Incidence of hospital readmission in patients diagnosed with DVT and PE: clinical burden of recurrent events

BACKGROUND

Venous thromboembolism (VTE), which comprises deep-vein thrombosis (DVT) and pulmonary embolism (PE), is associated with significant morbidity and mortality and represents a considerable economic burden to the US healthcare system. Although it is well established that patients with an initial VTE are at increased risk for recurrent VTE, limited data exist on the clinical burden of a secondary DVT or PE event. The objective of this retrospective observational study was to conduct an epidemiologic evaluation, from a hospital perspective, of patients with an initial DVT or PE who experienced a recurrent event postdischarge requiring hospital readmission.

METHODS

Hospital claims containing DVT or PE as a primary diagnosis for hospitalisation during the period October 2009 to April 2013 were identified by retrospective analysis using the MarketScan database. The time to hospital readmission for DVT or PE was assessed using the MarketScan Treatment Pathways tool.

RESULTS

Of 214,901 patient admissions identified with a diagnosis of DVT or PE at hospital admission, approximately 4% were subsequently readmitted to the hospital with a diagnosis of PE (8217) or DVT (9138). Of all readmitted patients with a diagnosis of DVT on initial admission, 66% were rehospitalised with a diagnosis of DVT, and 34% were rehospitalised with a diagnosis of PE. Of all readmitted patients with a diagnosis of PE on initial admission, 63% were rehospitalised with a diagnosis of PE and 37% with a diagnosis of DVT. Of all hospital readmissions with a diagnosis of PE or DVT, 62% and 58% occurred within the first 30 days following an initial PE or DVT event, respectively.

CONCLUSIONS

The burden of DVT or PE is large, not only because of the initial hospitalisation event but also because of the high number of hospital readmissions, more than half of which occur within 30 days.

Warfarin dose requirements in a patient with the CYP2C9*14 allele

We describe a 64-year-old male of Indian descent with a history of atrial fibrillation who was started on warfarin after hospital admission for acute stroke. He received genotype-guided warfarin dosing as per the standard-of-care at our hospital, with daily dose recommendations provided by the pharmacogenetics service. Genotyping revealed the rare CYP2C9*1/*14 genotype and warfarin insensitive VKORC1 -1639GG and CYP4F2 433Met/Met genotypes. The patient received an initial warfarin loading dose of 4 mg for 2 days, followed by 2-3 mg/day for the following 11 days. He reached a therapeutic international normalized ratio on day 5, which was maintained over the following week. This report adds to the limited data of the effects of the CYP2C9*14 allele on warfarin dose requirements.

Daily costs of hospitalization in non-valvular atrial fibrillation patients treated with anticoagulant therapy

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac rhythm disturbance in the US, with an estimated prevalence of 2.7-6.1 million persons in 2010.

OBJECTIVE

This study evaluates the progression of daily hospitalization costs among non-valvular atrial fibrillation (NVAF) patients treated with anticoagulant therapy.

METHODS

A claims analysis was conducted with Premier Perspective Comparative Hospital Database records from January 2009-March 2013. Patients of 18 years or older who were diagnosed with NVAF and used anticoagulant therapy were studied. Treatment patterns and mean daily costs of hospitalization per patient as well as total costs of hospitalization were reported. Comparisons of mean daily costs with those of the previous day were presented to identify statistical cost differences between hospitalization days.

RESULTS

A total of 375,560 patients were identified; 67,017 with AF as admitting/primary diagnosis, and 308,543 with AF as a secondary diagnosis. The mean age of the overall population, primary AF diagnosis cohort, and secondary AF diagnosis cohort was 73.8, 67.9, and 75.0 years, while their proportion of females was 46.3%, 45.6%, and 46.5%, respectively. The mean length of stay was 6.8 days, 3.7 days, and 7.5 days for the overall population, the primary AF diagnosis cohort, and the secondary AF diagnosis cohort, respectively. For all cohorts, mean daily costs stabilized on the third day (overall population: $2103; primary AF diagnosis cohort: $1505; secondary AF diagnosis cohort: $2208).

LIMITATIONS

Claims data may have contained inaccuracies or omissions in coded procedures, diagnoses, or pharmacy claims.

CONCLUSION

The study showed that daily hospitalization costs for NVAF patients stabilized on the third day of hospitalization and that any reduction or prolongation in hospital length of stay could have a significant impact on the cost burden associated with AF.

Balance of academic responsibilities of clinical track pharmacy faculty in the United States: a survey of select American College of Clinical Pharmacy Practice and Research Network Members

STUDY OBJECTIVES

To characterize the balance of clinical and academic responsibilities of clinical track pharmacy faculty in the United States and evaluate organizational structures that promote satisfactory balance between these responsibilities.

DESIGN

Prospective cross-sectional survey.

SETTING

A 22-item online survey was developed and distributed via Qualtrics software.

PARTICIPANTS

Clinical faculty members of the American College of Clinical Pharmacy Adult Medicine, Ambulatory Care, Cardiology, Critical Care, Gastrointestinal/Liver/Nutrition, Immunology/Transplantation, Infectious Disease, and Pediatrics Practice and Research Networks (PRNs) were invited to participate via the PRN electronic mailing list.

MEASUREMENTS AND MAIN RESULTS

The survey comprised questions related to demographics, organizational structure, and balance of clinical and academic responsibilities. A total of 344 participants responded to some or all of the survey questions. The demographics were relatively equally balanced between faculty at state and private academic institutions, academic rank, and practice setting. Expected and actual effort allocations were similar for each of the clinical and academic responsibilities, with direct patient care and clinical teaching representing more than 50% effort allocation cumulatively. Clinical faculty at state institutions devoted a larger proportion of time to clinical service, whereas clinical faculty at private institutions devoted a greater proportion of time to didactic teaching. When asked about time constraints, 157 (69.8%) of the 225 survey participants responding to this question did not believe they had sufficient time to fulfill their nonclinical academic needs. Clinical faculty who were provided "protected time" away from clinical service had a significantly more favorable opinion of this question.

CONCLUSION

Most of the clinical track pharmacy faculty indicated that they have insufficient time to fulfill their nonclinical academic responsibilities. Provision of protected time may alleviate some of these time constraints.

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

PURPOSE

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

SUMMARY

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

CONCLUSION

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

Evaluation of dabigatran bleeding adverse reaction reports in the FDA adverse event reporting system during the first year of approval

STUDY OBJECTIVE

Evaluate dabigatran adverse event reports with a reported bleeding event and/or reported fatal outcome compared with warfarin.

DESIGN

Retrospective analysis of the FDA Adverse Event Reporting System (FAERS) database.

MEASUREMENTS AND MAIN RESULTS

We identified reports from October 1, 2010, through December 31, 2011, in the United States listing dabigatran or warfarin as the primary suspected agent. Bleeding events and related outcomes were determined. A bleeding-related mortality rate was calculated based on national dabigatran treatment data.

RESULTS

Dabigatran was the primary suspected agent in 9029 adverse reports. Of these, 2347 (26%) were bleeding events; a fatal outcome was reported in 348 (15%) of the bleeding events. In comparison, warfarin was the suspected agent in 2038 reports, of which 647 (32%) were reported as bleeding events. Among the warfarin bleeding reports, 46 (7.1%) reported a fatal outcome. Based on national dabigatran use and adverse bleed reports with fatal outcomes, we estimate a lower bound of 150 bleeding-related fatalities per 100,000 dabigatran patient-years. Because of underreporting bias, these estimates represent a lower bound on the population bleeding mortality rates.

CONCLUSION

Reports from FAERS are subject to significant bias but suggest that fatal outcomes among dabigatran reports are higher in clinical practice than they were in controlled clinical trials.

Risk factors associated with myocardial infarction in venous thromboembolism patients

BACKGROUND

Although risk factors for MI have been described in the general population, there is a lack of data on the assessment of risk factors associated with MI in venous thromboembolism (VTE) patients.

OBJECTIVE

The purpose of this study was to identify risk factors associated with MI in VTE patients.

PATIENTS AND METHODS

Health insurance claims between January 2004 and September 2008 from the Ingenix IMPACT database were analyzed. Patients aged ≥18 years were identified as of the date of their first VTE diagnosis with ≥1 year of continuous insurance coverage before the index VTE. The risk of MI for VTE patients with 1, 2, and ≥3 major risk factors as identified by published guidelines was calculated. Multivariate Cox proportional hazard models were conducted to identify the most predictive risk factors associated with MI.

RESULTS

A total of 177,885 VTE patients were identified; 4412 (2.5%) developed an MI during a mean follow-up period of 1.3 years. Previous MI, age (≥65 years), and coronary artery disease were the most predictive risk factors of MI with adjusted hazard ratios (HRs; 95% CI) of 5.47 (5.01-5.97), 1.78 (1.66-1.91), and 1.60 (1.48-1.74), respectively. Adjusted HRs (95% CI) for VTE patients with 1, 2, and ≥3 major risk factors relative to no major risk factor were 2.34 (1.94-2.81), 3.21 (2.67-3.85), and 6.93 (5.85-8.22), respectively.

LIMITATIONS

These included possible inaccuracies or omissions in diagnoses, classification bias such as the identification of false-positive MI events, and the likely undercoding of some risk factors such as social issues.

CONCLUSIONS

Traditional major cardiovascular risk factors are also predictive of MI in VTE patients. Having multiple major risk factors significantly increases the probability of developing MI events in VTE patients.

Cost-effectiveness of rivaroxaban compared with enoxaparin plus a vitamin K antagonist for the treatment of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), comprised of deep vein thrombosis (DVT) and pulmonary embolism (PE), is commonly treated with a low-molecular-weight heparin such as enoxaparin plus a vitamin K antagonist (VKA) to prevent recurrence. Administration of enoxaparin + VKA is hampered by complexities of laboratory monitoring and frequent dose adjustments. Rivaroxaban, an orally administered anticoagulant, has been compared with enoxaparin + VKA in the EINSTEIN trials. The objective was to evaluate the cost-effectiveness of rivaroxaban compared with enoxaparin + VKA as anticoagulation treatment for acute, symptomatic, objectively-confirmed DVT or PE.

METHODS

A Markov model was built to evaluate the costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios associated with rivaroxaban compared to enoxaparin + VKA in adult patients treated for acute DVT or PE. All patients entered the model in the 'on-treatment' state upon commencement of oral rivaroxaban or enoxaparin + VKA for 3, 6, or 12 months. Transition probabilities were obtained from the EINSTEIN trials during treatment and published literature after treatment. A 3-month cycle length, US payer perspective ($2012), 5-year time horizon and a 3% annual discount rate were used.

RESULTS

Treatment with rivaroxaban cost $2,448 per-patient less and was associated with 0.0058 more QALYs compared with enoxaparin + VKA, making it a dominant economic strategy. Upon one-way sensitivity analysis, the model's results were sensitive to the reduction in index VTE hospitalization length-of-stay associated with rivaroxaban compared with enoxaparin + VKA. At a willingness-to-pay threshold of $50,000/QALY, probabilistic sensitivity analysis showed rivaroxaban to be cost-effective compared with enoxaparin + VKA approximately 76% of the time.

LIMITATIONS

The model did not account for the benefits associated with an oral and minimally invasive administration of rivaroxaban. 'Real-world' applicability is limited because data from the EINSTEIN trials were used in the model. Also, resource utilization and costs were based on the US healthcare system.

CONCLUSION

Rivaroxaban is a cost-effective option for anticoagulation treatment of acute VTE patients.

A pharmacogenetics service experience for pharmacy students, residents, and fellows

OBJECTIVE

To utilize a comprehensive, pharmacist-led warfarin pharmacogenetics service to provide pharmacy students, residents, and fellows with clinical and research experiences involving genotype-guided therapy.

DESIGN

First-year (P1) through fourth-year (P4) pharmacy students, pharmacy residents, and pharmacy fellows participated in a newly implemented warfarin pharmacogenetics service in a hospital setting. Students, residents, and fellows provided genotype-guided dosing recommendations as part of clinical care, or analyzed samples and data collected from patients on the service for research purposes.

ASSESSMENT

Students', residents', and fellows' achievement of learning objectives was assessed using a checklist based on established core competencies in pharmacogenetics. The mean competency score of the students, residents, and fellows who completed a clinical and/or research experience with the service was 97% ±3%.

CONCLUSION

A comprehensive warfarin pharmacogenetics service provided unique experiential and research opportunities for pharmacy students, residents, and fellows and sufficiently addressed a number of core competencies in pharmacogenetics.

Genetic variants associated with warfarin dose in African-American individuals: a genome-wide association study

BACKGROUND

VKORC1 and CYP2C9 are important contributors to warfarin dose variability, but explain less variability for individuals of African descent than for those of European or Asian descent. We aimed to identify additional variants contributing to warfarin dose requirements in African Americans.

METHODS

We did a genome-wide association study of discovery and replication cohorts. Samples from African-American adults (aged ≥18 years) who were taking a stable maintenance dose of warfarin were obtained at International Warfarin Pharmacogenetics Consortium (IWPC) sites and the University of Alabama at Birmingham (Birmingham, AL, USA). Patients enrolled at IWPC sites but who were not used for discovery made up the independent replication cohort. All participants were genotyped. We did a stepwise conditional analysis, conditioning first for VKORC1 -1639G→A, followed by the composite genotype of CYP2C9*2 and CYP2C9*3. We prespecified a genome-wide significance threshold of p<5×10(-8) in the discovery cohort and p<0·0038 in the replication cohort.

FINDINGS

The discovery cohort contained 533 participants and the replication cohort 432 participants. After the prespecified conditioning in the discovery cohort, we identified an association between a novel single nucleotide polymorphism in the CYP2C cluster on chromosome 10 (rs12777823) and warfarin dose requirement that reached genome-wide significance (p=1·51×10(-8)). This association was confirmed in the replication cohort (p=5·04×10(-5)); analysis of the two cohorts together produced a p value of 4·5×10(-12). Individuals heterozygous for the rs12777823 A allele need a dose reduction of 6·92 mg/week and those homozygous 9·34 mg/week. Regression analysis showed that the inclusion of rs12777823 significantly improves warfarin dose variability explained by the IWPC dosing algorithm (21% relative improvement).

INTERPRETATION

A novel CYP2C single nucleotide polymorphism exerts a clinically relevant effect on warfarin dose in African Americans, independent of CYP2C9*2 and CYP2C9*3. Incorporation of this variant into pharmacogenetic dosing algorithms could improve warfarin dose prediction in this population.

FUNDING

National Institutes of Health, American Heart Association, Howard Hughes Medical Institute, Wisconsin Network for Health Research, and the Wellcome Trust.

Feasibility of implementing a comprehensive warfarin pharmacogenetics service

STUDY OBJECTIVE

To determine the procedural feasibility of a pharmacist-led interdisciplinary service for providing genotype-guided warfarin dosing for hospitalized patients newly starting warfarin.

DESIGN

Prospective observational study.

SETTING

A 438-bed tertiary care hospital affiliated with a large academic institution.

PATIENTS

Eighty patients who started warfarin therapy and were managed by a newly implemented pharmacogenetics service.

INTERVENTION

All patients received routine warfarin genotyping and clinical pharmacogenetics consultation.

MEASUREMENTS AND MAIN RESULTS

The primary outcomes were percentage of genotype-guided dose recommendations available prior to the second warfarin dose and adherence of the medical staff to doses recommended by the pharmacogenetics service. Of 436 genotype orders placed during the first 6 months of the service, 190 (44%) were deemed appropriate. For the 80 patients on the service who consented to data collection, 76% of the genotypes were available prior to the second warfarin dose. The median (range) time from genotype order to genotype result was 26 hours (7-80 hrs), and the time to genotype-guided dose recommendation was 30 hours (7-80 hrs). A total of 73% of warfarin doses ordered by the medical staff were within 0.5 mg of the daily dose recommended by the pharmacogenetics consult service.

CONCLUSION

Providing routine genotype-guided warfarin dosing supported by a pharmacogenetics consult service is feasible from a procedural standpoint, with most genotypes available prior to the second warfarin dose and good adherence to genotype-guided dose recommendations by the medical staff.

Rivaroxaban: practical considerations for ensuring safety and efficacy

Rivaroxaban is the first agent available within a new class of anticoagulants called direct factor Xa inhibitors. Rivaroxaban is approved for use in the United States for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation, for the prevention of deep vein thrombosis in patients undergoing total hip replacement and total knee replacement, for the treatment of deep vein thrombosis and pulmonary embolism, and for the reduction in risk of recurrence of deep vein thrombosis and pulmonary embolism (with additional indications under review). Rivaroxaban dose and frequency of administration vary depending on the indication. As of result of predictable pharmacokinetics and pharmacodynamics, a fixed dose of rivaroxaban is administered without routine coagulation testing. Rivaroxaban has a short half-life, undergoes a dual mode of elimination (hepatic and renal), and is a substrate for P-glycoprotein. Rivaroxaban has a lower potential for drug interactions compared with warfarin. Despite the advantages of a once/day fixed-dose oral agent, in many clinical situations limited evidence is available to guide optimal management of rivaroxaban therapy. In this article, we review the available evidence and provide recommendations where possible for such situations including the desire to monitor the anticoagulation intensity, use in special patient populations, managing drug interactions, and transitioning across anticoagulant agents. Potential strategies for reversing rivaroxaban's anticoagulant effect are reviewed. Health systems will need to perform a systematic safety evaluation and ensure that numerous hospital policies related to anticoagulation are updated to include rivaroxaban. A comprehensive approach to education is needed for clinicians, patients, and technical support personnel involved in patient interactions to ensure safe use.

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.

Pharmacoeconomic implications of thromboprophylaxis with new oral anticoagulants after total hip or knee replacement in the USA

INTRODUCTION

Adequate thromboprophylaxis after total hip or knee replacement (THR or TKR) is essential to reduce the incidence of venous thromboembolism (VTE) and its associated complications. Although effective, traditional anticoagulants are associated with a considerable economic burden, particularly when used outside the hospital setting. This article explores whether newer oral anticoagulants can reduce costs of VTE prophylaxis and therapy.

AREAS COVERED

Cost associated with vitamin K antagonists; indirect costs associated with complicated or inconvenient anticoagulation regimens, non-adherence and associated complications; potential of the newer oral anticoagulants, including direct thrombin inhibitors and direct factor Xa inhibitors, to produce indirect cost savings after THR or TKR through a potential reduction in VTE rates and administration and monitoring costs.

EXPERT OPINION

The use of new anticoagulants for VTE prophylaxis after THR or TKR can result in direct and indirect cost savings through improved efficacy by reducing VTE rates and decreased drug administration and monitoring costs compared with traditional anticoagulants. Future research will need to focus on cost analyses driven by clinical outcomes measured on the performance of these agents in actual clinical practice.

All-cause and potentially disease-related health care costs associated with venous thromboembolism in commercial, Medicare, and Medicaid beneficiaries

BACKGROUND

Patients with venous thromboembolism (VTE) are at increased risk of developing recurrent VTE and post-thrombotic syndrome (PTS), a complication of deep vein thrombosis (DVT) characterized by venous reflux and residual venous obstruction that may manifest as chronic pain and swelling. Therefore, formulary/policy decision makers should understand the clinical and economic consequences associated with VTE.

OBJECTIVES

To describe the real-world clinical complications, such as recurrent VTE and PTS, associated with VTE and quantify the incremental direct all-cause and potentially disease-related health care costs associated with VTE.

METHODS

Health insurance claims between January 2004 and December 2008 from the Ingenix Impact database were used. Adult patients with an initial VTE diagnosis (index DVT, pulmonary embolism [PE], or both) with at least 12 months of enrollment prior to the index VTE were matched 1:1 with comparison patients without VTE. Matching criteria included demographic factors, baseline health care costs, and diagnoses of VTE risk factors such as multiple traumas, malignant cancer, or major surgery. Each patient's observation period began on the date of the index VTE, or corresponding study index date for comparison cases, and ended on the earliest of 1 year after the study index date, the health plan disenrollment date, or December 31, 2008. The proportions of patients with (a) recurrent hospital-documented VTE, defined as an inpatient episode with a diagnosis of VTE in any claim field; (b) PTS; and (c) other potentially disease-related diagnoses (thrombocytopenia, superficial venous thrombosis, venous ulcer, pulmonary hypertension, stasis dermatitis, and venous insufficiency) were calculated. Health care costs were defined as standardized net provider payments after subtraction of member cost-sharing amounts. All-cause incremental health care costs and disease-related costs, defined as provider payments for hospitalization or outpatient claims with a primary or secondary diagnosis of VTE, PTS, or any of the potentially disease-related diagnoses, were computed. Costs were calculated per patient per year (PPPY) by weighting each patient's total cost for up to 1 year post-index by the length of follow-up.

RESULTS

The matched VTE and no-VTE cohorts included 16,969 subjects in each group. The index VTE event was DVT, PE, or both in 12,711, 2,473, and 1,785 patients, respectively. In the VTE cohort, the risks of recurrent VTE and PTS during the follow-up period (mean [SD] observation of 271.7 [121.6] days) were 3.6% and 7.1%, respectively. Patients with VTE had significantly higher average PPPY all-cause costs compared with the no-VTE patients (mean [SD] $33,531 [$70,393] vs. $17,590 [$42,011]; cost difference = $15,941, 95% CI = $14,819-$17,012). Corresponding potentially disease-related health care costs PPPY were also significantly higher for the VTE group (mean [SD] $3,141 [$17,055] vs. $228 [$3,221]; cost difference = $2,913, 95% CI = $2,693-$3,157) and represented 18.3% (i.e., $2,913 of $15,941) of the all-cause cost difference between the 2 groups.

CONCLUSIONS

In this large matched-cohort study, VTE was associated with a 3.6% risk of hospital-documented recurrence and a 7.1% risk of PTS up to 1 year after index VTE. Potentially disease-related costs represented approximately one-fifth of the incremental all-cause costs associated with VTE.

Anticoagulation patient self-monitoring in the United States: considerations for clinical practice adoption

Systematic management models such as anticoagulation clinics have emerged in order to optimize warfarin effectiveness and to minimize related complications. Most of these models are structured so that patients come to a clinic for in-person testing and evaluation, thus making this model of care difficult to access and time consuming for many patients. The emergence of portable instruments for measuring anticoagulant effect in capillary whole blood made it possible for patients receiving warfarin to self-monitor the effect of their anticoagulant therapy. Self-monitoring empowers patients, offers the advantage of more frequent monitoring, and increases patient convenience by allowing testing at home and avoiding the need for frequent laboratory and clinic visits. Self-monitoring can entail patient self-testing (PST) and/or patient self-management (PSM). Several studies have evaluated and shown the benefit of both PST and PSM models of care when compared with either routine medical care or anticoagulation clinic management of anticoagulation therapy. Self-monitoring (PSM and/or PST) of anticoagulation results in lower thromboembolic events, lower mortality, and no increase in major bleeding when compared with standard care. Despite favorable results and enhanced patient convenience, the adoption of self-monitoring into clinical practice in the United States has been limited, especially in higher risk, disadvantaged populations. Although the emergence of a multitude of novel oral anticoagulants will permit clinicians to better individualize anticoagulant therapy options by choosing the optimum regimen based on individual patient characteristics, it is also expected that traditional agents will continue to play a role in a significant subset of patients. For those patients treated with traditional anticoagulants such as warfarin, future models of care will entail patient-centered management such as PST and PSM. The incorporation of technology (i.e., Web-based expert systems) is expected to further improve the outcomes realized by PST and PSM. Further studies are needed to explore factors that influence the adoption of self-monitoring in the United States and to evaluate the feasibility and implementation in real-life clinical settings.

Association of the GGCX (CAA)16/17 repeat polymorphism with higher warfarin dose requirements in African Americans

OBJECTIVE

Little is known about genetic contributors to higher than usual warfarin dose requirements, particularly for African Americans. This study tested the hypothesis that the γ-glutamyl carboxylase (GGCX) genotype contributes to warfarin dose requirements greater than 7.5 mg/day in an African American population.

METHODS

A total of 338 African Americans on a stable dose of warfarin were enrolled. The GGCX rs10654848 (CAA)n, rs12714145 (G>A), and rs699664 (p.R325Q); VKORC1 c.-1639G>A and rs61162043; and CYP2C9*2, *3, *5, *8, *11, and rs7089580 genotypes were tested for their association with dose requirements greater than 7.5 mg/day alone and in the context of other variables known to influence dose variability.

RESULTS

The GGCX rs10654848 (CAA)16 or 17 repeat occurred at a frequency of 2.6% in African Americans and was overrepresented among patients requiring greater than 7.5 mg/day versus those who required lower doses (12 vs. 3%, P=0.003; odds ratio 4.0, 95% confidence interval, 1.5-10.5). The GGCX rs10654848 genotype remained associated with high dose requirements on regression analysis including age, body size, and VKORC1 genotype. On linear regression, the GGCX rs10654848 genotype explained 2% of the overall variability in warfarin dose in African Americans. An examination of the GGCX rs10654848 genotype in warfarin-treated Caucasians revealed a (CAA)16 repeat frequency of only 0.27% (P=0.008 compared with African Americans).

CONCLUSION

These data support the GGCX rs10654848 genotype as a predictor of higher than usual warfarin doses in African Americans, who have a 10-fold higher frequency of the (CAA)16/17 repeat compared with Caucasians.

Association of apolipoprotein E genotype with duration of time to achieve a stable warfarin dose in African-American patients

STUDY OBJECTIVE

To test the hypothesis that genotypes for proteins affecting vitamin K availability influence the duration of time required to achieve a stable warfarin dose in African-American patients.

DESIGN

Retrospective cohort study.

SETTING

Pharmacist-managed antithrombosis clinic.

PATIENTS

Ninety-two African-American adults whose warfarin therapy was initiated between September 2, 1999, and July 8, 2009.

MEASUREMENTS AND MAIN RESULTS

During a routine anticoagulation clinic visit, a sample was collected from each patient for genetic analysis. genotyping was performed for the following variants: apolipoprotein E ε2, ε3, and ε4; NAD(P)H:quinone oxidoreductase (NQO1)*2; cytochrome P450 (CYP) 4F2 V433M; CYP2C9*2, *3, *5, *8, and *11; and vitamin K epoxide reductase complex 1 (VKORC1) -1639G>A. Patients' medical records were then reviewed, and data were collected retrospectively for each anticoagulation clinic visit during the first 6 months of warfarin therapy or until dose stabilization. The median time required to reach a stable warfarin dose, defined as the dose that produced therapeutic anticoagulation for three consecutive clinic visits, was 83 days. Compared with the 46 patients who achieved a stable warfarin dose within 83 days, the 46 patients who required longer durations for dose stabilization had a higher frequency of the apolipoprotein E ε3/ε3 genotype (37% vs 59%, p=0.037). Sixty-one percent of patients with the ε3/ε3 genotype versus 40% of those with an ε2 or ε4 allele had a delay in achieving a stable dose (p=0.037). Neither the CYP4F2 nor NQO1 genotype was associated with warfarin dose stabilization.

CONCLUSION

Our data support the hypothesis that the apolipoprotein E genotype is associated with duration of time to reach a stable warfarin dose in African-American patients. Further insight into the genetic effects on warfarin dose stabilization could reveal novel methods to improve anticoagulation control during the warfarin initiation period.