A systematic review of therapeutic enoxaparin dosing in obesity

Enoxaparin is a hydrophilic drug with obesity having little effect on its apparent volume of distribution, therefore patients with obesity receiving standard 1 mg/kg dosing may be at a higher risk of supratherapeutic dosing. Conversely, dose reducing patients with obesity could place already at risk patients at higher risk of a thrombotic event. Data and recommendations are variable for the most appropriate weight-based dose of therapeutic enoxaparin in obese patients, particularly those a weight > 100 kg or a body mass index (BMI) ≥ 40 kg/m2. The purpose of this systematic review was to globally evaluate these data to surmise optimal dosing recommendations for patients with obesity. A systematic review of English language studies was conducted and identified articles via Pubmed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) searches. Studies were included if they reported therapeutic enoxaparin use in adult patients with a BMI ≥ 40 kg/m2 or body weight > 100 kg and the percentage of patients achieving a therapeutic anti-Xa based on a weight-based dose or the weight-based dose required to produce a therapeutic anti-Xa level. Therapeutic attainment of anti-Xa levels were assessed across enoxaparin weight-based dosing categories including a very low dose group: < 0.75 mg/kg, low dose group: 0.75-0.85 mg/kg, and standard dose group: ≥ 0.95 mg/kg. Rates of bleeding and thrombosis were also evaluated. A total of eight studies were included. For anti-Xa level assessment, 682 patients were included. A total of 62% of anti-Xa levels were therapeutic in the very low dose group, 66% in the low dose group, and 42% in the standard dose group. Overall rates of total bleeding and thrombosis were assessed in 798 patients. A total of 29 bleedings (3.6%) occurred, and 27 reported a relationship to dose. Most bleedings, 85.2% (n = 23/27), occurred with doses in the standard dose group (≥ 0.95 mg/kg). Thrombosis occurred in 5 patients (0.6%). Utilization of a reduced weight-based dosing strategy for therapeutic enoxaparin in obese patients may increase the percentage of patients with a therapeutic anti-Xa level.

Comparison of Higher-Than-Standard to D-Dimer Driven Thromboprophylaxis in Hospitalized Patients With COVID-19

Introduction: Coronavirus disease 2019 is a global health threat often accompanied with coagulopathy. Despite use of thromboprophylaxis in this population, thrombotic event rates are high. Materials and methods: This was a multicenter, retrospective cohort study comparing the safety and effectiveness of thromboprophylaxis strategies at 2 institutions in hospitalized patients with coronavirus disease 2019. Regimen A utilized a higher-than-standard thromboprophylaxis dosage and Regimen B received full-dose anticoagulation for any D-dimer 3 mcg/mL or greater and prophylactic for less than 3 mcg/mL. The primary outcome compared the rate of thrombotic events between treatment groups. Secondary endpoints compared rates of major or clinically relevant non-major bleeding as well as the proportion of patients in each group experiencing thrombotic events within 30 days of discharge. Results: One-hundred fifty-three patients were included in the analysis, 64 receiving Regimen A and 89 receiving Regimen B. Seven (4.6%) thrombotic events occurred, 3 (4.7%) in patients receiving Regimen A, and 4 (4.5%) in Regimen B (P = 1.0). Twelve patients (13.5%) receiving Regimen B had a bleeding event versus 2 (3.1%) in Regimen A (P = .04), half of which were major in each group. All patients who bled in either treatment group were receiving mechanical ventilation, and 12 of 14 were receiving full-dose anticoagulation. One patient receiving Regimen A was readmitted with a pulmonary embolism. Conclusions: In this study, the thromboprophylactic regimen impacted bleeding, but no significant difference was seen with thrombotic outcomes. Almost all patients who experienced a bleed were mechanically ventilated and receiving full-dose anticoagulation. The use of full-dose anticoagulation should be cautioned in this population without an additional indication.

Stability of 2 mg/mL Adenosine Solution in Polyvinyl Chloride and Polyolefin Infusion Bags

Adenosine is a potent endogenous mediator of vasodilation. Compounded sterile solutions of adenosine are used in cardiac catheterization lab to perform stress tests on the heart. These tests are used to determine the fractional flow reserve (FFR) and are commonly used in the management and diagnosis of cardiovascular conditions. The purpose of this study was to assess the physical and chemical stability of 2 mg/mL adenosine in 0.9% Sodium Chloride Injection, USP in polyvinyl chloride [PVC]) and polyolefin infusion bags stored at room temperature (20°C-25°C) and under refrigeration (2°C-8°C). The compounding and analytical methods used in this study were very similar to those described in the prior publications from the authors' laboratory. To ensure a uniform starting concentration of all stability samples, a batch of 2 mg/mL adenosine solution was prepared and then packaged into empty PVC and polyolefin infusion bags. These stability samples were prepared in triplicate for each bag type and storage temperature (a total of 12 samples). The infusion bag samples were assessed for stability immediately after preparation and after 1 day, 3 days, 7 days, and 14 days. At each time point, the infusion bags were first visually inspected against a light background for color change, clarity, and particulates. Aliquots were drawn from each sample at each time point for pH analysis and high-performance liquid chromatography (HPLC) analysis. Over 14 days of storage at room temperature or refrigeration, no considerable change in visual appearance or pH was observed in any bags. All samples retained 90% to 110% of the initial drug concentration. No significant degradation peaks were observed in the HPLC chromatograms.

An evaluation of the behaviour-change techniques used on Canadian cancer centre Web sites to support physical activity behaviour for breast cancer survivors

Background

Cancer centre Web sites can be a useful tool for distributing information about the benefits of physical activity for breast cancer (bca) survivors, and they hold potential for supporting health behaviour change. However, the extent to which cancer centre Web sites use evidence-based behaviour change techniques to foster physical activity behaviour among bca survivors is currently unknown. The aim of our study was to evaluate the presentation of behaviour-change techniques on Canadian cancer centre Web sites to promote physical activity behaviour for bca survivors.

Methods

All Canadian cancer centre Web sites (n = 39) were evaluated by two raters using the Coventry, Aberdeen, and London-Refined (calo-re) taxonomy of behaviour change techniques and the eEurope 2002 Quality Criteria for Health Related Websites. Descriptive statistics were calculated.

Results

The most common behaviour change techniques used on Web sites were providing information about consequences in general (80%), suggesting goal-setting behaviour (56%), and planning social support or social change (46%). Overall, Canadian cancer centre Web sites presented an average of M = 6.31 behaviour change techniques (of 40 that were coded) to help bca survivors increase their physical activity behaviour. Evidence of quality factors ranged from 90% (sites that provided evidence of readability) to 0% (sites that provided an editorial policy).

Conclusions

Our results provide preliminary evidence that, of 40 behaviour-change techniques that were coded, fewer than 20% were used to promote physical activity behaviour to bca survivors on cancer centre Web sites, and that the most effective techniques were inconsistently used. On cancer centre Web sites, health promotion specialists could focus on emphasizing knowledge mobilization efforts using available research into behaviour-change techniques to help bca survivors increase their physical activity.

Efficacy and Safety of High-Dose Subcutaneous Unfractionated Heparin Prophylaxis for the Prevention of Venous Thromboembolism in Obese Hospitalized Patients

BACKGROUND

Obese patients experience a higher risk of venous thromboembolism (VTE) than their nonobese counterparts, which may warrant a more aggressive approach to thromboprophylaxis in this population.

OBJECTIVE

The purpose of this study was to compare rates of nosocomial VTE in obese patients treated with high-dose versus conventional-dose subcutaneous unfractionated heparin sodium (UFH) for thromboprophylaxis.

METHODS

A retrospective, single-center, cohort study was conducted to evaluate obese, adult, hospitalized patients admitted between April 2011 and April 2014 who received heparin 5,000 or 7,500 units subcutaneously every 8 hours for thromboprophylaxis. The primary outcome assessed the rate of nosocomial VTE in obese patients treated with high-dose heparin (7,500 units subcutaneously q 8 h) versus conventional-dose heparin (5,000 units subcutaneously q 8 h). Additionally, a secondary outcome assessed safety by quantifying bleeding events.

RESULTS

Nosocomial VTE occurred in 2/196 (1.02%) patients who received high-dose heparin thromboprophylaxis and in 5/2,182 (0.23%) patients who received conventional-dose heparin (p = .05). Bleeding occurred in 0/196 (0%) patients in the high-dose heparin group and in 2/2,182 (0.09%) patients in the conventional-dose heparin group (p = .67). All bleeding events were minor.

CONCLUSIONS

This study failed to demonstrate a statistically significant reduction in the rate of nosocomial VTE in obese patients who received high-dose heparin thromboprophylaxis. Despite receiving a higher heparin dose, no increased risk of bleeding was observed in the high-dose group. Further investigation is needed to identify the optimal heparin dose for thromboprophylaxis in obese patients.

Abstract 203: Outcomes Comparison of Low Risk Medical and Surgical Patients Treated with Unfractionated Heparin vs. Enoxaparin

Objectives: We sought to compare the relative risks for adverse arterial vascular events in patients considered to be low risk for venous thromboembolism (VTE) events who were treated with enoxaparin compared to unfractionated heparin (UFH) for VTE prophylaxis, while comparing clinical efficacy for VTE and overall inpatient costs.

Methods: We retrospectively identified patients admitted to the medical and general surgical services who received VTE prophylaxis with either UFH or enoxaparin and compared outcomes before and after implementation of a evidenced based anticoagulation protocol during a twelve month period. Exclusions were: (1) high risk surgical patients, specifically patients undergoing orthopedic, cardiovascular, and bariatric surgery; (2) high risk medical patients, specifically patients admitted with, or having a history of, pulmonary embolism (PE), deep venous thrombosis, atrial fibrillation, or valve replacement; and (3) patients with a therapeutic INR (>2.0) on admission. Using Logistic regression analysis, the following outcomes were compared between the UFH and enoxaparin treated groups: deep venous thrombosis, PE, myocardial infarction (MI), stroke, transient ischemic attack (TIA), heparin induced thrombocytopenia (HIT) and mortality among both groups. Length of hospital stay (LOS) and length of intensive care unit (ICU) LOS were compared using multiple regression analysis. Total costs between the two treatment groups were also compared using a t-test.

Results: From the study group, a total of 6,390 patients received UFH prophylaxis and 1,565 received enoxaparin. The enoxaparin patients’ average age was younger than the UFH treated patients’ age by 2.4 years (59.1 and 61.5 years old, respectively, p<0.0001). The incidence of deep venous thrombosis, PE and HIT was similar in both groups. The enoxaparin group had a 52% higher odds for TIA (3.64 vs. 2.49 per 100 patients, OR=1.52, CI 1.113,2.078, p= 0.0024), 61% higher odds for stroke (9.3 vs. 6.6 per 100 patients, OR=1.589, CI 1.298, 1.945, p= 0.0009), while having a 54% lower odds for MI (2.1 vs. 4.7 per 100 patients, OR=0.46,CI 0.32, 0.66, p<0.0001) and lower mortality rate (0 vs. 1.3 per 100 patients). The hospital LOS in the enoxaparin group was 0.73 days lower than in the heparin group (4.41 days vs. 5.13 days, p<0.0001) and the ICU LOS was also shorter by 0.6 days (0.095 vs. 0.69 days, p<0.0001). The total cost (20, 690 vs. 25,946 dollars) was lower in the enoxaparin group.

Conclusions: In low-risk medical and general surgical patients, UFH was as effective as enoxaparin in the prevention of thromboembolic events, with no difference in the incidence of HIT. When compared to UFH, enoxaparin was associated with lower MI and mortality rates, and shorter LOS and ICU LOS, at the expense of higher rates of stroke and TIA. Enoxaparin was associated with lower total inpatient costs than UFH.

Correlation of antifactor Xa concentrations with renal function in patients on enoxaparin

Enoxaparin is a low molecular weight heparin (LMWH) that has been shown to be effective in deep vein thrombosis, pulmonary embolism, and unstable angina. Because renal function plays an important role in the clearance of LMWH, the authors sought to investigate the effect of renal function on enoxaparin. This prospective multiple-dose study evaluated 18 patients with varying degrees of renal function initiated on enoxaparin 1 mg/kg subcutaneously every 12 hours. Peak blood levels of anti-Xa concentrations were obtained 4 +/- 0.5 hours postdose after receiving at least three doses of enoxaparin. The median antifactor Xa levels were higher in patients with creatinine clearance (CLCr) < or = 30 mL/min compared to CLCr > or = 31 mL/min (1.34 IU/mL vs. 0.91 IU/mL, respectively, p < 0.05). A linear correlation was established between creatinine clearance and anti-Xa concentrations (p < 0.0005). On the basis of the data, the authors believe that a dose adjustment is necessary in patients receiving repeated doses of enoxaparin with CLCr < or = 30 mL/min.