Evaluation of weight based enoxaparin dosing on anti-Xa concentrations in patients with obesity

A Quality Initiative to Improve Appropriate Medication Dosing in Pediatric Patients with Obesity

Introduction

Emerging evidence supports the use of alternative dosing weights for medications in patients with obesity. Pediatric obesity presents a particular challenge because most medications are dosed based on patient weight. Additionally, building system-wide pediatric obesity safeguards is difficult due to pediatric obesity definitions of body mass index-percentile-for-age via the Center for Disease Control growth charts. We describe a quality initiative to increase appropriate medication dosing in inpatients with obesity. The specific aim was to increase appropriate dosing for 7 high-risk medications in inpatients with obesity ≥2 years old from 37% to >74% and to sustain for 1 year.

Methods

The Institute for Healthcare Improvement model for improvement was used to plan interventions and track outcomes progress. Interventions included a literature review to establish internal dosing guidance, electronic health record (EHR) functionality to identify pediatric patients with obesity, a default selection for medication weight with an opt-out, and obtaining patient heights in the emergency department.

Results

Appropriate dosing weight use in medication ordered for patients with obesity increased from 37% to 83.4% and was sustained above the goal of 74% for 12 months.

Conclusions

Implementation of EHR-based clinical decision support has increased appropriate evidence-based dosing of medications in pediatric and adult inpatients with obesity. Future studies should investigate the clinical and safety implications of using alternative dosing weights in pediatric patients.

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.

Monitoring anti-Xa Levels to Optimize Low-Molecular-Weight-Heparin Thromboprophylaxis in High-Risk Hospitalized Patients: A Stratified Meta-Analysis

It is uncertain whether monitoring or targeting anti-Xa levels is necessary when using low-molecular-weight-heparin (LMWH) to prevent venous thromboembolism (VTE). This stratified meta-analysis assessed whether monitoring trough or peak anti-Xa levels with LMWH dosing would reduce risk of VTE. Twelve non-randomized studies involving 3604 hospitalized patients met the inclusion criteria and were subject to meta-analysis. Eight studies assessed the association between VTE and peak anti-Xa levels (between .2 and .5 IU/ml) and four studies assessed the benefits of targeting the trough anti-Xa levels (>.1 IU/ml). Achieving an adequate peak or trough anti-Xa level was associated with a reduced risk of VTE (random-effects model odds ratio [OR] .52, 95% confidence interval [CI] .34-.77; P = .001, I2 = 30% and P-value for heterogeneity = .171) compared with using a fixed standard dose of LMWH. Targeting the trough level (OR .40, 95%CI 0.22-.75, P = .004) appeared to be more effective than targeting the peak level (OR .62, 95%CI 0.37-1.03, P = .066), although a formal interaction analysis did not confirm they were statistically different (ratio of ORs = 1.52, 95%CI 0.68-3.40; z score = 1.03, P = .306). Targeting a higher anti-Xa level did not appear to increase the risk of bleeding or transfusion (OR 1.20, 95%CI 0.46-3.17, P = .707).

Evaluation of the Quality and Safety of Venous Thromboembolism Prophylaxis Among Gastroenterology Inpatients at a Tertiary Hospital in Australia

Background and objective: Hospital acquired venous thromboembolisms (VTEs) are common and preventable. The Queensland Health VTE prophylaxis guidelines, developed in 2018, provide guidance for risk assessment, and prescribing of anticoagulation for prophylaxis and treatment of hospital inpatients. Currently, there are limited recommendations for gastroenterology patients. This study investigated the completion of VTE risk assessments, and the appropriateness of VTE prophylaxis regimens, in accordance with Queensland Health guidelines for gastroenterology patients. The quality and safety of VTE prophylaxis regimens was assessed based on their VTE risk and bleeding risk. Method: A retrospective study was conducted by obtaining a random sample of gastroenterology patients admitted to a tertiary Australian hospital, from 1st May 2019 and 1st May 2020, to determine the compliance of VTE risk assessment and thromboprophylaxis prescribing with state-wide VTE guidelines. The quality and safety of thromboprophylaxis was evaluated using the modified Caprini and HASBLED scores, and subsequent thromboprophylaxis-related complications. Results: Of the 94 patients reviewed, 68 did not have contraindications to thromboprophylaxis. Of these 68 patients, 32 (47%) had no VTE risk assessment recorded in their clinical records and were not prescribed any thromboprophylaxis during the hospitalization. There was no significant difference between thromboprophylaxis prescribing for patients with low VTE risk, compared to moderate to high VTE risk (P = .075). There was a trend for decrease in thromboprophylaxis prescribing as HASBLED bleeding risk score increased, and patients with moderate-high bleed risk were less likely to be prescribed thromboprophylaxis (P = .006). There were no thromboprophylaxis related complications identified. Conclusion: It is essential that all patients have a clearly documented risk assessment and are prescribed thromboprophylaxis according to best practice guidelines. The prescription of venous thromboembolism prophylaxis should continue to be individualized, with each patient assessed holistically.

Strategies involving low-molecular-weight heparin for the treatment and prevention of venous thromboembolism in patients with obesity: A systematic review and meta-analysis

INTRODUCTION

Recent studies have indicated that the dosage of LMWH in patients with specific weights may be controversial. Therefore, we conducted a meta-analysis to explore an appropriate dosage of LMWH for the prevention and treatment of venous thromboembolism (VTE) in patients with obesity.

MATERIALS AND METHODS

We searched the PubMed, EMBASE, and Cochrane Library databases up to July 23, 2022. Study selection, bias analysis, and information extraction were performed by three independent reviewers. The occurrence or recurrence of VTE and bleeding events were the primary outcomes we assessed.

RESULTS

Eleven studies (a total of 6266 patients) were included in the prevention group, and 6 studies (a total of 3225 patients) were included in the treatment group. For VTE prophylaxis, compared with the standard-dosage group, the high-dosage group had a lower incidence of VTE (OR: 0.47, 95% CI: 0.27-0.82, P=0.007) and a similar incidence of bleeding events (OR: 0.86, 95% CI: 0.69-1.08, P=0.020). For VTE therapy, compared to the standard-dosage group, the reduced-dosage group had a similar incidence of VTE recurrence (OR: 0.86, 95% CI: 0.11-6.84, P=0.89) but a lower incidence of bleeding events (OR: 0.30, 95% CI: 0.10-0.89, P=0.03).

CONCLUSION

In patients with obesity, increasing the dosage of LMWH is a more appropriate option for the prevention of VTE. Due to the limited evidence, reducing the therapeutic dosage of LMWH requires careful consideration. Larger-scale, well-designed randomized controlled trials are necessary.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?, identifier ID=CRD42022298128.

Comparison of two escalated enoxaparin dosing regimens for venous thromboembolism prophylaxis in obese hospitalized patients

Standard fixed-dose enoxaparin dosing regimens may not provide adequate prophylaxis against venous thromboembolism among obese hospitalized patients. While several escalated doses have been shown to result in more frequent attainment of target anti-factor Xa levels than standard doses, few studies compare escalated doses to each other. In this prospective, multi-center trial, enoxaparin 0.5 mg/kg daily (weight-based dosing) and enoxaparin 40 mg twice daily were compared to determine if either dose resulted in more frequent attainment of anti-factor Xa levels within the goal range of 0.2-0.5 IU/mL. Eighty patients with a BMI ≥ 40 kg/m² were enrolled. There was no difference in the percent of patients achieving goal anti-factor Xa levels (72.5% vs. 70.0%, respectively; p = 0.72). Patients were more likely to attain anti-factor Xa levels below goal range than above. No bleeding or thrombotic events occurred. Either weight-based or twice-daily escalated enoxaparin dosing regimens appear effective at achieving target anti-factor Xa levels among hospitalized patients, and no safety events were noted. Future studies are needed to determine the clinical significance of this result.

Dosage of Anticoagulants in Obesity: Recommendations Based on a Systematic Review

Anticoagulants are frequently used as thromboprophylaxis and in patients with atrial fibrillation (AF) or venous thromboembolism (VTE). While obesity rates are reaching epidemic proportions worldwide, the optimal dosage for obese patients has not been established for most anticoagulants, including low-molecular-weight heparin (LMWH), non-vitamin K antagonist oral anticoagulants (NOAC), and pentasaccharides (fondaparinux). The aim of the present systematic review was to summarize the current knowledge and provide recommendations on dosage of LMWH, NOAC, and fondaparinux in obese patients (body mass index [BMI] ≥ 30 kg/m² or body weight ≥ 100 kg). Based on a systematic search in PubMed and Embase, a total of 72 studies were identified. For thromboprophylaxis with LMWH in bariatric surgery (n = 20 studies), enoxaparin 40 mg twice daily, dalteparin 5,000 IE twice daily, or tinzaparin 75 IU/kg once daily should be considered for patients with BMI ≥ 40 kg/m². For thromboprophylaxis with LMWH in nonbariatric surgery and in medical inpatients (n = 8 studies), enoxaparin 0.5 mg/kg once or twice daily or tinzaparin 75 IU/kg once daily may be considered in obese patients. For treatment with LMWH (n = 18 studies), a reduced weight-based dose of enoxaparin 0.8 mg/kg twice daily should be considered in patients with BMI ≥ 40 kg/m², and no dose capping of dalteparin and tinzaparin should be applied for body weight < 140 kg. As regards NOAC, rivaroxaban, apixaban, or dabigatran may be used as thromboprophylaxis in patients with BMI < 40 kg/m² (n = 4 studies), whereas rivaroxaban and apixaban may be administered to obese patients with VTE or AF, including BMI > 40 kg/m², at standard fixed-dose (n = 20 studies). The limited available evidence on fondaparinux (n = 3 studies) indicated that the treatment dose should be increased to 10 mg once daily in patients weighing > 100 kg.

Complications and Failure to Rescue After Abdominal Surgery for Trauma in Obese Patients

BACKGROUND

Although obesity is considered an epidemic in the United States, there is mixed evidence regarding the impact of obesity on outcomes after traumatic injury and major surgery. We hypothesized that obese patients undergoing trauma laparotomy would be at increased risk of failure to rescue (FTR), defined as death after a complication.

METHODS

We analyzed trauma registry data for adult patients who underwent abdominal exploration for trauma at all 30 level I and II Pennsylvania trauma centers, 2011-2014. We used competing risks regression to identify significant risk factors for complications. We used multivariable logistic regression to identify significant risk factors for FTR.

RESULTS

Of 95,806 admitted patients, 15,253 (15.9%) were categorized as obese. Overall, 3228 (3.4%) underwent laparotomy, including 2681 (83.1%) nonobese and 547 (17.0%) obese patients. Among obese patients, 47.2% had at least one complication and 28.7% had two or more complications, compared with 33.5% and 18.7% of nonobese patients, respectively. The most common complication was pneumonia (15.0% of obese and 10.5% of nonobese patients; P = 0.003), followed by sepsis (8.8% versus 4.2%; P < 0.001) and deep vein thrombosis (8.4% versus 5.9%; P < 0.001). Obesity was independently associated with complications (hazard ratio, 1.4; 95% confidence interval, 1.2-1.6). In multivariable analysis, obesity was not associated with FTR (odds ratio, 1.3; 95% confidence interval, 0.9-2.0).

CONCLUSIONS

Obesity is a risk factor for complications after traumatic injury but not for FTR. The increased risk of complications may reflect processes of care that are not attuned to the needs of this population, offering opportunities for improvement in care.