A Phase 2 interventional study of Fixed Dose Enoxaparin and Variable Dose Enoxaparin in Venous Thromboembolism, Deep Venous Thrombosis and Surgery, sponsored by University of Utah. Completed at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2020-07-08.
Sponsored by University of Utah · Phase 2, Interventional, and Other
The aim of this research is to better understand how patient-level factors can be used to predict the appropriate enoxaparin dose to maximize venous thromboembolism (VTE) risk reduction and minimize bleeding.
VTE encompasses deep venous thrombosis and pulmonary embolus and is the proximate cause of death in over 100,000 hospitalized patients per year 4,5. To put this in better context, VTE kills more people each year than the annual morbidity from motor vehicle crashes and breast cancer combined-and one third of these deaths are known to occur after surgical procedures 34. "Breakthrough" VTE events occur in patients despite the receipt of guideline-compliant chemical prophylaxis. These events can be frustrating for surgeons, can represent a resource and financial burden for hospital systems, and most importantly, can be life or limb threatening for patients.
Existing data from our group and others suggests that inadequate enoxaparin dosing, quantified by aFXa levels, represents a plausible explanatory mechanism for "breakthrough" VTE events that occur among thoracic surgery patients. This project will examine the pharmacodynamics of fixed dose enoxaparin (40mg/day) after VATS-this dose and frequency were the most commonly prescribed VTE chemical prophylaxis strategy in a recent survey of thoracic surgeons 35. If inadequate aFXa levels are observed with fixed enoxaparin dosing, the study will design, implement and test a weight-based dosing approach to optimize aFXa levels. The study will also examine how alteration of enoxaparin dose magnitude affects peak aFXa levels and risk for VTE and major bleeding events.
Aim 1: To evaluate peak steady-state aFXa levels in response to a fixed dose of enoxaparin prophylaxis (40mg once daily) in VATS patients.
Rationale: Over 12% of thoracic surgery patients have "breakthrough" VTE events despite receipt of fixed dose chemical prophylaxis 29. Fixed dose enoxaparin prophylaxis has been shown to be inadequate for the majority of patients in other surgical subspecialties.
Hypothesis: Peak steady state aFXa levels will be within the accepted range (0.3-0.5 IU/mL) in 40% of patients after VATS.
Aim 2: To compare the effect of fixed (40mg once daily) and weight-based (0.5mg/kg once daily) enoxaparin prophylaxis on peak steady state aFXa levels after VATS.
Rationale: Our preliminary data shows a potential association between body weight and aFXa levels in response to fixed dosing; this will be confirmed using a multi-center approach in Aim #1. Body weight may be an important predictor of appropriate enoxaparin dose.
Hypothesis: Weight-based enoxaparin prophylaxis, when compared to fixed dose prophylaxis, will increase the proportion of patients with in-range peak aFXa levels from 40% to 80%.
Aim 3: To examine rates of 90-day VTE and clinically relevant bleeding events in VATS patients who receive fixed dose vs. weight-based enoxaparin prophylaxis.
Rationale: This observational Aim will allow us to better understand VTE and bleeding rates after VATS. Since these are rare events it is impossible to power the study to detect increases or decreases in risk between the dose groups. This study does provide a way to demonstrate an unexpected, very large difference in risk.
Hypothesis: Rates of post-operative VTE and clinically relevant bleeding will be less than 2% in each group.
Exclusion Criteria:
Eligible patients will be administered 40 mg enoxaparin daily and will have steady state peak and trough anti-Xa levels drawn after the third enoxaparin dose.
Drug: Fixed Dose Enoxaparin
Eligible patients will be administered 0.5 mg/kg enoxaparin daily and will have steady state peak and trough anti-Xa levels drawn after the third enoxaparin dose.
Drug: Variable Dose Enoxaparin
Eligible patients will be administered 40 mg enoxaparin daily and will have steady state peak and trough anti-Xa levels drawn after the third enoxaparin dose. For patients in-range (levels 0.3-0.5IUmL), no intervention will be undertaken. For patients out of range, enoxaparin dose will be adjusted according to an established dose adjustment algorithm. Repeat levels will be checked after the third administration of the new dose.
Eligible patients will be administered 0.5 mg/kg enoxaparin daily and will have steady state peak and trough anti-Xa levels drawn after the third enoxaparin dose. For patients in-range (levels 0.3-0.5IUmL), no intervention will be undertaken. For patients out of range, enoxaparin dose will be adjusted according to an established dose adjustment algorithm. Repeat levels will be checked after the third administration of the new dose.
Number of Patients With in Range Initial Peak Xa Level
Number of patients with in range initial peak Xa level
Time frame: 36 hours
Number of Participants With Venous Thromboembolism Events or Death
Any symptomatic venous thromboembolism events, including deep venous thrombosis or pulmonary embolus occurring within 90 days of surgery
Time frame: 90 days
Number of Participants With Bleeding Events
Bleeding events requiring alteration in the course of care within 90 days of surgery
Time frame: 90 days
| Milestone | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| Started | 65 | 66 |
| Completed | 56 | 61 |
| Not completed | 9 | 5 |
| Withdrew: Inappropriate xa level timing | 6 | 3 |
| Withdrew: No peak xa level drawn | 2 | 0 |
| Withdrew: Bled prior to xa level | 1 | 2 |
Number of patients with in range initial peak Xa level
| Participants | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| Number of Patients With in Range Initial Peak Xa Level | 27 | 27 |
Any symptomatic venous thromboembolism events, including deep venous thrombosis or pulmonary embolus occurring within 90 days of surgery
| Participants | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| Number of Participants With Venous Thromboembolism Events or Death | 1 | 0 |
Bleeding events requiring alteration in the course of care within 90 days of surgery
| Participants | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| Number of Participants With Bleeding Events | 1 | 3 |
Collected over 90 days. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Fixed Dose Enoxaparin | 1/65 (1.5%) | 1/65 (1.5%) | 1/65 (1.5%) |
| Weight Tiered Enoxaparin | 0/66 (0%) | 0/66 (0%) | 3/66 (4.5%) |
| Event | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| 90-day DeathBlood and lymphatic system disorders | 1/65 | 0/66 |
| Event | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin |
|---|---|---|
| clinically relevant bleedingBlood and lymphatic system disorders | 1/65 | 3/66 |
| DVT/PEBlood and lymphatic system disorders | 0/65 | 0/66 |
Group 1 65 plus Group 2 66 =131 total
| Age, Categorical(Participants) | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin | Total |
|---|---|---|---|
| <=18 years | 0 | 0 | 0 |
| Between 18 and 65 years | 32 | 33 | 65 |
| >=65 years | 33 | 33 | 66 |
| Age, Continuous(years) | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin | Total |
|---|---|---|---|
| Mean | 60.9 ± 15.6 | 59.0 ± 16.8 | 60.0 ± 16.2 |
| Sex: Female, Male(Participants) | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin | Total |
|---|---|---|---|
| Female | 37 | 32 | 69 |
| Male | 28 | 34 | 62 |
| Race (NIH/OMB)(Participants) | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 0 | 0 | 0 |
| Native Hawaiian or Other Pacific Islander | 0 | 2 | 2 |
| Black or African American | 1 | 0 | 1 |
| White | 61 | 63 | 124 |
| More than one race | 3 | 1 | 4 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Region of Enrollment(Participants) | Fixed Dose Enoxaparin | Weight Tiered Enoxaparin | Total |
|---|---|---|---|
| United States | 65 | 66 | 131 |
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