Weight-Based Compared With Fixed-Dose Enoxaparin Prophylaxis After Cesarean Delivery: A Randomized Controlled Trial

Comparison of different intervention methods to reduce the incidence of venous thromboembolism: study protocol for a cluster-randomized, crossover trial

BACKGROUND

Venous thromboembolism (VTE) remains a priority challenge among orthopedic trauma patients. It is crucial to further improve the prophylaxis against VTE in routine orthopedic treatment. This study aims to compare the efficacy of two low molecular weight heparin (LMWH) regimens and additional intermittent pneumatic compression in preventing VTE among orthopedic trauma patients.

METHODS AND ANALYSIS

This is a cluster-randomized crossover clinical study conducted in four hospitals in Shanghai from December 2019 to December 2023. The unit of randomization is orthopedic wards, and each ward will define a cluster. All clusters will implement four diverse intervention measures and one control measure in a given random sequence. Perioperative orthopedic trauma patients aged ≥ 18 years with stable vital signs, Caprini score > 2, and no contraindication of anticoagulation or intermittent pneumatic compression (IPC) devices will be eligible. The sample size will be determined to be 2590, considering cluster effect, period effect, and interactions. We will generally use the intention-to-treat (ITT) at the subject level for each outcome. For the primary outcome of the study, the incidence of VTE will be presented as risk ratio and 95% CIs. Generalized estimating equation (GEE) will be deployed to compare differences and adjust cluster effect, period effect, and interaction among interventions and periods if applicable.

DISCUSSION

VTE is a complication that cannot be underestimated after major orthopedic surgery. Early identification, early assessment, and early prevention can significantly reduce the incidence of VTE. Most guidelines recommend both medical and physical prevention, and we hope to demonstrate how they would affect the incidence among perioperative orthopedic patients. We want to explore if there is a difference between the two types of LWMH with or without an IPC device to provide more evidence for future guidelines and prevent more patients from the threat of VTE.

ETHICS AND DISSEMINATION

The study received approval from the IRB of the coordinating center and all participating hospitals. Findings will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION

ChiCTR1900027659. Registered on 17 November 2019.

Projected impact of guidelines on incidence of venous thromboembolism after cesarean delivery in the United States

BACKGROUND

There is large variation in recommended for postcesarean delivery venous thromboembolism (VTE) prophylaxis among commonly used guidelines.

OBJECTIVES

The aim of the study is to estimate implications of adoption of VTE prevention guidelines for rates of receipt of VTE prophylactic therapy and VTE following cesarean delivery (CD).

METHODS

We used administrative data from the 2015-2019 Nationalwide Readmissions Database to identify cesarean deliveries and rates of VTE stratified by risk factors, leading to different prophylactic strategies based on several national guidelines. We used input parameters from the literature to construct a hybrid decision tree/Markov model to project the implications of guideline adoption on VTE rates for the first 6 weeks following delivery.

RESULTS

Adoption of either the 2011 American College of Obstetricians and Gynecologists or the 2018 American Society for Hematology guidelines would avert a relatively small proportion (5%) of VTE cases, albeit with little low-molecular-weight heparin (LMWH) use (87-115 doses per 1000 CD patients). The 2012 American College of Chest Physicians guidelines were predicted to be more effective at averting VTE (21.2% reduction) with more LMWH usage (570 doses per 1000 deliveries). The 2015 Royal College of Obstetricians and Gynaecologists guidelines and universal use of 6 weeks of LMWH would avert an even larger proportion of cases (37.4% and 57.6%, respectively), at the cost of much higher rates of LMWH utilization (7233 doses per 1000 patients and 38 648 doses per 1000 patients).

CONCLUSIONS

Adoption of different guidelines would have notably varying implications for clinical practice and potential for alteration of the national rate of VTE following CD.

Comparison of postpartum anti-Xa levels following enoxaparin administration to prevent venous thromboembolism using 2 weight-based protocols: a randomized controlled trial

BACKGROUND

During the postpartum period, enoxaparin is given to high-risk women to prevent venous thromboembolism, a leading cause of maternal mortality. Enoxaparin activity is measured by peak plasma anti-Xa levels. The prophylactic range of anti-Xa is 0.2 to 0.6 IU/mL. Values above and below this range represent subprophylactic and supraprophylactic levels, respectively. Weight-based enoxaparin administration was superior to fixed-dose enoxaparin administration in achieving an anti-Xa prophylactic range. However, it is unknown which weight-based enoxaparin administration is superior (once daily weight categories vs 1 mg/kg body weight).

OBJECTIVE

This study aimed to compare the efficacy in reaching prophylactic anti-Xa levels and adverse effects profile of the 2 weight-based enoxaparin dosing protocols.

STUDY DESIGN

A randomized open-label controlled trial was conducted. Women after delivery, who were intended to receive enoxaparin, were randomized to receive either enoxaparin treatment according to 1 mg/kg (up to 100 mg) or weight categories (≤90 kg, 40 mg; 91-130 kg, 60 mg; 131-170 kg, 80 mg; >170 kg, 100 mg). Plasma anti-Xa levels were obtained 4 hours after the second enoxaparin administration (day 2 of enoxaparin treatment). If the woman was still hospitalized, anti-Xa levels were also obtained on day 4. The primary endpoint was the proportion of women with anti-Xa levels within the prophylactic range at day 2. In addition, data regarding anti-Xa levels in different weight groups and rates of venous thromboembolism and adverse effects were evaluated.

RESULTS

Of note, 60 and 64 women received enoxaparin according to 1 mg/kg and weight categories, respectively; moreover, 55 (92%) and 27 (42%) women reached the prophylactic range of anti-Xa at day 2, respectively (P<.0001). The mean anti-Xa levels on day 2 were 0.34±0.09 and 0.19±0.06 IU/mL, respectively (P<.0001). The anti-Xa levels were higher in the 1 mg/kg group than in the weight categories group in the subanalysis of different weight categories (51-70, 71-90, and 91-130 kg). There was no difference in anti-Xa levels on day 4 compared with day 2 in both cohorts (n=25). There was no case of supraprophylactic anti-Xa levels, venous thromboembolism events, or serious hemorrhage.

CONCLUSION

Postpartum enoxaparin administration at 1 mg/kg was superior to weight categories in reaching anti-Xa prophylactic levels without leading to serious adverse effects. Given the high efficacy and safety profile, enoxaparin at 1 mg/kg once daily should be considered the preferred protocol for postpartum venous thromboembolism prophylaxis.