acute major bleeding. Plasma is the only other product approved for this use in the United States. (1) Inconsistent recommendations, significant barriers (e.g., clinician-, therapy-, or logistics-based barriers), and a lack of approved treatment pathways in some institutions can be potential impediments to timely and evidence-based management of AAICH with available therapies. Patient assessment, therapy selection, whether to use a reversal or factor repletion agent alone or in combination with other agents, determination of site-of-care management, eligibility for neurosurgery, and potential hematoma evacuation are the responsibilities of the neurosurgeon, but ultimate success requires a multidisciplinary approach with consultation from the emergency department (ED) physician, pharmacist, hematologist, intensivist, neurologist, and, in some cases, the trauma surgeon.

Preoperative dosing of low-molecular-weight heparin in hepatopancreatobiliary surgery

BACKGROUND

Venous thromboembolism is a common cause of morbidity. Guidelines recommend perioperative thromboprophylaxis, but clinicians remain cautious of bleeding after major oncologic resections.

METHODS

Retrospective analysis of a single institution's prospective hepatopancreatobiliary database was performed for patients undergoing surgery between January 2010 and February 2013. A total of 223 patients received postoperative thromboprophylaxis and 93 patients were dosed with low-molecular-weight heparin (LMWH) preoperatively.

RESULTS

Two hundred twenty-three patients were analyzed; 50.6% underwent pancreatic and 49.3% underwent liver resection. There were no differences in previous venous thromboembolism (3.8% vs 3.3%; P = .56) or preoperative venous thromboembolism scores (5.74 vs 5.67; P = .82). Estimated blood loss (537 mL vs 592 mL; P = .54), transfusions (25.4% vs 30.4%; P = .25), and complications (52.3% vs 43.5%; P = .12) were equivalent. Incidence of thromboembolic events was lower (6.1% vs 1.1%; P = .05); however, bleeding requiring intervention was increased in the preoperative LMWH group (10.9% vs 3.1%; P = .026).

CONCLUSIONS

Caution must be exercised when using LMWH, as bleeding remains a concern for oncologic hepatopancreatobiliary surgery.

Anticoagulation management by community pharmacists in New Zealand: an evaluation of a collaborative model in primary care

Objectives

Despite the introduction of new oral anticoagulants, vitamin K antagonists remain the mainstay of the prevention and treatment of thromboembolism. The advent of affordable point-of-care testing presents an opportunity for community pharmacists to provide anticoagulation management services, better utilizing their training, reducing the workload on medical practices and improving accessibility and convenience for patients. This study aimed to determine the effectiveness of anticoagulation management by community pharmacists.

Methods

All patients enrolled in a pilot programme for a community pharmacy anticoagulation management service using point-of-care international normalized ratio testing and computer-assisted dose adjustment were included in a follow-up study, including before–after comparison. Outcomes included time in therapeutic range (TTR), time above and below range, number and proportion of results outside efficacy and safety thresholds, and a comparison of care led by pharmacists and care led by a primary-care general practitioner (GP).

Key findings

A total of 693 patients were enrolled, predominantly males over 65 years of age with atrial fibrillation. The mean TTR was 78.6% (95% CI 49.3% to 100%). A subgroup analysis (n = 221) showed an increase in mean TTR from 61.8% under GP-led care to 78.5% under pharmacist-led care (P &lt; 0.001), reflecting a reduction in the time above and, in particular, below the range. The mean TTR by pharmacy ranged from 71.4% to 84.1%. The median number of tests per month was not statistically different between GP- and pharmacist-led care.

Conclusions

Community-pharmacist-led anticoagulation care utilizing point-of-care testing and computerized decision support is safe and effective, resulting in significant improvements in TTR. Our results support wider adoption of this model of collaborative care.

Anticoagulation Management of Atrial Fibrillation: The Relationship of Prevailing Adherence to a Dose Protocol and Recall Schedule on TTR in Primary Care

Objective:

To investigate the prevailing level of adherence to a dosing algorithm and a recall schedule and its relationship with the time in therapeutic range (TTR) among patients with atrial fibrillation.

Methods:

The study was carried out at a regional primary care clinic in Malaysia. Patients on anticoagulation therapy aged older than 18 years were included in the study. The participants have received continuation of their anticoagulation therapy at the primary care clinic for at least 6 months to 1 year after being discharged from a tertiary center. Correlation and multiple regression studies were performed to determine the significance of the predictors of TTR.

Results:

A majority (217) of patients with atrial fibrillation received anticoagulation therapy at the clinic followed by patients with mitral valve replacement and aortic valve replacement. The mean TTR for patients with atrial fibrillation was 57.6%. General practitioners (GPs) adhered to 75.5% of the dose protocol but fared poorly in adhering to the recall schedule (36.2%). The concordance to the dose algorithm and recall schedule were significantly related to TTR. Multiple regression analysis proved that the concordance to the dose algorithm and recall schedule were important predictors of the level of TTR in patients with atrial fibrillation.

Discussion:

The study provides preliminary evidence on the relationship between a validated dose algorithm that is integrated with a recall schedule in the control of TTR in patients with atrial fibrillation on anticoagulation treatment. A larger multicenter study is needed to confirm the results of this finding.

Computerized clinical decision support improves warfarin management and decreases recurrent venous thromboembolism

BACKGROUND

An explicit approach to warfarin dose adjustment using computerized clinical decision support (CDS) improves warfarin management. We report metrics of quality for warfarin management before and after implementation of CDS in a large health care system.

METHODS

A total of 2591 chronically anticoagulated patients were eligible for inclusion. We compared interpatient time in therapeutic range (TTR) and international normalized ratio (INR) variability before and after implementation of CDS. We report outcomes of major bleeding, thrombosis, and health care utilization.

RESULTS

Implementation of CDS significantly improved TTR (from 63.99% to 65.13%; P = .04) and reduced out-of-range INRs (from 42.39% to 39.97%; P < .001). Venous thromboembolism (relative risk [RR] 0.41; P < .001) emergency department utilization (RR 0.62; P < .001), and hospitalization (RR 0.62; P < .001) were reduced after CDS implementation. Major hemorrhage was more frequent after CDS implementation (RR 1.42; P = .01).

CONCLUSION

The CDS warfarin management was associated with improved TTR and decreased INR variability in a large cohort of chronically anticoagulated patients. Clinically relevant outcomes were broadly improved, although more bleeding events were observed.

Warfarin pharmacogenetics

The cytochrome P450 (CYP) 2C9 and vitamin K epoxide reductase complex 1 (VKORC1) genotypes have been strongly and consistently associated with warfarin dose requirements, and dosing algorithms incorporating genetic and clinical information have been shown to be predictive of stable warfarin dose. However, clinical trials evaluating genotype-guided warfarin dosing produced mixed results, calling into question the utility of this approach. Recent trials used surrogate markers as endpoints rather than clinical endpoints, further complicating translation of the data to clinical practice. The present data do not support genetic testing to guide warfarin dosing, but in the setting where genotype data are available, use of such data in those of European ancestry is reasonable. Outcomes data are expected from an on-going trial, observational studies continue, and more work is needed to define dosing algorithms that incorporate appropriate variants in minority populations; all these will further shape guidelines and recommendations on the clinical utility of genotype-guided warfarin dosing.

Use of rivaroxaban in a patient with history of nephrotic syndrome and hypercoagulability

OBJECTIVE

Hypercoagulability, resulting in thromboembolic events, can be a life-threatening complication of nephrotic syndrome (NS). Conventional anticoagulants, such as warfarin, have been the standard of care for more than 50 years; however, the availability of target-specific oral anticoagulants (TSOACs) have provided additional options for the treatment and prevention of thromboembolic events. Documented use of the TSOACs in patients with NS and hypercoagulability is currently limited.

CASE SUMMARY

We present the case of an 18-year-old young woman with NS and renal vein thrombosis who was readmitted with bilateral pulmonary emboli on therapeutic doses of warfarin, with a goal international normalized ratio of 2.0 to 3.0. The decision was made to transition the patient from warfarin to rivaroxaban, an oral factor Xa inhibitor.

DISCUSSION

Rivaroxaban was the first of the emerging TSOACs to be FDA approved for both prevention and treatment of venous thromboembolism. With favorable safety and efficacy data compared with warfarin in addition to a predictable pharmacokinetic profile and the lack of requirement of routine monitoring, rivaroxaban provides a useful alternative in this patient population.

SUMMARY

While on therapeutic anticoagulation, a patient previously diagnosed with NS and renal vein thrombosis experienced pulmonary emboli on a conventional anticoagulant and was switched to a target-specific oral anticoagulant with documented completion of 6 months of therapy without recurrent thromboembolism.

Shock

Critically ill patients with undifferentiated shock are complex and challenging cases in the ED. A systematic approach to assessment and management is essential to prevent unnecessary morbidity and mortality. The simplified, systematic approach described in this article focuses on determining the presence of problems with cardiac function (the pump), intravascular volume (the tank), or systemic vascular resistance (the pipes). With this approach, the emergency physician can detect life-threatening conditions and implement time-sensitive therapy.

PROF-ETEV study: prophylaxis of venous thromboembolic disease in critical care units in Spain

PURPOSE

Venous thromboembolic disease (VTE) in critically ill patients has a high incidence despite prophylactic measures. This fact could be related to an inappropriate use of these measures due to the absence of specific VTE risk scores. To assess the current situation in Spain, we have performed a cross-sectional study, analyzing if the prophylactic measures were appropriate to the patients' VTE risk.

METHODS

Through an electronic questionnaire, we carried out a single day point prevalence study on the VTE prophylactic measures used in several critical care units in Spain. We performed a risk stratification for VTE in three groups: low, moderate-high, and very high risk. The American College of Chest Physicians guidelines were used to determine if the patients were receiving the recommended prophylaxis.

RESULTS

A total of 777 patients were included; 62% medical, 30% surgical, and 7% major trauma patients. The median number of the risk factors for VTE was four. According to the proposed VTE risk score, only 2% of the patients were at low risk, whereas 83% were at very high risk. Sixty-three percent of patients received pharmacological prophylaxis, 12% mechanical prophylaxis, 6% combined prophylaxis, and 19% did not receive any prophylactic measure. According to criteria suggested by the guidelines, 23% of medical, 71% of surgical, and 70% of major trauma patients received an inappropriate prophylaxis.

CONCLUSIONS

Most critically ill patients are at high or very high risk of VTE, but there is a low rate of appropriate prophylaxis. The efforts to improve the identification of patients at risk, and the implementation of appropriate prevention protocols should be enhanced.

Oral anticoagulants and status of antidotes for the reversal of bleeding risk

Anticoagulants have been used in clinical practice for more than 50 years. Their indications expand, as more people are diagnosed each year with atrial fibrillation and venous thromboembolism. Vitamin K antagonists have been the most popular choice due to their effectiveness and their ability to reverse bleeding using a known antidote; oral and intravenous vitamin K have long been known to reverse the effects of warfarin. With new classes of anticoagulants making their way onto the market, such as factor Xa inhibitors (rivaroxaban, apixaban) and direct thrombin inhibitors (dabigatran), the need for new reversal agents is paramount. Patients tend to be more receptive to these medications because they do not require routine blood monitoring, can be used at fixed doses, and do not have major drug or food interactions. Antidotes for these medications have shown promise in animal models and are currently in clinical trials.

Warfarin monitoring in antiphospholipid syndrome and lupus anticoagulant

OBJECTIVE

To review the available literature on international normalized ratio (INR) and chromogenic factor X (CFX) monitoring in patients with antiphospholipid syndrome (APS), specifically lupus anticoagulant (LA), and furthermore, to identify benefits of one monitoring test compared with the other in the presence of LA.

DATA SOURCES

A literature search was conducted through MEDLINE (1946-May 2014) utilizing the following MeSH terms chromogenic compounds, anticoagulants, and factor X. Further articles were identified from original literature citations.

STUDY SELECTION

All English-language studies were included that involved INR and/or CFX monitoring in APS patients that focused on a therapeutic anticoagulation level with warfarin therapy.

DATA SYNTHESIS

A total of 55 articles were identified, of which nine are referenced because of their relevance for this review: three articles focus on the efficacy of utilizing INR monitoring in patients with APS, five focus on CFX compared with INR for therapeutic warfarin dosing, and one compares different thromboplastins utilizing both INR and CFX monitoring. INR monitoring in patients with APS, specifically LA, was not found to be reliable because thromboplastin reagents are sensitive to LA. Furthermore, when INR was compared to CFX, patients with LA had supratherapeutic INRs despite having CFX within goal range.

CONCLUSIONS

In a subgroup of APS patients, INR monitoring may not be safe for determining the dose of warfarin because their INR values can be falsely elevated. Although CFX monitoring is more accurate, it too comes with its own downsides. Managing warfarin therapy in the APS population needs to be individualized.

Warfarin pharmacogenetics: to genotype or not to genotype, that is the question

Genotype is well recognized to influence the dose of warfarin necessary for therapeutic anticoagulation. Recent randomized controlled trials evaluating the clinical utility of genotype-guided warfarin dosing have produced varying results. We review the design and results of the recent clinical trials, assess the impact of their findings on warfarin dosing, and examine unanswered questions related to clinical implementation of warfarin pharmacogenetics.

New oral anticoagulants vs. warfarin treatment: no need for pharmacogenomics?

For patients requiring long-term anticoagulation, oral vitamin K antagonists (VKAs) such as warfarin have overwhelming efficacy data and present significant challenges. In addition to the potential exposure to numerous drug-drug and drug-food interactions, patients receiving warfarin require frequent monitoring. It had been hoped that the integration of pharmacogenomic with clinical information would improve anticoagulation control with warfarin, but trials have not supported this aim. Novel oral anticoagulants (NOACs) offer both advantages and disadvantages and deserve consideration in appropriate patients.

Management of hemorrhage with the target-specific oral anticoagulants

The target-specific oral anticoagulants have recently been introduced as alternatives to warfarin for both prophylactic and therapeutic indications. Although their efficacy and side-effect profiles have been favorable, there is significant concern about management of hemorrhage with these agents as there is no direct reversal agent available. It is important for clinicians to be aware of these agents and the issues that surround them. Most of the management of hemorrhage is based on expert opinion and case reviews. Given the potentially catastrophic consequences of acute hemorrhage while patients are on anticoagulation, specific treatments are needed. Some methods that have been described include activated charcoal, hemodialysis, prohemostatic agents, and transfusions. Target-specific therapies have been shown to be effective in early studies in animal models; however, the effects in humans are still under investigation. More investigation is needed on the management of bleeding complications from target-specific oral anticoagulants.

Loading dose vs. maintenance dose of warfarin for reinitiation after invasive procedures: a randomized trial

BACKGROUND

There is uncertainty regarding the optimal dosing regimen for the resumption of warfarin after interruption for invasive procedures.

AIM

To determine the efficacy and safety of warfarin resumption with loading doses or with the most recent maintenance dose.

METHODS

Patients receiving warfarin treatment and planned for invasive procedures with an expected hospital stay of ≤ 1 day were randomized to resume warfarin on the day of the procedure, defined as day 1, with most recent maintenance dose or with 2 initial days of double maintenance dose. Efficacy outcomes were proportion of international normalized ratio (INR) levels ≥ 2.0 on day 5 (primary outcome) and day 10. Safety outcomes were bleeding and thromboembolic events. In addition, D-dimer levels were analyzed on days 5 and 10 in a subset of the population.

RESULTS

There were 49 patients analyzed in each group. INR of ≥ 2.0 had been achieved by day 5 for 13% in the maintenance-dose group and for 50% in the loading-dose group (relative risk [RR] 0.27, 95% confidence interval [CI] 0.10-0.60) and by day 10 for 68% and 87%, respectively (RR 0.78, 95% CI 0.65-1.00). There were no thromboembolic events, and there was one major bleed before resumption of warfarin and one minor bleed, both in the maintenance-dose group. There was no difference between the groups in the proportion of patients with excessive INRs or elevated D-dimer levels or in the median D-dimer level.

CONCLUSION

Resumption of warfarin after minor-moderately invasive procedures with two loading doses achieves therapeutic INR faster than does only maintenance dose.

New oral anticoagulant-induced bleeding: clinical presentation and management

Bleeding is a significant complication of anticoagulant therapy. With the emergence of new oral anticoagulants (NOACs; ie, direct factor IIa or Xa inhibitors), this risk is further compounded by the lack of validated reversal strategies for these agents. Emerging postmarketing evidence suggests that the bleeding risks are in line with results observed in head-to-head clinical trials of NOACs versus traditional anticoagulants. Several guidelines have recommended the use of hemostatic agents for NOAC reversal in patients with life-threatening bleeding. Ultimately, adequately powered studies will be crucial for full assessment of the effectiveness and safety of any proposed reversal strategies.

New oral pharmacotherapeutic agents for venous thromboprophylaxis after total hip arthroplasty

Patients undergoing total hip arthroplasty (THA) are at high risk for developing venous thromboembolism and, therefore, require short term prophylaxis with antithrombotic agents. Recently, target specific oral anticoagulants (TSOA) including the direct thrombin inhibitor, dabigatran, and the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban have been approved for THA thrombopropylaxis in various countries. The TSOAs provide a rapid acting, oral alternative to parenteral agents including low-molecular weight heparins (LMWH) and fondaparinux; and compared to warfarin, they do not require routine laboratory monitoring and possess much fewer drug-drug interactions. Based on phase III clinical studies, TSOAs have established themselves as an effective and safe option for thromboprophylaxis after THA compared to LMWH, particularly enoxaparin, but require additional evaluation in specific populations such as the renally impaired or elderly. The ability to monitor and reverse these TSOAs in the case of bleeding complications or suspected sub- or supra-therapeutic anticoagulation is of importance, but remains investigational. This review will focus on the drug-specific characteristics, efficacy, safety, and economic impact of the TSOAs for thromboprophylaxis following THA, as well as the aspects of therapeutic monitoring and anticoagulation reversal in the event of bleeding complications or a need for urgent reversal.

Shorter or longer anticoagulation to prevent recurrent venous thromboembolism: systematic review and meta-analysis

INTRODUCTION

Venous thromboembolism (VTE) is a major disease associated with short-term and long-term morbidity and mortality. Patients with a VTE provoked by surgery or immobilisation are at low risk of recurrence and do not require long-term anticoagulation; those with a VTE and metastatic cancer are at high risk of recurrence and require lifetime thromboprophylaxis. In those at intermediate risk of recurrence, it remains controversial whether prolonging anticoagulation and thus incurring treatment burden and bleeding risk is warranted.

METHODS AND ANALYSIS

We will conduct a systematic review and meta-analysis of randomised controlled trials enrolling patients with VTE at intermediate risk of recurrence and evaluating short-term anticoagulation (12 weeks to 9 months initial therapy) versus longer term anticoagulation (at least 6 months additional anticoagulation beyond the course of treatment in the shorter arm). Anticoagulation could consist of vitamin K antagonists or new oral anticoagulants. Outcomes of interest include recurrent non-fatal thrombosis (deep venous thrombosis and pulmonary embolism), major non-fatal bleeding and mortality. We will systematically search CINAHL, EMBASE, MEDLINE and the Cochrane Central Registry of Controlled Trials. Teams of two reviewers will, independently and in duplicate, screen titles and abstracts and complete full text reviews to determine eligibility, and subsequently abstract data and assess risk of bias in eligible trials. We will conduct meta-analyses to establish the effect of short-term versus long-term anticoagulation on the outcomes of interest and evaluate confidence in estimates (quality of evidence) using the GRADE (grading of recommendations, assessment, development and evaluation) approach.

ETHICS AND DISSEMINATION

Our review will facilitate evidence-based management of patients with unprovoked or recurrent VTE. For purposes of privacy and confidentiality, the systematic review will be limited to studies with deidentified data. The study will be disseminated by peer-review publication and conference presentation.

TRIAL REGISTRATION NUMBER

PROSPERO (CRD42014007620).

The emerging era of pharmacogenomics: current successes, future potential, and challenges

The vast range of genetic diversity contributes to a wonderful array of human traits and characteristics. Unfortunately, a consequence of this genetic diversity is large variability in drug response between people, meaning that no single medication is safe and effective in everyone. The debilitating and sometimes deadly consequences of adverse drug reactions (ADRs) are a major and unmet problem of modern medicine. Pharmacogenomics can uncover associations between genetic variation and drug safety and has the potential to predict ADRs in individual patients. Here we review pharmacogenomic successes leading to changes in clinical practice, as well as clinical areas probably to be impacted by pharmacogenomics in the near future. We also discuss some of the challenges, and potential solutions, that remain for the implementation of pharmacogenomic testing into clinical practice for the significant improvement of drug safety.

Efficacy of the prothrombin complex concentrate prothromplex in patients requiring urgent reversal of vitamin K antagonists or presenting with uncontrolled bleeding: a retrospective, single center study

The objective of the present study was to investigate the efficacy of a four-factor prothrombin complex concentrate (Prothromplex, PTX) in shortening prolonged international normalized ratio or controlling life-threatening bleeding. The study was a retrospective single-centre study that included 142 patients treated with PTX and allocated in three groups: patients on vitamin K antagonists (VKA) (acenocumarol) and undergoing invasive procedure or presenting with severe bleeding (n = 76), patients treated with VKA presenting with intracranial haemorrhage (n = 22), and patients not on VKA and presenting with uncontrolled bleeding (n = 44). The primary outcome variable was international normalized ratio (INR) return to the norm after PTX infusion. Secondary outcome variables included bleeding control and reduction of transfusion rate. Overall, patients received a median of 1200 IU (≈15 IU/kg) of PTX, and INR decreased from 4 ± 3 to 1.7 ± 1.2 (P < 0.01) in all groups, although it remained at least 1.4 in 38% of patients (29.3% among patients receiving 25 IU/kg vs. 42.6% among those receiving 15 IU/kg; P < 0.05). Patients with initial INR at least 4 benefited the most from treatment. After PTX administration, there was a significant reduction in both transfused blood components units (P < 0.01) and estimated blood loss volume (from 1500 ± 1500 to 200 ± 100 ml; P < 0.01), and only one episode of deep venous thrombosis was observed. Administration of fixed doses of PTX shortened prolonged international normalized ratio and improved life-threatening bleeding in patients with or without VKA therapy. Higher dose attained a more adequate post-infusion INR.

Management of bleeding and reversal strategies for oral anticoagulants: clinical practice considerations

PURPOSE

Currently available clinical data and optimal strategies for reversing oral anticoagulants in patients who are bleeding or need an urgent invasive procedure or operation are reviewed.

SUMMARY

Bleeding from oral anticoagulants, including new target-specific oral agents (TSOAs), is a common cause of morbidity and mortality, especially in elderly patients. Limited clinical data are available to guide the reversal of warfarin or TSOAs in patients who are bleeding or need an urgent invasive procedure or operation. A panel of five experts with diverse backgrounds in anticoagulation therapy, cardiology, critical care, and emergency medicine and with experience in managing complications of anticoagulation therapy was convened to develop practical strategies for managing patients receiving oral anticoagulants who are bleeding or have an urgent need for an invasive procedure. The strategies were designed to guide clinicians in the acute care setting by providing efficient and potentially effective management concepts to avoid delays in initiating treatment that could adversely affect patient outcomes. The consensus of this expert panel is summarized herein. Recommendations are based on currently available evidence from a comprehensive review of the literature and other pertinent data, along with the experience and expert opinion of the panelists.

CONCLUSION

Bleeding is a serious complication of the use of oral anticoagulants, and limited information is available to guide the reversal of warfarin or TSOAs in patients who are bleeding or are in need of an urgent invasive procedure. Use of a systematic approach to assessing and treating these patients based on available evidence and expert opinion can help avoid delays that could adversely affect patient outcomes.

The clinical impact of different coagulometers on patient outcomes

Introduction

Long-term anticoagulation therapy using vitamin K antagonists (VKA) is used in millions of patients worldwide to reduce the risk of thrombotic or thromboembolic events. Control and monitoring of VKA therapy is improved by the regular self-measurement of international normalized ratio (INR) using a home monitoring device. This retrospective analysis of a large cohort of patients in the Netherlands seeks to determine whether the choice of INR monitor could have a clinical impact on patient outcomes.

Methods

The National Thrombosis Service provides medical supervision, training and support to anticoagulant patients eligible for home-monitoring of INR in the Netherlands. Two INR monitors (CoaguChek XS and INRatio2) have been distributed at random to patients since June 2011, and patient self-testing data (INR measurements and other clinical parameters) have been recorded to measure and improve treatment outcomes. The data have been retrospectively analyzed to determine any effect of the choice of monitor. Univariate and multivariate statistical tests are used to assess any differences between groups in terms of efficacy and safety parameters.

Results

Data from 4,326 patients were collated, and 156,507 INR values were included in the analysis. Over half the patients (54.3%) were being treated for atrial fibrillation, and 77.6% were prescribed acenocoumarol. There were few differences between the patient populations using the two different monitors. Anticoagulant control overall was good, with high percentage of time (87.9%) in the appropriate INR range and low incidence of excessively high or low INR values (0.085/month). Minor clinical events related to safety were low (0.78 per patient-year) and showed few differences between monitors. Mortality rates were similar [hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.65–1.70].

Conclusion

Self-testing data from a large cohort of patients in the Netherlands suggest that there is no clinically relevant effect of the choice of coagulation monitor (CoaguChek XS or INRatio2) on the time in therapeutic range (TTR), minor or fatal outcomes of long-term anticoagulation management.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0124-x) contains supplementary material, which is available to authorized users.

New oral anticoagulants in practice: pharmacological and practical considerations

Although highly effective, warfarin use is complicated by its unpredictable narrow therapeutic window, genetic heterogeneity in pharmacokinetic response, numerous food and drug interactions, and the need for regular international normalized ratio (INR) monitoring. Currently, several novel oral anticoagulant (NOAC) drugs (dabigatran, rivaroxaban, apixaban) are available on the market as alternatives to warfarin. These agents all feature more predictable pharmacodynamic and pharmacokinetic properties than warfarin. Additionally, the NOACs do not require routine monitoring of coagulation parameters, and have a relatively lower potential for interactions with drug, herb, and dietary constituents, which enhances the convenience of management for both patients and health professionals alike. However, there are other considerations regarding the use of NOACs that must be taken into account during management of therapy. In contrast to warfarin, most NOACs need dosage adjustments in renal impairment and are contraindicated in severe liver impairment, and there are no specific antidotes for treating NOAC-related over-anticoagulation. The more frequent dosing needed for NOACs may reduce adherence, especially in elderly patients with polypharmacy. Furthermore, NOACs, especially dabigatran, are not as well tolerated as warfarin in patients with gastrointestinal diseases. Overall, the availability of the NOACs has expanded the treatment armamentarium, but they are not without risk. Given the limited experience with the NOACs, their limited range of indications, and their cost, the characteristics of each anticoagulant must be carefully considered to carefully select the agent that will provide the optimal risk/benefit profile in the individual patient.