Introducing the "Bleeding Team": Urgent Reconstruction of an Open Fracture in a Patient Receiving Acenocoumarol: A Case Report

CASE

An elderly, polytrauma patient receiving vitamin K antagonist (VKA) for atrial fibrillation required immediate surgery for open distal tibial fracture. As the initial reversal with vitamin K and fresh frozen plasma by the trauma team was ineffective, the "Bleeding Team" was convened and administrated the appropriate four-factor prothrombin complex regimen, reversing the VKA in a timely manner. Surgery was performed under peripheral nerve blockade subsequently. The postoperative course of the patient was uneventful.

CONCLUSION

The individualized approach and the multidisciplinary experts' team guidance is of outmost importance in patients who are treated with anticoagulants and present for nonelective surgery.

Vitamin K antagonist anticoagulant usage is associated with increased incidence and progression of osteoarthritis

OBJECTIVES

Vitamin K is hypothesised to play a role in osteoarthritis (OA) pathogenesis through effects on vitamin K-dependent bone and cartilage proteins, and therefore may represent a modifiable risk factor. A genetic variant in a vitamin K-dependent protein that is an essential inhibitor for cartilage calcification, matrix Gla protein (MGP), was associated with an increased risk for OA. Vitamin K antagonist anticoagulants (VKAs), such as warfarin and acenocoumarol, act as anticoagulants through inhibition of vitamin K-dependent blood coagulation proteins. VKAs likely also affect the functioning of other vitamin K-dependent proteins such as MGP.

METHODS

We investigated the effect of acenocoumarol usage on progression and incidence of radiographic OA in 3494 participants of the Rotterdam Study cohort. We also examined the effect of MGP and VKORC1 single nucleotide variants on this association.

RESULTS

Acenocoumarol usage was associated with an increased risk of OA incidence and progression (OR=2.50, 95% CI=1.94-3.20), both for knee (OR=2.34, 95% CI=1.67-3.22) and hip OA (OR=2.74, 95% CI=1.82-4.11). Among acenocoumarol users, carriers of the high VKORC1(BB) expression haplotype together with the MGP OA risk allele (rs1800801-T) had an increased risk of OA incidence and progression (OR=4.18, 95% CI=2.69-6.50), while this relationship was not present in non-users of that group (OR=1.01, 95% CI=0.78-1.33).

CONCLUSIONS

These findings support the importance of vitamin K and vitamin K-dependent proteins, as MGP, in the pathogenesis of OA. Additionally, these results may have direct implications for the clinical prevention of OA, supporting the consideration of direct oral anticoagulants in favour of VKAs.

Unintentional ingestion of a high dose of acenocoumarol in a young child

Acute intoxication with a vitamin K antagonist may cause serious coagulopathy. We report the accidental ingestion of a high dose of acenocoumarol in a young child. Two intravenous administrations of 5 mg of vitamin K, in combination with fast and repeated administration of activated charcoal and sodium sulfate, were sufficient to prevent coagulopathy and related symptoms, despite a confirmed elevated blood acenocoumarol concentration (260 µg/L).

IgA vasculitis induced by acenocoumarol

We present the case of a 73-year-old man with IgA vasculitis after administration of acenocoumarol, confirmed by anatomopathological study. He had cutaneous, joint and renal involvement. With the reintroduction of the drug, the clinical manifestations worsened. They were completely resolved with its suspension, without additional maintenance treatment.

Acquired haemophilia A in a patient with breast cancer and lung carcinoma: a case report and literature review

Acquired haemophilia A is a rare disorder caused by spontaneous formation of auto-antibodies (inhibitors) against coagulation factor VIII. This can lead tolife-threatening haemorrhages. Six to twenty-two percent of patients with acquired haemophilia have an underlying malignancy. We describe a 69-year-old woman with metastatic breast cancer and non-small cell lung carcinoma who presented at the emergency room with spontaneous bruising, and who was using a vitamin K antagonist. She had a prolonged activated partial thromboplastin time (aPTT) due to a coagulation factor VIII deficiency caused by factor VIII antibodies. She was treated with prednisone and cyclophosphamide.

Pharmacogenetics in the Treatment of Cardiovascular Diseases and Its Current Progress Regarding Implementation in the Clinical Routine

There is a special interest in the implementation of pharmacogenetics in clinical practice, although there are some barriers that are preventing this integration. A large part of these pharmacogenetic tests are focused on drugs used in oncology and psychiatry fields and for antiviral drugs. However, the scientific evidence is also high for other drugs used in other medical areas, for example, in cardiology. In this article, we discuss the evidence and guidelines currently available on pharmacogenetics for clopidogrel, warfarin, acenocoumarol, and simvastatin and its implementation in daily clinical practice.

Analysis of acenocoumarol and levofloxacin interaction in elderly institutionalized patients

OBJECTIVE

To analyze the interaction between acenocoumarol and  levofloxacin in the elderly. We also assessed how hypoalbuminemia affects international normalized ratio variation.

METHOD

Retrospective study carried on elderly institutionalized patients who were prescribed levofloxacin concomitantly with acenocoumarol.  International normalized ratio variation during levofloxacin treatment was analyzed with the t-Student test. Correlation between albuminemia and international normalized ratio variation was calculated using Pearson´s correlation coefficient.

RESULTS

The mean international normalized ratio previous to treatment with levofloxacin was 2.5 (standard deviation: 0.6) and during treatment it was  4.7 (standard deviation: 1.9) (p < 0.05). In 54.3% of the cases, the  international normalized ratio value was equal to or greater than 4.5. Not  linear association between albuminemia and international normalized ratio  increase was found using Pearson´s test (R = -0.16).

CONCLUSIONS

In more than half of the occasions international normalized ratio raised to clinically rellevant values (≥ 4.5). No influence of hypoalbuminemia in the increase in international normalized ratio was shown.

Management of blunt hepatic and splenic injuries (grade ≤ III) in patients receiving antithrombotic therapy

BACKGROUND

Non-operative management (NOM) may be particularly challenging in patients receiving synchronous antithrombotic therapy (AT). The current study examined the feasibility of NOM in patients under AT who sustained blunt splenic or hepatic injuries.

METHODS

We analyzed the results of a 5-year (2010-2014) pre-decided treatment protocol, including 15 patients under AT who were treated for splenic and/or hepatic injuries at our institution. The antithrombotic therapy consisted of acenocoumarol 4 mg, acetylsalicylic acid 100 mg and clopidogrel 75 mg. Vitamin K (Vit K), Fresh frozen plasma (FFP) and Prothrombin Complex Concentrate (PCC) were transfused to patients receiving anticoagulant therapy, while platelets (PLTs) were given to patients under antiplatelet therapy if their level was excessively low. The organ injury grading scale, injury severity score (ISS), the need for blood transfusion and intensive care unit (ICU)/ high dependency unit (HDU) admission, morbidity, mortality and duration of hospital stay were also recorded.

RESULTS

Ten patients fulfilled the criteria for NOM and were treated accordingly. No conversion to operative management (OM) was required (success rate 100%). Five patients were managed surgically due to hemodynamic instability and/or signs of peritonitis. Reversal of AT was attempted in all cases.

CONCLUSIONS

Hemodynamically stable patients under AT with blunt hepatic or splenic injuries (grade ≤ III) and no signs of peritonitis, may be good candidates for NOM, despite their bleeding tendency. The type of AT does not seem to influence the final outcome. Reversal of AT should be stratified individually.

KEY WORDS

Antithrombotic therapy, Hemodynamic stability, Non-operative management.

Estimated Effectiveness and Safety of Nonvitamin K Antagonist Oral Anticoagulants Compared With Optimally Acenocoumarol Anticoagulated "Real-World" in Patients With Atrial Fibrillation

Nonvitamin K antagonist oral anticoagulants (NOACs) have been proposed as an alternative to vitamin K antagonists in atrial fibrillation (AF) patients but the comparative benefits between NOACs and optimally anticoagulated patients is unknown. We estimated the absolute benefit in clinical outcomes rates of real-world effect of NOACs in optimally anticoagulated AF patients with acenocoumarol. We included 1,361 patients stable on acenocoumarol with time in therapeutic range of 100% and 6.5 years of follow-up. Estimation of clinical events avoided was calculated applying hazard ratio, absolute and relative risk reduction from the real-world meta-analysis. Compared with an optimally anticoagulated population, dabigatran 110 mg had the highest estimated stroke reduction (0.97%/year vs 1.47%/year; p = 0.002), and the benefit was higher than in RE-LY trial. For major bleeding, apixaban showed the highest estimated reduction (1.81%/year vs 2.83%/year; p <0.001). For mortality, the largest estimated reduction was with apixaban (2.68%/year). For gastrointestinal bleeding, only apixaban had a significant reduction compared with acenocoumarol (0.69%/year vs 1.10%/year; p = 0.004), and the reduction was significantly higher than in ARISTOTLE trial. All NOACs showed significantly lower rates for intracranial hemorrhage and had a positive Net Clinical Benefit compared with acenocoumarol. Apixaban showed the highest extended estimated Net Clinical Benefit 2.64 (95%CI 2.34 to 2.96). In conclusion, in optimally acenocoumarol anticoagulated AF patients, estimated reductions in all clinical outcomes with various NOACs are evident, with the best effectiveness and safety profile with apixaban. Indeed, the estimated effect with "real world" NOACs would probably be higher than that seen in phase-III clinical trials.

Meta-Analysis of Genotype-Guided Versus Standard Dosing of Vitamin K Antagonists

Vitamin K antagonist (VKA) is a commonly prescribed anticoagulant with a narrow therapeutic window. Genetic polymorphisms account for high VKA dosage variability. Hence, we performed an updated meta-analysis of all randomized clinical trials (RCTs) comparing genotype-guided VKA versus standard dosing algorithms. We conducted a systematic search of electronic databases from inception to October 2017 for all RCTs. The primary outcome was the percentage of time in therapeutic range (TTR). Secondary outcomes were international normalized ratio >4, major and all bleeding events, thromboembolism, adverse and serious adverse events, and all-cause mortality. We calculated the weighted mean difference for the primary outcome and risk ratio (RR) for secondary outcomes using a random-effect model. We included 20 RCTs and analyzed a total of 5,980 adult patients. Our pooled analysis showed greater improvement in TTR for the genotype-guided group in comparison with the standard group (mean difference 3.41%, 95% confidence interval [CI] 0.71 to 6.10, p = 0.01). In addition, there were significant reductions in major and all bleeding events ((RR 0.35, 95% CI 0.20 to 0.63, p = 0.0004) and (RR 0.79, 95% CI 0.66 to 0.95, p = 0.01), respectively). However, there were no significant differences between the groups for international normalized ratio >4 (RR 0.89, 95% CI 0.80 to 1.00, p = 0.06), thromboembolism (RR 0.81, 95% CI 0.56 to 1.17, p = 0.25), serious adverse events (RR 0.79, 95% CI 0.61 to 1.03, p = 0.08), any adverse events (RR 0.94, 95% CI 0.88 to 1.01, p = 0.07), or all-cause mortality (RR 0.73, 95% CI 0.32 to 1.66, p = 0.46). In conclusion, genotype-guided VKA dosing can improve the TTR and reduce the risk for bleeding episodes, in comparison with standard dosing algorithms.

Antiplatelet therapy combined with acenocoumarol in relation to major bleeding, ischaemic stroke and mortality

BACKGROUND

Vascular disease is a frequent comorbidity in atrial fibrillation (AF) patients, resulting in concomitant use of antiplatelet therapy. In the present study, we investigated the incidence and risk of major bleeding, ischaemic stroke, and mortality in a cohort of AF patients taking acenocoumarol plus antiplatelet therapy, in comparison with AF patients taking only acenocoumarol monotherapy.

METHODS

We consecutively included 1361 "real-world" AF patients stable for at least the previous 6 months on acenocoumarol (INR 2.0-3.0). The primary endpoint was major bleeding defined using the 2005 International Society on Thrombosis and Haemostasis (ISTH) criteria. As secondary endpoints, we analysed ischaemic strokes and all-cause mortality. During follow-up, all adverse events were recorded and compared within patients taking acenocoumarol plus antiplatelet therapy and patients taking only acenocoumarol.

RESULTS

During 6.5 years (IQR 4.3-7.9) of follow-up, there were 250 (2.83%/year) bleeds, 130 (1.47%/year) ischaemic strokes and 511 (6.23%/year) deaths. After multivariate Cox regression analyses, combined antithrombotic therapy was associated with major bleeding (HR 1.40, 95% CI 1.01-1.94; P = .048), but not lower mortality (HR 0.95, 95% CI 0.75-1.21; P = .674) or ischaemic stroke (HR 1.45, 95% CI 0.97-2.17; P = .072).

CONCLUSIONS

In AF patients, the risk of bleeding is higher when antiplatelet therapy is combined with acenocoumarol, but the risk of mortality and stroke was not significantly different from that of patients taking only acenocoumarol.

Characteristics and quality of oral anticoagulation treatment in pediatric patients in the Netherlands based on the CAPS cohort

Essentials The knowledge of quality and safety of acenocoumarol and phenprocoumon use in children is limited. We used data from a multicenter retrospective follow-up study in children in the Netherlands. The quality of anticoagulation control in the first month of use was low, but improved thereafter. No thromboembolic events occurred, however bleeding events occurred in 1-3 out of 10 patients.

SUMMARY

Background The use of vitamin-K antagonists in pediatric patients is rare and information on the quality and safety of treatment with acenocoumarol and phenprocoumon is limited. Objectives To assess the quality, safety and effectiveness during the first year of acenocoumarol and phenprocoumon treatment in pediatric patients in the Netherlands. Methods The Children Anticoagulation and Pharmacogenetics Study (CAPS) was designed as a multicenter retrospective follow-up study. Patients who used acenocoumarol or phenprocoumon at an age of ≤ 18 years, were selected from four pediatric hospitals and one anticoagulation clinic in the Netherlands. The quality of treatment was assessed by calculating the percentage of time in therapeutic INR range (TTR) for the first month and for every 3 months of use during the first year of treatment. Effectiveness and safety were assessed by the number of thromboembolic and bleeding events. Results In total, 213 patients participated, of whom 187 (155 acenocoumarol; 32 phenprocoumon) were included in this analysis. The mean TTR was 47.0% and 51.4% in the first month of use for acenocoumarol and phenprocoumon, respectively. After the first 3 months the mean TTR for both VKAs was above 64%. In 14.6% (acenocoumarol) and 31.3% (phenprocoumon) of the patients a bleeding event occurred during the first year of treatment; no thromboembolic events were reported. Conclusions The quality of anticoagulation treatment was low during the first month of use and leaves room for improvement. After the first month it increased to an acceptable level. However, bleeding events occurred frequently during the first year.

Predictors for total hospital and cardiology cost claims among patients with atrial fibrillation initiating dabigatran or acenocoumarol in The Netherlands

AIMS

The prevalence of atrial fibrillation (AF) has increased over the past years due to aging of the population, and healthcare costs associated with AF reflect a significant financial burden. The aim of this study was to explore predictors for the real-world AF-related in-hospital costs in patients that recently initiated anticoagulation with acenocoumarol or dabigatran.

METHODS

Predictors for claimed total hospital care costs and cardiology costs in AF patients were explored by using hospital financial claims data from propensity score matched patient groups in a large Dutch community hospital. This study analyzed the total dataset (n = 766) and carried out a secondary analysis for all matched pairs of anticoagulation naïve AF patients (n = 590) by ordinal regression.

RESULTS

Dabigatran was a predictor for significantly lower cardiology and total hospital care costs (Odds Ratio [OR] = 0.43, 95% confidence interval (CI) = 0.33-0.57; and OR = 0.60, 95% CI = 0.46-0.79, respectively). Female gender was a predictor for lower total hospital care costs. Predictors for an increase in total hospital care costs were the occurrence of stroke or systemic embolism, major bleeding, and minor bleeding. The costs predictors were comparable when limiting the analysis to patients that were anticoagulation naïve. Age and CHA₂DS₂-VASc were not predictors for either cardiology or total hospital care costs in both analyses.

CONCLUSION

Dabigatran treatment was as a predictor for lower cardiology costs and lower total hospital care costs in AF patients that initiated oral anticoagulation.

The risk of bleeding complications in patients with cytochrome P450 CYP2C9*2 or CYP2C9*3 alleles on acenocoumarol or phenprocoumon

The principal enzyme involved in coumarin metabolism is CYP2C9. Allelic variants of CYP2C9, CYP2C9*2 and CYP2C9*3, code for enzymes with reduced activity. Despite increasing evidence that patients with these genetic variants require lower maintenance doses of anticoagulant therapy, there is lack of agreement among studies on the risk of bleeding and CYP2C9 polymorphisms. It was, therefore, our objective to study the effect of the CYP2C9 polymorphisms on bleeding complications during initiation and maintenance phases of coumarin anticoagulant therapy. The design of the study was a population-based cohort in a sample of the Rotterdam Study, a study in 7,983 subjects. All patients who started treatment with acenocoumarol or phenprocoumon in the study period from January 1, 1991 through December 31, 1998 and for whom INR data were available were included. Patients were followed until a bleeding complication, the end of their treatment, death or end of the study period. Proportional hazards regression analysis was used to estimate the risk of a bleeding complication in relation to CYP2C9 genotype after adjustment for several potentially confounding factors such as age, gender, target INR level, INR, time between INR measurements, and aspirin use. The effect of variant genotype on bleeding risk was separately examined during the initiation phase of 90 days after starting therapy with coumarins. The 996 patients with analysable data had a mean follow-up time of 481 days (1.3 years); 311 (31.2%) had at least 1 variant CYP2C9 allele and 685 (68.8%) had the wild type genotype. For patients with the wild type genotype, the rate of minor bleeding, major bleeding and fatal bleeding was 15.9, 3.4 and 0.2 per 100 treatmentyears, respectively. For patients with a variant genotype, the rate of minor, major and fatal bleeding was 14.6, 5.4 and 0.5 per 100 treatment-years. Patients with a variant genotype on acenocoumarol had a significantly increased risk for a major bleeding event (HR 1.83, 95% CI: 1.01-3.32). During the initiation phase of therapy we found no effect of variant genotype on bleeding risk. In this study among outpatients of an anticoagulation clinic using acenocoumarol or phenprocoumon, having a variant allele of CYP2C9 was associated with an increased risk of major bleeding events in patients on acenocoumarol, but not in patients on phenprocoumon. Although one might consider the assessment of the CYP2C9 genotype of a patient for dose adjustment before starting treatment with acenocoumarol, a prospective randomised trial should demonstrate whether this reduces the increased risk of major bleeding events.

Comparing thrombin generation in patients with hemophilia A and patients on vitamin K antagonists

Essentials It is unknown if hemophilia patients with atrial fibrillation need anticoagulation. Endogenous thrombin potentials (ETP) in hemophilia patients and patients on coumarins were compared. Severe hemophilia patients had comparable ETP to therapeutic international normalized ratio (INR). In non-severe hemophilia, 33% had higher ETP than therapeutic INR and may need anticoagulation. Click to hear Dr Negrier's perspective on global assays for assessing coagulation SUMMARY: Background It is unknown whether patients with hemophilia A with atrial fibrillation require treatment with vitamin K antagonists (VKAs) to the same extent as the normal population. Objective To compare hemostatic potential in hemophilia patients and patients on VKAs using thrombin generation (TG). Methods In this cross-sectional study, TG, initiated with 1pM tissue factor, was measured in 133 patients with severe (FVIII < 1%, n = 15) and non-severe (FVIII 1-50%, n = 118) hemophilia A, 97 patients on a VKA with an international normalized ratio (INR) ≥ 1.5 and healthy controls. Endogenous thrombin potential (ETP) (nm*min) was compared according to FVIII level (< 1%, 1-19% and 20-50%) with healthy controls and patients with sub-therapeutic INR (1.5-1.9) and therapeutic INR (≥ 2.0). Medians and interquartile ranges (IQRs) were calculated. Results Compared with healthy controls (898 [IQR 803-1004]), both hemophilia patients and patients on VKAs had lower median ETPs at 304 (196-449) and 176 (100-250), respectively. ETP was quite similar in severe hemophilia patients (185 [116-307]) and patients with a therapeutic INR (156 [90-225]). Compared with patients with therapeutic INR, ETP in patients with FVIII 1-19% and patients with FVIII 20-50% was higher at 296 (203-430) and 397 (219-632), respectively. All patients with therapeutic INR had an ETP < 400. Considering this threshold, 93% of severe hemophilia patients, 70% of patients with FVIII 1-19% and 52% of patients with FVIII 20-50% had an ETP < 400. Conclusion In severe hemophilia patients, TG was comparable to that in patients with a therapeutic INR. In one-third of non-severe hemophilia patients, TG was higher. These results suggest that anticoagulation therapy should be considered in a substantial proportion of non-severe hemophilia patients.

Acenocoumarol as a risk factor for calciphylaxis: a feature clinicians should be aware of

In contrast with uraemic calciphylaxis in end-stage renal disease, causes of and risk factors for non-uraemic calciphylaxis are relatively unknown to clinicians and have yet to become fully established. This report describes a case of non-uraemic calciphylaxis, in which the use of acenocoumarol might have been a risk factor. It is important to raise awareness about this association among clinicians, as vitamin K antagonists have to be stopped for an optimal treatment of this severe condition.

Extraperitoneal hemorrhagic rupture of a simple hepatic cyst. A case report and literature review

Hemorrhagic rupture is a very rare complication of a simple hepatic cyst. We report the first case of a totally extraperitoneal rupture of a recurrent cyst, occurred in a 73-year-old man who presented with acute right hypochondralgia. Computed tomography revealed the rupture of a large hemorrhagic cyst in the right liver lobe and the formation of a voluminous hematoma in the retroperitoneal space. Despite the absence of hemoperitoneum, the entity of the bleeding led us to perform an urgent and successful surgical intervention. A review of the literature was conducted. To date, 9 cases of hemorrhagic rupture of simple hepatic cyst have been described and our case is the first one characterized by extraperitoneal bleeding. Our clinical management was in accordance with the majority of the other Authors. Different surgical procedures have been proposed and the best approach has not been established yet. However, the laparotomic approach should be preferred for a better control of the bleeding. In conclusion, the hemorrhagic rupture of a liver cyst is a life-threatening complication and a prompt surgery is necessary to prevent the hypovolemic shock.

KEY WORDS

Extraperitoneal rupture, Hemorrhagic rupture, Simple hepatic cyst.

The impact of CYP4F2, ABCB1, and GGCX polymorphisms on bleeding episodes associated with acenocoumarol in Russian patients with atrial fibrillation

BACKGROUND

Oral anticoagulants are commonly used to treat patients with thromboembolic pathology. Genetic variations could influence personal response to anticoagulant drugs. Acenocoumarol (AC) is a vitamin K antagonist used in anticoagulant therapy and as a prophylaxis measure in Europe. In this study, we assessed the effect of CYP4F2 rs2108622, ABCB1, and GGCX polymorphisms on the safety profile and regime dosing of AC in patients with nonvalvular atrial fibrillation.

METHODS

Fifty patients aged 40-70 years were included. All patients received AC in the dose of 1-6 mg daily with a target international normalized ratio of 2.0-3.0. Genotyping for polymorphism markers C3435T for the ABCB1 gene, rs2108622 for the CYP4F2 gene, and rs11676382 for the GGCX gene were designed using polymerase chain reaction and restriction fragment length polymorphism. Statistical analysis was performed using the Fisher exact test and the Mann-Whitney U test.

RESULTS

We found that CYP4F2 rs2108622 CT carriers required a higher AC dose than CC (p=0.0366), and CT and TT carriers required a higher AC dose than CC (p=0.0314).

CONCLUSIONS

We found that ABCB1 CT and TT genotypes are associated with a higher risk of bleeding. No influence of ABCB1 and GGCX polymorphisms on the doses of AC was established. CYP4F2 could still be a genetic factor responsible for the personal variability of AC metabolism.

Optimization of vitamin K antagonist drug dose finding by replacement of the international normalized ratio by a bidirectional factor: validation of a new algorithm

ESSENTIALS: We developed a new algorithm to optimize vitamin K antagonist dose finding. Validation was by comparing actual dosing to algorithm predictions. Predicted and actual dosing of well performing centers were highly associated. The method is promising and should be tested in a randomized trial.

SUMMARY

BACKGROUND

Oral vitamin K antagonists (VKAs) have a narrow therapeutic window and thus require frequent monitoring of its intensity by the international normalized ratio (INR). Improvement of VKA dosing defined as more time in therapeutic range (TTR) can reduce thrombotic disease and bleeding. Computerized decision support programs (CDSs) are used to optimize VKA dosing, but the effects are heterogeneous. CDSs significantly improve the proportion of time in the therapeutic INR range for initiation therapy but not the quality of anticoagulant management in an outpatient setting. One of the major problems of VKA dose finding is that the INR is a ratio and does not present linearity. We developed a new dose-finding algorithm, based on a novel bidirectional factor (BF). This BF is linear transformation of the nonlinear INR.

METHODS

We compared the outcomes of the new algorithm, called BF-N, with dose finding performed at three highly ranked Dutch anticoagulation centers, using both acenocoumarol and phenprocoumon.

RESULTS

The outcomes of the BF-N algorithm showed a linear correlation with VKA doses of the three centers (y = 1.001x, r(2) 0.999 for acenocoumarol and y = 0.999x, r(2) 0.999 for phenprocoumon), with a standard deviation of 3.83%. The rate of automated dosage proposals increased to 100%.

CONCLUSION

The BF-N algorithm performs well in real-life settings and increases the rate of automated dosage proposals. The algorithm can be easily built into existing CDSs. Experienced staff remains necessary for complicated situations. The new algorithm needs to be evaluated in a prospective trial.

Effectiveness and safety of dabigatran versus acenocoumarol in 'real-world' patients with atrial fibrillation

Aims

Randomized trials showed non-inferior or superior results of the non-vitamin-K-antagonist oral anticoagulants (NOACs) compared with warfarin. The aim of this study was to assess the effectiveness and safety of dabigatran (direct thrombin inhibitor) vs. acenocoumarol (vitamin K antagonist) in patients with atrial fibrillation (AF) in daily clinical practice.

Methods and results

In this observational study, we evaluated all consecutive patients who started anticoagulation because of AF in our outpatient clinic from 2010 to 2013. Data were collected from electronic patient charts. Primary outcomes were stroke or systemic embolism and major bleeding. Propensity score matching was applied to address the non-randomized design. In total, 920 consecutive AF patients were enrolled (442 dabigatran, 478 acenocoumarol), of which 2 × 383 were available for analysis after propensity score matching. Mean follow-up duration was 1.5 ± 0.56 year. The mean calculated stroke risk according to the CHA₂DS₂-VASc score was 3.5%/year in dabigatran vs. 3.7%/year acenocoumarol-treated patients. The actual incidence rate of stroke or systemic embolism was 0.8%/year [95% confidence interval (CI): 0.2–2.1] vs. 1.0%/year (95% CI: 0.4–2.1), respectively. Multivariable analysis confirmed this lower but non-significant risk in dabigatran vs. acenocoumarol after adjustment for the CHA₂DS₂-VASc score [hazard ratio (HR)_dabigatran = 0.72, 95% CI: 0.20–2.63, P = 0.61]. According to the HAS-BLED score, the mean calculated bleeding risk was 1.7%/year in both groups. Actual incidence rate of major bleeding was 2.1%/year (95% CI: 1.0–3.8) in the dabigatran vs. 4.3%/year (95% CI: 2.9–6.2) in acenocoumarol. This over 50% reduction remained significant after adjustment for the HAS-BLED score (HR_dabigatran = 0.45, 95% CI: 0.22–0.93, P = 0.031).

Conclusion

In ‘real-world’ patients with AF, dabigatran appears to be as effective, but significantly safer than acenocoumarol.

Acenocoumarol: A Review of Anticoagulant Efficacy and Safety

Anticoagulant treatment is required for the treatment and prevention of thromboembolic disorders. Vitamin K antagonists are commonly used oral anticoagulants worldwide. Acenocoumarol is mono-coumarin derivative with racemic mixture of R (+) and S (-) enantiomers. Efficacy and safety of acenocoumarol has been evaluated in atrial fibrillation, cardiac valve replacement, after myocardial infarction, treatment of deep vein thrombosis, after major surgeries and after critical illness requiring prolonged hospitalization. Acenocoumarol is effective and safe in all age groups. It offers an advantage over warfarin in terms of better stability of anti-coagulant effect. Due to its economic advantage acenocoumarol may be suitable oral anticoagulant for long term use in countries like India.

[Serious delayed intracranial complications after mild traumatic brain injury in oral anticoagulant use]

BACKGROUND

Patients with mild traumatic brain injury (TBI) who use anticoagulants prior to injury have an increased risk of intracranial complications. Sometimes these complications are delayed, even if the initial CT scan of the head is normal.

CASE DESCRIPTION

An 84-year-old woman who was using acenocoumarol presented elsewhere with mild TBI. She had no focal neurological deficit. The initial CT scan revealed no abnormalities and the patient was discharged home. That evening she had diffuse headache. The next day she was found with a reduced level of consciousness and was brought to our hospital. Her INR was 9.0 and a new CT scan showed an acute, left-sided subdural haematoma with a large mass effect.

CONCLUSION

Serious delayed intracranial complications in patients with mild TBI who use anticoagulants are rare. In these patients INR measurement and a CT scan of the head are always indicated. Admission for observation may be considered. On discharge it is necessary to give clear instructions about warning symptoms.

[Does acetylsalicylic acid and vitamin K antagonists are risk factors of macular degeneration related with age?]

AIM

The aim of this study was to evaluate the effects of chronic use of acetylsalicylic acid (ASA) and vitamin K antagonists (VKA) on the incidence of age related macular degeneration (AMD).

MATERIALS AND METHODS

The study included 292 individuals (187 women, 105 men, aged 45-94 (mean 73.2 ± 10.2 years). All individuals completed a survey and underwent a full eye examination. Patients were divided into four groups according to the presence or absence of degenerative changes at the bottom of an eye: group D - 80 patients with drusen (23 men and 57 women), 27,4% of studied population, group GA - 25 patients with geographic atrophy (10 men, 15 women), 8,56% of studied population, group CNV - 52 patients with neovascular form of AMD (28 men, 24 women), 17,81% of studied population, group Z - 135 healthy people (44 men, 91 women), 46,23% of studied population. Among study group 79 patients (27,1%) used aspirin, 32 people (11%) used vitamin K antagonists (acenocoumarol or warfarin), 181 people (61,9%) didn't use any drug.

RESULTS

Patients from D and CNV group took ASA and VKA more often than patients from GA and Z group. The percentages were: in a group Z - 30,37%, in group D - 46,25%, in group GA - 32%, in group CNV - 48,08% (p=0,0407). There was no relationship between belonging to a group and use of ASA (p=0,3169). A statistically significant relationship between belonging to a group and use of VKA was discovered. The number of people using VKA in group D and CNV was statistically significantly higher than in the healthy control group and percentage were as follows: in group Z - 8,15%, in group D - 17,5%, in group GA 0%, in group CNV - 13,46% (p=0,0159). Patient groups differed statistically significantly due to age (p=0,0043), sex (p=0,0197), family history of macular diseases (p <0,0001), smoking (p=0,011), prevalence of hypercholesterolemia (p=0,0437), ischemic heart disease (p= 0,0173). The consumption of fish at least once a week and eating fruits and vegetables more often than once a day was associated with a reduced incidence of AMD p=0,0009, p=0,0003. Patients without AMD assessed their quality of life at a higher level than people with AMD (p<0,0001). ASA and VKA intake was found not to be an independent risk factor for AMD. Positive family history was an independent risk factor for AMD in all groups. Also age ≥75, fish consumption > 1 week, male gender were independent risk factors for AMD in specified groups.

CONCLUSIONS

Patients with drusen and exudative form of AMD took ASA and VKA more often than healthy people and patients with geographic atrophy. ASA or VKA intake was found not to be an independent risk factor for AMD. Positive family history was an independent risk factor for AMD in all groups. In selected groups: age ≥75, male gender and reduced consumption of fish was found to be an independent risk factor for AMD. Number of people taking ASA and VKA is increasing and further studies are needed to assess their impact on the organ of vision.

Understanding adverse drug reactions in older adults through drug-drug interactions

AIMS

The aims of this study are to evaluate prevalence and characteristics of adverse drug reactions (ADRs) and to evaluate the potential contribution of specific medications, therapeutic categories and drug-drug interactions (DDIs) in older adults.

METHODS

All ADR reporting forms of persons aged 65+ years collected by the pharmacovigilance of one of the main hospitals in Italy during 2013 were evaluated. DDIs were analysed by a computerized prescription system (INTERCheck) and based on the interactions' database managed by the Istituto di Ricerche Farmacologiche Mario Negri. DDIs were classified according to their clinical relevance as contraindicated, major, and moderate.

RESULTS

Amongst all the ADR reporting forms (n=1014) collected during 2013, 343 affected older adults. The most frequent ADRs were: haemorrhages (n=122, 35.5%), allergic reactions (n=56, 16.3%), and elevated International Normalized Ratio (INR>6, n=54, 15.7%). The specific medications that contributed to ADRs were warfarin (42.5%), acenocumarol (9%), and allopurinol (8.5%); while the therapeutic categories were haematological agents (67%) and proton pump inhibitors (13%). A total of 912 DDIs were found; one third of them were contraindicated or major and 31.5% of them potentially contributed to ADRs; of these, the most frequent were: warfarin and heparin (contraindicated, n=5); warfarin and a statin (major, n=38); warfarin and a proton pump inhibitor (moderate, n=40). At least one DDI contributed to 66 haemorrhages out of 122 (54%) and to 41 elevated INR out of 54 (76%).

CONCLUSION

DDIs significantly contribute to the onset of ADRs in older adults and intervention programmes, e.g., the employment of a computerized system, may reduce the burden of iatrogenic illnesses in the elderly.

[Diffuse superficial siderosis of the central nervous system: four case reports and review of the literature]

INTRODUCTION

Diffuse superficial siderosis of the central nervous system (CNS) is a rare condition due to hemosiderin deposits in the subpial layers of the brain and spinal cord. The source of chronic or recurrent bleeding into the subarachnoid space is detected in only 50 % of cases. The most characteristic symptoms are cerebellar ataxia and sensorineural hearing impairment. T2-weighted gradient echo magnetic resonance imaging constitutes the diagnostic method of choice.

CASE REPORTS

We report four patients of diffuse superficial siderosis of the CNS associated to cerebral amyloid angiopathy, oral anticoagulation, schwannoma VIII, and without known source of bleeding in one case. Two patients developed cerebellar ataxia, three of them present transient focal neurological episodes, one dementia and, the last one, the diffuse superficial siderosis of the CNS is a radiological finding. No clinical progression was observed during follow-up (2-11 years) in three of them. The patient with cerebral amyloid angiopathy progresses to dementia.

CONCLUSIONS

Transient focal neurological episodes were the most common symptom in our cases of diffuse superficial siderosis of the CNS. The natural history of this condition is not very known and may be regarded as a radiological finding.

Risk factors associated with a thrombotic or bleeding event in patients treated with vitamin K antagonists

AIM

To identify, in a case-control study, the risk factors associated with a thrombotic or bleeding event in patients treated with vitamin K antagonists.

MATERIALS AND METHODS

We performed a single-centre observational study during a three-month period where we consecutively included patients admitted to the emergency department of a secondary-level hospital and treated with vitamin K antagonists, regardless the reason for admission. Patients admitted for a thrombotic or bleeding event were included as cases and the other patients served as controls. Main thrombotic or bleeding risk factors during vitamin K antagonist therapy were a priori identified in literature and tested in conditional logistic regression.

RESULTS

Two hundred and forty subjects were identified, 40 of which (17%) were admitted for a bleeding event, 19 (8%) for a thrombotic event and 181 (75%) for another reason. Over 85% of patients were treated with fluindione. No risk factor was significantly associated with bleeding or thrombotic event in patients treated with vitamin K antagonist. Patients presenting a thrombotic event were however more likely to have a chronic respiratory disease.

CONCLUSIONS

In this study, no risk factor significantly associated with a bleeding or thrombotic event in patients treated with vitamin K antagonist were identified. The occurrence of these events supposes other risk factors, including potential genetic polymorphisms that should be considered in future studies.

The clinical impact of different coagulometers on patient outcomes

Introduction

Long-term anticoagulation therapy using vitamin K antagonists (VKA) is used in millions of patients worldwide to reduce the risk of thrombotic or thromboembolic events. Control and monitoring of VKA therapy is improved by the regular self-measurement of international normalized ratio (INR) using a home monitoring device. This retrospective analysis of a large cohort of patients in the Netherlands seeks to determine whether the choice of INR monitor could have a clinical impact on patient outcomes.

Methods

The National Thrombosis Service provides medical supervision, training and support to anticoagulant patients eligible for home-monitoring of INR in the Netherlands. Two INR monitors (CoaguChek XS and INRatio2) have been distributed at random to patients since June 2011, and patient self-testing data (INR measurements and other clinical parameters) have been recorded to measure and improve treatment outcomes. The data have been retrospectively analyzed to determine any effect of the choice of monitor. Univariate and multivariate statistical tests are used to assess any differences between groups in terms of efficacy and safety parameters.

Results

Data from 4,326 patients were collated, and 156,507 INR values were included in the analysis. Over half the patients (54.3%) were being treated for atrial fibrillation, and 77.6% were prescribed acenocoumarol. There were few differences between the patient populations using the two different monitors. Anticoagulant control overall was good, with high percentage of time (87.9%) in the appropriate INR range and low incidence of excessively high or low INR values (0.085/month). Minor clinical events related to safety were low (0.78 per patient-year) and showed few differences between monitors. Mortality rates were similar [hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.65–1.70].

Conclusion

Self-testing data from a large cohort of patients in the Netherlands suggest that there is no clinically relevant effect of the choice of coagulation monitor (CoaguChek XS or INRatio2) on the time in therapeutic range (TTR), minor or fatal outcomes of long-term anticoagulation management.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0124-x) contains supplementary material, which is available to authorized users.

Increased INR after gefitinib and acenocoumarol co-administration

INTRODUCTION

Drug interactions can cause many clinical problems, particularly when the drugs are administered in combination with anticancer agents.

CASE REPORT

A patient required two hospitalizations due to risk of bleeding with altered INR probably due to an interaction between gefitinib and acenocoumarol, which resulted in the potentiation of the effect of the latter and acenocoumarol dose adjustment was needed. A causality assessment between the drug-drug interaction and the augmented INR was conducted according to Naranjo algorithm and was classified as a definite adverse drug reaction.

CONCLUSIONS

Patient's management recommended is to closely monitor for changes in the effects of coumarin derivatives, if administered concomitantly with antineoplasic agents.

Calciphylaxis treated with sodium thiosulfate: report of two cases

Although traditionally observed in patients with end-stage renal disease and secondary hyperparathyroidism, calciphylaxis has been reported in patients with normal renal and parathyroid function. There is no evidence-based therapy available. The use of sodium thiosulfate (STS) has been increasingly described. Herein we describe two patients who responded well to this treatment.

Successful catheter directed thrombolysis in postpartum deep venous thrombosis complicated by nicoumalone-induced skin necrosis and failure in retrieval of inferior vena caval filter

Venous thromboembolism is an important cause for maternal morbidity and mortality in postpartum period. Though catheter-directed thrombolysis (CDT) is now considered as a safe and effective therapy for the management of deep venous thrombosis (DVT) but still it is not indicated in postpartum DVT. We are presenting a case of 22-year-old female patient who presented with post-partum lower limb DVT and managed successfully with CDT by using injection streptokinase and temporary inferior vena caval filter was inserted as prophylactic for pulmonary embolism as she had extensive DVT extending into inferior vena cava (IVC). During follow-up, she developed large skin necrosis in left lower limb which was managed by adding injection low-molecular-weight heparin. IVC filter also could not be retrieved even after trying all manoeuvres during follow-up after 2 weeks.

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.

The Influence of NSAIDs on Coumarin Sensitivity in Patients with CYP2C9 Polymorphism After Total Hip Replacement Surgery

OBJECTIVE

To determine the influence of NSAIDs on the international normalized ratio (INR) in patients with cytochrome P450 (CYP)-2C9 enzyme variants starting acenocoumarol (an oral coumarin) therapy during the first 7 days after total hip replacement surgery.

METHODS

In this prospective study, an age-dependent protocol was used for the initiation of the acenocoumarol dose. Low-molecular-weight heparin was given for 5 days. The study included 100 patients undergoing total hip replacement surgery. After the inclusion of the last patient, polymerase chain reaction CYP2C9 mutation testing was performed for all patients. Drug-use evaluation of NSAIDs and other potential coumarin-drug interactions was also performed.

RESULTS

Eleven patients had an INR on 1 or more days >4.9. There were 52 patients who were using NSAIDs. Patients with a CYP2C9 mutation had a mean INR curve similar to patients without the mutation when NSAIDs were not coadministered. Within the group of patients heterozygous for a CYP2C9 mutation (n=30) only concomitant use of a NSAID resulted in an INR >4.9 (0% vs 38.9%, p<0.05).

CONCLUSION

In the group of patients with a CYP2C9 variant (*2 or *3 alleles), only concomitant use of a NSAID resulted in INRs >4.9. The cost effectiveness of CYP2C9 screening before elective surgery has yet to be determined.

An evaluation of gene-gene interaction between the CYP2C9 and VKORC1 genotypes affecting the anticoagulant effect of phenprocoumon and acenocoumarol

BACKGROUND

Previous studies have provided contradictory results regarding the interaction between the CYP2C9 and VKORC1 genotypes affecting various outcome measures.

OBJECTIVES

We aimed to provide a definite answer regarding the question whether there exists a gene-gene interaction between the CYP2C9 and VKORC1 genotypes affecting the anticoagulant effect of phenprocoumon and acenocoumarol.

PATIENTS/METHODS

The EU-PACT cohort dataset, which contains data on 624 phenprocoumon and 471 acenocoumarol patients, was used. Patient characteristics, pharmacogenetic data, International Normalized Ratios (INRs) and dosages were available. We investigated whether there was an interaction between the CYP2C9 and VKORC1 genotypes affecting the maintenance dose, time to severe over-anticoagulation and time to achieve stability during the first 180 days of phenprocoumon and acenocoumarol therapy, in addition to the effect of the separate genotypes. The interaction effect was investigated by adding the product term of the CYP2C9 and VKORC1 genotype classes for four different commonly used CYP2C9 classifications to the linear regression model - for the outcome measure maintenance dose - or to the Cox regression models - for the outcome measures time to severe over-anticoagulation and time to achieve stability.

RESULTS

No significant interactions - all P-values above 0.23 for phenprocoumon and 0.30 for acenocoumarol - were observed for all outcome measures.

CONCLUSIONS

There are no interactions between the CYP2C9 and VKORC1 genotypes affecting the maintenance dose, time to severe over-anticoagulation and time to achieve stability for phenprocoumon and acenocoumarol.

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.

[Increased INR from concomitant use of acenocoumarol and capecitabine]

BACKGROUND

A drug interaction between capecitabine and coumarin may result in an increased INR and bleeding complications.

CASE DESCRIPTION

We describe an 80-year-old woman who presented with rectal bleeding and an increased INR due to the concomitant use of acenocoumarol and capecitabine for atrial fibrillation and metastatic cecal cancer, respectively.

CONCLUSION

In patients with a compelling indication for treatment with capecitabine and anticoagulant therapy, conversion to low-molecular weight heparin should be considered.

[The bleeding into the emphysematosus bulla imitating lung tumor]

Bleeding into the lung parenchyma is a rare phenomenon that usually occurs as a result of chest trauma, other causes are anticoagulant therapy, and infections. The following case presents a patient admitted to the hospital due to haemoptysis, which was a symptom of bleeding into the emphysematosus bulla caused by anticoagulation therapy. The decisive diagnostic examination was chest magnetic resonance. This imaging method allows the precise differentiation of tissues. Using modern imaging techniques can often dispense with invasive diagnostic methods.

Residual vein thrombosis for assessing duration of anticoagulation after unprovoked deep vein thrombosis of the lower limbs: the extended DACUS study

The safest duration of anticoagulation after idiopathic deep vein thrombosis (DVT) is unknown. We conducted a prospective study to assess the optimal duration of vitamin K antagonist (VKA) therapy considering the risk of recurrence of thrombosis according to residual vein thrombosis (RVT). Patients with a first unprovoked DVT were evaluated for the presence of RVT after 3 months of VKA administration; those without RVT suspended VKA, while those with RVT continued oral anticoagulation for up to 2 years. Recurrent thrombosis and/or bleeding events were recorded during treatment (RVT group) and 1 year after VKA withdrawal (both groups). Among 409 patients evaluated for unprovoked DVT, 33.2% (136 of 409 patients) did not have RVT and VKA was stopped. The remaining 273 (66.8%) patients with RVT received anticoagulants for an additional 21 months; during this period of treatment, recurrent venous thromboembolism and major bleeding occurred in 4.7% and 1.1% of patients, respectively. After VKA suspension, the rates of recurrent thrombotic events were 1.4% and 10.4% in the no-RVT and RVT groups, respectively (relative risk = 7.4; 95% confidence interval = 4.9-9.9). These results indicate that in patients without RVT, a short period of treatment with a VKA is sufficient; in those with persistent RVT, treatment extended to 2 years substantially reduces, but does not eliminate, the risk of recurrent thrombosis.

[Hemoptysis and dyspnea in a woman treated with acenocoumarol due to venous thrombosis]

A case report of young woman diagnosed as having microscopic polyangiitis (MPO) presenting with diffuse alveolar hemorrhage (DAH). DAH is a rare, but life-threatening disorder. The patients presented with dyspnea, cough, hemoptysis (not constant). The radiographic features are very characteristic and reveal the signs of diffuse, bilateral alveolar filling in chest HRCT especially in middle and lower zones. Anaemia with iron deficiency and hypoxic respiratory failure. Elevation of diffuse capacity (above 30% of predicted) is often recognized as a result of presence of blood in the alveoli. Broncho-alveolar lavage reveal haemosiderin laden macrophages. It may occurs most frequently as a secondary condition due to microscopic polyangiitis (MPA), Wegener's granulomatosis (WG), Goodpasture syndrome. Among the many conditions it can accompany connective tissue disorders, antiphospholipid antibody syndrome, some medicines or toxic exposures.

[CYP2C9 and VKORC1 gene polymorphism and acenocoumarol anticoagulant activity in Russian patients at high risk of thromboembolic complications]

The study included 25 patients at high risk of thromboembolic complications. All of them were treated with acenocoumarol for 6 months under control of the frequency of hemorrhage and episodes of severe hypocoagulation (a more than 3-fold rise in INR). All the patients underwent CYP2C9 and VKORC1 genotyping. It was shown that the presence of CYP2C9*2 and CYP2C9*3 alleles in the CYP2C9 locus and the AA genotype of the polymorphous G-1639(3673)A marker of the VKORC1 gene was not associated with the development of severe hypocoagulation episodes (p = 0.261--for CYP2C9, p = 0.616 and 0.361 for VKORC1 in the total group and a subgroup of patients having the CYP2C9*1/*1 genotype respectively and treated with acenocoumarol. The search for other genetic markers of efficacy and safety of this drug should be continued.

Oral rivaroxaban for symptomatic venous thromboembolism

BACKGROUND

Rivaroxaban, an oral factor Xa inhibitor, may provide a simple, fixed-dose regimen for treating acute deep-vein thrombosis (DVT) and for continued treatment, without the need for laboratory monitoring.

METHODS

We conducted an open-label, randomized, event-driven, noninferiority study that compared oral rivaroxaban alone (15 mg twice daily for 3 weeks, followed by 20 mg once daily) with subcutaneous enoxaparin followed by a vitamin K antagonist (either warfarin or acenocoumarol) for 3, 6, or 12 months in patients with acute, symptomatic DVT. In parallel, we carried out a double-blind, randomized, event-driven superiority study that compared rivaroxaban alone (20 mg once daily) with placebo for an additional 6 or 12 months in patients who had completed 6 to 12 months of treatment for venous thromboembolism. The primary efficacy outcome for both studies was recurrent venous thromboembolism. The principal safety outcome was major bleeding or clinically relevant nonmajor bleeding in the initial-treatment study and major bleeding in the continued-treatment study.

RESULTS

The study of rivaroxaban for acute DVT included 3449 patients: 1731 given rivaroxaban and 1718 given enoxaparin plus a vitamin K antagonist. Rivaroxaban had noninferior efficacy with respect to the primary outcome (36 events [2.1%], vs. 51 events with enoxaparin-vitamin K antagonist [3.0%]; hazard ratio, 0.68; 95% confidence interval [CI], 0.44 to 1.04; P<0.001). The principal safety outcome occurred in 8.1% of the patients in each group. In the continued-treatment study, which included 602 patients in the rivaroxaban group and 594 in the placebo group, rivaroxaban had superior efficacy (8 events [1.3%], vs. 42 with placebo [7.1%]; hazard ratio, 0.18; 95% CI, 0.09 to 0.39; P<0.001). Four patients in the rivaroxaban group had nonfatal major bleeding (0.7%), versus none in the placebo group (P=0.11).

CONCLUSIONS

Rivaroxaban offers a simple, single-drug approach to the short-term and continued treatment of venous thrombosis that may improve the benefit-to-risk profile of anticoagulation. (Funded by Bayer Schering Pharma and Ortho-McNeil; ClinicalTrials.gov numbers, NCT00440193 and NCT00439725.).