Safety and efficacy of low-dose fondaparinux (1.5 mg) for the prevention of venous thromboembolism in acutely ill medical patients with renal impairment: the FONDAIR study

[Optimal prevention of VTE in cancer surgery patients with impaired renal function]

Despite notable progress in the prevention of venous thromboembolic complications (VTE) and its widespread use in recent decades, mortality in cancer patients from VTE is still second only to the main disease. Some features and limitations in cancer patients, such as a decrease in kidney function and platelet count, an increased risk of bleeding, and the difficulty of monitoring the adequacy and safety of thromboprophylaxis, as well as the use of aggressive chemotherapy, determine the need for more effective and safer ways to solve the problem of VTE. Also, in the case of surgical interventions in such patients, the need for preoperative thromboprophylaxis raises new challenges for doctors. The article presents a review of the issue using a clinical case.

Net-clinical benefit of extended prophylaxis of venous thromboembolism with betrixaban in medically ill patients aged 80 or more

BACKGROUND

Extended-duration thromboprophylaxis with betrixaban reduces the risk of venous thromboembolism (VTE) without increasing major bleeding rates in acutely ill medical patients as compared to standard duration enoxaparin. We aimed to assess the risk-benefit of betrixaban in patients aged ≥ 80 years enrolled in the APEX trial.

METHODS

APEX was a randomized, double-blind trial in which patients hospitalized for acute medical illnesses received enoxaparin 40 mg qd for 10 ± 4 days or oral betrixaban 80 mg qd for 35 to 42 days. The primary efficacy outcome was VTE, the principal safety outcome was major bleeding. Net clinical benefit (NCB) was defined by the occurrence of VTE or major bleeding.

RESULTS

Of 7513 patients enrolled in the APEX trial, 2781 (37%) were aged ≥ 80 years. In this subgroup, VTE or major bleeding occurred in 7.0% of betrixaban patients and in 8.4% of enoxaparin patients, for a relative risk in the NCB of 0.82 (95% confidence interval 0.62-1.10). The relative risk reduction obtained with betrixaban was similar between those aged ≥ 80 years and patients younger than 80 years (5.0% and 6.7%, respectively, NCB 0.75, 0.58-0.96, P = .024), with no significant interaction across age groups (P = .33).

CONCLUSIONS

Event rates were higher in medically ill patients aged ≥ 80 years enrolled in the APEX study than in patients younger than 80 years. The predefined NCB was reduced with extended betrixaban therapy in both groups with no signs of age-related interactions. However, the primary efficacy endpoint was not achieved with betrixaban for patients 80 years of age or older.

Venous Thromboembolism Prophylaxis and Risk for Acutely Medically Ill Patients Stratified by Different Ages and Renal Disease Status

The objectives of this study were to examine venous thromboembolism (VTE) prophylaxis patterns and risk for VTE events during hospitalization and in the outpatient continuum of care among patients hospitalized for acute illnesses in the United States with stratification by different age groups and renal disease status. Acutely ill hospitalized patients were identified from the MarketScan databases (January 1, 2012-June 30, 2015) and grouped by age (<65, 65-74, ≥75 years old) and whether or not they had a baseline diagnosis of renal disease, separately. Of acutely ill hospitalized patients, 60.1% (n = 10 748) were <65 years old, 15.7% (n = 2803) were 65 to 74 years old, and 24.3% (n = 4344) were ≥75 years old; 32.9% (n = 5892) had baseline renal disease. Among the study cohorts, the majority of patients received no VTE prophylaxis regardless of age or baseline renal status (52.1%-63.6%). Rates of VTE during hospitalization and in the 6 months postdischarge were 4.7%, 4.6%, and 4.5% for patients <65, 65 to 74, and ≥75 years old, respectively, and 6.3% and 3.8% for patients with and without baseline renal disease. The risk for VTE was elevated for 30 to 40 days after index admission regardless of age and renal disease status.

Has time come for the use of direct oral anticoagulants in the extended prophylaxis of venous thromboembolism in acutely ill medical patients? Yes

Betrixaban is a direct factor Xa inhibitor with a renal excretion of only approximately 5-7%. On June 23rd 2017, it became the first direct oral anticoagulant to receive Food and Drug Administration approval for the prevention of venous thromboembolism in acutely ill medical patients, and the first anticoagulant agent to be approved for extended-duration thromboprophylaxis after hospital discharge in this setting. Approval followed the results of the APEX trial, a phase III clinical trial comparing betrixaban (80 mg) administered for 35-42 days with enoxaparin (40 mg) administered for 10 ± 4 days. This study for the first time applied a risk assessment model, integrating clinical factors and a laboratory marker to identify high risk patients. To improve safety, a dose reduction was used for patients with creatinine clearance between 15 and 30 mL/min (betrixaban 40 mg and enoxaparin 20 mg) and for patients receiving concomitant treatment with potent P-glycoprotein inhibitors (betrixaban 40 mg). The primary prespecified analysis tested the hypothesis that the benefit of extended thromboprophylaxis with betrixaban was greatest in patients with elevated D-dimer, but the 21% relative risk reduction failed to meet the prespecified threshold for statistical significance. However, the analysis of the overall study population showed a favorable net clinical benefit with betrixaban, with a statistically significant reduction in all efficacy outcomes and no increase in major bleeding rates. An ongoing trial, MARINER, is also assessing a combined approach for risk stratification comparing extended-duration rivaroxaban with standard duration low molecular weight heparin.

Variation in Definitions of Immobility in Pharmacological Thromboprophylaxis Clinical Trials in Medical Inpatients: A Systematic Review

BACKGROUND

Although immobility is a common risk factor for venous thromboembolism (VTE) in medical inpatients, lack of a consistent definition of this term may limit accurate assessment of VTE risk for thromboprophylaxis.

OBJECTIVE

To examine various definitions of immobility used in recent pharmacological thromboprophylaxis clinical trials.

DATA SOURCES

PubMed and relevant references from articles/reviews from 2008 to 2016 were searched. Randomized controlled trials (RCTs) and other clinical studies involving adult hospitalized medical patients in acute care hospital settings that used the term immobility were selected. Two investigators independently abstracted data in duplicate, and accuracy was checked by a third investigator.

RESULTS

Twenty-one clinical studies were included. There was heterogeneity among individual VTE risk factors, with respect to the definition of immobility in medical inpatients in these trials. Thirteen studies utilized objective criteria to define "immobility" including duration (12 studies) and distance or time walked (6 studies). In contrast, 7 studies focused principally on subjective definitions (ie, describing the nature of immobility rather than specifying its quantitative measurement). Three RCTs vaguely defined the level of patient's immobility after hospitalization.

CONCLUSION

Despite the well-known effectiveness of pharmacological thromboprophylaxis for the prevention of VTE in acutely ill medical patients, there is no current consensus on how to define immobility. The heterogeneous nature of definitions of immobility has led to uncertainty about the importance of immobility in VTE risk assessment models. Although clinical studies have incorporated varying definitions of immobility into their inclusion criteria, immobility as a specific VTE risk factor has not been clearly defined.

Pentasaccharides for the prevention of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a common condition with potentially serious and life-threatening consequences. The standard method of thromboprophylaxis uses an anticoagulant such as low molecular weight heparin (LMWH) or warfarin. In recent years, another type of anticoagulant, pentasaccharide, an indirect factor Xa inhibitor, has shown good anticoagulative effect in clinical trials. Three types of pentasaccharides are available: short-acting fondaparinux, long-acting idraparinux and idrabiotaparinux. Pentasaccharides cause little heparin-induced thrombocytopenia and are better tolerated than unfractionated heparin, LMWH and warfarin. However, no consensus has been reached on whether pentasaccharides are superior or inferior to other anticoagulative methods.

OBJECTIVES

To assess effects of pentasaccharides versus other methods of thromboembolic prevention (thromboprophylaxis) in people who require anticoagulant treatment to prevent venous thromboembolism.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (last searched March 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2). The CIS searched trial databases for details of ongoing and unpublished studies. Review authors searched LILACS (Latin American and Caribbean Health Sciences) and the reference lists of relevant studies and reviews identified by electronic searches.

SELECTION CRITERIA

We included randomised controlled trials on any type of pentasaccharide versus other anticoagulation methods (pharmaceutical or mechanical) for VTE prevention.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed methodological quality and extracted data in predesigned tables.

MAIN RESULTS

We included in this review 25 studies with a total of 21,004 participants. All investigated fondaparinux for VTE prevention; none investigated idraparinux or idrabiotaparinux. Studies included participants undergoing abdominal surgery, thoracic surgery, bariatric surgery or coronary bypass surgery; acutely ill hospitalised medical patients; people requiring rigid or semirigid immobilisation; and those with superficial venous thrombosis. Most studies focused on orthopaedic patients. We lowered the quality of the evidence because of heterogeneity between studies and a small number of events causing imprecision.When comparing fondaparinux with placebo, we found less total VTE (risk ratio (RR) 0.24, 95% confidence interval (CI) 0.15 to 0.38; 5717 participants; 8 studies; I2 = 64%; P < 0.00001), less symptomatic VTE (RR 0.15, 95% CI 0.06 to 0.36; 6503 participants; 8 studies; I2 = 0%; P < 0.0001), less total DVT (RR 0.25, 95% CI 0.15 to 0.40; 5715 participants; 8 studies; I2 = 67%; P < 0.00001), less proximal DVT (RR 0.12, 95% CI 0.04 to 0.39; 2746 participants; 7 studies; I2 = 64%; P = 0.0004) and less total pulmonary embolism (PE) (RR 0.16, 95% CI 0.04 to 0.62; 6412 participants; 8 studies; I2 = 0%; P = 0.008) in the fondaparinux group. The quality of the evidence was moderate for total VTE, total DVT and proximal DVT, and high for symptomatic VTE and total PE.When fondaparinux was compared with LMWH, analyses indicated that fondaparinux reduced total VTE and DVT (RR 0.55, 95% CI 0.42 to 0.73; 9339 participants; 11 studies; I2 = 64%; P < 0.0001; and RR 0.54, 95% CI 0.40 to 0.71; 9356 participants; 10 studies; I2 = 67%; P < 0.0001, respectively), and showed a trend toward reduced proximal DVT (RR 0.58, 95% CI 0.33 to 1.02; 8361 participants; 9 studies; I2 = 53%; P = 0.06). Symptomatic VTE (RR 1.03, 95% CI 0.65 to 1.63; 12240 participants; 9 studies; I2 = 35%; P = 0.90) and total PE (RR 1.24, 95% CI 0.65 to 2.34; 12350 participants; 10 studies; I2 = 0%; P = 0.51) indicated no difference between fondaparinux and LMWH. The quality of the evidence was moderate for total VTE, symptomatic VTE, total DVT and total PE, and low for proximal DVT.We showed that fondaparinux increased major bleeding compared with both placebo and LWMH (RR 2.56, 95% CI 1.48 to 4.44; 6659 participants; 8 studies; I2 = 0%; P = 0.0008; moderate-quality evidence; and RR 1.38, 95% CI 1.09 to 1.75; 12,501 participants; 11 studies; I2 = 24%; P = 0.008; high-quality evidence, respectively). All-cause mortality was not different between fondaparinux and placebo or LMWH (RR 0.76, 95% CI 0.48 to 1.22; 6674 participants; 8 studies; I2 = 14%; P = 0.26; moderate-quality evidence; and RR 0.88, 95% CI 0.63 to 1.22; 12,400 participants; 11 studies; I2 = 0%; P = 0.44; moderate-quality evidence, respectively).One study compared fondaparinux with variable and fixed (1 mg per day) doses of warfarin after elective hip or knee replacement surgery and showed no difference in primary and secondary outcomes between fondaparinux and both variable and fixed doses of warfarin. The quality of the evidence was very low. One small study compared fondaparinux with edoxaban in patients with severe renal impairment undergoing lower-limb orthopaedic surgery and reported no thromboembolic events, major bleeding events or deaths in either group. The quality of the evidence was very low. One small study compared fondaparinux with mechanical thromboprophylaxis. Results showed no difference in total VTE and total DVT between fondaparinux and mechanical thromboprophylaxis. This study reported no cases pertaining to the other outcomes of this review. The quality of the evidence was low.There were insufficient studies to permit meaningful conclusions for subgroups of clinical conditions other than orthopaedic surgery.

AUTHORS' CONCLUSIONS

Moderate to high quality evidence shows that fondaparinux is effective for short-term prevention of VTE when compared with placebo. It can reduce total VTE, DVT, total PE and symptomatic VTE, and does not demonstrate a reduction in deaths compared with placebo. Low to moderate quality evidence shows that fondaparinux is more effective for short-term VTE prevention when compared with LMWH. It can reduce total VTE and total DVT and does not demonstrate a reduction in deaths when compared with LMWH. However, at the same time, moderate to high quality evidence shows that fondaparinux increases major bleeding when compared with placebo and LMWH. Therefore, when fondaparinux is chosen for the prevention of VTE, attention should be paid to the person's bleeding and thrombosis risks. Most data were derived from patients undergoing orthopaedic surgery. Therefore, the conclusion predominantly pertains to these patients. Data on fondaparinux for other clinical conditions are sparse.

Guidance for the practical management of the heparin anticoagulants in the treatment of venous thromboembolism

Venous thromboembolism (VTE) is a serious and often fatal medical condition with an increasing incidence. Despite the changing landscape of VTE treatment with the introduction of the new direct oral anticoagulants many uncertainties remain regarding the optimal use of traditional parenteral agents. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance based on existing guidelines and consensus expert opinion where guidelines are lacking. This specific chapter addresses the practical management of heparins including low molecular weight heparins and fondaparinux. For each anticoagulant a list of the most common practice related questions were created. Each question was addressed using a brief focused literature review followed by a multidisciplinary consensus guidance recommendation. Issues addressed included initial anticoagulant dosing recommendations, recommended baseline laboratory monitoring, managing dose adjustments, evidence to support a relationship between laboratory tests and meaningful clinical outcomes, special patient populations including extremes of weight and renal impairment, duration of necessary parenteral therapy during the transition to oral therapy, candidates for outpatient treatment where appropriate and management of over-anticoagulation and adverse effects including bleeding and heparin induced thrombocytopenia. This article concludes with a concise table of clinical management questions and guidance recommendations to provide a quick reference for the practical management of heparin, low molecular weight heparin and fondaparinux.

Safety and Efficacy of Fondaparinux in Renal Impairment

Objective: To evaluate the cumulative evidence regarding the efficacy and safety of using fondaparinux in renal impairment, manifested by preventing new or recurrent thrombosis and the incidence of bleeding, respectively. Data Sources: We searched the MEDLINE and Cochrane databases for relevant studies from 1966 until November 2014, using the terms "fondaparinux" and "renal failure" or "dialysis." Additional references were identified from review of literature citations. Study Selection and Data Extraction: Inclusion criteria were articles in English language and patients with creatinine clearance (CrCl) less than 50 mL/min. Exclusion criteria were using fondaparinux as an anticoagulant for dialyzer circuit patency, abstracts, case reports, case series, pediatrics (<18 years), and pharmacokinetic studies with no clinical efficacy and safety results. Data Synthesis: Our search retrieved 4 cohort studies, 1 clinical trial, and 1 randomized clinical trial (RCT) subgroup analysis. A total of 3237 patients received fondaparinux with a dose ranging from 1.25 mg to 2.5 mg daily. Three studies investigated fondaparinux as a prophylactic agent, 2 as a treatment agent, and 1 study investigated both. The only study with control group was the RCT subgroup analysis, which compared fondaparinux to enoxaparin. A total of 470 patients developed thromboembolic complications or death and 169 developed major bleeding. The composite outcome of safety and efficacy in the RCT subgroup analysis was significantly lower in fondaparinux group compared with the enoxaparin group (P = .001). Conclusions: Current evidence regarding the safety and efficacy of fondaparinux in renally impaired patients is limited and does not support its use in such population.

Clinical experience with prophylactic fondaparinux in critically ill patients with moderate to severe renal impairment or renal failure requiring renal replacement therapy

BACKGROUND

Fondaparinux has an increased bleeding risk in patients with a CrCl ≤ 50 mL/min and is contraindicated if CrCl < 30 mL/min. Data regarding dosing and anti-Xa monitoring are lacking in this population.

OBJECTIVE

To describe dosing, monitoring, and safety outcomes of prophylactic fondaparinux in critically ill patients with moderate to severe renal impairment, including renal replacement therapy (RRT).

METHODS

Retrospective analysis from October 2006 to November 2012 of patients ≥ 18 years old who received fondaparinux for ≥ 72 hours with ≥ 1 dose in an intensive care unit and a CrCl ≤ 50 mL/min or RRT during therapy. Participants were divided into 4 cohorts: moderate impairment (CrCl = 30-50 mL/min), severe impairment (CrCl < 30 mL/min), hemodialysis (HD), or continuous venovenous hemofiltration (CVVH). Outcomes included the incidence of clinically significant bleeding and thromboembolic events. Fondaparinux dose, dosing frequency, and anti-Xa level monitoring are described. Pharmacokinetic modeling was performed to assess drug accumulation.

RESULTS

In all, 95 patients met inclusion criteria: 64 (67.4%) with moderate impairment, 10 (10.5%) with severe impairment, 5 (5.3%) with HD, and 16 (16.8%) with CVVH. The median defined daily doses in the moderate, severe, HD, and CVVH cohorts were 2.5, 2.5, 0.9, and 1.9 mg. Anti-Xa monitoring occurred in 19 (20%) patients, although few concentrations were peaks. Clinically significant bleeding occurred in 4 (4.2%) patients. A pharmacokinetic model demonstrated drug accumulation.

CONCLUSIONS

Empirical dose adjustments may be prudent in critically ill patients with renal dysfunction; however, the optimal fondaparinux dosage in this population remains unknown. Peak anti-Xa concentrations may help guide therapy.

Thromboprophylaxis in acutely ill medical patients: results of a survey among Italian physicians

AIMS

acutely ill medical patients are at increased risk of venous thromboembolism (VTE) and often require thromboprophylaxis, but patient selection and adequate therapeutic decisions may be difficult due to the heterogeneity and the complexity of this population. We conducted a survey among a large cohort of Italian physicians to assess their approach to some important "grey" areas of VTE prevention in this setting.

METHODS

a questionnaire was distributed during the meeting of a national society of Internal Medicine (FADOI), held in May 2013. Four clinical scenarios describing areas of clinical uncertainty were administered to participants: the first on a patient with acute ischemic stroke; the second on a patient with severe renal insufficiency; the third on the duration of prophylaxis in the post-acute setting; and the last on a patient at high risk of VTE and at moderate risk of bleeding with preserved mobility.

RESULTS

453 questionnaires were returned (participants mean age 48.5 years). About 70% of participants systematically assess VTE and bleeding risk in their clinical practice, but a minority of them use risk assessment models. Prolonged prophylaxis in the post-acute setting was voted by more than eighty percent of participants; replies to the other three clinical scenarios were more heterogeneous with none of the options selected by more than 60% of participant.

CONCLUSION

physicians approach to "grey" areas of antithrombotic prophylaxis in the medical setting is quite heterogeneous and sometimes partially in contrast to recent guidelines, reinforcing the need for educational programs and high quality studies in this setting.

Thromboprophylaxis with fondaparinux in high-risk postoperative patients with renal insufficiency

Fondaparinux is an antithrombin-dependent factor Xa inhibitor that is used for thromboprophylaxis of patients undergoing hip fracture surgery, hip or knee replacement, or abdominal surgery. It is cleared by the kidney and should be used with caution in patients with renal impairment and avoided in patients with severe renal insufficiency. Recently, several studies have demonstrated that a lower dose of fondaparinux in patients with moderate renal impairment appears to be safe and effective. The purpose of this study was to obtain pharmacokinetic and clinical data on the use of prophylactic fondaparinux in patients with renal insufficiency undergoing major abdominal surgery for cancer (n=8) or orthopedic surgery (n=1). Anti-factor Xa levels were obtained, and a published population pharmacokinetic model for fondaparinux was fit to the data. The data were analyzed using NONMEM software. Fondaparinux did not appear to accumulate in these patients, even when the drug was administered for up to twelve days. Pharmacokinetic analysis revealed that the apparent clearance in this population, who were primarily undergoing cancer surgery, was similar to prior studies in orthopedic surgery patients. In contrast, lower estimates were obtained for volume of distribution and absorption rate constant parameters. None of the patients sustained a hemorrhagic complication attributable to fondaparinux. One patient developed hypoxia in the setting of transient atrial fibrillation and clinical suspicion for pulmonary embolism, but this was not confirmed radiographically. These results support the use of 1.5mg of fondaparinux every 24hours for thromboprophylaxis in patients with renal insufficiency undergoing high-risk surgical procedures.

Prevention of venous thromboembolism in hospitalized acutely ill medical patients: focus on the clinical utility of (low-dose) fondaparinux

Venous thromboembolism (VTE) is a frequent complication among acutely ill medical patients hospitalized for congestive heart failure, acute respiratory insufficiency, rheumatologic disorders, and acute infectious and/or inflammatory diseases. Based on robust data from randomized controlled studies and meta-analyses showing a reduced incidence of VTE by 40% to about 60% with pharmacologic thromboprophylaxis, prevention of VTE with low molecular weight heparin (LMWH), unfractionated heparin (UFH), or fondaparinux is currently recommended in all at-risk hospitalized acutely ill medical patients. In patients who are bleeding or are at high risk for major bleeding, mechanical prophylaxis with graduated compression stockings or intermittent pneumatic compression may be suggested. Thromboprophylaxis is generally continued for 6 to 14 days or for the duration of hospitalization. Selected cases could benefit from extended thromboprophylaxis beyond this period, although the risk of major bleeding remains a concern, and additional studies are needed to identify patients who may benefit from prolonged prophylaxis. For hospitalized acutely ill medical patients with renal insufficiency, a low dose (1.5 mg once daily) of fondaparinux or prophylactic LMWH subcutaneously appears to have a safe profile, although proper evaluation in randomized studies is lacking. The evidence on the use of prophylaxis for VTE in this latter group of patients, as well as in those at higher risk of bleeding complications, such as patients with thrombocytopenia, remains scarce. For critically ill patients hospitalized in intensive care units with no contraindications, LMWH or UFH are recommended, with frequent and careful assessment of the risk of bleeding. In this review, we discuss the evidence for use of thromboprophylaxis for VTE in acutely ill hospitalized medical patients, with a focus on (low-dose) fondaparinux.

NOACs for thromboprophylaxis in medical patients

The risk of venous thrombosis extends for an indeterminate length of time following admission to hospital with a medical or surgical condition. Observational studies in surgery show this risk extends for months and perhaps more than one year, for medical patients the risk extends for at least several weeks. Large bodies of evidence support the heightened risk status of hospitalised surgical and medical patients, and that prophylactic measures significantly reduce the risk of thrombosis. Extending thromboprophylaxis for 4-6 weeks with anticoagulants both old and new has been shown to be efficacious and safe in surgical patients. However in populations of medical patients although prolonged anticoagulant thromboprophylaxis has been shown to be efficacious it also results in more bleeding and the risk benefit is not clear. Hence no therapies are approved for prolonged thromboprophylaxis in medical patients. In this area there have been one phase III study of low molecular weight heparin and two completed phase III studies of NOACs. This article briefly summarises our understanding of the background to preventing venous thromboembolism in hospitalised medical patients and reviews the details of the studies using NOACs.