A multicomponent intervention to prevent major bleeding complications in older patients receiving warfarin. A randomized, controlled trial

Anticoagulation: Effect of a Warfarin Adherence Aid on Anticoagulation Control in an Inner-City Anticoagulation Clinic Population

Background:

Poor adherence to warfarin therapy is a major contributor to subtherapeutic anticoagulation.

Objective:

To determine whether use of a monthly medication organizer, filled at each clinic visit, improves anticoagulation control among warfarin-treated patients.

Methods:

Patients who had a history of nonadherence to warfarin and were attending an inner-city anticoagulation clinic were enrolled in this prospective cohort study and provided with a 28-day medication organizer. Patients were instructed to bring their organizers and warfarin tablets to each anticoagulation clinic visit over the following 3 months. At each visit, the international normalized ratio (INR) was measured, warfarin adherence was assessed, and the organizer was filled with the prescribed warfarin regimen until the next scheduled visit. Data on warfarin adherence and INR values during the 3 months prior to enrollment were collected from medical records and compared with postenrollment data.

Results:

Thirteen patients were enrolled and completed at least one postenrollment clinic visit. Adherence to warfarin therapy improved with use of the medication organizer (mean ± SD preenrollment 55 ± 25%, postenrollment 67 ± 21%; p = 0.06). There was a significant decrease in the proportion of subtherapeutic INR values (60 ± 25% to 35 ± 29%; p = 0.04) and a significant improvement in the percent of time spent within the therapeutic INR range (32 ± 22% to 56 ± 28%; p = 0.03) after enrollment.

Conclusions:

Use of a monthly medication organizer significantly reduced the percent of subtherapeutic INR values and improved the time spent within the therapeutic anticoagulation range among previously nonadherent patients managed in an inner-city anticoagulation clinic.

Prevention of venous thromboembolism after surgery

Venous thromboembolism, including deep vein thrombosis and pulmonary embolism, is the third leading cause of cardiovascular death after myocardial infarction and stroke in the United States. Recommendations regarding the type and duration of prophylaxis for the various conditions are summarized herein.

Evaluation of a telemedicine-based service for the follow-up and monitoring of patients treated with oral anticoagulant therapy

The authors have designed and developed a telemedicine-based service for the follow-up and monitoring of patients on oral anticoagulant therapy (OAT) that consists of two phases; the first involving self-testing and the second involving guided self-management. To evaluate the first phase of the protocol, a project was conducted with 108 patients, with a mean age of 72.7 years and a mean treatment time at the start of the study of 55.2 months, divided into two groups: telemedicine and control (conventional procedure). The degree of anticoagulation control was similar in the two groups: individual in-range international normalized ratios (59.2% vs 61.1%; p = 0.55) and individual time within target range (65.7% vs 66.4%; p = 0.85) showed no significant differences. The incidence of adverse events--death (5.5% vs 5.5%; p = 1.0), major hemorrhagic complications (0% vs 1.8%; p = 1.0), minor hemorrhagic complications (7.4% vs 3.7%; p = 0.67), and thromboembolism (1.8% vs 3.7%; p = 1.0)--was also similar, with no significant differences. Acceptability of the change, measured in terms of quality of life (SF-12 and Sawicki questionnaires) and anxiety (state-trait anxiety inventory questionnaire) at the beginning and end of the study period was higher in the telemedicine group, with statistically significant improvements in mental component summary (3.6 vs -6.2; p = 0.02), dissatisfaction (-0.8 vs 0.2; p = 0.001), stress (-0.3 vs 0.05; p = 0.03), limitations (-0.2 vs 0.3; p = 0.005), social problems (-0.1 vs 0.3; p = 0.03), and state anxiety (-2.5 vs 2.3; p = 0.04). Parameters related to costs, such as the mean number per patient of office visits due to OAT (1.7 vs 13.8; p << 0.001) and other office visits (10.1 vs 11.5; p = 0.028), were also more favorable in the telemedicine group, as were additional parameters that enabled an exhaustive evaluation of the service. The positive results obtained indicate that the second phase of the trial can be initiated.

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

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

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

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

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

[Optimum duration of anticoagulant treatment after an episode of venous thromboembolism]

Vitamin K antagonists are the mainstay for the treatment for venous thromboembolism. The optimum (VTE) course of oral anticoagulant therapy is determined according to the risk of recurrent VTE after stopping anticoagulant therapy and the risk of anticoagulant-related bleeding while on antivitamin K. The risk of recurrent VTE is low when the initial episode is provoked by a reversible major-risk factor (surgery), whereas this risk is high when VTE is not provoked or associated with a persistent-risk factor (cancer). Conversely, the influence of biochemical and morphological tests is uncertain. The optimum balance of the benefits and the risks of oral anticoagulant therapy is based on the frequency as well as the consequences of the risk of recurrent VTE and anticoagulant-related bleeding. After VTE provoked by a major reversible-risk factor, three months of anticoagulation is optimal, whereas after unprovoked VTE, anticoagulation should be extended. However, given the number of unresolved issues, a randomised trial comparing different durations of anticoagulation is needed.

Optimising anticoagulant education in the paediatric setting using a validated model of education

OBJECTIVE

Providing education to patients requiring anticoagulant therapy may be associated with improved outcomes. This study investigated the knowledge outcomes of a validated educational intervention.

METHODS

Parents of children with congenital heart disease requiring warfarin therapy took part in an educational intervention. Warfarin knowledge was assessed prior to commencing the program, immediately following its completion and 6 months following completion.

RESULTS

Parents demonstrated a statistically significant improvement in their warfarin knowledge immediately following completion of the program (p < 0.0001), with this improvement being sustained over time.

CONCLUSION

Current approaches to educating parents of children requiring warfarin therapy are likely suboptimal. Using a validated model of education may be associated with improved knowledge outcomes for patients.

PRACTICE IMPLICATIONS

Consideration to the processes used in delivering patient education may result in improved patient knowledge outcomes.

Duration of anticoagulant therapy for patients with venous thromboembolism

In principle, the answer to this question is obvious: "as long as the risk of continued therapy is outweighed by the benefit." In practice, determining an individual patient's risk of recurrent venous thromboembolism (VTE) without warfarin or other vitamin K antagonists is difficult. However, there are many factors (both intrinsic and environmental) that can alter the risk of VTE recurrence. This paper will discuss evidence and considerations (including the issue of bleeding risk) that may be relevant to decisions about duration of anticoagulant therapy for patients with VTE.

Role of pharmacodiagnostic of CYP2C9 variants in the optimization of warfarin therapy in Malaysia: a 6-month follow-up study

1. A retrospective study was conducted to explore the importance of CYP2C9 genotyping for the initiation and maintenance therapy of warfarin in clinical practice. A total of 191 patients on warfarin therapy in a local hospital were recruited after written informed consent. Their medical records were reviewed and no intervention of warfarin dose was performed. 2. A total of 5 ml of blood were taken from each subject for DNA extraction and identification of 1, 2, 3 and 4 CYP2C9 alleles, using a nested-allele-specific-multiplex-polymerase chain reaction (PCR). Half the patients were Malays and the remaining were Chinese. 3. Two genotypes were detected; 93.2% had CYP2C9 1/1 and 6.8% were CYP2C9 1/3. Warfarin doses were higher in patients with CYP2C91/1. Patients with the 1/3 genotype experienced a higher rate of serious and life-threatening bleeding; 15.4 versus 6.2 per 100 patients per 6 months. 4. The observation clearly highlights the inadequacy of the current dosing regimens and the need to move toward a more individualized approach to warfarin therapy. Prospective clinical studies are now being conducted to assess dosing algorithms that incorporate the contribution of the genotype to allow the individualization of warfarin dose.

Use of pharmacogenetic and clinical factors to predict the therapeutic dose of warfarin

Initiation of warfarin therapy using trial-and-error dosing is problematic. Our goal was to develop and validate a pharmacogenetic algorithm. In the derivation cohort of 1,015 participants, the independent predictors of therapeutic dose were: VKORC1 polymorphism -1639/3673 G>A (-28% per allele), body surface area (BSA) (+11% per 0.25 m(2)), CYP2C9(*)3 (-33% per allele), CYP2C9(*)2 (-19% per allele), age (-7% per decade), target international normalized ratio (INR) (+11% per 0.5 unit increase), amiodarone use (-22%), smoker status (+10%), race (-9%), and current thrombosis (+7%). This pharmacogenetic equation explained 53-54% of the variability in the warfarin dose in the derivation and validation (N= 292) cohorts. For comparison, a clinical equation explained only 17-22% of the dose variability (P < 0.001). In the validation cohort, we prospectively used the pharmacogenetic-dosing algorithm in patients initiating warfarin therapy, two of whom had a major hemorrhage. To facilitate use of these pharmacogenetic and clinical algorithms, we developed a nonprofit website, http://www.WarfarinDosing.org.

EDUC'AVK: reduction of oral anticoagulant-related adverse events after patient education: a prospective multicenter open randomized study

BACKGROUND

Long-term oral anticoagulation treatment is associated with potential morbidity. Insufficient patient education is linked to poorly controlled anticoagulation. However the impact of a specific educational program on anticoagulation related morbidity remains unknown.

OBJECTIVE

To evaluate the effect of an oral anticoagulation patient education program in reducing both hemorrhagic and recurrent thrombotic complications.

DESIGN/PARTICIPANTS

We conducted a prospective, multicenter open randomized study, comparing an interventional group who received a specific oral anticoagulation treatment educational program with a control group. Eligible patients were older than 18 and diagnosed as having deep vein thrombosis or pulmonary embolism requiring therapy with a vitamin K antagonist for 3 months or more. Our primary outcome was the occurrence of hemorrhagic or thromboembolic events.

RESULTS

During the 3-month follow-up the main outcome criteria were observed 20 times (6.6% of patients), 5 (3.1%) in the experimental and 15 (10.6%) in the control group. Consequently, in multivariate analysis, the cumulative risk reduction in the experimental group was statistically significant (OR 0.25, 95% CI 0.1-0.7, p < 0.01).

CONCLUSIONS

Patient education using an educational program reduced VKA-related adverse event rates.

Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations. Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh the risks, burdens, and costs. Grade 2 recommendations suggest that the individual patient's values may lead to different choices. (For a full understanding of the grading, see the "Grades of Recommendation" chapter by Guyatt et al, CHEST 2008; 133:123S-131S.) Among the key recommendations in this article are the following: for dosing of VKAs, we recommend the initiation of oral anticoagulation therapy, with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 1B); we suggest against pharmacogenetic-based dosing until randomized data indicate that it is beneficial (Grade 2C); and in elderly and other patient subgroups who are debilitated or malnourished, we recommend a starting dose of < or = 5 mg (Grade 1C). The article also includes several specific recommendations for the management of patients with nontherapeutic INRs, with INRs above the therapeutic range, and with bleeding whether the INR is therapeutic or elevated. For the use of vitamin K to reverse a mildly elevated INR, we recommend oral rather than subcutaneous administration (Grade 1A). For patients with life-threatening bleeding or intracranial hemorrhage, we recommend the use of prothrombin complex concentrates or recombinant factor VIIa to immediately reverse the INR (Grade 1C). For most patients who have a lupus inhibitor, we recommend a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. We recommend that physicians who manage oral anticoagulation therapy do so in a systematic and coordinated fashion, incorporating patient education, systematic INR testing, tracking, follow-up, and good patient communication of results and dose adjustments [Grade 1B]. In patients who are suitably selected and trained, patient self-testing or patient self-management of dosing are effective alternative treatment models that result in improved quality of anticoagulation management, with greater time in the therapeutic range and fewer adverse events. Patient self-monitoring or self-management, however, is a choice made by patients and physicians that depends on many factors. We suggest that such therapeutic management be implemented where suitable (Grade 2B).

Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about treatment for venous thromboembolic disease is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see "Grades of Recommendation" chapter). Among the key recommendations in this chapter are the following: for patients with objectively confirmed deep vein thrombosis (DVT) or pulmonary embolism (PE), we recommend anticoagulant therapy with subcutaneous (SC) low-molecular-weight heparin (LMWH), monitored IV, or SC unfractionated heparin (UFH), unmonitored weight-based SC UFH, or SC fondaparinux (all Grade 1A). For patients with a high clinical suspicion of DVT or PE, we recommend treatment with anticoagulants while awaiting the outcome of diagnostic tests (Grade 1C). For patients with confirmed PE, we recommend early evaluation of the risks to benefits of thrombolytic therapy (Grade 1C); for those with hemodynamic compromise, we recommend short-course thrombolytic therapy (Grade 1B); and for those with nonmassive PE, we recommend against the use of thrombolytic therapy (Grade 1B). In acute DVT or PE, we recommend initial treatment with LMWH, UFH or fondaparinux for at least 5 days rather than a shorter period (Grade 1C); and initiation of vitamin K antagonists (VKAs) together with LMWH, UFH, or fondaparinux on the first treatment day, and discontinuation of these heparin preparations when the international normalized ratio (INR) is > or = 2.0 for at least 24 h (Grade 1A). For patients with DVT or PE secondary to a transient (reversible) risk factor, we recommend treatment with a VKA for 3 months over treatment for shorter periods (Grade 1A). For patients with unprovoked DVT or PE, we recommend treatment with a VKA for at least 3 months (Grade 1A), and that all patients are then evaluated for the risks to benefits of indefinite therapy (Grade 1C). We recommend indefinite anticoagulant therapy for patients with a first unprovoked proximal DVT or PE and a low risk of bleeding when this is consistent with the patient's preference (Grade 1A), and for most patients with a second unprovoked DVT (Grade 1A). We recommend that the dose of VKA be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations (Grade 1A). We recommend at least 3 months of treatment with LMWH for patients with VTE and cancer (Grade 1A), followed by treatment with LMWH or VKA as long as the cancer is active (Grade 1C). For prevention of postthrombotic syndrome (PTS) after proximal DVT, we recommend use of an elastic compression stocking (Grade 1A). For DVT of the upper extremity, we recommend similar treatment as for DVT of the leg (Grade 1C). Selected patients with lower-extremity (Grade 2B) and upper-extremity (Grade 2C). DVT may be considered for thrombus removal, generally using catheter-based thrombolytic techniques. For extensive superficial vein thrombosis, we recommend treatment with prophylactic or intermediate doses of LMWH or intermediate doses of UFH for 4 weeks (Grade 1B).

Is long-term pharmacist-managed anticoagulation service efficient? A pragmatic randomized controlled trial

BACKGROUND

Some pharmacist-managed anticoagulation services (PMAS) provide initial follow-up to patients on oral anticoagulant, who are transferred to their physician once they are stabilized. This may be as effective as and less expensive than long-term PMAS follow-up.

METHODS

Once PMAS patients were stabilized and ready for discharge, they were randomized to be transferred to their physician or stay with the PMAS. Quality of international normalized ratio (INR) control, incidence of complications, health-related quality of life, use of health care services, and direct incremental cost of PMAS follow-up were evaluated.

RESULTS

One hundred thirty-eight physicians and 250 patients participated. Patients were initially followed at the PMAS for a mean of 11.3 weeks and afterwards were followed by their physician (n = 122) or by the PMAS pharmacists (n = 128) for a mean of 14.9 and 14.5 weeks, respectively. Pharmacist-managed anticoagulation services' and physician's patients were within the exact target range 77.3% and 76.7% of the time (95% CI of the difference -4.9% to 6.0%) and within the extended range 93.0% and 91.6% of the time (95% CI -2.1% to 4.7%), respectively. Pharmacist-managed anticoagulation services patients have seen their family physician less often (95% CI -3.1 to -0.1 visit per year). Number of INR tests, incidence of complications, and health-related quality of life were similar in both groups. The incremental cost of PMAS follow-up was estimated at CAN$123.80 per patient year.

CONCLUSION

Once PMAS patients are well stabilized, maintaining a PMAS follow-up or transferring them to their physician is associated with excellent INR control. However, long-term PMAS follow-up may be more expensive.

Patient self-testing and self-management of oral anticoagulation

The development of portable instruments for measuring the prothrombin time (PT) in capillary whole blood has made it possible for patients on lifelong coumarin therapy to monitor the effect of the anticoagulant themselves (patient self-testing) and to adjust the dosage if necessary on their own (patient self-management). Dosage variations between individual patients and the narrow therapeutic range of the anticoagulant account for the need to monitor its effect, in order to minimize the risk of thromboembolism resulting from inadequate anticoagulation as well as the risk of bleeding due to overanticoagulation. This review focuses on the prerequisites for the successful implementation of patient self-testing and self-management, such as the selection of eligible patients, appropriate training and the reliability of available instruments. The outcomes of relevant clinical studies involving patient self-testing and self-management are also discussed.

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.

Effect of setting, monitoring intensity and patient experience on anticoagulation control: a systematic review and meta-analysis of the literature

OBJECTIVES

To investigate the relationship between time spent in the recommended target International Normalised Ratio (INR) range and the setting and intensity of anti coagulant monitoring, in both treatment-experienced and treatment-naive atrial fibrillation (AF) patients receiving oral anticoagulation (OAC) therapy for the prevention of ischaemic stroke.

RESEARCH DESIGN AND METHODS

Systematic review of published studies on participants with atrial fibrillation on anticoagulation therapy. We compared frequent monitoring (well-controlled, according to a strict protocol) versus infrequent monitoring (frequency representative of routine clinical practice), specialised care versus usual care, and naive versus prior anticoagulant use. Meta-analysis was performed using a random effects model.

RESULTS

36 studies were included, 22 (primary data) of AF patients managed in line with the consensus guidelines target INR range of 2.0-3.0, and 14 studies (secondary data) of mixed patient groups, including AF, with an INR target of 2.0-3.5. Both data sets were combined for sensitivity analysis. Pooled mean time in INR range was 59.1% (95% CI: 55.5, 62.8%) and 64.3% (95% CI: 60.5, 68.0%) for infrequent monitoring and frequent monitoring, respectively. Significantly more time was spent in range in specialist care settings compared to usual care: +11.3% (95% CI: 0.1-21.7%). Naive OAC users spent less time in range 56.5% (95% CI: 45.5-67.5%) than existing users 61.2% (95% CI: 57.2-65.2%). All of these differences were found to be significant in the sensitivity analyses.

CONCLUSIONS

INR control is variable and dependent on monitoring intensity and duration of anticoagulant therapy.

Genetic determinants of response to warfarin during initial anticoagulation

BACKGROUND

Genetic variants of the enzyme that metabolizes warfarin, cytochrome P-450 2C9 (CYP2C9), and of a key pharmacologic target of warfarin, vitamin K epoxide reductase (VKORC1), contribute to differences in patients' responses to various warfarin doses, but the role of these variants during initial anticoagulation is not clear.

METHODS

In 297 patients starting warfarin therapy, we assessed CYP2C9 genotypes (CYP2C9 *1, *2, and *3), VKORC1 haplotypes (designated A and non-A), clinical characteristics, response to therapy (as determined by the international normalized ratio [INR]), and bleeding events. The study outcomes were the time to the first INR within the therapeutic range, the time to the first INR of more than 4, the time above the therapeutic INR range, the INR response over time, and the warfarin dose requirement.

RESULTS

As compared with patients with the non-A/non-A haplotype, patients with the A/A haplotype of VKORC1 had a decreased time to the first INR within the therapeutic range (P=0.02) and to the first INR of more than 4 (P=0.003). In contrast, the CYP2C9 genotype was not a significant predictor of the time to the first INR within the therapeutic range (P=0.57) but was a significant predictor of the time to the first INR of more than 4 (P=0.03). Both the CYP2C9 genotype and VKORC1 haplotype had a significant influence on the required warfarin dose after the first 2 weeks of therapy.

CONCLUSIONS

Initial variability in the INR response to warfarin was more strongly associated with genetic variability in the pharmacologic target of warfarin, VKORC1, than with CYP2C9.

Best strategies for patient education about anticoagulation with warfarin: a systematic review

Background

Patient education is an essential component in quality management of the anticoagulated patient. Because it is time consuming for clinicians and overwhelming for patients, education of the anticoagulated patient is often neglected. We surveyed the medical literature in order to identify the best patient education strategies.

Methods

Study Selection: Two reviewers independently searched the MEDLINE and Google Scholar databases (last search March 2007) using the terms "warfarin" or "anticoagulation", and "patient education". The initial search identified 206 citations, A total of 166 citations were excluded because patients were of pediatric age (4), the article was not related to patient education (48), did not contain original data or inadequate program description (141), was focused solely on patient self-testing (1), was a duplicate citation (3), the article was judged otherwise irrelevant (44), or no abstract was available (25).

Data Extraction: Clinical setting, study design, group size, content source, time and personnel involved, educational strategy and domains, measures of knowledge retention.

Results

Data Synthesis: A total of 32 articles were ultimately used for data extraction. Thirteen articles adequately described features of the educational strategy. Five programs used a nurse or pharmacist, 4 used a physician, and 2 studies used other personnel/vehicles (lay educators (1), videotapes (1)). The duration of the educational intervention ranged from 1 to 10 sessions. Patient group size most often averaged 3 to 5 patients but ranged from as low as 1 patient to as much as 11 patients. Although 12 articles offered information about education content, the wording and lack of detail in the description made it too difficult to accurately assign categories of education topics and to compare articles with one another. For the 17 articles that reported measures of patient knowledge, 5 of the 17 sites where the surveys were administered were located in anticoagulation clinics/centers. The number of questions ranged from as few as 4 to as many as 28, and questions were most often of multiple choice format. Three were self-administered, and 2 were completed over the telephone. Two reports described instruments along with formal testing of the validity and reliability of the instrument.

Conclusion

Published reports of patient education related to warfarin anticoagulation vary greatly in strategy, content, and patient testing. Prioritizing the educational domains, standardizing the educational content, and delivering the content more efficiently will be necessary to improve the quality of anticoagulation with warfarin.

Prospective study of warfarin dosage requirements based on CYP2C9 and VKORC1 genotypes

Polymorphisms in CYP2C9 and VKORC1 have been shown to be associated with warfarin dose requirements and could be used to predict warfarin dose. We conducted a prospective study in which warfarin dose was prescribed based on CYP2C9 and VKORC1 polymorphisms in 108 Han-Chinese patients without prior warfarin treatments. Using the genotype-based dosing, 83% of patients reached stable, therapeutic international normalized ratio (INR) within 2 weeks of treatment initiation and none of the patients developed clinical bleeding or thromboembolic event. Ten percent (11) of patients with INR > 4 and no clinical bleeding were detected during this study. At 12 weeks, 69% of the patients' maintenance doses matched the prediction. Dosing algorithms incorporating genetic factors, age, and body surface area were developed, which could explain up to 62% of the total variation (R(2) of 0.62). This study demonstrated that pharmacogenetics-based dosing could improve time to stable, therapeutic INR, reduce adverse events, and achieve high sensitivity.

Anticoagulation in women with nonvalvular atrial fibrillation: insights from clinical trials

There is emerging evidence that women with atrial fibrillation, particularly those aged over 75 years, are more prone to strokes than men. It is also generally believed that older women are more vulnerable than men to warfarin-associated hemorrhage, leading to reluctance among physicians to anticoagulate women with atrial fibrillation. In the SPORTIF trials, the largest randomized cohort of women with atrial fibrillation on anticoagulation, including those aged over 75 years, women developed stroke (either ischemic or hemorrhagic) and systemic embolic events more often than men. In population-based studies such as the ATRIA study, female gender increased the relative risk of stroke significantly (incremental relative risk: 20-90%). Both types of studies demonstrated that maintaining the international normalized ratio within the therapeutic range of 2.0-3.0 was associated with similar rates of major bleeding in older women, younger women and men. Better validated predictors of bleeding than gender should be considered when selecting antithrombotic therapy. New oral anticoagulants are under development to reduce the burden and risk of warfarin-associated anticoagulation.

CYP2C9 genotypes and the quality of anticoagulation control with warfarin therapy among Brazilian patients

OBJECTIVE

To evaluate the impact of the two most common CYP2C9 variant alleles (*2 and *3) on the maintenance dose of warfarin and on the quality of anticoagulation control in Brazilians.

METHODS

Patients (n = 103) initiated warfarin therapy with 5 mg/day (or 2.5 mg/day when over 80 years old). The international normalized ratio (INR) was targeted between 2 and 3, monitored every week until four consecutive adequate measures had been obtained, and then monthly. Serious hemorrhagic events were defined by the need for inpatient hospitalization. CYP2C9 genotyping was obtained by PCR-RFLP.

RESULTS

The frequencies of CYP2C9*2 and CYP2C9*3 were 0.097 and 0.073, respectively, with genotypic distribution fitting Hardy-Weinberg equilibrium. CYP2C9 genotype was the only clinical feature associated with the risk of severe bleeding (one-sided P = 0.019, Fisher exact method), with an odds ratio of 4.8 (95% confidence interval of 1.4-16.6) for any variant genotype as compared to CYP2C9*1*1. Patients with either CYP2C9*2 or CYP2C9*3 were equally difficult to maintain in the INR target range, showing significantly (one-sided P = 0.038, Mann-Whitney U-test) reduced ratio of adequate INR measures (0.54 +/- 0.2), when compared to CYP2C9*1*1 patients (0.63 +/- 0.2). Patients with CYP2C9*3, but not CYP2C9*2, required significantly (one-sided P = 0.001, Mann-Whitney U-test) lower warfarin maintenance doses (3.1 +/- 1.8 mg) than CYP2C9*1*1 patients (5.3 +/- 2.1 mg).

CONCLUSION

Patients with either CYP2C9*2 or CYP2C9*3 show higher risk of over-anticoagulation compared to CYP2C9*1*1 subjects and could benefit from a reduction in the initial warfarin standard dose (e.g., to 2.5 mg/day).

Pharmacogenetics of warfarin: regulatory, scientific, and clinical issues

Using pharmacogenetics-based therapy, clinicians can estimate the therapeutic warfarin dose by genotyping patients for single nucleotide polymorphisms (SNPs) that affect warfarin metabolism or sensitivity. SNPs in the cytochrome P450 complex (CYP2C9) affect warfarin metabolism: patients who have the CYP2C9*2 and/or CYP2C9*3 variants metabolize warfarin slowly and are more likely to have an elevated International Normalized Ratio INR or to hemorrhage during warfarin initiation than patients without these variants. SNPs in vitamin K epoxide reductase (VKORC1) correlate with warfarin sensitivity. Patients who are homozygous for a common VKORC1 promoter polymorphism, -1639 G>A (also designated as VKOR 3673, haplotype A, or haplotype*2), are warfarin sensitive and typically require lower warfarin doses. By providing an estimate of the therapeutic warfarin dose, pharmacogenetics-based therapy may improve the safety of anticoagulant therapy. To improve drug safety, the FDA updates labels of previously approved drugs as new clinical and genetic evidence accrues. The labels of medical products serve to inform prescribers and patients about potential ways to improve the benefit/risk ratio and/or optimize doses of medical products. On August 16, 2007, the FDA updated the label of warfarin to include information on pharmacogenetic testing and to encourage, but not require, the use of this information in dosing individual patients initiating warfarin therapy. The FDA completed the label update in August 2007.

Efficacy of inferior vena cava filters in anticoagulated patients

BACKGROUND AND OBJECTIVES

The benefit of an inferior vena cava (IVC) filter in addition to standard anticoagulation regimens is unknown.

METHODS

We examined data for patients who received IVC filters with anticoagulation (AC-Filter) after an episode of venous thromboembolism (VTE) and compared them with data for those who received anticoagulation only (AC-Only). Outcome measures were new pulmonary embolism (PE), recurrent deep vein thrombosis (DVT), and mortality at 90 days and at 5 years. Demographic data included age, gender, and ethnicity/race, prior thromboembolic history, cancer, serum albumin, and time in therapeutic range. In addition, subsets matched for age, gender and race/ethnicity were examined in detail.

RESULTS

AC-Filter patients (n = 251), when compared to AC-Only patients (n = 1377), did not differ significantly with regard to gender or cancer status, but white males in general had better outcomes. AC-Filter patients were more likely to have had a previous history of PE or VTE (P < 0.001). In comparison to AC-Only patients, AC-Filter patients had lower mean serum albumin levels (3.1 +/- 0.8 vs. 3.6 +/-0.8 mg dL(-1), P < 0.001) and were older (65 +/- 16.1 years vs. 60 +/- 17.5 years, P < 0.001). After stratification according to previous history of PE or VTE prior to the index VTE event, no differences in the outcome measures of new PE, recurrent DVT or mortality were identified between groups, but patients with a prior history of PE from either group were more likely to have a new PE (hazard ratio 1.9, P < 0.001).

CONCLUSIONS

These data suggest that IVC filters may not provide any substantial additional benefit for patients who can tolerate anticoagulant therapy.

Genetic-based dosing in orthopedic patients beginning warfarin therapy

High variability in drug response and a narrow therapeutic index complicate warfarin therapy initiation. No existing algorithm provides recommendations on refining the initial warfarin dose based on genetic variables, clinical data, and international normalized ratio (INR) values. Our goal was to develop such an algorithm. We studied 92 patients undergoing primary or revision total hip or knee replacement. From each patient we collected a blood sample, clinical variables, current medications, and preoperative and postoperative laboratory values. We genotyped for polymorphisms in the cytochrome P450 (CYP) 2C9 and vitamin K epoxide reductase (VKORC1) genes. Using stepwise regression, we developed a model for refining the warfarin dose after the third warfarin dose. The algorithm explained four fifths of the variability in therapeutic dose (R(2)(adj) of 79%). Significant (P > .05) predictors were INR value after 3 doses (47% reduction per 0.25-unit rise), first warfarin dose (+7% per 1 mg), CYP2C9*3 and CYP2C9*2 genotype (-38% and -17% per allele), estimated blood loss (interacting with INR(3)), smoking status (+20% in current smokers), and VKORC1 (-11% per copy of haplotype A). If validated, this model should provide a safer, more effective process for initiating warfarin therapy.

Direct-to-patient expert system and home INR monitoring improves control of oral anticoagulation

BACKGROUND AND OBJECTIVE

Internet-based disease management programs have the potential to improve patient care. The objective of this study was to determine whether an interactive, internet-based system enabling supervised, patient self-management of oral anticoagulant therapy provided management comparable to an established anticoagulation clinic.

PATIENTS/METHODS

Sixty patients receiving chronic oral anticoagulant therapy who had access to the internet and a printer, were enrolled into this prospective, single-group, before-after study from a single clinic and managed between March 2002 and January 2003. Patients learned how to use a home prothrombin time monitor and how to access the system through the internet. Patients used the system for six months, with daily review by the supervising physician. The primary outcome variable was the difference in time in therapeutic range prior to and following introduction of internet-supervised patient self-management.

RESULTS

The mean time in therapeutic range increased from 63% in the anticoagulation clinic (control period) to 74.4% during internet-supervised patient self-management (study period). The mean difference score between control and study periods was 11.4% (P = 0.004, 95% confidence interval 5.5-17.3%). There were no hemorrhagic or thromboembolic complications.

CONCLUSIONS

This novel approach of internet-supervised patient self-management improved time in therapeutic range compared to an anticoagulation clinic. This is the first demonstration of an internet-based expert system enabling remote and effective management of patients on oral anticoagulants. Expert systems may be applicable for management of other chronic diseases.

Frequency of adverse events in patients with poor anticoagulation: a meta-analysis

BACKGROUND

Patients taking anticoagulants orally over the long term have international normalized ratios (INRs) outside the individual therapeutic range more than one-third of the time. Improved anticoagulation control will reduce hemorrhagic and thromboembolic event rates. To gauge the potential effect of improved anticoagulation control, we undertook to determine the proportion of anticoagulant-associated events that occur when INRs are outside the therapeutic range.

METHODS

We conducted a meta-analysis of all studies that assigned hemorrhagic and thromboembolic events in patients taking anticoagulants to discrete INR ranges. We identified studies using the MEDLINE (1966-2006) and EMBASE (1980-2006) databases. We included studies reported in English if the majority of patients taking oral anticoagulants had an INR range with a lower limit between 1.8 and 2 and an upper limit between 3 and 3.5, and their INR at the time of the hemorrhagic or thromboembolic event was recorded.

RESULTS

The final analysis included results from 45 studies (23 that reported both hemorrhages and thromboemboli; 14 that reported hemorrhages only; and 8, thromboemboli only) involving a median of 208 patients (limits of interquartile range [25th-75th percentile] 131-523 subjects; total n = 71 065). Of these studies, 64% were conducted at community practices; the remainder, at anticoagulation clinics. About 69% of the studies were classed as having moderate or high quality. Overall, 44% (95% confidence interval [CI] 39%-49%) of hemorrhages occurred when INRs were above the therapeutic range, and 48% (95% CI 41%-55%) of thromboemboli took place when below it. The mean proportion of events that occurred while the patient's INR was outside the therapeutic range was greater for studies with a short mean follow-up (< 1 yr). Between-study heterogeneity was significant (p < 0.001).

INTERPRETATION

Improved anticoagulation control could decrease the likelihood of almost half of all anticoagulant-associated adverse events.

Anticoagulation control in the peri-hospitalization period

Oral anticoagulants (OAC) are effective and safe if the international normalized ratio (INR) is maintained within a narrow therapeutic range. Hospitalization is independently associated with poor anticoagulation control. The objective of this study is to describe how anticoagulation control changes in the peri-hospitalization period. This study is a retrospective cohort study using population-based administrative databases. INR results were retrieved from a population-based laboratory database. INR levels between laboratory measures were estimated using linear interpolation. Auto-regressive, integrated, moving average (ARIMA) time-series modeling was used to determine how anticoagulation control changed in the peri-hospitalization period. The study included 5,380 elderly patients in Eastern Ontario between 1 September 1999 and 1 September 2000 taking OACs. Results showed that 951 (17.7%) were hospitalized during their OAC therapy [thrombotic, n = 52 (1.0%); hemorrhagic, n = 140 (2.6%); other hospitalization types, n = 759 (14.1%)]. All measures of anticoagulation control changed significantly in the peri-hospitalization period. Before hemorrhagic admissions, mean INR and proportion with INR > 5 increased significantly (daily increase 0.024, P = .03 and 0.2%, P = .01). Following other hospitalization types, the proportion of patients with INR < 1.5 was significantly increased (daily increase 0.19%, P = .02). Patients admitted to the hospital for a variety of indications have significantly worse anticoagulation control in the peri-hospitalization period. Anticoagulated patients discharged after medical hospitalizations could be targeted for improved anticoagulation control.

Atrial fibrillation in the elderly

Atrial fibrillation is increasingly prevalent among older adults. It causes approximately 24% of strokes in patients aged 80 to 89 years. The management of atrial fibrillation is directed at preventing thromboembolism and controlling the heart rate and rhythm. Stroke prevention is most effectively accomplished through administering anticoagulants such as warfarin, although older patients have higher hemorrhagic risk. Cognitive dysfunction, functional impairments, and increased fall risk further complicate warfarin management in elderly patients. The use of risk stratification schemes can help guide the anticoagulation decision, although the benefits of warfarin generally outweigh the risks in most older patients with atrial fibrillation. Pharmacologic rate control has been shown to result in similar outcomes compared with pharmacologic restoration of sinus rhythm and should be the initial therapy for elderly patients. Anti-arrhythmic medications should be selected based on an individual patient's coexisting medical conditions. In symptomatic patients who fail pharmacologic therapy, invasive strategies such as AV nodal ablation may help improve quality of life and symptoms, although such strategies do not obviate the need for antithrombotic therapy.

Incidence and predictors of severe bleeding during warfarin treatment

BACKGROUND

Optimal warfarin prescription requires correct, individualized assessment of the warfarin-related bleeding risk, which randomised controlled trials may underestimate . Observational studies have reported a range of bleeding risks that differ 40-fold. This variation may be caused by time trends, variation in bleeding definition and study subject selection. We investigated the incidence of, and risk factors for severe bleeding in un-selected warfarin-treated patients from Sweden.

METHODS

Between 2001 and 2005, 40 centres recruited warfarin-naïve patients commencing warfarin therapy and followed them prospectively with continuous registration of clinical data. The primary outcome was severe bleeding, according to the WHO universal definition of severe adverse drug reactions. The influence of potential risk factors was investigated by means of a Cox proportional-hazards model.

RESULT

A total of 1523 patients contributed 1276 warfarin-exposed patient-years. The incidence of first-time severe bleeding was 2.3 per 100 patient-years (95% confidence interval 1.4 to 3.1). Male sex and use of drugs potentially interacting with warfarin were the only independent risk factors of severe bleeding, with hazard ratios of 2.8 and 2.3, respectively. Age, target International Normalized Ratio (INR), time spent outside target INR range, and warfarin dose requirement were not significantly associated with bleeding risk.

CONCLUSIONS

The risk of severe bleeding in a large naturalistic, prospective cohort of first-time warfarin users was lower than reported in some previous reports. Male gender was an independent predictor of severe bleeding as was the receipt of warfarin-interacting medications at the onset of anticoagulation therapy. Further studies are required to evaluate the effect these findings may have on the quality of current risk-benefit analysis involved in warfarin prescription.

Assessing differential attrition in clinical trials: self-monitoring of oral anticoagulation and type II diabetes

Background

Analyzing drop out rates and when they occur may give important information about the patient characteristics and trial characteristics that affect the overall uptake of an intervention.

Methods

We searched Medline and the Cochrane library from the beginning of the databases to May 2006 for published systematic reviews that compared the effects of self-monitoring (self-testing) or self-management (self-testing and self-dosage) of oral anticoagulation or self-monitored blood glucose in type 2 diabetics who were not using insulin. We assessed all study withdrawals pre-randomization and post randomization and sought information on the reasons for discontinuation of all participants.

To measure the differential between groups in attrition we used the relative attrition (RA), which is equivalent to relative risk but uses attrition as the outcome (i.e. attrition in intervention group/attrition in control group). We determined the percentage drop outs for control and intervention groups and used DerSimonian and Laird random effects models to estimate a pooled relative attrition. L'abbe type plots created in R (version 2.0.2) were used to represent the difference in the relative attrition among the trials with 95% confidence areas and weights derived from the random effects model.

Results

With self-monitoring of blood glucose in type 2 diabetes, attrition ranged from 2.3% to 50.0% in the intervention groups and 0% to 40.4% in the control groups. There was no significant difference between the intervention and control, with an overall RA of 1.18 [95% CI, 0.70–2.01]. With self-monitoring of oral anticoagulation attrition ranged from 0% to 43.2% in the intervention groups and 0% to 21.4% in the control group. The RA was significantly greater in the intervention group, combined RA, 6.05 [95% CI, 2.53–14.49].

Conclusion

This paper demonstrates the use of relative attrition as a new tool in systematic review methodology which has the potential to identify patient, intervention and trial characteristics which influences attrition in trials.

Reducing medical costs and improving quality via self-management tools

The authors consider the advantages and limitations of self-management tools used for treating chronic illness.

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

BACKGROUND

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.

OBJECTIVE

To compare warfarin therapy prescribed and monitored by physicians to a pharmacist-monitored anticoagulation service in a cohort of older veterans.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Descriptive analysis of the process and quality of oral anticoagulation management in real-life practice in patients with chronic non-valvular atrial fibrillation: the international study of anticoagulation management (ISAM)

BACKGROUND/OBJECTIVES

Expert oral anticoagulation management is the key to good outcomes and is performed variably in different health care systems throughout the world. We set out to assess the quality of anticoagulation management in five countries in patients receiving vitamin K antagonists (VKAs) for stroke prophylaxis in chronic non-valvular atrial fibrillation (NVAF), and to compare the anticoagulation management practices in these countries.

METHODS AND RESULTS

This was a retrospective, multi-centre cohort study in the United States, Canada, France, Italy, and Spain. About 1,511 patients were randomly recruited from representative practices (routine medical care (RMC) in the US, Canada, and France; anticoagulation clinics in Italy and Spain) and data pertaining to their oral anticoagulation care were abstracted from their medical records. The predominant anticoagulant in use was warfarin in the US, Canada, and Italy; acenocoumarol in Spain; and fluindione in France. Documentation of care was poor in the US, Canada, and France, countries where RMC was studied. Percent INRs or time-in-therapeutic range was greater in the two anticoagulation clinic samples compared with the RMC samples.

CONCLUSION

Oral anticoagulation care varies considerably from country to country. Findings suggest that anticoagulation clinic care (ACC) may provide better outcomes as assessed by international normalized ratio (INR) time-in-range. Physicians tend to under treat more than over treat. Finally, documentation of care is often inadequate. Condensed Abstract Oral anticoagulation management (routine medical care or anticoagulation clinic care) was retrospectively assessed in 5 countries using a uniform, structured assessment tool. Major management differences were detected, especially between anticoagulation clinic care and routine care. Documentation was often a problem in the latter setting. Less time in therapeutic INR range was noted in routine medical care. Findings suggest that anticoagulation clinic care may provide better outcomes as assessed by international normalized ratio (INR) time-in-range. Physicians tend to under treat more than over treat. Finally, documentation of care is often inadequate.