Guidance for the practical management of the heparin anticoagulants in the treatment of venous thromboembolism.

Venous thromboembolism (VTE) is a serious and often fatal medical condition with an increasing incidence. Despite the changing landscape of VTE treatment with the introduction of the new direct oral anticoagulants many uncertainties remain regarding the optimal use of traditional parenteral agents. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance based on existing guidelines and consensus expert opinion where guidelines are lacking. This specific chapter addresses the practical management of heparins including low molecular weight heparins and fondaparinux. For each anticoagulant a list of the most common practice related questions were created. Each question was addressed using a brief focused literature review followed by a multidisciplinary consensus guidance recommendation. Issues addressed included initial anticoagulant dosing recommendations, recommended baseline laboratory monitoring, managing dose adjustments, evidence to support a relationship between laboratory tests and meaningful clinical outcomes, special patient populations including extremes of weight and renal impairment, duration of necessary parenteral therapy during the transition to oral therapy, candidates for outpatient treatment where appropriate and management of over-anticoagulation and adverse effects including bleeding and heparin induced thrombocytopenia. This article concludes with a concise table of clinical management questions and guidance recommendations to provide a quick reference for the practical management of heparin, low molecular weight heparin and fondaparinux.

Integrating electronic health records in the delivery of optimized anticoagulation therapy.

Integration of accepted practice standards into electronic health record systems can facilitate standardization of anticoagulation care delivery and result in improved anticoagulation safety. However, the majority of commonly used electronic health record systems are lacking the specialized features necessary for optimal anticoagulation management. The Task Force on Electronic Health Records of the New York State Anticoagulation Coalition provides such a Consensus Statement in this issue of the journal. The Anticoagulation Forum endorses these recommendations and advises the electronic health record industry and health information technology programmers at the institutional level to adopt these recommendations in a comprehensive and timely manner.

Delivery of optimized inpatient anticoagulation therapy: consensus statement from the anticoagulation forum.

OBJECTIVE: To provide recommendations for optimized anticoagulant therapy in the inpatient setting and outline broad elements that need to be in place for effective management of anticoagulant therapy in hospitalized patients; the guidelines are designed to promote optimization of patient clinical outcomes while minimizing the risks for potential anticoagulation-related errors and adverse events. DATA SOURCES: The medical literature was reviewed using MEDLINE (1946-January 2013), EMBASE (1980-January 2013), and PubMed (1947-January 2013) for topics and key words including, but not limited to, standards of practice, national guidelines, patient safety initiatives, and regulatory requirements pertaining to anticoagulant use in the inpatient setting. Non-English-language publications were excluded. Specific MeSH terms used include algorithms, anticoagulants/administration and dosage/adverse effects/therapeutic use, clinical protocols/standards, decision support systems, drug monitoring/methods, humans, inpatients, efficiency/ organizational, outcome and process assessment (health care), patient care team/organization and administration, program development/standards, quality improvement/organization and administration, thrombosis/ drug therapy, thrombosis/prevention and control, risk assessment/standards, patient safety/standards, and risk management/methods. STUDY SELECTION AND DATA EXTRACTION: Because of this document's scope, the medical literature was searched using a variety of strategies. When possible, recommendations are supported by available evidence; however, because this paper deals with processes and systems of care, high-quality evidence (eg, controlled trials) is unavailable. In these cases, recommendations represent the consensus opinion of all authors and are endorsed by the Board of Directors of the Anticoagulation Forum, an organization dedicated to optimizing anticoagulation care. The board is composed of physicians, pharmacists, and nurses with demonstrated expertise and experience in the management of patients receiving anticoagulation therapy. DATA SYNTHESIS: Recommendations for delivering optimized inpatient anticoagulation therapy were developed collaboratively by the authors and are summarized in 8 key areas: (1) process, (2) accountability, (3) integration, (4) standards of practice, (5) provider education and competency, (6) patient education, (7) care transitions, and (8) outcomes. Recommendations are intended to inform the development of coordinated care systems containing elements with demonstrated benefit in improvement of anticoagulation therapy outcomes. Recommendations for delivering optimized inpatient anticoagulation therapy are intended to apply to all clinicians involved in the care of hospitalized patients receiving anticoagulation therapy. CONCLUSIONS: Anticoagulants are high-risk medications associated with a significant rate of medication errors among hospitalized patients. Several national organizations have introduced initiatives to reduce the likelihood of patient harm associated with the use of anticoagulants. Health care organizations are under increasing pressure to develop systems to ensure the safe and effective use of anticoagulants in the inpatient setting. This document provides consensus guidelines for anticoagulant therapy in the inpatient setting and serves as a companion document to prior guidelines relevant for outpatients.

Impact of target-specific oral anticoagulants on transitions of care and outpatient care models.

Patients with acute or chronic illness experience transitions of care when they leave one healthcare setting and move to another. Care transitions are points of increased patient risk. Numerous care transition models have been developed that focus on improving the hospital discharge process to prevent adverse events after hospital discharge and to reduce readmission rates. Anticoagulants are a common cause of adverse drug events in hospitals, and of adverse events that lead to patient harm and hospital readmission. Anticoagulation management services improve the outcomes of anticoagulant therapy in both hospitalized and ambulatory patients. The services they provide, including improved communication, medication management, and patient education, are also central tenets of care transition models. These services have traditionally been focused around warfarin and heparin. Recently, new target specific oral anticoagulants have been approved in the US for various indications that traditionally have been treated with warfarin. These new agents are administered in fixed doses without the need for routine laboratory monitoring or frequent dosing adjustments. Yet as high risk drugs, they will require systematic efforts to assure their safety and minimize potential adverse events. These concerns are of particular importance during transitions of care. Anticoagulation management services, must be prepared to establish practices that improve patient outcomes regardless of the anticoagulant prescribed, using the established principals of care transition models.

New oral anticoagulants: a practical guide for clinicians.

The search for an oral anticoagulant with acceptable efficacy and safety in the treatment and prevention of venous and arterial thromboembolism, but with practical advantages over warfarin, has been a focus of drug development for many years. Three oral agents, dabigatran, rivaroxaban, and apixaban, are nearing approval in the US. Their use in practice will be guided by the clinical trials available, as well as their pharmacokinetic and pharmacodynamic properties. Practitioners need to be fully aware of these characteristics in order to use these agents appropriately in clinical practice. This review compares the results of the phase 3 trials investigating these agents in the prevention of venous thromboembolism in patients undergoing orthopedic surgery, examines the reporting of bleeding complications in the trials, and highlights various practical considerations regarding their use in clinical practice.

Pharmacogenomic trial design: use of a PK/PD model to explore warfarin dosing interventions through clinical trial simulation.

OBJECTIVE: Variants of two genes, CYP2C9 and VKORC1, explain approximately one third of variability in warfarin maintenance dose requirements. However, the clinical utility of using this information in addition to clinical and demographic data ('pharmacogenomic-guidance') is unclear, as few comparative clinical trials have been conducted to date. The objective of this study was to explore the incremental effect of pharmacogenomic-guided warfarin dosing under various conditions using clinical trial simulation. METHODS: We used an existing pharmacokinetic/pharmacodynamic model to perform clinical trial simulations of pharmacogenomic-guided versus standard of care warfarin therapy. The primary outcome was the percentage of patient time spent in therapeutic range over the first month of therapy. We assessed the influence of the frequency of INR monitoring, and the use of a loading dose and dose increase delay in patients with CYP2C9 variants. RESULTS: Pharmacogenomic guidance resulted in a 3-4 percentage point absolute increase in time spent in therapeutic range over the first month of therapy compared with standard of care. The improvement in time in range was greater when the frequency of INR monitoring in both arms was assumed to be lower. The absolute difference increased to 6-8 percentage points with the use of a loading dose and dose increase delay in patients with a CYP2C9 variant. CONCLUSION: Our initial results imply that pharmacogenomic-guided warfarin dosing may be more useful in settings with less intensive patient follow-up, and when adjustments are made for slower therapeutic response in patients with a CYP2C9 variant. Further pharmacokinetic/pharmacodynamic model development may be useful for warfarin pharmacogenomic trial design.

Adherence to guidelines for the management of excessive warfarin anticoagulation.

OBJECTIVES: The American College of Chest Physicians (ACCP) provides guidelines for the management of excessive anticoagulation in patients receiving warfarin. This multi-site prospective cohort study evaluated patient-level practice patterns and adherence to ACCP guidelines. METHODS: Patients presenting with an INR > or = 4.5 between January 3 and April 29, 2005 were observed and therapeutic management documented. Adherence was assessed retrospectively. RESULTS: Four hundred and seventeen patients from 22 centers were observed. The mean, initial INR was 7.7. At enrollment, 85% of the patients had an INR < 9 or were not bleeding; 15% were seriously bleeding. Treatment for 170 patients (41%) did not adhere to guidelines. Among those, 15% were undertreated, 48% overtreated. Lack of adherence was attributed primarily to excessive doses (mean initial dose = 6.9 mg) and inappropriate routes of administration (subcutaneous or intramuscular) of vitamin K1. CONCLUSION: Adherence to the ACCP guidelines is low. Inappropriate use of vitamin K1 is the primary reason.

An analysis of the relative effects of VKORC1 and CYP2C9 variants on anticoagulation related outcomes in warfarin-treated patients.

The objective of this study was to assess the relative influence of VKORC1 and CYP2C9 genetic variants on several clinical outcomes related to warfarin treatment. We conducted a retrospective cohort analysis of 172 anticoagulation clinic patients followed from warfarin initiation. We assessed the following clinical outcomes: time to stable dose; time in, above, and below therapeutic range; the probability of overanticoagulation (international normalized ratio [INR] >5); frequency of anticoagulation clinic visits; and the contribution of genetics to maintenance dose. Patients with CYP2C9 variants, compared to those without, achieved stable dose 48% later (p < 0.01), spent a higher proportion of time above range in the first month of therapy (14% vs. 25%, p = 0.07), and had a higher odds ratio (OR) of an INR >5 (OR: 4.15, p = 0.03). In contrast, the only statistically significant effect with VKORC1 was a higher odds of an INR >5 (OR: 4.47, p = 0.03) for patients homozygous for the VKORC1 low-dose haplotype (AA) compared to heterozygotes. We did not detect an influence of CYP2C9 nor VKORC1 on the frequency of clinic visits. CYP2C9 alone, VKORC1 alone, and a combination of genetic and clinical factors explained 12%, 27%, and 50%, respectively, of the variation in warfarin maintenance dose. In conclusion, genetic variation in VKORC1 appears to have a different influence than CYP2C9 on anticoagulation-related outcomes such as bleeding events and time in therapeutic range. This difference may be due, in part, to pharmacokinetics factors (e.g. drug half-life), which are influenced primarily by CYP2C9; these findings should be confirmed in additional studies.

Discrepancies in identification of major bleeding events in patients taking warfarin.

STUDY OBJECTIVE: To assess the level of agreement between one subjective definition of major bleeding (criteria A) and two objective definitions: the International Society on Thrombosis and Haemostasis ([ISTH] criteria B) and the Italian Study of Complications of Anticoagulant Therapy ([ISCOAT] criteria C). DESIGN: Retrospective cohort study. SETTING: Four anticoagulation clinics at a university-affiliated medical center. PATIENTS: One hundred twenty patients aged 21-96 years who were taking long-term warfarin therapy and experienced a nonminor bleeding event between July 1, 2001, and June 30, 2006. MEASUREMENTS AND MAIN RESULTS: Bleeding events were evaluated using three definitions of major bleeding: criteria A-event was fatal or required hospitalization; criteria B-event was fatal, was symptomatic in a critical area or organ, caused a decrease in hemoglobin level of 2 g/dl or more, and/or led to transfusion of 2 or more units of whole blood or red blood cells; and criteria C-event met criteria B definition (but less inclusively identifies critical areas or organs) and/or necessitated surgical or angiographic intervention. One hundred thirty-eight bleeding events in the 120 patients met at least one of the definitions of major bleeding and thus were included in the analysis. Level of agreement among the definitions was determined by the kappa statistic. The level of agreement between criteria B and C was excellent; no discrepancies were found; however, the level of agreement between criteria A and criteria B or C was poor, with a kappa statistic value of -0.134 (95% confidence interval -0.196 to -0.071). Use of criteria A resulted in underreporting of 31 major bleeding events by excluding events that were managed on an outpatient basis. CONCLUSION: The discrepant event rates determined by using three different definitions of major bleeding underscore the need for implementation of a standardized objective definition. Use of a standardized definition in clinical trials to accurately predict and compare patient outcomes and in clinical practice as a marker for patient safety will increase quality of care and decrease total costs of care in patients treated with warfarin. We suggest implementation of the ISTH criteria in clinical practice as a method to standardize the reporting of major bleeding events.

Delivery of optimized anticoagulant therapy: consensus statement from the Anticoagulation Forum.

OBJECTIVE: To provide recommendations, policies, and procedures pertaining to the provision of optimized anticoagulation therapy designed to achieve desired clinical endpoints while minimizing the risk of anticoagulant-related adverse outcomes (principally bleeding and thrombosis). STUDY SELECTION AND DATA EXTRACTION: Due to this document's scope, the medical literature was searched using a variety of strategies. When possible, recommendations are supported by available evidence; however, because this paper deals with processes and systems of care, high-quality evidence (eg, controlled trials) is unavailable. In these cases, recommendations represent the consensus opinion of all authors who constitute the Board of Directors of The Anticoagulation Forum, an organization dedicated to optimizing anticoagulation care. The Board is composed of physicians, pharmacists, and nurses with demonstrated expertise and significant collective experience in the management of patients receiving anticoagulation therapy. DATA SYNTHESIS: Recommendations for delivering optimized anticoagulation therapy were developed collaboratively by the authors and are summarized in 9 key areas: (I) Qualifications of Personnel, (II) Supervision, (III) Care Management and Coordination, (IV) Documentation, (V) Patient Education, (VI) Patient Selection and Assessment, (VII) Laboratory Monitoring, (VIII) Initiation and Stabilization of Warfarin Therapy, and (IX) Maintenance of Therapy. Recommendations are intended to inform the development of care systems containing elements with demonstrated benefit in improvement of anticoagulation therapy outcomes. Recommendations for delivering optimized anticoagulation therapy are intended to apply to all clinicians involved in the care of outpatients receiving anticoagulation therapy, regardless of the structure and setting in which that care is delivered. CONCLUSIONS: Anticoagulation therapy, although potentially life-saving, has inherent risks. Whether a patient is managed in a solo practice or a specialized anticoagulation management service, a systematic approach to the key elements outlined herein will reduce the likelihood of adverse events. The need for continued research to validate optimal practices for managing anticoagulation therapy is acknowledged.

Discrepancies in identification of bleeding events after percutaneous coronary intervention.

STUDY OBJECTIVE: To evaluate the level of agreement between two sets of criteria, the Thrombolysis in Myocardial Infarction (TIMI) criteria and investigator-developed criteria, for identifying bleeding events in patients who had undergone a percutaneous coronary intervention (PCI) and to measure length of hospital stay (LOS) as a surrogate marker of bleeding severity. DESIGN: Retrospective chart review. SETTING: Two university-affiliated medical centers. PATIENTS: Four hundred twenty-two consecutive patients who had undergone PCI from December 1, 2001-June 30, 2002. MEASUREMENTS AND MAIN RESULTS: Data were collected on the number of bleeding events that occurred within 1 week after PCI (limited to one event/patient) and on LOS. Bleeding was assessed by TIMI criteria and by investigator-developed criteria. Bleeding according to TIMI criteria included intracranial hemorrhage, spontaneous hematuria or hematemesis, or decreases in hemoglobin level. Bleeding according to investigator-developed criteria included intracranial, retroperitoneal, intraocular, or clinically overt bleeding without a specified decrease in hemoglobin level. Agreement between criteria was assessed by means of the kappa statistic. Of the 422 patients, 23 (5%) experienced TIMI-defined bleeding events and 229 (54%) investigator-defined bleeding events. A kappa value of 0.09 (95% confidence interval 0.06-0.13) indicated a poor level of agreement between the two sets of bleeding criteria. The effect of this discrepancy on LOS was 66 fewer days of care when TIMI criteria were applied versus investigator-developed criteria in the 206 patients who experienced bleeding events that met investigator criteria (total LOS 645 days) but not TIMI criteria (total LOS 579 days). CONCLUSION: Bleeding assessment with use of TIMI criteria versus investigator-developed criteria yielded discrepant bleeding event rates and LOS, making it difficult to accurately compare bleeding rates and consequences across clinical trials and in practice. Consensus bleeding criteria are needed for applications in clinical evaluations of antithrombotic agents.

Warfarin-related outcomes in patients with antiphospholipid antibody syndrome managed in an anticoagulation clinic.

Patients with antiphospholipid antibody syndrome (APA) are at elevated risk of venous and arterial thromboembolic complications. Oral anticoagulation with warfarin is recommended for secondary prevention of thromboembolism, but warfarin-related outcomes have not been systematically investigated when warfarin therapy is managed by a dedicated anticoagulation clinic. The objectives of the study were to evaluate warfarin-related monitoring outcomes, clinical endpoints and the use of healthcare resources as a result of warfarin-related complications in patients with APA compared to a group of patients without APA, all of whom were managed in an anticoagulation clinic setting. A retrospective observational cohort design was used to investigate patients with and without APA, all of whom had a history of venous or arterial thromboembolism, and were matched for age, gender and indication for oral anticoagulation. Thirty-six APA patients taking warfarin were compared to a matched cohort of 36 patients without APA. Monitoring outcomes (time in therapeutic range, clinic visits per year, frequency of warfarin dosing adjustments, reasons for out-of-range INRs) were similar between groups, as was the frequency of major bleeding complications (3.2%/pt-yr vs. 3.1%/pt-yr). However, recurrent thromboembolic events (9.6%/pt-yr vs 0) occurred more frequently in APA patients. APA patients required more emergency room visits (6.4%/pt-yr vs. 1.6%/pt-yr) and hospital admissions (14.4%/pt-yr vs.3.0%/pt-yr) to manage complications of warfarin therapy. In conclusion, despite similar monitoring outcomes obtained in a dedicated anticoagulation clinic setting, adverse clinical outcomes are significantly more frequent in patients with APA syndrome than in those without APA, and require more frequent use of healthcare resources.

Outcomes of oral anticoagulant therapy managed by telephone vs in-office visits in an anticoagulation clinic setting.

BACKGROUND: Anticoagulation management by a dedicated anticoagulation clinic improves patient outcomes compared to routine medical care. Telephone-based anticoagulation management has been described but has not been compared to management with traditional office-based visits. The objective of this study was to compare warfarin-related monitoring outcomes, clinical end points, and the use of health-care resources as a result of warfarin-related complications in anticoagulation clinic patients whose management was conducted by telephone or in-office-based visits. SETTING: Two university-affiliated anticoagulation clinics in Seattle, WA, and Chicago, IL. METHODS: A retrospective, observational cohort design was used to investigate anticoagulation clinic patients who were managed by telephone encounters compared to those managed during face-to-face in-office encounters. RESULTS: A total of 234 patients were evaluated; 117 patients managed by telephone were compared to 117 patients managed in office-based clinic visits. Monitoring outcomes (ie, time in therapeutic range and clinic visits per patient-year) were similar between groups. Differences in major bleeding (5.67% vs 5.62% per patient-year, respectively) and thromboembolic events (1.42% vs 2.81% per patient-year, respectively) between telephone-managed and face-to-face-managed patients did not reach statistical significance. The same was true for differences in the frequency of emergency department visits and hospital admissions to manage complications of warfarin therapy. CONCLUSIONS: Telephone-based management of oral anticoagulation through a pharmacist-staffed anticoagulation clinic yielded clinical outcomes that were at least as favorable as those associated with traditional office-based visits. Telephone follow-up can be successfully used to manage warfarin therapy in patients who are unable to present in person to an anticoagulation clinic.

Choosing the appropriate antithrombotic agent for the prevention and treatment of VTE: a case-based approach.

OBJECTIVE: To review the risk of venous thromboembolism (VTE) in various patient populations and evaluate the agents available for the prevention and treatment of VTE using a case-based approach. DATA SOURCES: A MEDLINE search (1995-July 2006) was conducted to identify relevant literature. Additional references were reviewed from selected articles. STUDY SELECTION AND DATA EXTRACTION: Articles related to the prevention of VTE in orthopedic surgery, general surgery, and medically ill patients, as well as the treatment of VTE, were reviewed. DATA SYNTHESIS: Pharmacologic options for the prevention and treatment of VTE include warfarin, unfractionated heparin (UFH), low-molecular-weight heparins (LMWH), and fondaparinux. Current guidelines support the use of warfarin, LMWH, or fondaparinux for VTE prophylaxis following lower limb major orthopedic surgery. For VTE prophylaxis in hospitalized medical patients or patients undergoing general surgery, use of UFH and LMWH is supported; however, recent data on fondaparinux suggest that it is also effective in these patient populations. The use of UFH or LMWH (both in conjunction with warfarin) for treatment of acute deep venous thrombosis or nonmassive pulmonary embolism is recommended. Recent data suggest that fondaparinux (in conjunction with warfarin) is also effective for the treatment of VTE. A variety of pharmacokinetic, pharmacodynamic, and pharmacoeconomic factors differentiate each agent for the various indications. CONCLUSIONS: Currently, a "one-size-fits-all" anticoagulant is not available for treatment of VTE. A variety of patient factors, including type of surgery, medical indication, thrombotic risk factors, bleeding risk, history of heparin-induced thrombocytopenia, and a variety of comorbid conditions can affect the safety, efficacy, and selection of appropriate VTE therapy.

Antithrombotic therapy practices in US hospitals in an era of practice guidelines.

BACKGROUND: Antithrombotic therapy is efficacious for the prevention of thromboembolic disease, but it necessitates careful risk-benefit assessment. METHODS: Antithrombotic therapy data were retrospectively collected from inpatient medical records at 38 US hospitals. Patients treated for atrial fibrillation, acute myocardial infarction, deep vein thrombosis, or pulmonary embolism and patients given prophylaxis for total knee replacement, total hip replacement, or hip fracture surgery between July 1, 2000, and June 30, 2003, were randomly selected. RESULTS: The medical records of 3778 patients (53.3% men) were included. The mean patient age was 66.1 years. Of patients with atrial fibrillation at high risk for stroke, only 54.7% received warfarin sodium, and 20.6% received neither aspirin nor warfarin. Of patients with acute myocardial infarction, only 75.5% received aspirin on hospital arrival. After orthopedic surgery procedures, only 85.6% of patients received prophylaxis with a parenteral anticoagulant agent or warfarin. In 49.4% of patients with deep vein thrombosis, pulmonary embolism, or both, unfractionated or low-molecular-weight heparin use was discontinued before an international normalized ratio of 2.0 or greater was achieved for 2 consecutive days. Patients with deep vein thrombosis or pulmonary embolism were rarely discharged from the hospital with bridge therapy (an injectable anticoagulant agent plus warfarin), although the length of hospitalization was significantly shorter than if discharged taking warfarin alone (4.0 vs 8.1 days; P < .001). CONCLUSIONS: A significant percentage of hospitalized patients do not receive adequate antithrombotic therapy for the primary and secondary prevention of thromboembolic disease.

Managing transitions from oral factor Xa inhibitors to unfractionated heparin infusions.

PURPOSE: Published evidence regarding the effects of oral factor Xa inhibitors on anticoagulation monitoring tests is reviewed with a focus on monitoring concerns that can arise during transitions to i.v. heparin therapy. SUMMARY: Assays that measure inhibition of factor Xa activity (i.e., anti-Xa assays) are widely used in U.S. institutions to monitor i.v. heparin therapy and, in some cases, for monitoring other types of anticoagulation therapy. Clinicians have raised concerns that the use of anti-Xa assays to monitor heparin levels in hospitalized patients who must be transitioned from oral factor Xa inhibitor therapy to i.v. unfractionated heparin (UFH) infusions could yield unquantifiable or inaccurate results, leading to unnecessary UFH dose reductions and potential treatment failures; the manufacturer labeling of oral factor Xa inhibitors (apixaban, edoxaban, and rivaroxaban) does not provide specific guidance on this issue. Results of a literature review indicated that residual effects of oral factor Xa inhibitor use can result in substantial interference with the currently available chromogenic anti-Xa assays but negligible to moderate effects on global coagulation assays, which measure activated partial thromboplastin time (aPTT) or prothrombin time. Therefore, during the transition from an oral factor Xa inhibitor to i.v. UFH therapy, it may be prudent to consider an aPTT assay for anticoagulation monitoring. CONCLUSION: The use of oral factor Xa inhibitors appears to affect the accuracy of anti-Xa assay results, with results of global coagulation assays affected to a lesser degree.

Barriers to patient self-testing of prothrombin time: national survey of anticoagulation practitioners.

Oral anticoagulation with warfarin requires routine monitoring of prothrombin time, expressed as the international normalized ratio (INR). Patient self-testing for INR is common in Europe but not in the United States. In order to determine the frequency of INR self-testing among patients whose anticoagulant therapy is managed in U.S. anticoagulation clinics, to describe the processes that support this self-testing, and to identify the barriers as experienced by anticoagulation clinic providers, a three-part survey was mailed to 538 anticoagulation specialists in the United States. The response rate was 43.7%. Policies and procedures of almost 60% of anticoagulation clinics prohibited INR self-testing for enrolled patients. In addition, less than 1% of patients being managed by U.S. anticoagulation clinics use self-testing to obtain INR results. Primary barriers were the cost of self-testing instruments (78.7% of respondents), cost of reagent cartridges (60.4%), and fear that self-testing might lead to unintended self-management (35.7%). Over 75% of respondents believed that some reimbursement for the cost of self-testing devices and supplies would increase the likelihood that anticoagulation clinics would recommend INR self-testing.

Thromboembolic complications of malignancy. Part 1: Risks.

Thromboembolism affects many patients with solid tumors and clonal hematologic malignancies. Pathogenetic mechanisms include inflammatory- and tissue factor-mediated coagulation, natural anticoagulant deficiencies, fibrinolytic alterations, hyperviscosity, and activation of platelets, endothelial cells, and leukocytes. High rates of venous thromboembolism (VTE) occur with advanced pancreatic, breast, ovarian, germ cell, lung, prostate, and central nervous system cancers. Hodgkin disease, non-Hodgkin's lymphoma, myeloma, paroxysmal nocturnal hemoglobinuria, and certain leukemias also predispose to venous thromboembolism. Arterial and venous events occur with polycythemia vera and essential thrombocythemia. Central venous catheters and prothrombotic antitumor regimens augment the risk in some patients. Part 1 of this two-part article addresses pathophysiology, clinical presentations, and risk of malignancy-associated thrombosis. Part 2, which will appear in next month's issue, covers prophylaxis and treatment of these thromboembolic complications.

Thromboembolic complications of malignancy. Part 2: management.

Thromboembolism affects many patients with solid tumors and clonal hematologic malignancies. Thromboprophylaxis with low-molecular-weight heparin (LMWH) is indicated for surgery and other high-risk situations, but not routinely for central venous catheters or nonsurgical, ambulatory management. Thrombotic events require full anticoagulation for the duration of active disease and/or the prothrombotic stimulus. LMWHs are safe and more effective than both unfractionated heparin for initial therapy and warfarin for secondary prevention. Anti-inflammatory and antiangiogenic properties might account for this advantage and for a survival benefit of chronic LMWH in subgroups of cancer patients. Ongoing studies are characterizing the cost-effectiveness and antitumor mechanisms of LMWHs, the potential utility of newer anticoagulants, and the ability of predictive models to identify high-risk candidates for thromboprophylaxis.