Achievement of goal anti-Xa activity with weight-based enoxaparin dosing for venous thromboembolism prophylaxis in trauma patients

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.

Evaluation of a novel blood volume-based enoxaparin dosing guideline for venous thromboembolism prophylaxis in trauma patients

PURPOSE

Fixed-dose and body mass index (BMI)-based enoxaparin regimens provide inadequate venous thromboembolism (VTE) prophylaxis for many trauma patients. The purpose of this study was to evaluate the effectiveness of a novel blood volume (BV)-based enoxaparin guideline vs a historical BMI-based guideline for VTE prophylaxis in trauma patients.

METHODS

This was a retrospective pre/post study completed at a large academic level 1 trauma center. All adult trauma patients admitted from October through December 2019 and August through October 2020 who received prophylactic enoxaparin per guideline were included. The BV dosing was as follows: patients with a BV of 3 to 4.9 L received enoxaparin 30 mg every 12 hours, those with a BV of 5 to 6.9 L received 40 mg every 12 hours, and those with a BV of ≥7 L received 60 mg every 12 hours. The primary outcome was the percentage of patients who attained a target anti-factor Xa (anti-Xa) postdosing level at the first steady-state assessment (0.2 to 0.5 IU/mL).

RESULTS

A total of 241 patients (99 for the BMI group and 142 for the BV group) were included. The study groups had a median age of 38 vs 42 years, a mean BMI of 27.4 vs 27.7 kg/m2, and a mean BV of 5.1 vs 5.1 L, respectively. A total of 63 patients (62.6%) in the BMI group attained target anti-Xa levels compared to 115 patients (81%) in the BV group (P = 0.008). In multivariate regression, the BV-based guideline was the only variable associated with attainment of target anti-Xa levels (adjusted odds ratio, 2.02; P = 0.01). Clinically relevant bleeding and VTE rates were similar between the groups.

CONCLUSION

Dosing prophylactic enoxaparin using a BV-based dosing guideline significantly increased attainment of target anti-Xa levels.

Residual anti-Xa activity in plasma of patients presenting for electively planned neuraxial regional anesthesia

OBJECTIVE

To determine the incidence of increased anti-Xa activity within plasma levels 24 hours after administration of therapeutic dose low-molecular-weight heparin in patients presenting for elective neuraxial anesthesia.

BACKGROUND

Guidelines for neuroaxial regional anesthesia for patients with antithrombotic drugs recommend time intervals for waiting. There is scientific evidence to suggest that the recommended interval of 24 hours may be insufficient in patients treated with therapeutic dose low-molecular-weight heparin.

METHODS

Retrospective cohort analysis of 74 patients who received therapeutic dose low-molecular-weight heparin before planned neuraxial anesthesia between April 1, 2015 and April 1, 2020 at Freiburg University Hospital. Primary endpoint was the occurrence of elevated plasma anti-Xa levels in prophylactic range or higher (>0.2 IU/mL) 24 hours after the last application of the therapeutic dose.

RESULTS

24 hours after the last dose of therapeutic low-molecular-weight heparin, 18.0% of patients had elevated anti-Xa activity levels >0.2 IU/mL. A weak correlation between the time since the last administration of low-molecular-weight heparin and plasma anti-Xa levels could be found. No other risk factors were seen.

CONCLUSIONS

Relevant residual anticoagulant activity, as measured by plasma anti-Xa levels within a prophylactic range, is measurable 24 hours after the last administration of therapeutic dose low-molecular-weight heparin.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS00022099.

Proceedings from the 2022 Consensus Conference to Implement Optimal Venous Thromboembolism Prophylaxis in Trauma

ABSTRACT

On May 4 and 5, 2022, a meeting of multidisciplinary stakeholders in the prevention and treatment of venous thromboembolism (VTE) after trauma was convened by the Coalition for National Trauma Research, funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health, and hosted by the American College of Surgeons in Chicago, Illinois. This consensus conference gathered more than 40 in-person and 80 virtual attendees, including trauma surgeons, other physicians, thrombosis experts, nurses, pharmacists, researchers, and patient advocates. The objectives of the meeting were twofold: (1) to review and summarize the present state of the scientific evidence regarding VTE prevention strategies in injured patients and (2) to develop consensus on future priorities in VTE prevention implementation and research gaps.To achieve these objectives, the first part of the conference consisted of talks from physician leaders, researchers, clinical champions, and patient advocates to summarize the current state of knowledge of VTE pathogenesis and prevention in patients with major injury. Video recordings of all talks and accompanying slides are freely available on the conference website ( https://www.nattrauma.org/research/research-policies-templates-guidelines/vte-conference/ ). Following this curriculum, the second part of the conference consisted of a series of small-group breakout sessions on topics potentially requiring future study. Through this process, research priorities were identified, and plans of action to develop and undertake future studies were defined.The 2022 Consensus Conference to Implement Optimal VTE Prophylaxis in Trauma answered the National Trauma Research Action Plan call to define a course for future research into preventing thromboembolism after trauma. A multidisciplinary group of clinical champions, physicians, scientists, and patients delineated clear objectives for future investigation to address important, persistent key knowledge gaps. The series of papers from the conference outlines the consensus based on the current literature and a roadmap for research to answer these unanswered questions.

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.

What Do We Know about Thromboprophylaxis and Its Monitoring in Critically Ill Patients?

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is an important complication in patients hospitalized in intensive care units (ICU). Thromboprophylaxis is mainly performed with Low Molecular Weight Heparin (LMWH) and, in some specific patients, with Unfractionated Heparin (UFH). These intensive units are an environment where individual patient variability is extreme and where traditional antithrombotic protocols are frequently ineffective. This was known for a long time, but the hospitalization of many patients with COVID-19 inflammatory storms suddenly highlighted this knowledge. It is therefore reasonable to propose variable antithrombotic prevention protocols based initially on a series of individual criteria (weight, BMI, and thrombotic risks). Secondly, they should be adjusted by the monitoring of anticoagulant activity, preferably by measuring the anti-Xa activity. However, we still face unresolved questions, such as once- or twice-daily LMWH injections, monitoring at the peak and/or trough, and poorly defined therapeutic targets. Equally surprisingly, we observed a lack of standardization of the anti-Xa activity kits.