Assessment of a Bleeding Risk Index in Two Cohorts of Patients Treated with Oral Anticoagulants

The impact of renal function on clinical outcomes of patients with cancer-associated isolated distal deep vein thrombosis: Insights from the ONCO DVT study

BACKGROUND

The multicenter, open-label, randomized clinical trial ONCO DVT compared 3-month and 12-month edoxaban treatment regimens for isolated distal deep vein thrombosis (DVT) and suggested potential benefits of prolonged edoxaban treatment in terms of thrombotic risk. However, the risk-benefit balance of prolonged edoxaban treatment in patients with renal function remains unclear.

OBJECTIVES

To compare the safety and efficacy of 3-month and 12-month edoxaban treatment regimens in patients with cancer-associated isolated distal DVT and different renal functions.

METHODS

This pre-specified subgroup analysis of the ONCO DVT study included 601 patients divided into subgroups according to renal function using a 50 mL/min creatinine clearance (Ccr) cutoff. The primary endpoint was symptomatic recurrent venous thromboembolism (VTE) and VTE-related death at 12 months and the major secondary endpoint was major bleeding at 12 months.

RESULTS

Among the 601 patients, 131 (21.8 %) comprised the renal dysfunction subgroup. The primary endpoint occurred in 6 (9.7 %) and 1 (1.4 %) patients in the 3-month and 12-month edoxaban groups in the renal dysfunction subgroup, respectively, and in 16 (6.6 %) and 2 (0.9 %) patients in the no renal dysfunction subgroup, respectively. The major secondary endpoint occurred in 9 (14.5 %) and 7 (10.1 %) patients in the 12-month and 3-month edoxaban groups in the renal dysfunction subgroup, and in 13 (5.3 %) and 21 (9.3 %) patients in the no renal dysfunction subgroup, respectively.

CONCLUSIONS

A 12-month edoxaban regiment was superior to a 3-month treatment in terms of thrombotic risk irrespective of renal function. A higher bleeding risk was not identified in patients with renal dysfunction who received prolonged edoxaban treatment.

Risk of More Advanced Lesions at Hysterectomy after Initial Diagnosis of Non-Atypical Endometrial Hyperplasia in Patients with Postmenopausal Bleeding and Oral Anticoagulant Treatment

Background and Objectives: Endometrial hyperplasia (EH) is a precursor lesion to endometrial cancer (EC), and when cellular atypia is present, in 40% of cases, they are diagnosed with EC on hysterectomy. Usually, EH is clinically manifested by uterine bleeding. In patients with oral anticoagulant therapy (OAT), the uterus is the second most common source of bleeding. The aim of the study was to show that uterine bleeding in postmenopausal patients undergoing OAT may reveal precancerous endometrial lesions with atypia, or neoplastic lesions in patients with an initial diagnosis of endometrial hyperplasia without atypia (non-atypical endometrial hyperplasia, NAEH) on dilation and curettage (D&C). We will be able to estimate the risk of a postmenopausal female patient with uterine bleeding during an OAT to have a precancerous endometrial lesion. Materials and Methods: The subjects of the study were 173 female patients with uterine bleeding, who have had total hysterectomy with bilateral salpingoovarectomy, of whom 99 underwent an OAT. There were 101 female patients initially diagnosed with NAEH, of which 60 did not have anticoagulant treatment (mean age 57.36 ± 6.51) and 41 had anticoagulant treatment (mean age 60.39 ± 7.35) (p = 0.006). From the pathology diagnosis moment, the surgery was performed at 42.09 ± 14.54 days in patients without OAT and after 35.39 ± 11.29 days in those who received such treatment (p = 0.724). Results: Initial diagnosis of NAEH established at D&C was changed at the final diagnosis after hysterectomy in EH with cellular atypia (atypical endometrial hyperplasia AEH) or EC in 18.18% of patients without OAT, and in 40.54% of patients who received this treatment. Conclusions: Based on a logistic regression model, it is estimated that female patients with an initial histopathological diagnosis of NAEH and who underwent OAT have, on average, 4.85 times greater odds (OR = 4.85, 95% CI 1.79–14.06) than the others of being identified postoperatively with more advanced lesions.

Bleeding Risk Assessment in Patients with Venous Thromboembolism

The recommended treatment for patients with venous thromboembolism (VTE) is anticoagulation for at least 3 months. However, anticoagulant treatment increases the risk of bleeding, and patients at high risk for major bleeding might benefit from treatment discontinuation. In this review, we discuss strategies for assessing bleeding risk and compare different bleeding risk tools. Bleeding risk assessment is best viewed as a continuous approach with varying challenges throughout the acute and chronic phase. At diagnosis, bleeding risk factors must be identified and reversible risk factors treated or modified. After initial treatment, repeated bleeding risk assessment is crucial for the decision on extended/long-term anticoagulation. Current clinical prediction models (e.g., HAS-BLED, RIETE, or VTE-BLEED scores) are externally validated tools with relevant differences in specificity and sensitivity, which can aid in clinical decision-making. Unfortunately, none of the current bleeding risk assessment tools has been investigated in clinical trials and provides evidence to withhold anticoagulation treatment based on the score. Nevertheless, the HAS-BLED or RIETE score can be used to identify patients at high risk for major bleeding during the initial treatment phase, while the VTE-BLEED score might be used to identify patients at low risk for bleeding and, therefore, to safely administer extended/long-term anticoagulation for secondary thromboprophylaxis. As clinical prediction scores still lack predictive value, future research should focus on developing biomarker-based risk assessment models.

Drug-drug interactions with metronidazole and itraconazole in patients using acenocoumarol

PURPOSE

Various population-based cohort studies have shown that antimicrobial agents increase the risk of overanticoagulation in patients using coumarins. In this study, we assessed this association in hospitalized patients.

METHODS

We included all patients hospitalized in the Spaarne Gasthuis (Haarlem/Hoofddorp, the Netherlands), who started using an antimicrobial agent during acenocoumarol treatment or vice versa between 1 January 2015 and 1 July 2019. Patients were followed from start of concomitant therapy until 48 h after termination of the concomitant therapy or discharge, whichever came first. We analyzed the association between the antimicrobial agents and the risk of overanticoagulation, defined as an interpolated INR above 6, using Cox regression analysis. We corrected for multiple testing with the Bonferroni correction. Patients who started using acenocoumarol and amoxicillin/clavulanic acid were used as reference group.

RESULTS

In the study population, sixteen antimicrobial agents were started frequently concomitantly with acenocoumarol treatment. We included 2157 interaction episodes in 1172 patients. Patients who started using the combination of co-trimoxazole (HR 3.76; 95% CI 1.47-9.62; p = 0.006), metronidazole (HR 2.55; 95% CI 1.37-4.76; p = 0.003), or itraconazole (HR 4.11; 95% CI 1.79-9.45; p = 0.001) concomitantly with acenocoumarol treatment had an increased risk of overanticoagulation compared with patients using acenocoumarol and amoxicillin/clavulanic acid concomitantly. The associations for metronidazole (p = 0.045) and itraconazole (p = 0.015) remained statistically significant after correction for multiple testing.

CONCLUSION

Co-trimoxazole, metronidazole, and itraconazole increase the risk of overanticoagulation in patients using acenocoumarol. These combinations should be avoided if possible or otherwise acenocoumarol doses should be reduced and INR measured more frequently.

Risk of major bleeding during extended oral anticoagulation in patients with first unprovoked venous thromboembolism: a systematic review and meta-analysis protocol

BACKGROUND

The optimal duration of anticoagulation after a first unprovoked venous thromboembolism (VTE) remains controversial. Deciding to stop or continue anticoagulant therapy indefinitely after completing 3 to 6 months of initial treatment requires balancing the long-term risk of recurrent VTE if anticoagulation is stopped against the long-term risk of major bleeding if anticoagulation is continued. However, knowledge of the long-term risk for major bleeding events during extended anticoagulation in this patient population is limited. We plan to conduct a systematic review and meta-analysis to quantify the risk for major bleeding events during extended oral anticoagulation in patients with first unprovoked VTE.

METHODS

Electronic databases including MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials will be systematically searched with the assistance of an information specialist (from inception to March 1, 2019) to identify randomized controlled trials and prospective cohort studies reporting major bleeding during extended oral anticoagulation in patients with first unprovoked VTE, who have completed at least 3 months of initial anticoagulant therapy. Study selection, risk of bias assessment, and data extraction will be performed independently by at least two investigators. The number of major bleeding events and person-years of follow-up will be used to calculate the rate (events per 100 person-years) with its 95% confidence interval for each study cohort, during clinically relevant time periods of extended anticoagulant therapy. Results will be pooled using random effect meta-analysis.

DISCUSSION

The planned systematic review and meta-analysis will provide reliable estimates of the risk for major bleeding events during extended anticoagulation. This information will help inform patient prognosis and assist clinicians with balancing the risks and benefits of treatment to guide management of unprovoked VTE.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019128597 .

Bleeding and asymptomatic overdose in patients under Vitamin K antagonist therapy: Frequency and risk factors

Background

Vitamin K antagonists are widely used in the treatment and prevention of thromboembolic disease. However, these drugs can cause serious side effects, especially bleeding. This study aims to evaluate frequency and risk factors of both bleeding and asymptomatic overdose in North African patients undergoing Vitamin K antagonist therapy.

Methods

We performed a cross-sectional study in patients undergoing Vitamin K antagonist therapy. A statistical analysis has been conducted to identify overdose and bleeding risk factors by using chi-square test (p < .05).

Results

One hundred and eleven patients were included. We recorded 14 cases of bleeding and 26 cases of asymptomatic overdose. Advanced age, poor adherence, concomitant use of paracetamol and history of previous bleeding are significant risk factors of over-anticoagulation. An INR value over 6 at admission, a high therapeutic target range for INR, concomitant use of acetylsalicylic acid, lack of information on overdose signs and measures to be taken in case of bleeding were identified as risk factors for bleeding.

Conclusion

Most of the risk factors identified in our study seem to be related to patients lack of information and education. These results highlight the importance of creating a therapeutic patient education program.

Bleeding risk in patients with unprovoked venous thromboembolism: A critical appraisal of clinical prediction scores

Patients with unprovoked venous thromboembolism (VTE) should receive anticoagulant treatment for at least 3 to 6months. Thereafter, the decision to extend treatment indefinitely for secondary prevention of recurrent events is based on a personalized assessment of the risks of recurrent VTE and anticoagulant-related bleeding. Whereas there are clinical factors that identify patients at higher risk of recurrent VTE, factors to aid the prediction of major bleeding events during anticoagulant therapy have received much less attention. It is now clear that establishing an accurate estimate of the risk of major bleeding is required in treatment decision making. Several studies aimed at deriving new, or validating existing, clinical prediction scores for major bleeding in patients with VTE have been published. The aim of this review is to provide an overview of the available clinical prediction scores, highlighting the methodological shortcomings with their derivation and validation, summarize their performance, and provide considerations for bleeding risk assessment in clinical practice.

Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report

BACKGROUND

We update recommendations on 12 topics that were in the 9th edition of these guidelines, and address 3 new topics.

METHODS

We generate strong (Grade 1) and weak (Grade 2) recommendations based on high- (Grade A), moderate- (Grade B), and low- (Grade C) quality evidence.

RESULTS

For VTE and no cancer, as long-term anticoagulant therapy, we suggest dabigatran (Grade 2B), rivaroxaban (Grade 2B), apixaban (Grade 2B), or edoxaban (Grade 2B) over vitamin K antagonist (VKA) therapy, and suggest VKA therapy over low-molecular-weight heparin (LMWH; Grade 2C). For VTE and cancer, we suggest LMWH over VKA (Grade 2B), dabigatran (Grade 2C), rivaroxaban (Grade 2C), apixaban (Grade 2C), or edoxaban (Grade 2C). We have not changed recommendations for who should stop anticoagulation at 3 months or receive extended therapy. For VTE treated with anticoagulants, we recommend against an inferior vena cava filter (Grade 1B). For DVT, we suggest not using compression stockings routinely to prevent PTS (Grade 2B). For subsegmental pulmonary embolism and no proximal DVT, we suggest clinical surveillance over anticoagulation with a low risk of recurrent VTE (Grade 2C), and anticoagulation over clinical surveillance with a high risk (Grade 2C). We suggest thrombolytic therapy for pulmonary embolism with hypotension (Grade 2B), and systemic therapy over catheter-directed thrombolysis (Grade 2C). For recurrent VTE on a non-LMWH anticoagulant, we suggest LMWH (Grade 2C); for recurrent VTE on LMWH, we suggest increasing the LMWH dose (Grade 2C).

CONCLUSIONS

Of 54 recommendations included in the 30 statements, 20 were strong and none was based on high-quality evidence, highlighting the need for further research.

Acenocoumarol Pharmacogenetic Dosing Algorithms and Their Application in Two Bulgarian Patients with Low Anticoagulant Requirements

BACKGROUND

The anticoagulant therapy with acenocoumarol is generally associated with a high risk of bleeding and thromboembolic events.

PURPOSE

We applied eight already existing acenocoumarol dosing algorithms to Bulgarian patients with low acenocoumarol dose requirements and investigated which of these algorithms would predict most precisely the dose anticoagulant.

MATERIALS AND METHODS

Two patients with Bulgarian origin were referred to the outpatient clinical laboratory of "St. Ekaterina" University Hospital for Cardiovascular Surgery and Cardiology, Sofia, Bulgaria. After obtaining written informed consent, both patients were genotyped for polymorphisms in genes for Cytochrome P450 2C9 (CYP2C9), Vitamin K epoxide reductase (VKORC1), Apolipoprotein E (APOE), and Cytochrome P450 4F2 (CYP4F2).

RESULTS

All applied acenocoumarol dosing algorithms predicted relatively similar doses of coumarin anticoagulant in both patients. However, van Schie et al.'s algorithm allowed more accurate calculation of the optimal dose in our patients with extremely low acenocoumarol requirements. Genotyping of selected polymorphic variants in CYP2C9 and VKORC1 showed that both patients were compound heterozygotes for CYP2C9 (CYP2C9*2/*3) and homozygotes for both variants in VKORC1 (VKORC1 1173 T/T, and VKORC1-1639 A/A). This combination of genotypes suggested high sensitivity to acenocoumarol leading to the low anticoagulant dose requirements (0.25 and 1 mg/day, respectively) needed to reach the target International Normalized Ratio of 2.5-3.5.

CONCLUSIONS

The genotyping of polymorphic variants in VKORC1 and CYP2C9, together with clinical and demographic parameters, can serve for more precise definition of the individual starting and maintenance doses of coumarin derivatives in each patient.

Comparison of four scores to predict major bleeding in patients receiving anticoagulation for venous thromboembolism: findings from the RIETE registry

Stratification of the individual bleeding risk prior to initiation of anticoagulation in patients with acute venous thromboembolism (VTE) has the potential to assist clinicians in making decisions about the proper intensity and duration of antithrombotic therapy. It is unclear which of the validated and internationally accepted scores recommended for the achievement of this important task has the best predictive value. We compared the predictive value of four validated scores (by Landefeld, Beyth, Kuijer and Ruiz-Gimenez, respectively) for the development of major bleeding complications occurring in the first 3 months in patients with acute VTE treated with conventional anticoagulation. Based on the population of RIETE Registry (international registry of patients with acute VTE), we identified those patients presenting all the required prognostic variables, and then calculated the ability of each score for predicting the bleeding risk. Of 40,265 eligible patients, we identified 8,717 meeting the recruitment criteria. Overall, 0.9 % of patients experienced at least one episode of major bleeding within 90 days of the index event. The proportion of patients classified as having a low risk varied between 1.2 and 3.7 %, that of patients having an intermediate risk between 76 and 93 %, and that of patients classified as having a high risk between 6.1 and 18 %. The area under the receiver operating characteristic ranged between 0.55 and 0.60, the positive predictive value between 1.5 and 3.2, and the likelihood ratio between 0.72 and 1.59. In conclusion, all four scores show a very low ability to predict the bleeding risk in patients with acute VTE undergoing conventional anticoagulation.

Predicting anticoagulant-related bleeding in patients with venous thromboembolism: a clinically oriented review

Diagnosis of venous thromboembolism (VTE) requires prompt treatment with anticoagulants in therapeutic doses. Since these drugs are associated with the occurrence of haemorrhage, identification of patients at increased risk of major bleeding is of utmost clinical importance for defining the optimal treatment regimen and duration of anticoagulation. Current suggested prediction scores for bleeding risk in VTE patients have been derived from observational studies of moderate quality, or from patients with various indications for therapeutic anticoagulation other than VTE. To date, none of the scores have been adequately validated in cohorts that underwent dedicated monitoring and independent adjudication of bleeding complications. In addition, while the scarce available evidence has focused on patients treated with heparins and/or vitamin K antagonists, risk stratification scores for bleeding complications in VTE patients treated with non-vitamin K dependent anticoagulants have not yet been developed. This clinically oriented review covers the incidence and risk factors of anticoagulation-related bleeding in VTE patients treated with different anticoagulant drugs as well as the available bleeding-prediction scores. Further, we attempt to provide guidance for bleeding-prevention in clinical practice and speculate on developments in the near future that may fundamentally change our current thinking on VTE management.

The Ross Operation in Children and Young Adults

Objectives:

To determine UK national trends and results of the Ross operation in relation to all aortic valve interventions.

Methods:

Examination of the UK Congenital Central Cardiac Audit Database for all aortic valve procedures performed between 2000 and 2011 in children (0-16 years) and young adults (16-30 years).

Results:

A total of 2,206 aortic valve procedures were performed in children and 1,824 in young adults, the proportions in the two groups being: Ross operation (19% vs 15%, respectively), surgical valvoplasty (9.5% vs 4%), surgical valvotomy (9.5% vs 1%), aortic valve replacement (AVR; 11% vs 55%), aortic root replacement (4% vs 18%), and balloon valvoplasty (47% vs 7%). The 30-day and 1-year survival after Ross is 99.3% and 98.7%, respectively, in the last four years achieving 100%. In children, the proportion of balloon valvoplasty increased from an average of 43% in 2000 to 2006 to 53% in 2007 to 2011, whereas the Ross operation decreased from 22% to 16% ( P < .001). In young adults, the figures are an increase from 49% to 58% for AVR compared to a decrease from 23% to 9% for Ross ( P < .001). Our own single-center series of 91 patients also shows standard results for early- and long-term survival and freedom from reoperation, but gradually fewer Ross operations performed. The year-on-year changes show a significant decreasing trend locally and nationally.

Conclusions:

Despite an excellent track record, the Ross operation is performed less frequently in the United Kingdom. This report is a first step in comparing treatment modalities at national level.

Influence of sex on risk of bleeding in anticoagulated patients: a systematic review and meta-analysis

BACKGROUND

The risk of bleeding on anticoagulation varies between patients. It is uncertain whether sex influences this risk.

OBJECTIVES

To determine if the risk of major bleeding differs between men and women receiving anticoagulation for atrial fibrillation or venous thromboembolism(VTE).

METHODS

We searched MEDLINE, EMBASE, and Cochrane databases, and relevant conference proceedings, until February 2013. We included randomized controlled trials and prospective cohort studies of patients on therapeutic anticoagulation for atrial fibrillation or VTE. Two reviewers independently extracted data. The relative risk of bleeding in men compared to women was pooled using a random-effects model.

RESULTS

Forty-two studies including 94 293 patients were eligible; 78 044 patients (83%) had atrial fibrillation; 16 156 patients (17%) had VTE; 37 250 patients were women (40%); and there were 4147 major bleeds. The relative risk of major bleeding for men vs. women was 1.02(95% CI 0.95–1.10; P = 0.27 for heterogeniety). The relative risk was 1.02 (95% CI 0.95–1.09) in patients with atrial fibrillation and 0.80 (95% CI 0.65–0.98) in patients with VTE (P = 0.03 for subgroup effect). Type of anticoagulant,intensity of anticoagulation, and whether patients began or were already established on anticoagulants at enrollment did not influence the relative risk of major bleeding in men compared to women.

CONCLUSIONS

The risk of major bleeding on anticoagulation appears to be the same in men and women, particularly if patients have atrial fibrillation. This finding is less certain for patients with VTE, in whom the risk of bleeding may be marginally lower in men compared to in women.

Novel oral anticoagulants for stroke prevention in the geriatric population

Prior to the availability of several newer anticoagulant medications, there had been no new advances in anticoagulation management for stroke prevention since the advent of warfarin in the 1950s. The availability of the novel oral anticoagulants (NOACs) dabigatran, rivaroxaban,and apixaban represent improvements over warfarin in many respects, including the elimination of the need for therapeutic drug monitoring, fewer drug and food interactions,and favorable efficacy; however, these agents are not without risk. Specifically, the use of the NOACs in the geriatric population, who are more likely to have an increased risk of stroke due to atrial fibrillation and other medical comorbidities, is not without risk. The objective of this review is to update the clinician on the use of the NOACs in the geriatric population and introduce the controversies and risks surrounding these newer therapies.

Management of Anticoagulant Therapy for Patients with Prosthetic Heart Valves or Atrial Fibrillation

There is a wide array of recommendations for the management of anticoagulant therapy in patients with mechanical heart valves. Especially the optimal intensity of vitamin K antagonists (VKA) is a ongoing matter of debate. On the basis of several studies, recommendations for daily clinical practice can be made. In this review, we discussed the studies and the different guidelines. Guidelines for the prevention of thromboembolic complications in patients with atrial fibrillation are more stringent. VKA with a target INR between 2.0 and 3.0 is more effective in the prevention of stroke than aspirin, especially in the presence of riskfactors for thromboembolism (age above 65, previous thromboembolism, history of hypertension and diabetes, enlarged left atrial diameter and left ventricular dysfunction). In the absence of clinical or echocardiographical riskfactors for thromboembolism, patients may be safely treated with aspirin.

Hospitalization for vitamin-K-antagonist-related bleeding: treatment patterns and outcome

BACKGROUND

Bleeding complications are common side effects of vitamin-K antagonist (VKA) therapy. Data on the in-hospital management and outcomes of these bleeding events are scarce and information is mostly derived from trial cohorts.

OBJECTIVES

The objective was to collect data on the management and clinical outcome of hospitalizations owing to VKA-related bleeding in real-world practice.

PATIENTS AND METHODS

We performed a multicenter observational cohort study involving 21 secondary and tertiary care hospitals in the administrative district Dresden, Saxony, Germany throughout the year 2005. All consenting patients presenting with VKA-related bleeding complications were included. No exclusion criteria applied. Data were collected at admission, at discharge and at 90 days to evaluate resource consumption, length of hospital stay and risk factors for in-hospital- and 3-month mortality.

RESULTS

Two hundred and ninety patients were included (median age 74 years; 50.7% male). The main indications for VKA therapy were atrial fibrillation (63.4%), prior thromboembolism (18.6%) and mechanical heart valves (11.4%), and most common bleeding localizations were large hematoma (23.1%), upper gastrointestinal (GI) tract (17.9%) and intracranial bleeding (14.1%). On hospital admission, the median International Normalized Ratio (INR) was 3.0 (range 0.9-12.5, interquartile range [IQR] 2.1-3.9). In-hospital mortality was 7.6% with impaired renal function as the most relevant risk factor. At 90 days mortality was 14.1% and 15.3% of survivors were help-dependent.

CONCLUSIONS

VKA-related bleeding leading to hospitalization is associated with long hospitalization, relevant resource utilization, high mortality or persistent sequlae. Patient-related factors such as impaired renal function, chronic cardiac or pulmonary disease and dementia are predictive of in-hospital and 3-month mortality.

Identification and weighting of the most critical "real-life" drug-drug interactions with acenocoumarol in a tertiary care hospital

PURPOSE

The objective of this study was to identify the most clinically relevant drug-drug interactions (DDIs) at risk of affecting acenocoumarol safety in our tertiary care university hospital, a 2,000 bed institution.

METHODS

We identified DDIs occurring with acenocoumarol by combining two different sources of information: a 1-year retrospective analysis of acenocoumarol prescriptions and comedications from our Computerized Physician Order Entry (CPOE) system (n = 2,439 hospitalizations) and a retrospective study of clinical pharmacology consultations involving acenocoumarol over the past 14 years (1994-2007) (n = 407). We classified these DDIs using an original risk-analysis method. A criticality index was calculated for each associated drug by multiplying three scores based on mechanism of interaction, involvement in a supratherapeutic international normalized ratio (INR) (≥ 6) and involvement in a severe bleeding.

RESULTS

One hundred and twenty-six DDIs were identified and weighted. Twenty-eight drugs had a criticality index ≥ 20 and were therefore considered at high risk for interacting with acenocoumarol by increasing its effect: 75% of these drugs involved a pharmacokinetic mechanism and 14 % a pharmacodynamic mechanism. An unknown mechanism of interaction was involved in 11 % of drugs.

CONCLUSION

Twenty-eight specific drugs were identified as being at high risk for interacting with acenocoumarol in our hospital using an original risk-analysis method. Most analyzed drugs interact with acenocoumarol via a pharmacokinetic mechanism. Actions such as the implementation of alerts in our CPOE system should be specifically developed for these drugs.

Predicting the risk of venous thromboembolism recurrence

Venous thromboembolism (VTE) is a chronic disease with a 30% ten-year recurrence rate. The highest incidence of recurrence is in the first 6 months. Active cancer significantly increases the hazard of early recurrence, and the proportions of time on standard heparin with an APTT ≥ 0.2 anti-X(a) U/mL, and on warfarin with an INR ≥ 2.0, significantly reduce the hazard. The acute treatment duration does not affect recurrence risk after treatment is stopped. Independent predictors of late recurrence include increasing patient age and body mass index, leg paresis, active cancer and other persistent VTE risk factors, idiopathic VTE, antiphospholipid antibody syndrome, antithrombin, protein C or protein S deficiency, hyperhomocysteinemia and a persistently increased plasma fibrin D-dimer. A recommendation for secondary prophylaxis should be individualized based on the risk for recurrent VTE (especially fatal pulmonary embolism) and bleeding. The appropriateness of secondary prophylaxis should be continuously reevaluated, and the prophylaxis stopped if the benefit no longer exceeds the risk.

Long-term anticoagulant effects of the CYP2C9 and VKORC1 genotypes in acenocoumarol users

BACKGROUND

The required acenocoumarol dose and the risk of underanticoagulation and overanticoagulation are associated with the CYP2C9 and VKORC1 genotypes. However, the duration of the effects of these genes on anticoagulation is not yet known.

OBJECTIVES

In the present study, the effects of these polymorphisms on the risk of underanticoagulation and overanticoagulation over time after the start of acenocoumarol were investigated.

PATIENTS/METHODS

In three cohorts, we analyzed the relationship between the CYP2C9 and VKORC1 genotypes and the incidence of subtherapeutic or supratherapeutic International Normalized Ratio (INR) values (< 2 and > 3.5) or severe overanticoagulation (INR > 6) for different time periods after treatment initiation.

RESULTS

Patients with polymorphisms in CYP2C9 and VKORC1 had a higher risk of overanticoagulation (up to 74%) and a lower risk of underanticoagulation (down to 45%) in the first month of treatment with acenocoumarol, but this effect diminished after 1-6 months.

CONCLUSIONS

Knowledge of the patient's genotype therefore might assist physicians to adjust doses in the first month(s) of therapy.

Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This article addresses the treatment of VTE disease.

METHODS

We generated strong (Grade 1) and weak (Grade 2) recommendations based on high-quality (Grade A), moderate-quality (Grade B), and low-quality (Grade C) evidence.

RESULTS

For acute DVT or pulmonary embolism (PE), we recommend initial parenteral anticoagulant therapy (Grade 1B) or anticoagulation with rivaroxaban. We suggest low-molecular-weight heparin (LMWH) or fondaparinux over IV unfractionated heparin (Grade 2C) or subcutaneous unfractionated heparin (Grade 2B). We suggest thrombolytic therapy for PE with hypotension (Grade 2C). For proximal DVT or PE, we recommend treatment of 3 months over shorter periods (Grade 1B). For a first proximal DVT or PE that is provoked by surgery or by a nonsurgical transient risk factor, we recommend 3 months of therapy (Grade 1B; Grade 2B if provoked by a nonsurgical risk factor and low or moderate bleeding risk); that is unprovoked, we suggest extended therapy if bleeding risk is low or moderate (Grade 2B) and recommend 3 months of therapy if bleeding risk is high (Grade 1B); and that is associated with active cancer, we recommend extended therapy (Grade 1B; Grade 2B if high bleeding risk) and suggest LMWH over vitamin K antagonists (Grade 2B). We suggest vitamin K antagonists or LMWH over dabigatran or rivaroxaban (Grade 2B). We suggest compression stockings to prevent the postthrombotic syndrome (Grade 2B). For extensive superficial vein thrombosis, we suggest prophylactic-dose fondaparinux or LMWH over no anticoagulation (Grade 2B), and suggest fondaparinux over LMWH (Grade 2C).

CONCLUSION

Strong recommendations apply to most patients, whereas weak recommendations are sensitive to differences among patients, including their preferences.

Risk factors of vitamin K antagonist overcoagulation

OBJECTIVES

The aims of this prospective study were to identify, in vitamin K antagonist (VKA)-treated patients, factors associated with INR values: (i) greater than 6.0. and (ii) ranging from 4.0 to 6.0 complicated with bleeding. We also assessed VKA-related morbidity in these patients.

METHODS

During a 6-month period, 3090 consecutive patients were referred to our Department of Internal Medicine, including 412 VKA-treated patients. At admission, the medical records of VKA-treated patients were reviewed for type, duration and indication of VKA therapy, previous medical history of VKA-related hemorrhage, comorbidities and concomitant medications.

RESULTS

Forty of the 412 VKA-treated patients (9.7%) exhibited oral anticoagulant related overcoagulation. VKA overcoagulation was associated with high morbidity, leading to major bleeding in 27.5% of cases; moreover, 12.5% of these patients died, death being mainly due to major bleeding. Under multivariate analysis, significant factors for VKA-related overcoagulation were as follows: previous medical history of VKA therapy-related hemorrhage (P=0.00001) and INR levels over therapeutic range (P=0.0006), chronic liver disease (P=0.03), therapy with amiodarone (P=0.009); in contrast, statin therapy was found to be a protective factor of VKA overcoagulation (P=0.008).

CONCLUSIONS

The knowledge of predictive factors of VKA-related overcoagulation seems of utmost importance to improve patients' management. Our study underlines the fact that the potential of drug interaction should be taken into account when choosing amiodarone for patients receiving VKAs. Interestingly, long-term (>6 month) statin therapy may be a protective factor of VKA overcoagulation. Our findings, therefore, suggest that there may be no need to switch long-term users of VKA and statin to a safer alternative therapy.

Evidence-based approach to thrombophilia testing

Thrombophilia can be identified in about half of all patients presenting with VTE. Testing has increased tremendously for various indications, but whether the results of such tests help in the clinical management of patients has not been settled. I use evidence from observational studies to conclude that testing for hereditary thrombophilia generally does not alter the clinical management of patients with VTE, with occasional exceptions for women at fertile age. Because testing for thrombophilia only serves limited purpose this should not be performed on a routine basis.

Thrombophilia screening--at the right time, for the right patient, with a good reason

Thrombophilia can be identified in about half of all patients presenting with venous thromboembolism (VTE). Thrombophilia screening for various indications has increased tremendously, but whether the results of such tests help in the clinical management of patients is uncertain. Here, current recommendations for thrombophilia screening in selected groups of patients, and considerations whether other high-risk subjects should be tested are reviewed. The methods for determination of the most common thrombophilic defects (antithrombin, protein C, protein S deficiencies, Factor V Leiden and prothrombin G20210A) associated with strong to moderate risk of VTE are described, indicating the timing and location of thrombophilia screening. Circumstances when a positive result of thrombophilia screening helps clinicians decide if adjustments of the anticoagulant regime are needed are discussed. Finally, psychological, social and ethical dilemmas associated with thrombophilia screening are indicated.

Usefulness of microsimulation to translate valve performance into patient outcome: Patient prognosis after aortic valve replacement with the Carpentier–Edwards supra-annular valve

OBJECTIVE

Numerous reports have been published documenting the results of aortic valve replacement. It is often not easy to translate these outcomes involving the condition of the valve into the actual consequences for the patient. We previously developed an alternative method to study outcome after aortic valve replacement that allows direct estimation of patient outcome after aortic valve replacement: microsimulation modeling. The goal of this article is to provide insight into microsimulation methodology and to give an overview of the advantages and disadvantages of simulation methods (in particular microsimulation) in comparison with standard methods of outcome analysis.

METHODS

By using a primary dataset containing 1847 patients and 14,429 patient-years, advantages and disadvantages of standard methods of outcome analysis are discussed, and the potential role of microsimulation is illustrated by means of a step-by-step explanation of building, testing, and using such a model.

RESULTS

Total life expectancy, event-free life expectancy, and reoperation-free life expectancy for a 65-year-old male patient were 10.6 years, 9.2 years, and 9.8 years, respectively. Lifetime risk of reoperation due to structural valve deterioration was 13.3%.

CONCLUSIONS

Microsimulation is capable of providing accurate estimates of age-related life expectancy and lifetime risk of reoperation for patients who underwent aortic valve replacement with the Carpentier-Edwards supra-annular valve. It provides a useful tool to facilitate and optimize the choice for a specific heart valve prosthesis in a particular patient.

Warfarin metabolism and anticoagulant effect: a prospective, observational study of the impact of CYP2C9 genetic polymorphism in the presence of drug-disease and drug-drug interactions

BACKGROUND

Cytocbrome P450 (CYP) 2C9 polymorphism affects the warfarin dosage requirement in stable outpatients. However, it is not known whether the CYP2C9 genotype contributes to the variability in warfarin dosage in the presence of drug-disease and drug-drug interactions.

OBJECTIVE

The aim of this study was to examine the effects of CYP2C9 genetic polymorphism on warfarin dosage requirements in patients with severe comorbid conditions and those treated with medications that potentially interact with warfarin.

METHODS

This prospective, observational study was conducted at Hadassah University Hospital, Jerusalem, Israel. Data from consecutive patients treated with warfarin for at least 3 months and admitted to the internal medicine ward were eligible for inclusion. Clinical data, international normalized ratio (INR), and warfarin dosage were recorded from medical records. The CYP2C9 genotype was determined using polymerase chain reaction restriction fragment length polymorphism, and plasma concentrations of (S)- and (R)-warfarin were determined by high-performance liquid chromatography using chiral methods.

RESULTS

One hundred nineteen subjects (52% women) were studied. Mean age was 65.8 years (95% CI, 63.1-68.4), and weight was 74.9 kg (95% CI, 72.1-77.7). The mean warfarin dosage was 33% lower in patients with the CYP2C9-*1/*3 genotype (mean [SEM], 0.045 [0.006] mg/kg x d(-1)) compared with the CYP2C9-*1/*1 genotype (0.067 [0.004] mg/kg x d(-1)) (P=0.008); an intermediate value was found for the CYP2C9-*1/*2 genotype (0.062 [0.008] mg/kg x d(-1)). However, despite the lower dosage, INR was significantly higher in patients with the *1/*3 genotype (mean [95% CI], 3.29 [2.44-4.14]) (n=18) compared with the *1/*1 genotype (2.52 [2.34-2.71]) (n=64) (P=0.029). In addition to genotype, older age, congestive heart failure (CHF), and treatment with antibiotics were associated with lower warfarin dosages, whereas treatment with drug-metabolism inducers was associated with higher warfarin dosages. In addition, the ratios of (S)- to (R)-warfarin concentrations were significantly higher in patients with *1/*3 compared with those in patients with the *1/*1 genotype.

CONCLUSIONS

In this study population of patients with severe comorbid conditions and those treated with medications that potentially interact with warfarin, CYP2C9 *1/*3 genotype, older age, CHF, and the use of antibiotics were associated with lower warfarin dosage requirements. The CYP2C9*1/*3 genotype, compared with CYP2C9 *1/*1, was associated with 33% lower mean warfarin dosage requirements and higher INR values, which were higher than the upper therapeutic range of INR (ie, 3). Genetic CYP2C9 polymorphism contributed to the variability in warfarin dosage requirements in the presence of drug-disease and drug-drug interactions.

The quality of oral anticoagulant therapy and recurrent venous thrombotic events in the Leiden Thrombophilia Study

BACKGROUND

The International Normalized Ratio (INR) target range is a relatively narrow range in which the efficacy of oral anticoagulant treatment, i.e. prevention of extension and recurrence of thrombosis, is balanced with the risk of hemorrhagic complications. Over the years, different INR target ranges have been implemented for individual indications, depending on their thrombotic potential. In most of the studies defining these INR targets, the treatment of the patients was aimed at a certain INR range, but in the analysis no account was taken of the time that the patients spent within this range in reality.

METHODS

The Leiden Thrombophilia Study (LETS) is a population-based case-control study on risk factors for venous thrombosis, in which many genetic and acquired factors have been investigated. Our aim was to investigate the effect of the quality of the oral anticoagulant therapy for the initial venous thrombosis and its relationship with recurrence of thrombosis. Quality of anticoagulation was defined as the time spent at various INR levels during treatment, and we focused on the effect of sustained intensities above a certain INR in preventing recurrences later on.

RESULTS

Two hundred and sixty-six patients with a total follow-up of 2495 patient-years were studied. The mean duration of the initial anticoagulant therapy was 194.5 days (range 48-4671). During follow-up, 58 recurrences were diagnosed (cumulative recurrence rate of 21.8% over 9 years). The mean INR during initial therapy was 2.90, with 90.3% [95% confidence interval (CI) 88.4-92.3%] of the time being spent above an INR of 2.0, and 39.1% (95% CI 35.5-42.7%) above an INR of 3.0. Patients who spent more time below the target range, or who had a shorter duration of anticoagulation, did not experience a higher risk of recurrence after the initial period of anticoagulation had passed.

CONCLUSION

Provided that oral anticoagulant treatment is adequately managed, according to international guidelines, recurrent thrombosis cannot be ascribed to variation in the primary treatment. Further attempts to reduce the risk of recurrence should therefore be aimed at identifying other explanatory factors, and subsequently fine-tuning the target ranges.

Quantity and quality of potential drug interactions with coumarin anticoagulants in the Netherlands

OBJECTIVE

Coumarin anticoagulants are prone to potentially life-threatening drug-drug interactions due to a combination of unfavorable properties. However, real life data on the actual occurrence are scarce. The aim of this study was to quantify and qualify potential drug interactions with coumarin anticoagulants in daily practice.

METHODS

A cohort study including all users of phenprocoumon or acenocoumarol during the period 1991-2003 in the PHARMO Record Linkage System. All 24 individual drugs and 11 drug groups interacting with coumarins according to central database used in the Dutch pharmacies were considered.

MAIN OUTCOME MEASURE

Frequency and type of potential drug interactions during anticoagulant therapy with coumarins.

RESULTS

48,627 out of 76,455 mainly acenocoumarol-users (64%) were dispensed at least one potentially interacting drug (PID) during anticoagulant therapy. About 35% of these cases were dispensed a (very) strongly interacting drug, whereas 3% were dispensed a contraindicated drug. Antibacterial drugs and NSAIDs (39% and 37% of all users, respectively) were the most frequently dispensed PIDs.

CONCLUSION

Potential drug interactions with coumarins frequently occur in daily practice, confronting two-thirds of patients with an increased risk of bleeding. To a large part, this is attributable to commonly prescribed medication like antibacterial drugs and NSAIDs. This situation substantiates the need for proper monitoring or new anticoagulants with less drug-drug interactions.

VKORC1 and CYP2C9 genotypes and phenprocoumon anticoagulation status: interaction between both genotypes affects dose requirement

In a prospective follow-up study of the effects of VKORC1 and CYP2C9 genotypes on the anticoagulation status of patients, we assessed the CYP2C9 and the VKORC1 C1173T genotypes of patients during the initial 6 months of phenprocoumon treatment. We used linear regression models and Cox proportional hazard models to determine the effects of the VKORC1 and CYP2C9 genotypes on phenprocoumon dose requirements, overanticoagulation, and time to achieve stability. Allele frequencies of interest within the cohort (N=281) were 40.8% VKORC1 T-1173, 12.8% CYP2C9*2, and 6.9% CYP2C9*3. In patients with the VKORC1 CC genotype, carriers of a CYP2C9 polymorphism needed dosages that were nearly 30% lower than those for CYP2C9*1/*1 patients (P<0.001). In patients with a VKORC1 polymorphism, differences between carriers of a CYP2C9 polymorphism and CYP2C9*1/*1 were far smaller and largely not statistically significant. A larger part of the variability in dose requirement was explained by the VKORC1 genotype than by the CYP2C9 genotype (28.7% and 7.2%, respectively). Carriers of a combination of a CYP2C9 polymorphism and a VKORC1 polymorphism had a strongly increased risk of severe overanticoagulation (hazard ratio (HR) 7.20, P=0.002). Only carriers of a CYP2C9*2 allele had a decreased chance to achieve stability compared to CYP2C9*1/*1 patients (HR 0.61, P=0.004). In conclusion, the VKORC1 genotype modifies the effect of the CYP2C9 genotype on phenprocoumon dose requirements. A combination of polymorphisms of both genotypes is associated with a strongly increased risk of overanticoagulation, whereas delayed stabilization is mainly associated with the CYP2C9 genotype.

Duration of anticoagulation: decision making based on absolute risk

We are often faced with the question as to the optimum duration of secondary prophylaxis with oral anticoagulants after an episode of venous thromboembolism. Theoretically if we know the recurrence rate, the case-fatality, the effectiveness of oral anticoagulant therapy, and the rate of fatal haemorrhage on treatment, we can calculate whether being on or off treatment is safest. Using these data and considering only the risk of death we would treat idiopathic deep vein thrombosis for six months. For those with DVT associated with a transient risk factor it would be reasonable to stop treatment after 3 months in those over 50 years old and we should certainly stop after 3 months in those over 70 years old. There are data to suggest that pulmonary embolism may have a higher case-fatality than deep vein thrombosis if there is a recurrence. If these data were accepted most patients with idiopathic pulmonary embolism would get long-term treatment. We can use these models to modify our assessment if other factors such as antiphospholipid antibodies or cancer are present.

Population screening for single genes that codetermine common diseases in adulthood had limited effects

BACKGROUND AND OBJECTIVE

Familial hemochromatosis (FHEM), familial hypercholesterolemia (FH), familial mediterranean fever (FMF), and familial thrombophilia (FT) are relatively common genetically determined diseases of (early) adulthood. Chances, shortcomings, and practical aspects of population screening were considered.

METHODS

The literature, as well as existing data concerning the treatment of these diseases in The Netherlands, were studied.

RESULTS

In these four diseases there are so many modifying genes and environmental and lifestyle influences that accurate predictive testing at the population level is currently not sufficiently effective. The data indicate that the implementation of family clinics for FHEM and FH are necessary. There is need for further sociologic studies in the moslim population of Mediterranean and North African origin about acceptance of DNA diagnostics in relation to consanguinity and into the problem of "pseudodominance." There seems no need for early detection and preventive measures for FT in asymptomatic persons.

CONCLUSION

No population screening for these four genetically determined diseases of (early) adulthood is sufficiently effective at the present time. We propose to call these diseases "chronic diseases with a single gene component."

Clinical classification schemes for predicting hemorrhage: results from the National Registry of Atrial Fibrillation (NRAF)

BACKGROUND

Although warfarin and other anticoagulants can prevent ischemic events, they can cause hemorrhage. Quantifying the rate of hemorrhage is crucial for determining the risks and net benefits of prescribing antithrombotic therapy. Our objective was to find a bleeding classification scheme that could quantify the risk of hemorrhage in elderly patients with atrial fibrillation.

METHODS

We combined bleeding risk factors from existing classification schemes into a new scheme, HEMORR2HAGES, and validated all bleeding classification schemes. We scored HEMORR2HAGES by adding 2 points for a prior bleed and 1 point for each of the other risk factors: hepatic or renal disease, ethanol abuse, malignancy, older (age > 75 years), reduced platelet count or function, hypertension (uncontrolled), anemia, genetic factors, excessive fall risk, and stroke. We used data from quality improvement organizations representing 7 states to assemble a registry of 3791 Medicare beneficiaries with atrial fibrillation.

RESULTS

There were 162 hospital admissions with an International Classification of Diseases, Ninth Revision, Clinical Modification code for hemorrhage. With each additional point, the rate of bleeding per 100 patient-years of warfarin increased: 1.9 for 0, 2.5 for 1, 5.3 for 2, 8.4 for 3, 10.4 for 4, and 12.3 for > or =5 points. In patients prescribed warfarin, HEMORR2HAGES had greater predictive accuracy (c statistic 0.67) than other bleed prediction schemes (P < .001).

CONCLUSIONS

Adaptations of existing classification schemes, especially a new bleeding risk scheme, HEMORR2HAGES, can quantify the risk of hemorrhage and aid in the management of antithrombotic therapy.

Experience with INR self-management: patient selection and complication rates

BACKGROUND

INR self-management can reduce the risk of complications for patients with indication of long-term oral anticoagulation therapy. However, little is known about early indicators of complication risk.

METHODS

In a prospective study on 330 consecutive patients all participants were informed about oral anticoagulation by a structured teaching program. The two groups were divided as to whether they received usual medical care provided by a family physician (n=220) or self-management (n=110) on a portable coagulation monitor (CoaguChek System). After a mean follow up of 13.3+/-4.4 months, the participants of the study were interviewed by a structured questionnaire to obtain information about hemorrhagic and thromboembolic complications as well as survival.

RESULTS

In comparison to patients under usual care, patients with INR selfmanagement were significantly younger (58 vs 64 years) and had fewer comorbidities (diabetes and hypertension) as well as a higher ejection fraction (53.6 vs 51.1%). Indication for anticoagulation, age and heart rhythm explained 58% of the differences between the management groups. There was no significant difference in the overall complication rates between the two groups (usual care vs selfmanagement): major bleeding 0.5 vs 0.9%, cerebral embolism (TIA or stroke) 1.9 vs 0.9%, hospital admission 2.3 vs 1.8%. A high BMI (OR=1.5; 95% CI 1.06-1.25; p=0.001) or a high therapeutic INR range (OR=2.42; 95% CI 1.16-5.1; p=0.019) is associated with a higher complication rate.

CONCLUSIONS

Complication rates for patients with long-term oral anticoagulant therapy did not differ significantly between usual care and self-management. Rather, the patient's body weight and the requirement of high anticoagulation intensity drive the complication risk under both management systems.

Self-management of oral anticoagulation in nonvalvular atrial fibrillation (SMAAF study)

Most patients with atrial fibrillation are at risk of suffering thromboembolic events. This risk can be reduced by twothirds by efficient anticoagulation. This prospective multi-center trial investigated whether the quality of treatment can be improved by self-management in patients with atrial fibrillations (SMAAF Study) compared to conventional patient management by the family doctor.

METHODS

Two thousand patients suitable for self-management were to be randomized into the two arms of the study. In the period of investigation from December 1999 to July 2001, only 202 patients (64.3+/-9.2 years, 69.3% men) consented to participate. The study was discontinued prematurely since the number of patients was too low. As a consequence, the group comparison is confined to the evaluation of the INR values measured using the two-tailed t test.

RESULTS

Of the 202 patients included, 101 were assigned to the self-management group (64.6+/-9.6 years, 71.4% men) and 101 (64.1+/-8.9 years, 61.4% men, n.s.) were assigned to the group managed by the family doctor. The total number of INR measurements was 2 865. This comprised 2 072 measurements in patients under self-management and 793 in the family doctor group. The values were within the target range significantly more frequently (p=0.0061) in patients under self-management (67.8%) as compared to the family doctor group (58.5%). There was a trend with regard to the time within target range, but the difference was not significant (178.8+/-126 days as compared to 155.9+/-118.4 days). In the self-management group, there were two severe hemorrhages, and there was one thromboembolic event in the family doctor group.

CONCLUSION

Management of oral anticoagulation by INR self-management in patients with atrial fibrillation is not inferior to conventional care.

Main comedications associated with major bleeding during anticoagulant therapy with coumarins

OBJECTIVE

To study the main comedications associated with major bleeding during anticoagulant therapy with coumarins in a non-selected population under everyday circumstances.

METHODS

The study population for this retrospective cohort study included all new users of phenprocoumon or acenocoumarol aged 40-80 years, during the period 1992-2000 in the PHARMO Record Linkage System. All patients were followed until the last dispensing of phenprocoumon or acenocoumarol, the first bleeding complication requiring hospitalization, death, or the end of the study period. The number of days on coumarins alone and the number of days on coumarins in combination with several potentially interactive drugs during follow-up were determined for each patient.

RESULTS

The inclusion criteria of this study were met by 19,935 new users of phenprocoumon or acenocoumarol. During follow-up, 552 patients were hospitalized for bleeding. Of all potentially interactive drugs started during anticoagulant therapy by at least 50 patients and with at least five bleedings, antibacterial drugs were associated with a four to seven times increased risk of bleeding. Among non-steroidal anti-inflammatory drugs, naproxen had the highest relative risk. Antithrombotic salicylates and tramadol were associated with a three times increased risk of bleeding.

CONCLUSION

Antibacterial drugs, non-steroidal anti-inflammatory drugs, antithrombotic salicylates and tramadol were the main potentially interactive drugs associated with major bleeding during anticoagulant therapy with coumarins under everyday circumstances.

Oral anticoagulation strategies after a first idiopathic venous thromboembolic event

PURPOSE

The optimal duration and intensity of warfarin therapy after a first idiopathic venous thromboembolic event are uncertain. We used decision analysis to evaluate clinical and economic outcomes of different anticoagulation strategies with warfarin.

METHODS

We built a Markov model to assess 6 strategies to treat 40- to 80-year-old men and women after their first idiopathic venous thromboembolic event: 3-month, 6-month, 12-month, 24-month, and unlimited-duration conventional-intensity anticoagulation (International Normalized Ratio, 2-3) and unlimited-duration low-intensity anticoagulation (International Normalized Ratio, 1.5-2). The model incorporated age- and sex-specific clinical parameters, utilities, and costs. Using a societal perspective, we compared strategies based on quality-adjusted life-years (QALYs), lifetime costs, and incremental cost-effectiveness ratios.

RESULTS

In our baseline analysis, incremental cost-effectiveness ratios were lower in younger patients and in men, reflecting the higher bleeding risk at older ages, and the lower risk of recurrence among women. Based on a willingness-to-pay of <$50000/QALY, the 24-month strategy was most cost-effective in 40-year-old men ($48805/QALY), while the 6-month strategy was preferred in 40-year-old women ($35977/QALY) and 60-year-old men ($29878/QALY). In patients aged >/=80 years, 3-month anticoagulation was less costly and more effective than other strategies. Cost-effectiveness results were influenced by the risks associated with recurrent venous thromboembolism, the major bleeding risk of conventional-intensity anticoagulation and the disutility of taking warfarin.

CONCLUSION

Longer initial conventional-intensity anticoagulation is cost-effective in younger patients while 3 months of anticoagulation is preferred in elderly patients. Patient age, sex, clinical factors, and patient preferences should be incorporated into medical decision making when selecting an appropriate anticoagulation strategy.

Plasma coagulation markers in patients with solid tumors and venous thromboembolic disease receiving oral anticoagulation therapy

PURPOSE

To correlate the concentration of plasma coagulation markers at baseline and during follow-up in patients with solid tumors and venous thromboembolic disease with the risk of recurrence and death.

EXPERIMENTAL DESIGN

Patients (N = 223) with first episode of venous thromboembolic disease received oral anticoagulation with warfarin for a target international normalized ratio of 2 to 3. Plasma coagulation markers were measured before instituting warfarin and at 3 monthly intervals, thereafter.

RESULTS

The median duration of oral anticoagulation was 6.7 months (range 2 weeks to 11 months). Major bleeding episodes occurred in 18 patients (8%), and minor hemorrhagic events occurred in 15 (6.7%) patients. Patients with advanced malignancy (P = 0.032), history of surgery (P = 0.057), and those with poor performance status (P = 0.001) were more likely to encounter major bleeding episodes. Recurrence of venous thromboembolic disease was diagnosed in 31 patients (14%). At univariate analysis, advanced stage of cancer (P = 0.03), performance status > 1 (P = 0.001), treatment with chemotherapy (P = 0.01), the presence of metastatic liver disease (P = 0.03), higher d-dimer (P = 0.001), and thrombin antithrombin complex levels (P = 0.01) were features predictive of recurrent venous thromboembolic disease. At multivariate analysis, poor performance status (P = 0.01) and d-dimer levels (P = 0.001) were predictors of recurrent venous thromboembolic disease. Persistent activation of coagulation as indicated by an upward trend in d-dimer (P = 0.001) and antithrombin (P = 0.001) was observed in patients who developed recurrent thrombosis. Similar upward trends in d-dimer (P = 0.001), antithrombin (P = 0.001), and prothrombin fragment F1 + 2 (P = 0.001) was observed in the 76 patients who died during the study period and in the patients who received chemotherapy.

CONCLUSIONS

Successful oral anticoagulation with warfarin in patients with cancer and venous thromboembolic disease is more likely to be achieved in patients with early stage tumors and good performance status. The persistence of activation of hemostasis as shown by plasma coagulation markers is a strong predictor of recurrence and poor outcome.