Enoxaparin titrated by anti-Xa levels reduces venous thromboembolism in trauma patients

Anti-xa guided enoxaparin thromboprophylaxis is associated with less thromboembolism than fixed dose dalteparin in trauma patients admitted to intensive care

BACKGROUND

Venous Thromboembolism (VTE) is a common, preventable complication in trauma. Low-molecular-weight heparin (LMWH) is recommended for VTE prophylaxis (VTEp). We investigated whether switching from fixed-dose dalteparin to anti-Xa-guided enoxaparin prophylaxis reduces VTE without increasing the risk of bleeding among hospitalized trauma patients.

METHODS

This observational study compared injured patients admitted one year before (pre-P) and after (post-P) implementing a new VTEp protocol. The protocol was introduced as a performance improvement project (subcutaneous enoxaparin 30 mg twice daily), with dose calibration to peak plasma Anti-Xa level measured after the 3rd dose. The primary outcomes were the rate of VTE and bleeding.

RESULTS

After protocol implementation (post-P), 305 patients were compared to 350 pre-protocol patients (pre-P). Anti-Xa levels were measured in 83% of post-P and none in the pre-P. 40% had low levels of anti-Xa, suggesting inadequate prophylaxis, and enoxaparin doses were accordingly increased. 51% attained the desired anti-Xa levels, 9% had higher levels, and LMWH doses were subsequently reduced. VTE incidence after protocol implementation decreased from 4 to 1.3% (OR 0.31; 95% CI 0.1-0.9, P = 0.03) without increasing the bleeding rate. The time intervals between two consecutive PE events were significantly longer after protocol implementation. Among TBI patients, the rate of VTE was lower. However, it did not reach statistical significance. 75% of patients with VTE had low anti-Xa levels, while 20% of those with bleeding had high anti-Xa levels.

CONCLUSION

Among adult patients in the trauma ICU, compared to a fixed dose dalteparin, enoxaparin prophylaxis with dose calibration according to peak anti-Xa levels was associated with lower VTE rates without increasing the risk of bleeding. About 40% of patients who received initial enoxaparin doses of 30 mg twice daily had anti-Xa levels suggestive of inadequate prophylaxis. Calibrating LMWH dosing may improve VTEp following traumatic injury.

Multi-Modal Venous ThromboembolicProphylaxis Aids in Risk Reduction Following Splenectomy in Female and Male Mice

INTRODUCTION

Splenectomy (SPLN) is associated with elevated risk of venous thromboembolic (VTE) disease. Enoxaparin (ENX) is a low-molecular-weight heparin agent used in VTE chemoprophylaxis. Early aspirin administration ameliorates postSPLN platelet hyperaggregability in male mice. Previous literature has excluded female mice, citing potential effects of estrogen on platelet count and activation as a reason. We hypothesized that multimodal therapy using aspirin and ENX would mitigate postoperative platelet aggregability in mice across sexes.

METHODS

Murine models of SPLN included both male and female mice. Treatment groups included placebo gavage, sham laparotomy, SPLN alone, SPLN and aspirin, SPLN and ENX, and SPLN with aspirin and ENX (n = 5 per group). Chemoprophylaxis dosing was initiated before SPLN. Mice were euthanized on post-operative day (POD) 1 or 3; platelet counts were obtained and blood samples were analyzed via electrical impedance aggregometry.

RESULTS

Females on POD 3 following SPLN demonstrated increased platelet count compared to female mice with no treatment intervention. Male and female mice demonstrated increased adenosine diphosphate (ADP)-induced platelet aggregability on POD 3 following SPLN compared to the placebo group. Treatment with aspirin and ENX decreased this post-SPLN platelet hyperaggregability in both sexes. Females demonstrated significantly higher ADP-mediated platelet aggregability in placebo, SPLN, and SPLN with aspirin and ENX when compared to males of identical treatment groups on POD 3.

CONCLUSIONS

Platelet hyperaggregability following SPLN is mediated primarily by ADP in both males and females, but higher relative aggregability is demonstrated in females. Early administration of dual-agent VTE chemoprophylaxis utilizing aspirin and ENX mitigates this hyperaggregability and may aid in VTE risk reduction across sexes.

Severe Traumatic Brain Injury and Pulmonary Embolism: Risks, Prevention, Diagnosis and Management

Severe traumatic brain injury (sTBI) is a silent epidemic, causing approximately 300,000 intensive care unit (ICU) admissions annually, with a 30% mortality rate. Despite worldwide efforts to optimize the management of patients and improve outcomes, the level of evidence for the treatment of these patients remains low. The concomitant occurrence of thromboembolic events, particularly pulmonary embolism (PE), remains a challenge for intensivists due to the risks of anticoagulation to the injured brain. We performed a literature review on sTBI and concomitant PE to identify and report the most recent advances on this topic. We searched PubMed and Scopus for papers published in the last five years that included the terms "pulmonary embolism" and "traumatic brain injury" in their title or abstract. Exclusion criteria were papers referring to children, non-sTBI populations, and post-acute care. Our search revealed 75 papers, of which 38 are included in this review. The main topics covered include the prevalence of and risk factors for pulmonary embolism, the challenges of timely diagnosis in the ICU, the timing of pharmacological prophylaxis, and the treatment of diagnosed PE.

Thrombosis prophylaxis following trauma

PURPOSE OF REVIEW

This review explores the persistent occurrence of venous thromboembolic events (VTE) in major trauma patients despite standard thrombosis prophylaxis with low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH). It investigates the inadequacies of standard pharmacologic prophylaxis and proposes alternative approaches not covered in current trauma guidelines.

RECENT FINDINGS

Recent studies highlight the effectiveness of monitoring and adjusting subcutaneous LMWH doses based on anti-Xa levels for the purpose of reducing VTE in trauma patients. The need for dose adaptation arises due to factors like fluctuating organ function, varying antithrombin levels, interaction with plasma proteins, and altered bioavailability influenced by oedema or vasopressor use. Additionally, promising alternatives such as intravenous LMWH, UFH, and argatroban have shown success in intensive care settings.

SUMMARY

The standard dosing of subcutaneous LMWH is often insufficient for effective thrombosis prophylaxis in trauma patients. A more personalised approach, adjusting doses based on specific effect levels like anti-Xa or choosing an alternative mode of anticoagulation, could reduce the risk of insufficient prophylaxis and subsequent VTE.

Clinical outcomes associated with anti-Xa-monitored enoxaparin for venous thromboembolism prophylaxis

STUDY OBJECTIVE

The objective of the study was to assess clinical outcomes (composite of any venous thromboembolism [VTE], any bleeding, and mortality) associated with anti-Xa monitoring in the 30 days following enoxaparin initiation for VTE prophylaxis.

DESIGN

Retrospective cohort study.

SETTING

Hospital within an academic healthcare system.

PATIENTS

Propensity score-matched hospitalized adults receiving enoxaparin for VTE prophylaxis.

INTERVENTION

Low-molecular-weight heparin anti-Xa monitoring.

MEASUREMENTS AND MAIN RESULTS

During the 13-month study period, a total of 6611 patients received enoxaparin for VTE prophylaxis, 301 in the anti-Xa monitored group and 6310 in the unmonitored group (4.6% received monitoring). The mean age was 52.9 years and 52% of patients were male. The mean body mass index was 31 kg/m2 and the mean creatinine clearance was 109 mL/min. Twenty percent of patients had active cancer. The most common indication for enoxaparin prophylaxis was hospitalization for medical illness (52%) followed by nonorthopedic surgery (37%). The adjusted odds ratio for the primary outcome comparing monitored to unmonitored patients was 1.26 (95% confidence interval, 0.75-2.11). None of the between-group differences in the individual components of the composite outcome were statistically significant.

CONCLUSIONS

Thirty-day clinical outcomes in patients receiving enoxaparin for VTE prophylaxis were not improved by anti-Xa monitoring. Our results support current evidence-based guideline recommendations against anti-Xa monitoring for patients receiving enoxaparin for VTE prophylaxis.

Multicenter study evaluating target attainment of anti-Factor Xa levels using various enoxaparin prophylactic dosing practices in adult trauma patients

STUDY OBJECTIVE

Enoxaparin is standard of care for venous thromboembolism (VTE) prophylaxis in adult trauma patients, but fixed-dose protocols are suboptimal. Dosing based on body mass index (BMI) or total body weight (TBW) improves target prophylactic anti-Xa level attainment and reduces VTE rates. A novel strategy using estimated blood volume (EBV) may be more effective based on results of a single-center study. This study compared BMI-, TBW-, EBV-based, and hybrid enoxaparin dosing strategies at achieving target prophylactic anti-Factor Xa (anti-Xa) levels in trauma patients.

DESIGN

Multicenter, retrospective review.

DATA SOURCE

Electronic health records from participating institutions.

PATIENTS

Adult trauma patients who received enoxaparin twice daily for VTE prophylaxis and had at least one appropriately timed anti-Xa level (collected 3 to 6 hours after the previous dose after three consecutive doses) from January 2017 through December 2020. Patients were excluded if the hospital-specific dosing protocol was not followed or if they had thermal burns with > 20% body surface area involvement.

INTERVENTION

Dosing strategy used to determine initial prophylactic dose of enoxaparin.

MEASUREMENTS

The primary end point was percentage of patients with peak anti-Xa levels within the target prophylactic range (0.2-0.4 units/mL).

MAIN RESULTS

Nine hospitals enrolled 742 unique patients. The most common dosing strategy was based on BMI (43.0%), followed by EBV (29.0%). Patients dosed using EBV had the highest percentage of target anti-Xa levels (72.1%). Multiple logistic regression demonstrated EBV-based dosing was significantly more likely to yield anti-Xa levels at or above target compared to BMI-based dosing (adjusted odds ratio (aOR) 3.59, 95% confidence interval (CI) 2.29-5.62, p < 0.001). EBV-based dosing was also more likely than hybrid dosing to yield an anti-Xa level at or above target (aOR 2.30, 95% CI 1.33-3.98, p = 0.003). Other pairwise comparisons between dosing strategy groups were nonsignificant.

CONCLUSIONS

An EBV-based dosing strategy was associated with higher odds of achieving anti-Xa level within target range for enoxaparin VTE prophylaxis compared to BMI-based dosing and may be a preferred method for VTE prophylaxis in adult trauma patients.

Inadequate prophylaxis in patients with trauma: anti-Xa-guided enoxaparin dosing management in critically ill patients with trauma

Venous thromboembolism (VTE) causes significant morbidity in patients with trauma despite advances in pharmacologic therapy. Prior literature suggests standard enoxaparin dosing may not achieve target prophylactic anti-Xa levels. We hypothesize that a new weight-based enoxaparin protocol with anti-Xa monitoring for dose titration in critically injured patients is safe and easily implemented.

Methods

This prospective observational study included patients with trauma admitted to the trauma intensive care unit (ICU) from January 2021 to September 2022. Enoxaparin dosing was adjusted based on anti-Xa levels as standard of care via a performance improvement initiative. The primary outcome was the proportion of subtarget anti-Xa levels (<0.2 IU/mL) on 30 mg two times per day dosing of enoxaparin. Secondary outcomes included the dosing modifications to attain goal anti-Xa levels, VTE and bleeding events, and hospital and ICU lengths of stay.

Results

A total of 282 consecutive patients were included. Baseline demographics revealed a median age of 36 (26-55) years, and 44.7% with penetrating injuries. Of these, 119 (42.7%) achieved a target anti-Xa level on a starting dose of 30 mg two times per day. Dose modifications for subtarget anti-Xa levels were required in 163 patients (57.8%). Of those, 120 underwent at least one dose modification, which resulted in 78 patients (47.8%) who achieved a target level prior to hospital discharge on a higher dose of enoxaparin. Overall, only 69.1% of patients achieved goal anti-Xa level prior to hospital discharge. VTE occurred in 25 patients (8.8%) and major bleeding in 3 (1.1%) patients.

Conclusion

A majority of critically injured patients do not meet target anti-Xa levels with 30 mg two times per day enoxaparin dosing. This study highlights the need for anti-Xa-based dose modification and efficacy of a pharmacy-driven protocol. Further optimization is warranted to mitigate VTE events.

Level of evidence

Therapeutic/care management, level III.

Body Mass Index and Pharmacologic Venous Thromboembolism Prophylaxis in Traumatic Brain Injury

INTRODUCTION

Patients with traumatic brain injury (TBI) are at risk for developing venous thromboembolic complications. Previous work suggests venous thromboembolism (VTE) prophylaxis with low molecular weight heparin (LMWH) is protective compared to unfractionated heparin (UH) in trauma patients. The purpose of this study was to evaluate the role of body mass index (BMI) and type of pharmacological VTE prophylaxis in patients who develop VTE with severe TBI.

METHODS

Patients with a severe TBI who received VTE prophylaxis were queried from the 2019 American College of Surgeons Trauma Quality Improvement Program database. Demographics, injury characteristics, timing of VTE prophylaxis, and BMI were collected. Outcome measures include VTE, mortality, and neurosurgical interventions.

RESULTS

Of the 39,520 patients with severe TBI included in the study, 25,671 received LMWH and 13,849 received UH. Multivariable logistic regression found patients with a BMI 25-29.9 kg/m2 (odds ratio [OR] 1.375; 95% confidence interval [CI] 1.180-1.603; P < 0.0001) and a BMI>30 kg/m2 (OR 1.831; 95% CI 1.570-2.137; P < 0.0001) were independent predictors of VTE. Patients with BMI of 25-29.9 kg/m2 (OR 1.145; 95% CI 1.016-1.289; P = 0.0265) have a higher risk of mortality. For every hour delay in initiation to VTE prophylaxis, patients were 0.2% more likely to develop VTE (OR 1.002; 95% CI 1.002-1.003; P < 0.0001). Patients treated with UH were more likely to develop VTE complications (OR 1.085; 95% CI 1.058-1.112; P < 0.0001) and have increased mortality (OR 1.116; 95% CI 1.094-1.139; P < 0.0001), regardless of BMI and time to initiation of prophylaxis, compared to patients treated with LMWH.

CONCLUSIONS

In patients with severe TBI, higher BMI was associated with an increased risk of VTE and death. Delay in VTE prophylaxis initiation was associated with an increased risk of VTE. LMWH had a protective association with VTE.

Inadequate Venous Thromboembolism Chemoprophylaxis Is Associated With Higher Venous Thromboembolism Rates Among Trauma Patients With Epidurals

INTRODUCTION

Guidelines encourage higher doses of low molecular weight heparin (LMWH) for prophylaxis in trauma patients. The risks of LMWH must be considered for patients who require an epidural catheter. We compared adequate and inadequate prophylaxis to determine if venous thromboembolism (VTE) and complication rates differed among patients with epidural catheters.

METHODS

Trauma patients who required an epidural catheter between 2012 and 2019 were reviewed for VTE and epidural-related complications. Adequate dosing was defined as enoxaparin 30 mg or 40 mg twice daily. Inadequate dosing was defined as unfractionated heparin subcutaneously or enoxaparin once daily.

RESULTS

Over the 8-y study period, 113 trauma patients required an epidural catheter of which 64.6% were males with a mean age of 55.8 y and injury severity score of 14. Epidural catheters were associated with 11 (9.7%) patients developing an acute deep vein thrombosis (DVT) and 2 (1.8%) patients with an acute pulmonary embolism. Those patients who received adequate doses of enoxaparin were less likely to have any VTE or DVT. Complications associated with epidural catheters were not dependent on the type of pharmacological prophylaxis.

CONCLUSIONS

Given the high VTE rate observed in trauma patients who required an epidural catheter, along with the low complication rate that was observed independent of the type of pharmacological prophylaxis given, the data indicate that current efforts for higher doses of LMWH appear to be safe and associated with a lower VTE rate.

Rate of prophylactic anti-Xa achievement and impact on venous thromboembolism following oncologic hepato-pancreatico-biliary surgery: A prospective cohort study

BACKGROUND

Hepato-pancreatico-biliary (HPB) patients experience competing risk of venous thromboembolism (VTE) and bleeding. We sought to evaluate the effect of anti-Xa levels on VTE and bleeding, and to characterize factors associated with subprophylaxis.

METHODS

This prospective cohort study evaluated adult HPB surgical patients; cohorts were described by anti-Xa levels as subprophylactic (<0.2 IU/mL), prophylactic (0.2-0.5 IU/mL), and supraprophylactic (>0.5 IU/mL). Primary outcome evaluated bleeding and VTE complications. Secondary outcomes evaluated factors associated with subprophylaxis.

RESULTS

We included 157 patients: 68 (43.6%) attained prophylactic anti-Xa and 89 (56.7%) were subprophylactic. Subprophylactic patients experienced more VTE compared to prophylactic patients (6.9% vs 0%; p = 0.028) without differences in bleeding complications (14.6% vs 5.9%; p = 0.081). Factors associated with subprophylactic anti-Xa included female sex (OR 2.90, p = 0.008), and Caprini score (OR 1.30, p = 0.035). Enoxaparin was protective against subprophylaxis compared to tinzaparin (OR 0.43, p = 0.029).

CONCLUSIONS

Many HPB patients have subprophylactic anti-Xa levels, placing them at risk of VTE. Enoxaparin may be preferential, however, studies evaluating optimized prophylaxis are needed.

Efficacy and Safety of Anti-Xa-Guided Versus Fixed Dosing of Low Molecular Weight Heparin for Prevention of Venous Thromboembolism in Trauma Patients: A Systematic Review and Meta-Analysis

PURPOSE

Trauma patients are at high risk of venous thromboembolism (VTE). We summarize the comparative efficacy and safety of anti-Xa-guided versus fixed dosing for low molecular weight heparin (LMWH) for the prevention of VTE in adult trauma patients.

METHODS

We searched Medline and Embase from inception through June 1, 2022. We included randomized controlled trials or observational studies comparing anti-Xa-guided versus fixed dosing of LMWH for thromboprophylaxis in adult trauma patients. We incorporated primary data from 2 large observational cohorts. We pooled effect estimates using a random-effects model. We assessed risk of bias using the ROBINS-I tool for observational studies and assessed certainty of findings using GRADE methodology.

RESULTS

We included 15 observational studies involving 10,348 patients. No randomized controlled trials were identified. determined that, compared to fixed LMWH dosing, anti-Xa-guided dosing may reduce deep vein thrombosis [adjusted odds ratio (aOR); 0.52, 95% CI: 0.40-0.69], pulmonary embolism (aOR: 0.48, 95% CI: 0.30-0.78) or any VTE (aOR: 0.54, 95% CI: 0.42-0.69), though all estimates are based on low certainty evidence. There was an uncertain effect on mortality (aOR: 1.06, 95% CI: 0.85-1.32) and bleeding events (aOR: 0.84, 95% CI: 0.50-1.39), limited by serious imprecision. We used several sensitivity and subgroup analyses to confirm the validity of our assumptions.

CONCLUSION

Anti-Xa-guided dosing may be more effective than fixed dosing for prevention of deep vein thrombosis, pulmonary embolism, and VTE for adult trauma patients. These promising findings justify the need for a high-quality randomized study with the potential to deliver practice changing results.

Approaches for optimizing venous thromboembolism prevention in injured patients: Findings from the consensus conference to implement optimal venous thromboembolism prophylaxis in trauma

ABSTRACT

Venous thromboembolism (VTE) is a major issue in trauma patients. Without prophylaxis, the rate of deep venous thrombosis approaches 60% and even with chemoprophylaxis may be nearly 30%. Advances in VTE reduction are imperative to reduce the burden of this issue in the trauma population. Novel approaches in VTE prevention may include new medications, dosing regimens, and extending prophylaxis to the postdischarge phase of care. Standard dosing regimens of low-molecular-weight heparin are insufficient in trauma, shifting our focus toward alternative dosing strategies to improve prophylaxis. Mixed data suggest that anti-Xa-guided dosage, weight-based dosing, and thromboelastography are among these potential strategies. The concern for VTE in trauma does not end upon discharge, however. The risk for VTE in this population extends well beyond hospitalization. Variable extended thromboprophylaxis regimens using aspirin, low-molecular-weight heparin, and direct oral anticoagulants have been suggested to mitigate this prolonged VTE risk, but the ideal approach for outpatient VTE prevention is still unclear. As part of the 2022 Consensus Conference to Implement Optimal Venous Thromboembolism Prophylaxis in Trauma, a multidisciplinary array of participants, including physicians from multiple specialties, pharmacists, nurses, advanced practice providers, and patients met to attack these issues. This paper aims to review the current literature on novel approaches for optimizing VTE prevention in injured patients and identify research gaps that should be investigated to improve VTE rates in trauma.

One size does not fit all: Sex bias in pharmacologic venous thromboembolism prophylaxis

BACKGROUND

The optimal enoxaparin dosing strategy to achieve venous thromboembolism (VTE) prophylaxis in trauma patients remains unclear. Current dosing guidelines often include weight, age, and renal function but still fail to achieve appropriate prophylactic anti-Xa levels in many patients. We hypothesized that additional patient factors influence anti-Xa response to enoxaparin in trauma patients.

METHODS

This is a retrospective review of patients admitted to a Level 1 trauma center for ≥4 days from July 2015 to September 2020, who received enoxaparin VTE prophylaxis per protocol (50-59 kg, 30 mg/dose; 60-99 kg, 40 mg/dose; ≥100 kg, 50 mg/dose; all doses every 12 hours) and had an appropriately timed peak anti-Xa level. Multivariate regression was performed to identify independent predictors of prophylactic anti-Xa levels (0.2-0.4 IU/mL) upon first measurement.

RESULTS

The cohort (N = 1,435) was 76.4% male, with a mean ± SD age of 49.9 ± 20.0 years and a mean ± SD weight of 82.5 ± 20.2 kg (males, 85.2 kg; females, 73.7 kg; p <0.001). Overall, 68.6% of patients (n = 984) had a prophylactic anti-Xa level on first assessment (69.6% of males, 65.1% of females). Males were more likely to have a subprophylactic level than females (22.1% vs. 8.0%, p <0.001), whereas females were more likely to have supraprophylactic levels than males (26.9% vs. 8.3%, p < 0.001). When controlling for creatinine clearance, anti-Xa level was independently associated with dose-to-weight ratio (odds ratio, 0.191 for 0.5 mg/kg; p < 0.001; confidence interval, 0.151-0.230) and female sex (odds ratio, 0.060; p < 0.001; confidence interval, 0.047-0.072). Weight and age were not significant when controlling for the other factors.

CONCLUSION

Male patients have a decreased anti-Xa response to enoxaparin when compared with female patients, leading to a greater incidence of subprophylactic anti-Xa levels in male patients at all dose-to-weight ratios. To improve the accuracy of VTE chemoprophylaxis, sex should be considered as a variable in enoxaparin dosing models.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.