Anticoagulation Service Research Articles

4 years’ experience with a pharmacy warfarin dosing service for orthopedic rehabilitation inpatients

Rationale Complex, surgical patients are routinely referred to rehabilitation hospitals for subacute and transition care. Before 2003, there was no anticoagulation service at Providence Healthcare (PH). Objectives The goals of the pharmacy warfarin service were: (1) to optimize anticoagulation management; and (2) to improve patient outcomes. Design The key ingredients were a strong interdisciplinary team; certified anticoagulation pharmacists; an evidence-based medicine approach to anticoagulation management; and continuous quality improvement. Retrospective evaluations were completed 2003–2006, comparing two control groups to the anticoagulation service patients. Results The 2003/2004 (5month) pilot project started on an orthopedic rehabilitation unit. The control groups showed less favourable patient outcomes. Without warfarin nomograms, protocols or anticoagulation training, there was delayed time to therapeutic INR (3.03 days); less therapeutic INR results (50.9%); more subtherapeutic INRs (33.2%) and supratherapeutic INRs (14.9%); increased morbidity and mortality (e.g. 1 fatal PE, 2 major bleeds, 5 doses of vitamin K). The results showed that the warfarin dosing service was safer and more effective. Advantages included faster time to therapeutic INR (2.84 days); more INR results (67.9%) within the therapeutic range; less subtherapeutic INR results (22.7%) and supratherapeutic INR (9.4%); no vitamin K or FFP; no new diagnoses of DVT, PE or CVA; and no deaths. Two more 12-month evaluations were completed, also showing favourable results (for 2004/2005 and 2006). Upon demand, the anticoagulation service expanded into stroke and transitional rehabilitation units in 2006. Conclusion This cost-effective anticoagulation service is supported by a strong interdisciplinary team and 4 years of data analysis.

Survey of pharmacist-managed inpatient anticoagulation services

The scope of existing pharmacist-managed inpatient anticoagulation services and the roles and responsibilities of the pharmacists involved were studied. A general query regarding the provision of inpatient anticoagulation services was sent by e-mail to members of the American College of Clinical Pharmacists practice and research networks for cardiology, critical care, and general internal medicine. Those individuals whose institutions had such services were sent a written questionnaire and asked to describe the scope of the services provided. Data collected included a description of the type of service model and the management strategies for seven different antithrombotic agents: warfarin, unfractionated heparin, low-molecular-weight heparin, fondaparinux, argatroban, lepirudin, and bivalirudin. Survey results were entered into a database and sent to all participants for use as a resource. Of the 33 respondents to the initial e-mail, 25 completed the written questionnaire. A variety of service models were used, most of which were developed and implemented within the past seven years. The majority of services (92%) were consultation based, many of which incorporated daily pharmacist rounds. Less than half of the services were under the supervision of a physician, and only four services involved a multidisciplinary team. In addition, the management of individual antithrombotic agents varied between services, including the automatic management of all patients receiving targeted agents, strict institution-specific protocols, and general guidelines. All but one service provided educational opportunities for students and residents. Inpatient anticoagulation services described by survey respondents varied in design, structure, and level of responsibility of pharmacists.

Establishing an inpatient anticoagulation service: a step by step review

Inpatient anticoagulation services can reduce medication errors, reduce hospital costs, and improve patient care. However, before a hospital establishes an inpatient anticoagulation service, it is important to conduct a thoughtful, systematic review of the institution. Two factors that can determine the need for an inpatient anticoagulation service are the number of adverse drug events and the extent of medical-legal liability at the institution. Establishing an inpatient service that reduces these problems can justify the cost of the program. In addition to these factors, the institution's infrastructure and the scope of services to be provided should be evaluated, and parameters should be created to measure the clinical and financial impact of the inpatient anticoagulation service. Numerous publications in the literature have supported the need and positive impact of inpatient anticoagulation services on hospital costs and patient care. The size and scope of the service should be based upon the needs, experiences and resources of a specific institution.

Implementing anticoagulation management by pharmacists in the inpatient setting

This article identifies approaches for implementing an inpatient anticoagulation program involving pharmacists; two successful inpatient anticoagulation programs previously reported in the literature are described with a discussion of steps to consider in developing or expanding such a service. Two institutions implemented pharmacist-managed anticoagulation services. One institution identified an undesirable incidence of medication-related adverse events occurring in hospitalized patients receiving anticoagulants. Pharmacists were asked to assist. Pharmacist activities included the selection of anticoagulants, patient education, verification of insurance coverage of the patient's anticoagulant, and coordination of follow-up. Physicians were available to assist. At the other institution, the department of pharmacy was asked by the orthopedic surgeons to manage warfarin for the prophylaxis against venous thromboembolism. The pharmacy department worked with the medical staff to gain approval of all policies, guidelines, and protocols to establish an anticoagulation service. Because of the success of the program, the pharmacy department expanded the service beyond warfarin. The steps to establishment of an anticoagulation service are described. The challenges facing such programs are discussed, including the potential anticoagulants in development that will create ongoing challenges in deciding which anticoagulation approach to use and in identifying patients for whom the newer agents may or may not be best suited. Requirements for establishing a successful inpatient anticoagulation management program included defining the pharmacist's role in identifying patient needs, gaining support from other health care professionals, designing a program that addresses the needs of the patients, and managing unanticipated issues.

Stepwise approach to implementing ambulatory clinical pharmacy services

A methodological approach was developed to facilitate expansion of clinical pharmacist-managed anticoagulation services across an integrated health care delivery network. A stepwise approach to the development and implementation of ambulatory care clinical pharmacy services was used to facilitate expansion of pharmacist-managed anticoagulation clinics in a university hospital setting and a community hospital within the same health network. The Health Alliance of Greater Cincinnati successfully created a care delivery model using clinical pharmacists to provide comprehensive anticoagulation management services at a university hospital and a community hospital. The incidence of thromboembolic events was significantly lower in the pharmacy anticoagulation service patients versus the patients in the usual care setting (p=0.005). A statistically significant decrease in minor bleeding events was observed in the pharmacist-managed group (p=0.038). Although a decrease in major bleeding events was observed, it was not statistically significant (p=0.075). International Normalized Ratio values of the patients managed by the pharmacy anticoagulation clinics were within the therapeutic range approximately 75% of the time. A stepwise approach to the development and implementation of ambulatory care clinical pharmacy services has facilitated the expansion of pharmacist-managed anticoagulation clinics across an integrated health system. This may serve as a valuable template for other systems as they strive to develop medication therapy management services.

Falsely Elevated International Normalized Ratio Values in Patients Undergoing Anticoagulation Therapy: A Descriptive Evaluation

Background:Elevated international normalized ratio (INR) values have been linked to bleeding complications; however, elevated INR values are not always physiologic and can be falsely increased. This study describes the rate of falsely elevated INRs and characteristics predictive of falsely elevated INRs.Methods:This cross-sectional study was conducted among adult patients receiving anticoagulation therapy monitored by a centralized anticoagulation service during January 2000 through December 2004 (n = 29,536). Prevalence rates of all elevated (ie, value ≥ 10), falsely elevated, and truly elevated INRs were calculated. Multivariate logistic regression was performed to identify predictors of falsely elevated INRs among elevated INRs.Results:Of the 556,998 INRs included in the analysis, 793 INRs (prevalence, 0.14%; 95% confidence interval [CI], 0.10 to 0.19%), 53 INRs (prevalence, 0.01%; 95% CI, < 0.01 to 0.03%), and 740 INRs (prevalence, 0.13%; 95% CI, 0.09 to 0.18%) were elevated, falsely elevated, and truly elevated, respectively. The strongest independent predictor of a falsely elevated INR was a patient undergoing hemodialysis at the time of the elevated INR (adjusted odds ratio, 9.60; 95% CI, 4.96 to 18.58; p < 0.001). A low target INR was the only other factor found to be an independent predictor of a falsely elevated INR.Conclusions:Although INR values ≥ 10.0 occur infrequently, patients presenting with such values can present a challenge to the anticoagulation provider. Anticoagulation providers should be particularly vigilant for falsely elevated INRs when monitoring patients undergoing hemodialysis.

The impact of pharmacist-managed oral anticoagulation therapy in older veterans

Older adults frequently have conditions requiring oral anticoagulation. Although clearly benefiting from oral anticoagulation, they are at increased risk for bleeding complications. Regular monitoring to optimize anticoagulation and to reduce the chance of major bleeding complications is required. The impact of oral anticoagulation monitoring by pharmacists in patients older than 75 years of age has not been described well. To compare warfarin therapy prescribed and monitored by physicians to a pharmacist-monitored anticoagulation service in a cohort of older veterans. Retrospective chart review utilizing the Houston VA Medical Center's pharmacy database. Among all outpatients aged 75 years or older filling warfarin prescriptions between 1 March 2003 to 1 March 2005, and who were either monitored in a pharmacist's clinic or not, 103 patients per group were randomly selected. Information on demographics, indication for and length of warfarin therapy, INR values, and thromboembolic and bleeding events were abstracted. Differences were analysed using chi-squared test, Fisher's Exact test, and unpaired Student t-test. A total of 1521 patients (440 in the pharmacist-monitored group, 1081 in the traditionally monitored group) met our inclusion criteria. One hundred and three patients per group were randomly selected for chart review. Although no significant difference in percentage of therapeutic INR values (48.1% pharmacist group, 46.4% conventional group) or in the incidence of major bleeding events was found, thromboembolic events occurred significantly less frequently in the pharmacist-monitored group (2 events vs. 12 events, P = 0.01). Minor bleeding events were more frequent in the pharmacist-monitored group (50 vs. 17, P < 0.01). However, time to follow-up after a sub- or supra-therapeutic INR was significantly shorter in the pharmacist monitored group (22 days vs. 68 days, and 14 days vs. 32 days, respectively). Pharmacist-monitored anticoagulation was associated with reduced thromboembolic events, an increase in minor bleeding events, and no difference in major bleeding events. Overall such monitoring by pharmacists should be recommended for older adults.

Evaluation of the Hemochron Junior Signature Analyser for Oral Anticoagulant Point of Care Testing.

The community anticoagulant service in Tayside, Scotland provides point of care testing for around 5000 patients at 25 sites using 43 analysers. Since December 2004 this service has used the Hemochron Junior Signature (HJS) analyser (International Technidyne Corporation) for INR measurement.Following satisfactory initial laboratory evaluation, we have compared results of capillary samples analysed using the HJS to venous samples collected simultaneously and analysed in Ninewells Hospital using a Sysmex CA1500 analyser. Reagents used were Citrate PT test cuvettes (International Technidyne Corporation) which uses rabbit brain thromboplastin for the HJS and Dade Innovin (Dade Behring) for the CA1500. Samples for comparison were collected randomly from approximately every tenth patient tested in the anticoagulant clinics for a 12 month period. Results of the comparison are given for 3 separate periods within the 12 months of study as ongoing analysis of data during the study period led to the introduction of a correction factor for results obtained using the HJS analyser. The first correction factor was introduced after the first 4 weeks of study and there was a subsequent revision of this correction factor after a further 5 months.Results for these 3 periods are as follows (all results given are INR units).Period 1:Mean INR 2.8 CA 1500 vs. 3.8 HJS, mean difference −1.0, 95% upper limit of agreement 0.5, 95% lower limit of agreement −2.5 (n=145).Period 2:Mean INR 2.6 CA 1500 vs. 2.7 HJS, mean difference −0.1, 95% upper limit of agreement 1.1, 95% lower limit of agreement −1.2 (n=345).Period 3:Mean INR 2.7 CA 1500 vs. 2.8 HJS, mean difference 0.0, 95% upper limit of agreement 1.3, 95% lower limit of agreement −1.3 (n=662).Additionally, local external quality assurance was performed on 13 occasions (683 total tests) during the period of study. Cumulative results demonstrate that 86% of results were within 15% of the median.We have demonstrated an approach to quality assurance for oral anticoagulant point of care testing and conclude that the HJS is a suitable analyser for this purpose.

Community and Ambulatory Pharmacy: Evaluation of Patient Care Services and Billing Patterns Before Implementation of Medicare Part D

To provide a summary of community and ambulatory pharmacy practice and billing patterns for medication therapy management services before implementation of Medicare Prescription Drug Improvement and Modernization Act of 2003 (MMA). Cross-sectional survey. Ambulatory care and community pharmacy practice settings in the United States in January 2004. Members of the American College of Clinical Pharmacy Ambulatory Practice and Research Network, preceptors of the American Pharmacists Association (APhA) Community Pharmacy Residency Programs, and participants in the APhA Immunizing Pharmacist listserv. E-mail invitations to participate in a Web-based survey. Practice setting; pharmacy services performed; whether pharmacists were billing for pharmacy services; if billing, the billing technique used; if not billing, the reason for not billing. Of 349 respondents, 127 (36.4%) were practicing within a physician office, while 121 (34.7%) were practicing in community pharmacies. Diabetes, anticoagulation, dyslipidemia, hypertension, and smoking cessation management services were performed significantly more often in physician offices. Immunization delivery and diabetes, dyslipidemia, and osteoporosis screenings were performed significantly more often in community settings. A total of 190 (54.5%) pharmacists stated that they were billing for pharmacy services. More community pharmacists were billing for services compared with other combined practice settings (69.2% versus 46.7%, P < .001). Top reasons identified for not billing for services were salaried position, indigent population, and discomfort with the billing process. Valuable baseline data are provided regarding pharmacy services that have been successfully implemented in ambulatory and community practice settings and which billing techniques were used to receive reimbursement before the implementation of MMA.

Home Anticoagulation Testing: Predictors of Rural Patient Interest

Home anticoagulation testing (HAT) may be useful for rural patients who cannot attend an anticoagulation service clinic (ASC). Interest in HAT is unknown and was the focus of this study. Anticoagulated patients from two clinics, the ASC and vascular surgery clinic (VSC) were surveyed and compared for demographics, anticoagulation knowledge and opinions, and HAT interest. Logistic regression was performed, using the entire patient cohort, to identify factors associated with HAT interest. There were 211 (141 ASC, 70 VSC) patients surveyed. Differences between the ASC and VSC patients included education level (13.2 versus 12.1 years; P = 0.02), time spent testing (60.5 +/- 33.5 versus 46.4 +/- 20.7 min; P = 0.001), use of fingerstick testing (90% versus 2.9%; P < 0.001), and knowledge of the potential interaction of warfarin with medications or diet (79% versus 59% P = 0.003). HAT interest was similar (62.1% ASC versus 50% VSC; P = 0.14). Factors associated with HAT interest included employment [odds ratio (OR) 2.9, 95% confidence interval (CI) 1.2-6.7], knowledge of potential interactions between medications and warfarin (OR 3.9, 95% CI 1.9-8.1), and a willingness to check international normalized ratio values more frequently if recommended (OR 2.4, 95% CI 1.2-4.6). Patients who received family help with medications appeared less interested in HAT (OR 0.29, 95% CI 0.12-0.68). A slight majority of surveyed rural patients conveyed interest in HAT. Working patients and those assuming more responsibility for international normalized ratio control may be more interested in HAT. A possible association between anticoagulation knowledge and increased HAT interest was seen and should be further studied.

Cardiology groups’ antithrombotic guidelines challenge ACCP’s

The newest guidelines on antithrombotic therapy for patients with persistent atrial fibrillation—guidelines that do not consider old age a factor associated with a high risk of stroke—will likely alter the practice of only those pharmacists working with cardiologists or at cardiology clinics, said the clinician leading the effort to update ASHP’s therapeutic position statement on the therapy. “As far as primary care, internal medicine, anticoagulation clinics, anticoagulation services, the ACCP [American College of Chest Physicians] guidelines are the ones that are relied more heavily on,” said Edith Nutescu, director of the Antithrombosis Center at the University of Illinois at Chicago. The American College of Cardiology, which along with the American Heart Association and the European Society of Cardiology issued the newest antithrombotic therapy guidelines on August 2, claims to attract cardiologists and members of the cardiac care team. This was the second time that the three groups had released guidelines on managing the antithrombotic therapy of patients with atrial fibrillation. The executive summary of the guidelines appeared in the August 15 issues of Circulation1 and the Journal of the American College of Cardiology; the full text of the guidelines is online at http://content.onlinejacc.org/cgi/reprint/48/4/e149.pdf.

Management of Chinese patients on warfarin therapy in two models of anticoagulation service – a prospective randomized trial

To compare the treatment outcomes of a clinical pharmacist-managed anticoagulation service with physician-managed service in Chinese patients. A prospective, randomized clinical trial was conducted at the anticoagulation clinic of a teaching hospital in Hong Kong. Patients aged > or = 18 years who would required warfarin therapy for at least 3 months were recruited. Patients were randomized to the pharmacist-managed or physician-managed group. Primary clinical outcome was assessed by the percentage of patient time spent within the target international normalized ratio (INR) range. The incidence of major thromboembolic events (TEs) and major bleeding was assessed as secondary clinical outcomes. The cost per patient per month (cPPPM) was calculated and patient satisfaction was assessed by patient satisfaction questionnaire (PSQ)-18. One hundred and forty-one patients were recruited at the anticoagulation clinic and 137 patients completed the study. Patients in the pharmacist-managed group (n = 68) were in the target INR 64% of patient time vs. 59% in the physician-managed group (n = 69) (P < 0.001). There was no significant difference in incidence of major TEs or bleeding. The cPPPM in the pharmacist-managed group (76 +/- 95 US dollar) (43 +/- 53 British pound) was lower than in the physician-managed group (98 +/- 158 US dollar) (55 +/- 89 British pound) (P < 0.001). The PSQ-18 score of the pharmacist-managed group (3.8 +/- 0.2) was higher than that of the physician-managed group (3.6 +/- 0.3) (P < 0.001). The pharmacist-managed anticoagulation service was more effective and less costly than the physician-managed service in achieving target anticoagulation control for Chinese patients on warfarin therapy.

Anticoagulation monitoring services in primary care

A community anticoagulation service provides flexible care and opportunities for nurses

“Bridging” and Mechanical Heart Valves

Mechanical heart valves require anticoagulation to prevent valve-associated thrombosis and thromboembolic stroke. Oral vitamin K antagonists such as warfarin are prescribed universally; however, oral agents do not act immediately and usually require at least 5 days to achieve a therapeutic effect. Article p 564 Measurement of the prothrombin time, which is standardized by reporting the result as the international normalized ratio (INR), assesses the anticoagulant effect of warfarin. For most mechanical heart valves, the target INR ranges between 2.0 and 3.5. In the postoperative cardiac surgical setting, patients are usually started on low doses of warfarin because they tend to have impaired hepatic metabolism and suboptimal nutritional status. Even with low initial doses of warfarin, mechanical heart valve replacement patients are susceptible to excessively high INRs.1 This known exaggerated initial response to warfarin after heart valve replacement can lead to the habitual prescription of such low warfarin doses that warfarin as monotherapy may not achieve a stable and therapeutic INR for weeks after its initiation. To minimize the delay in achieving therapeutic anticoagulation, a “bridging” anticoagulant is prescribed. The “bridge” is administered parenterally, thereby providing an immediate anticoagulant effect. Traditionally, the “bridging” agent has been unfractionated heparin (UFH). More recently, physicians tend to select low-molecular-weight heparin (LMWH), even though few studies exist to validate the efficacy and safety of either LMWH or UFH in this setting. The rationale for shunning UFH has been to avoid the known perils and inconveniences of its use as a continuous peripheral intravenous infusion. UFH is rarely administered in an immediately therapeutic dose because of fear of precipitating bleeding complications. Especially in postoperative mechanical valve replacement patients, there is reluctance to follow the high dosing requirements for initial bolus and infusion regimens published in standardized nomograms. Instead, UFH is usually started in cautious small …

Major Bleeding Complications in a Specialized Anticoagulation Service

Major Bleeding Complications in a Specialized Anticoagulation Service

Safety and low molecular weight heparin in older people in a hospital with ambulatory care

To examine major bleeding and mortality rates of low molecular weight heparin (LMWH) and unfractionated heparin (UFH) for patients with pulmonary embolism (PE) and/or deep vein thrombosis (DVT), a retrospective review of the medical records for 286 patients who presented at a local hospital with PE and/or DVT during the period November 2002–August 2003 was performed. Data collected: presence of co-morbidities, concurrent medications, presence, site and severity of bleeding, outcome. Of all the patients, 50.7% received LMWH plus warfarin, 21.0% received UFH plus LMWH plus warfarin, 14.0% received UFH and warfarin, and 9.8% received LMWH only. There were nine minor bleeds and six major bleeds, which resulted in four deaths. Being a hospitalized patient and being age ≥70 years were associated with a major bleed ( p < 0.05). For hospital inpatients age ≥70 years on UFH and LMWH the number of major bleeds/1000 patient days was 18.9 and 9.2, respectively. The major bleeding rate is comparable if not better than that reported in the literature in our hospital setting where nearly half of the anticoagulation services were provided as ambulatory care. The increased rate of bleeding in the elderly we found is consistent with the findings of previous studies.

A Descriptive Evaluation of Routine Complete Blood Count Monitoring in Patients Receiving Anticoagulation Therapy

The most prevalent side effect associated with warfarin therapy is bleeding. Routine monitoring of laboratory tests, such as complete blood counts (CBC), may provide theoretical benefit in this patient population as a means of detecting occult bleeding through hemoglobin values that decrease compared to baseline. To describe the clinical outcomes associated with routine CBC monitoring in a large, diverse sample of anticoagulated patients. Forty-seven month retrospective, observational study. Large non-profit, group-model health maintenance organization with a centralized clinical pharmacy anticoagulation service that routinely orders baseline CBCs on all patients enrolled in the service with follow up CBCs repeated at 3 months and yearly thereafter. Patients continuously enrolled in the anticoagulation service for warfarin therapy monitoring for at least one year between January 1, 2000 and December 5, 2003. Medical records were reviewed to determine clinical outcomes associated with hemoglobin decreases of > or =2.0 gm/dL. Clinical outcomes included both overt and occult bleeding events and a determination of major or minor bleeding in these events. Of the 4033 patients included in the analysis, 578 (14.3%) experienced at least one decrease in hemoglobin > or =2.0 gm/dL. Occult bleeding was confirmed in 121 patients (3.0% of all patients monitored) with a decrease of hemoglobin > or =2.0 gm/dL but only 13 of these patients (0.3% of all patients monitored) experienced major bleeding. The annual detection rate of occult bleeding through routine CBC monitoring was 0.8%. Although routine CBC monitoring provides some utility in detecting occult bleeding, the yield of clinically important decreases in hemoglobin detected was low. For most anticoagulated patients, routine CBC monitoring appears to be clinically unnecessary.

Impact of Age, CYP2C9 Genotype and Concomitant Medication on the Rate of Rise for Prothrombin Time During the First 30 Days of Warfarin Therapy

To characterize the impact of several important clinical variables on the rate of anticoagulation during warfarin initiation (i.e., the first 30 days). Retrospective study. An anticoagulation service of a large horizontally integrated, multispecialty group practice in central and northern Wisconsin. Patients with sufficient laboratory data obtained during the initiation phase of warfarin treatment. Patients were consented and genotyped for cytochrome P450 (CYP) 2C9 polymorphisms. Anticoagulation laboratory data were then electronically abstracted and fitted to a logistic growth model. Rate of anticoagulation was compared between groups. During warfarin initiation, the mean slope for rise in International Normalized Ratio (INR) of prothrombin time was significantly associated with age (p = 0.03, n = 166). Because a relationship between diabetes and warfarin dosing has been suggested previously, we assessed the impact of this comorbidity in our model as well. Diabetes showed relatively little impact, but concomitant treatment with an anti-diabetic sulfonylurea medication was associated with an increase in slope (3-fold, p < 0.05). Since this drug interaction may occur at the level of CYP2C9, we also assessed the impact of CYP2C9 genotype in our model. The impact of CYP2C9 genotype was marginally significant (p = 0.119, non-pooled dataset; p = 0.053, data pooled for CYP2C9 *2/*2, *2/*3 and *3/*3). Age and concomitant sulfonylurea therapy alter the rate of anticoagulation during the first 30 days of warfarin therapy.

Major Bleeding Complications in a Specialized Anticoagulation Service

Major bleeding complications were investigated in 2,460 patients with 3,684 patient-years of warfarin exposure from 2000 to 2003. The most common indications for anticoagulation were atrial fibrillation (30%), venous thromboembolic disease (28%), and mechanical heart valve prosthesis (15%). Eleven patients had 12 nonfatal major bleeding complications, with no fatal bleeds during the study. The incidence of major bleeding complications was 0.12%/year; there were 0.32 bleeds/100 patient-years of coverage. Of the 12 bleeding events, 5 (42%) were intracranial hemorrhages. The average hospitalization cost per patient was dollar 15,988, and the average length of hospitalization was 6.0 days.

The Impact of Patient Self-Testing of Prothrombin Time for Managing Anticoagulation: Rationale and Design of VA Cooperative Study #481—The Home INR Study (THINRS)

Anticoagulation (AC) with warfarin reduces the risk of thromboembolism (TE) in a variety of applications, yet despite compelling evidence of the value and importance of high quality AC, warfarin remains underused, and dosing is often suboptimal. Approaches to improve AC quality include (1) an AC service (ACS), which allows the physician to delegate day-to-day details of AC management to another provider dedicated to AC care, and (2) incorporating into the treatment plan patient self-testing (PST) under which, after completing a training program, patients perform their own blood testing (typically, using a finger-stick blood analyzer), have dosage adjustments guided by a standard protocol, and forward test results, dosing and other information to the provider. Studies have suggested that PST can improve the quality of AC and perhaps lower TE and bleed rates. The purpose of Department of Veterans Affairs (VA) Cooperative Studies Program (CSP) #481, "The Home INR Study" (THINRS) is to compare AC management with frequent PST using a home monitoring device to high quality AC management (HQACM) implemented by an ACS with conventional monitoring of prothrombin time by international normalized ratio (INR) on major health outcomes. PST in THINRS involves use of an INR monitoring device that is FDA approved for home use. Sites are VA Medical Centers where the ACS has an active roster of more than 400 patients. THINRS includes patients with atrial fibrillation (AF) and/or mechanical heart valve (MHV) expected to be anticoagulated indefinitely. THINRS has two parts. In Part 1, candidates for PST are evaluated for 2 to 4 weeks for their ability to use home monitoring devices. In Part 2, individuals capable of performing PST are randomized to (1) HQACM with testing every 4 weeks and as indicated for out of range values, medication/clinical changes, or (2) PST with testing every week and as indicated for out of range values, medication/clinical changes. The primary outcome measure is event rates, defined as the percent of patients who have a stroke, major bleed, or die. Secondary outcomes include total time in range (TTR), other events (myocardial infarction (MI), non-stroke TE, minor bleeds), competence and compliance with PST, satisfaction with AC, AC associated quality of life (QOL), and cost-effectiveness. To assess the effect of PST frequency on TTR and other outcomes, at selected sites patients randomized to perform PST are assigned one of three test frequencies (weekly, twice weekly, or once every four weeks).