Clinical trial NCT03296033
Conditions: Anticoagulants and Bleeding Disorders Surgery Regional Anesthesia Morbidity
Keywords: enoxaparin thromboembolism coagulation factor Xa
Sponsor: Wake Forest University Health Sciences
Start date: 2017-10-24; Completion date: 2022-01-14
Enrollment: 122 participants; Allocation: RANDOMIZED; Intervention model: PARALLEL

Brief summary:
The main objective of this study is to determine the time interval following the last treatment dose of enoxaparin at which the amount of anti-Xa level activity is reliably less than 0.2 international unit per milliliter (IU/mL) in patients presenting for elective surgery.

Detailed description:
Enoxaparin is a factor Xa inhibitor commonly used for both prophylaxis against and treatment of thromboembolism. It is also frequently used off-label as a perioperative bridge for patients that are chronically anticoagulated prior to surgery, such as those taking Warfarin. It is an attractive option for perioperative use secondary to its predictable pharmacologic profile and the lack of recommended routine blood monitoring. Therefore, it is common to encounter a patient who has recently received a treatment dose of Enoxaparin prior to presenting for surgery. For these patients, and those on other anticoagulant medications, published guidelines have been developed to help guide clinical decision-making when the anesthetic/analgesic plan includes regional anesthesia.1 Currently, these guidelines recommend that a minimum of 24-hours should elapse following the last treatment dose of Enoxaparin before a neuraxial procedure is performed. However, a recently completed quality improvement project conducted at Wake Forest Baptist Medical Center found that almost 60% of patients presenting for surgery while on treatment dose enoxaparin still had significant anticoagulant activity 24-hours following their last dose, as demonstrated by anti-Xa level assay testing. Given that the risk of epidural hematoma formation is increased in the setting of abnormal coagulation parameters, the significance of this finding is that the risk of bleeding complications following a neuraxial procedure may still be increased 24-hours after the last treatment dose of enoxaparin.

While the routine use of anti-Xa level testing may be a viable option to determine when residual enoxaparin activity is present before proceeding with a neuraxial procedure on a patient-by-patient basis, it is not universally available at all hospitals. Therefore, it is important to determine the time interval following the last enoxaparin dose at which the likelihood that a clinically relevant amount of residual anti-Xa level activity no longer persists, so that providers can confidently proceed with a neuraxial procedure when anti-Xa level testing is not available.

Arms: arm 1: Group one will be instructed to administer their last dose of enoxaparin at 07:00 in the morning on the day prior to their scheduled surgery date. This will mean that patients who have their surgery scheduled for 07:00 the following day will be 24-hours removed from their last dose. Patients presenting for surgery later in the day would be slightly farther removed from their last dose, however this is currently considered normal clinical practice. arm 2: Group 2 will be instructed to administer their last dose of enoxaparin at 19:00 in the evening two days prior to their scheduled surgery date. Patients presenting for surgery at 07:00 two days later will be 36-hours removed from their last dose. Patients presenting for surgery later in the day would be slightly farther removed from their last dose, but again this mimics normal clinical practice in which the timing of the last dose of self-administered enoxaparin is not routinely adjusted based on the scheduled surgical start time.
Interventions: intervention 1: Enoxaparin intervention 2: Enoxaparin
Intervention descriptions: intervention 1: The intervention is the implementation of a 36-hour time period from the last dose of treatment dose Enoxaparin to the blood sampling for anti-Xa testing. intervention 2: This is the historical control arm. 24 hours removed from their last dose (time period from the last dose of treatment dose Enoxaparin to the blood sampling for anti-Xa testing)

Protocol documents:
Prot_SAP_001.pdf: 
Protocol version: 
Template updated 9.24.14 
1 
Official Title:  : Evaluation of Residual Anti-Xa Activity As A Function Of Time Following The 
Last Treatment Dose of Enoxaparin In Patients Presenting For Elective Surgery 
 
NCT03296033 
 
Date  Document was IRB-Approved:   4/6/2020


Protocol version: 
Template updated 9.24.14 
2 
Study Title: Evaluation of Residual Anti-Xa Activity As A Function Of Time Following The Last 
Treatment Dose of Enoxaparin In Patients Presenting For Elective Surgery 
 
Principal Investigator: Daryl S. Henshaw, MD; Co-investigator(s): James Turner, MD; Dan Forest, 
MD; Robert S. Weller, MD;  
 
Sponsor or funding source: Department of Anesthesiology, Wake Forest University School of Medicine 
 
Background, Rationale and Context 
 
Enoxaparin is a factor Xa inhibitor commonly used for both prophylaxis against and treatment of 
thromboembolism.  It is also frequently used off-label as a perioperative bridge for patients that are 
chronically anticoagulated prior to surgery, such as those taking Warfarin.  It is an attractive option for 
perioperative use secondary to its predictable pharmacologic profile and the lack of recommended routine 
blood monitoring.  Therefore, it is common to encounter a patient who has recently received a treatment 
dose of Enoxaparin prior to presenting for surgery.  For these patients, and those on other anticoagulant 
medications, published guidelines have been developed to help guide clinical decision-making when the 
anesthetic/analgesic plan includes regional anesthesia.1   
Currently, these guidelines recommend that a minimum of 24-hours should elapse following the 
last treatment dose of Enoxaparin before a neuraxial procedure is performed.  However, a recently 
completed quality improvement project conducted at Wake Forest Baptist Medical Center found that 
almost 60% of patients presenting for surgery while on treatment dose enoxaparin still had significant 
anticoagulant activity 24-hours following their last dose, as demonstrated by anti-Xa level assay testing.  
Given that the risk of epidural hematoma formation is increased in the setting of abnormal coagulation 
parameters2, the significance of this finding is that the risk of bleeding complications following a 
neuraxial procedure may still be increased 24-hours after the last treatment dose of enoxaparin. 
While the routine use of anti-Xa level testing may be a viable option to determine when residual 
enoxaparin activity is present before proceeding with a neuraxial procedure on a patient-by-patient basis, 
it is not universally available at all hospitals.  Therefore, it is important to determine the time interval 
following the last enoxaparin dose at which the likelihood that a clinically relevant amount of residual 
anti-Xa level activity no longer persists, so that providers can confidently proceed with a neuraxial 
procedure when anti-Xa level testing is not available.   
 
Objectives 
 
The main objective of this study is to determine the time interval following the last treatment dose 
of enoxaparin at which the amount of anti-Xa level activity is reliably less than 0.2IU/mL in patients 
presenting for elective surgery.    
 
Methods and Measures 
 
Design 
• 
This is a randomized prospective observation trial.   
 
Setting 
• 
This study will be conducted at a single institution (Wake Forest Baptist Medical Center), 
which is an academic level-1 trauma center. 
 
Subjects selection criteria 


Protocol version: 
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3 
Patients presenting for elective surgery who are either chronically on treatment-dose enoxaparin or 
who are being bridged with treatment-dose enoxaparin from another anticoagulant will be potentially 
recruited for this investigation.  
   
• 
Inclusion Criteria 
Eligible patients need to be on treatment dose (1mg/kg twice daily or 1.5mg/kg daily) 
enoxaparin at the time of presentation for elective surgery and must be able to accurately 
report the timing of their last dose and the administered dosage.  Patients must also be 
between the ages of 18-100 years of age and must be able to give written consent to 
participate.  Patients who are bridged with enoxaparin from one of the currently available oral 
Anti-Xa inhibitors (Abixaban [Eliquis], Edoxaban [Sayvasa], and Rivaroxaban [Xarelto]) will 
be eligible as long as the duration from their last oral Anti-Xa inhibitor dose to their date of 
surgery is at least 5 days (120-hours).   
• 
Exclusion Criteria 
Patients with severe renal insufficiency (creatinine clearance <30ml/min) will be excluded 
from the study, as the elimination of enoxaparin is known to be affected in this patient 
population.  Pregnant patients will also be excluded, as the elimination and metabolism of 
enoxaparin is known to be altered in this patient population, and dose adjustments are 
recommended if treatment dose enoxaparin is used during pregnancy.  Patients who are 
receiving enoxaparin as a bridge from another intravenous anti-Xa inhibiting medication will 
be excluded as this could unpredictably affect the results of anti-Xa testing.  These 
medications include: Fondaparinux. Patients who are on an oral Anti-Xa inhibitor (Abixaban 
[Eliquis], Edoxaban [Sayvasa], and Rivaroxaban [Xarelto]) will be excluded if the duration of 
time from their last dose to the date of surgery (i.e., the duration that they are bridged with 
enoxaparin) is less than 5 full days (120 hours).   .  
• 
Sample Size 
Historical data from a previous publication (which showed that at 24-hours 58% of patients 
had an anti-Xa level ≥ 0.2IU/mL) was used to conduct a power analysis. In this prior study, 
data points were collected between 23.25-hours and 32-hours, and anti-Xa levels ranged 
between 0 and 0.54IU/mL. Assuming a similar relationship between anti-Xa activity levels 
and time observed in the original study pertains to later times, simulations using a sample size 
of 150 patients resulted in a threshold of approximately 29-hours with 95% confidence limits 
of approximately 28-hours and 33-hours.  It was felt that a 5-hour window of the 95% 
confidence limit would provide acceptable guidance for clinical care. We expect some drop 
out and patient loss since some patients may have their surgical procedure cancelled 
following enrollment/randomization. In addition, occasionally the decision regarding the use 
of bridging therapy changes following a patient’s visit to the preoperative assessment clinic.  
Therefore, we plan to enroll upwards of 180 patients until 150 patients have completed the 
study and have their data available for analysis.  
 
Interventions and Interactions 
• 
Patients on treatment dose enoxaparin will be identified at the time of their preoperative 
anesthesia consultation.  These patients will be seen in the preoperative assessment clinic by a 
study team member and the study will be discussed with them at that time. 
• 
Patients may elect to consent during their preoperative anesthesia consultation visit, or if they 
would like to think it over and talk with family/friends, a study team member will follow-up 
with them by phone to answer further questions.  
• 
After consenting to the study, patients will be randomized to one of two groups.   
o Group one will be instructed to administer their last dose of enoxaparin at 07:00 
in the morning on the day prior to their scheduled surgery date.  This will mean 


Protocol version: 
Template updated 9.24.14 
4 
that patients who have their surgery scheduled for 07:00 the following day will 
be 24-hours removed from their last dose.  Patients presenting for surgery later in 
the day would be slightly farther removed from their last dose, however this is 
currently considered normal clinical practice.   
o Group 2 will be instructed to administer their last dose of enoxaparin at 19:00 in 
the evening two days prior to their scheduled surgery date.  Patients presenting 
for surgery at 07:00 two days later will be 36-hours removed from their last dose.  
Patients presenting for surgery later in the day would be slightly farther removed 
from their last dose, but again this mimics normal clinical practice in which the 
timing of the last dose of self-administered enoxaparin is not routinely adjusted 
based on the scheduled surgical start time.   
• 
All patients consented for the study will be called by a study team member or study 
coordinator two days before their surgical date to ensure they understand when they are 
supposed to self-administer their last dose of enoxaparin.  
• 
Upon arrival for surgery, all consented patients will have demographic information recorded 
(age, weight, gender) as well as the enoxaparin dosage and the timing of their last 
administration.   
• 
All patients in the study will have a blood sample drawn.  Two laboratory tests will be sent.  
1). Anti-Xa level assay (Heparin Assay) 
2). Basic Metabolic Panel (BMP) (for evaluation of creatinine). 
• 
When feasible, blood sampling will be performed at the same time that intravenous access for 
fluid/medication administration is obtained to minimize patient discomfort.   
• 
Anti-Xa level testing will be performed using a chromogenic assay and a hybrid 
heparin/enoxaparin curve (Biophen Heparin 6 kit). 
• 
The results of both of these tests will be collected from the electronic medical record after the 
results are posted.   
• 
Following collection of the blood samples, the patient’s participation in the study will be 
concluded.   
• 
The results of the anti-Xa level test will be shared with the patient and the risk-benefit 
decision of proceeding with neuraxial block (if indicated) will be left to the anesthesiologist 
of record.  
 
Outcome Measure(s) 
The primary outcome of the study is the measurement of anti-Xa activity levels following the last 
treatment dose of enoxaparin in patients presenting for elective surgery. Anti-Xa level activity will be 
measured using a chromogenic assay and a hybrid curve calibrated to both heparin and enoxaparin.  The 
randomization of patients to either the 24-hour group or the 36-hour group will allow for modeling, which 
will generate a prediction of the time point at which the level of anti-Xa activity can reliably be assumed 
to be lower than 0.2IU/mL.   
 
Secondary outcomes will include determining the relationship of anti-Xa level activity over time (by 
using curve fitting or best-fit function) as well as attempting to determine if there are any patient 
conditions or characteristics that can predict delayed clearance of enoxaparin (elevated anti-Xa levels).  
 
 
Analytical Plan 
For the primary analysis, logistic regression of success criterion (anti-Xa activity level < 0.2 IU/mL) and 
95% confidence limits at a success level (<0.2) of 95% likelihood will be utilized.  For secondary 
analyses we plan to describe the best-fit function for anti-Xa activity levels over time.  We also plan to 
explore clinical predictors for any anti-Xa activity levels > 1 standard deviation over the mean from the 
above function.   


Protocol version: 
Template updated 9.24.14 
5 
 
Human Subjects Protection 
 
Subject Recruitment Methods 
Patients on treatment dose enoxaparin will be identified at the time of their preoperative anesthesia 
consultation.  These patients will be seen in the preoperative assessment clinic by a study team member 
and the study will be discussed with them.  They will be given information related to the study (consent 
form). Patients may elect to consent to participation that day, or a study team member will follow-up with 
them by phone two days before their surgery to answer questions.  If they choose to participate at that 
time the consent paperwork will be completed the day of surgery, but they will be randomized and 
instructed on when to self-administer their last treatment dose of enoxaparin prior to surgery. 
 
Informed Consent 
Signed informed consent will be obtained from each subject.  Only providers listed as a primary or co-
investigator, study team member or study coordinator will obtain written informed consent.   
 
Confidentiality and Privacy 
Confidentiality will be protected by collecting only information needed to assess study outcomes, 
minimizing to the fullest extent possible the collection of any information that could directly identify 
subjects, and maintaining all study information in a secure manner.  To help ensure subject privacy 
and confidentiality, only a unique study identifier will appear on the data collection form.  Any 
collected patient identifying information corresponding to the unique study identifier will be 
maintained on a linkage file, store separately from the data.  The linkage file will be kept secure, with 
access limited to designated study personnel.  Following data collection subject identifying 
information will be destroyed 3 years after closure of the study by shredding the documentation, 
consistent with data validation and study design, producing an anonymous analytical data set.  Data 
access will be limited to study staff.  Data and records will be kept locked and secured, with any 
computer data password protected.  No reference to any individual participant will appear in reports, 
presentations, or publications that may arise from the study. 
 
Data and Safety Monitoring 
The principal investigator will be responsible for the overall monitoring of the data and safety of 
study participants.  The principal investigator will be assisted by other members of the study staff. 
 
The cost of both laboratory tests (anti-Xa level and BMP) will not be billed to the patient.  These 
costs will be covered by the study sponsor (Department of Anesthesiology).   
 
Reporting of Unanticipated Problems, Adverse Events or Deviations 
Any unanticipated problems, serious and unexpected adverse events, deviations or protocol changes 
will be promptly reported by the principal investigator or designated member of the research team to 
the IRB and sponsor or appropriate government agency if appropriate. 
 
References 
1. Horlocker T, et al.  Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic 
Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based 
Guidelines (Third Edition). Reg Anesth Pain Med 2010; 35:64-101. 
 
2. Gulur P, Tsui B, Pathak R, Koury M, Lee H. Restrospective analysis of the incidence of epidural 
haematoma in patients with epidural catheters and abnormal coagulation parameters.  Br J of 
Anaesth 2015; 114 (5): 808-11.   
 


Protocol version: 
Template updated 9.24.14 
6 
Appendix 
1. Data collection form 
2. Consent form  
 

ICF_000.pdf: 
NCT03296033
Official Title: Evaluation of Residual Anti-Xa Activity As A Function Of Time Following 
The Last Treatment Dose of Enoxaparin In Patients Presenting For Elective Surgery  
IRB-Approved Date:  2/1/22


Page 1 of 8
Adult Consent Form
Version: 03/19/2020_____________
Department of Anesthesiology, Section of Regional 
Anesthesia and Acute Pain Management
EVALUATION OF RESIDUAL ANTI-XA ACTIVITY AS A FUNCTION OF 
TIME FOLLOWING THE LAST TREATMENT DOSE OF ENOXAPARIN IN 
PATIENTS PRESENTING FOR ELECTIVE SURGERY 
Informed Consent Form to Participate in Research
Daryl S. Henshaw, MD, Principal Investigator
INTRODUCTION
You are invited to be in a research study. Research studies are designed to gain scientific 
knowledge that may help other people in the future. You are being asked to take part in this 
study because you have been on the blood thinner Enoxaparin and are presenting for a surgical 
procedure. Your participation is voluntary. Please take your time in making your decision as to 
whether or not you wish to participate. Ask your study doctor or the study staff to explain any 
words or information contained in this informed consent document that you do not understand. 
You may also discuss the study with your friends and family.
WHY IS THIS STUDY BEING DONE?
The purpose of this research study is to evaluate how much blood thinning effect remains after a 
patient takes the last dose of the medication Enoxaparin prior to presenting for surgery and to 
determine at what time-point (hours after the last dose) we can safely assume that the effect of 
the blood thinner is most likely no longer a concern.  Usually patients take Enoxaparin to treat an 
existing blood clot or as a means of preventing a blood clot from forming.  It is very common for 
this medication to be used for these purposes around the time of surgery because it is convenient 
for patients to administer this medication to themselves at home, if needed, and because the 
blood thinning effects of this particular medication do not last as long as other blood-thinning 
medications, especially those typically taken by mouth.  Traditionally, we have thought that 
taking the last dose of Enoxaparin 24-hours prior to surgery (taking the last dose the in the 
morning on the day prior to surgery) for treatment dose enoxaparin was most appropriate.  
However, a recent study performed here at our hospital showed that many patients still had more 
blood-thinning effects at this time-point than we previously expected, although this study only 
included a small number of patients.  The goal of this study is to further examine those previous 
findings and to determine how the amount of blood thinner that remains in a patient’s 
bloodstream changes over time so that we can predict when the blood-thinning effects of the 
medication have decreased to a level below which it is felt that proceeding with certain types of 
anesthesia procedures is safe. We will do this by having some patients wait 24-hours after the 
last dose of Enoxaparin (taking the last dose in  the morning the day prior to surgery) and having 
other patients wait 36-hours after the last dose of Enoxaparin (taking the last dose in the evening 
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 2 of 8
Adult Consent Form
Version: 03/19/2020_____________
two days prior to surgery). This will allow us to compare how much blood-thinning effect 
remains in these two groups of patients and to determine how long it takes on average for most 
of the Enoxaparin blood-thinning effect to go away.  
HOW MANY PEOPLE WILL TAKE PART IN THE STUDY?
150 total patients will be enrolled to participate in this study.  
WHAT IS INVOLVED IN THE STUDY?
A member of the study team will meet with you during your visit to the anesthesia preoperative 
assessment clinic to discuss the study with you.  After consenting, you will be randomized into 
one of the two study groups described below. Randomization means that you are put into a group 
by chance. It is like flipping a coin. You will have an equal chance of being placed in either 
group.
-Group 1 (24-hour group): This group of patients will be instructed to self-administer 
their last dose of enoxaparin at 07:00 AM on the day before surgery.  
-Group 2 (36-hour group): This group of patients will be instructed to self-administer 
their last dose of enoxaparin at 07:00 PM (1900) on the evening two days before surgery. 
We will give you instructions on when to self-administer your last dose of enoxaparin.  In 
addition, a member of the study team or a study coordinator will call you two days before your 
surgery to ensure you understand when to self-administer your last dose and to ensure you don’t 
have any questions.  
Following your last dose of enoxaparin we are interested in determining how much blood-
thinning effect is remaining in your bloodstream at the time you present to the hospital for 
surgery.  In order to determine that, we will need to draw a small amount of blood from you 
(roughly a tablespoon) so that it can be sent to the lab for analysis.  Some of this blood will also 
be used to perform what is called a Basic Metabolic Panel.  This will allow us to know how well 
your kidneys work.  This is important because your kidneys have to help eliminate Enoxaparin 
from your body and your kidney function might affect how much of the blood-thinning effect 
remains.  
To summarize, if you take part in this study, you will have the following tests and procedures:
A one-time blood draw will be performed on the day of your surgery so that we can check both 
your kidney function and the amount of blood-thinner that remains in your bloodstream.  You 
will have approximately 1 tablespoon of blood withdrawn from a vein on only one occasion.  
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 3 of 8
Adult Consent Form
Version: 03/19/2020_____________
HOW LONG WILL I BE IN THE STUDY?
You will be in the study until after your blood is drawn.  At that time, the study is complete.  
You can stop participating at any time. If you decide to stop participating in the study we 
encourage you to talk to the investigators or study staff first to learn about any potential health or 
safety consequences. 
WHAT ARE THE RISKS OF THE STUDY?
Being in this study involves some risk to you. You should discuss the risk of being in this study 
with the study staff. Risks and side effects related to the lab test we are studying include having 
your blood drawn.  You may experience discomfort, bruising and/or bleeding where the needle is 
inserted. Occasionally some people become dizzy or lightheaded or feel faint. Infection may 
occur on rare occasions.  Frequent donation of blood can result in low iron in your blood (iron 
deficient anemia).  
This study is comparing two approved methods for treating your condition. You will be 
randomly assigned to one of the two groups. It is possible that one treatment group may have a 
better response than the other. Therefore there is a risk that you may be assigned to a group that 
does not perform as well as its comparison. The medication Enoxaparin is typically used to 
prevent people from forming a blood clot, which can be serious and even fatal.  When people are 
on this medication and need to have surgery, our goal is to keep the time period where you are 
off this medication as short as possible.  This usually means we will stop the medication roughly 
24-hours before surgery and then restart it as soon as it is safe to do so following the surgery.  
There is always a balance between the risk of forming a blood clot and the risk of bleeding (from 
having blood that is too thin from the Enoxaparin).  
In the past, we thought holding the medication for 24-hours before surgery was long enough, and 
that very little of the Enoxaparin medication was left in a person’s bloodstream.  However, a 
recent study found that most people presenting for surgery who were taking Enoxaparin at high 
doses (to prevent or treat a blood clot) still had blood that was thinner than we expected.  
Because of this we think that the risk of bleeding from certain types of anesthesia procedures and 
possibly surgery might be increased and therefore we think that stopping Enoxaparin for a longer 
period of time before surgery could help reduce the risk of bleeding.  
However, because you will be stopping your blood thinning medication for a longer period of 
time before surgery, there is the possibility for a higher risk of developing a blood clot after 
stopping the Enoxaparin and before the time of surgery.  This risk should be very low and is 
balanced out by a potentially lower risk of bleeding during anesthesia and surgery. 
In addition, there is a slight risk of a breach of confidentiality.  We will do our best to protect 
your confidential information.  There also may be other side effects that we cannot predict. You 
should tell the research staff about all the medications, vitamins and supplements you take and 
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 4 of 8
Adult Consent Form
Version: 03/19/2020_____________
any medical conditions you have. This may help avoid side effects, interactions and other risks.
 
Taking part in this research study may involve providing information that you consider 
confidential or private.  Efforts, such as coding research records, keeping research records secure 
and allowing only authorized people to have access to research records, will be made to keep 
your information safe.
ARE THERE BENEFITS TO TAKING PART IN THE STUDY?
If you agree to take part in this study, there may or may not be direct benefit to you. We hope the 
information learned from this study will benefit other people in the future. The benefits of 
participating in this study may be that by stopping your Enoxaparin medication for a longer 
period of time prior to having surgery and anesthesia, it is possible that your risk of bleeding will 
be lower.  If certain types of anesthesia procedures (such as a spinal or epidural) are planned for 
your surgery, it is possible that the risk of bleeding from these procedures will be decreased 
depending on which group you are randomized to.  
WHAT OTHER CHOICES ARE THERE?
You do not have to be in this study to receive treatment. You should talk to your doctor about all 
the choices you have. Instead of being in this study, you have these options:
It will be discussed with you, the risk/benefit of stopping your Enoxaparin medication at 24 and 
36-hours prior to surgery.  You could stop your Enoxaparin medication at 36-hours prior to 
surgery even if you do not take part in the study.  This will be your own decision based on 
information received from education received during this discussion.
WHAT ARE THE COSTS?
All study costs, including the laboratory procedures related directly to the study, will be paid for 
by the study. Costs for your regular medical care, which are not related to this study, will be your 
own responsibility.
WILL YOUR RESEARCH RECORDS BE CONFIDENTIAL?
The results of this research study may be presented at scientific or medical meetings or published 
in scientific journals.  Your identity and/or your personal health information will not be disclosed 
unless it is authorized by you, required by law, or necessary to protect the safety of yourself or 
others.  There is always some risk that even de-identified information might be re-identified. 
Participant information may be provided to Federal and other regulatory agencies as required.  
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 5 of 8
Adult Consent Form
Version: 03/19/2020_____________
The Food and Drug Administration (FDA), for example, may inspect research records and learn 
your identity if this study falls within its jurisdiction.
WILL YOU BE PAID FOR PARTICIPATING?
You will receive no payment or other compensation for taking part in this study.
WHO IS SPONSORING THIS STUDY?
This study is being sponsored by The Department of Anesthesiology at Wake Forest University 
School of Medicine. The sponsor is providing money or other support to Wake Forest University 
Health Sciences to help conduct this study. The researchers do not, however, hold a direct 
financial interest in the sponsor or the product being studied.
WHAT HAPPENS IF YOU EXPERIENCE AN INJURY OR ILLNESS AS A 
RESULT OF PARTICIPATING IN THIS STUDY?
Should you experience a physical injury or illness as a direct result of your participation in this 
study, Wake Forest University School of Medicine maintains limited research insurance 
coverage for the usual and customary medical fees for reasonable and necessary treatment of 
such injuries or illnesses. To the extent research insurance coverage is available under this policy 
the reasonable costs of these necessary medical services will be paid, up to a maximum of 
$25,000. Wake Forest University Baptist Medical Center holds the insurance policy for this 
coverage. It provides a maximum of $25,000 coverage for each claim and is limited to a total of 
$250,000 for all claims in any one year. The Wake Forest University School of Medicine, and 
the North Carolina Baptist Hospitals, Incorporated do not assume responsibility to pay for these 
medical services or to provide any other compensation for such injury or illness. Additional 
information may be obtained from the Medical Center’s Director of Risk and Insurance 
Management, at 
.
If you are injured, the insurer may require information such as your name, social security 
number, and date of birth in order to pay for your care.  This is because the insurer is required by 
law to report any payments made to cover the care of any persons who are members of a 
government insurance plan to the Department of Health and Human Services.
You do not give up any legal rights as a research participant by signing this consent form. For 
more information on medical treatment for research related injuries or to report a study related 
illness, adverse event, or injury you should call Daryl S. Henshaw, MD at 
.
WHAT ABOUT MY HEALTH INFORMATION?
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 6 of 8
Adult Consent Form
Version: 03/19/2020_____________
In this research study, any information we collect from you and/or information we get from your 
medical records about your health or behaviors is considered Protected Health Information. The 
information we will collect for this research study includes: Your age, weight, height, gender, 
and the results of the laboratory tests we are getting for this study. 
If this research study involves the diagnosis or treatment of a medical condition, then Protected 
Health Information collected from you during this study will be placed in your medical record, 
and may be used to help treat you, arrange payment for your care, or assist with Medical Center 
operations. 
We will make every effort to keep your Protected Health Information private. We will store 
records of your Protected Health Information in a cabinet in a locked office or on a password 
protected computer. 
Your personal health information and information that identifies you (“your health information”) 
may be given to others during and after the study. This is for reasons such as to carry out the 
study, to determine the results of the study, to make sure the study is being done correctly, to 
provide required reports and to get approval for new products.  
Some of the people, agencies and businesses that may receive and use your health information 
are the research sponsor; representatives of the sponsor assisting with the research; investigators 
at other sites who are assisting with the research; central laboratories, reading centers or analysis 
centers; the Institutional Review Board; representatives of Wake Forest University Health 
Sciences and North Carolina Baptist Hospital; representatives from government agencies such as 
the Food and Drug Administration (FDA), the Department of Health and Human Services 
(DHHS) and similar agencies in other countries.
Some of these people, agencies and businesses may further disclose your health information. If 
disclosed by them, your health information may no longer be covered by federal or state privacy 
regulations.  Your health information may be disclosed if required by law. Your health 
information may be used to create information that does not directly identify you. This 
information may be used by other researchers. You will not be directly identified in any 
publication or presentation that may result from this study unless there are photographs or 
recorded media which are identifiable.
If required by law or court order, we might also have to share your Protected Health Information 
with a judge, law enforcement officer, government agencies, or others. If your Protected Health 
Information is shared with any of these groups it may no longer be protected by federal or state 
privacy rules.
Any Protected Health Information collected from you in this study that is maintained in the 
research records will be kept for at least six years after the study is finished. At that time any 
research information not already in your medical record will either be destroyed or it will be de-
identified.  This authorization does not expire and any research information entered into your 
medical record will be kept for as long as your medical record is kept by the Medical Center. 
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 7 of 8
Adult Consent Form
Version: 03/19/2020_____________
You will not be able to obtain a copy of your Protected Health Information in the research 
records until all activities in the study are completely finished. 
You can tell Daryl S. Henshaw, MD that you want to take away your permission to use and share 
your Protected Health Information at any time by sending a letter to this address:
Daryl S. Henshaw, MD
 
However, if you take away permission to use your Protected Health Information you will not be 
able to be in the study any longer. We will stop collecting any more information about you, but 
any information we have already collected can still be used for the purposes of the research 
study.
By signing this form you give us permission to use your Protected Health Information for this 
study.
If you choose to participate in this study, your medical record at Wake Forest University Baptist 
Medical Center will indicate that you are enrolled in a clinical trial.  Information about the 
research and any medications or devices you are being given as a participant may also be 
included in your medical record.  This part of the medical record will only be available to people 
who have authorized access to your medical record.  If you are not a patient at this Medical 
Center, a medical record will be created for you anyway to ensure that this important information 
is available to doctors in case of an emergency.
A description of this clinical trial will be available on http://www.ClinicalTrials.gov, as required 
by U.S. Law.  This website will not include information that can identify you.  At most, the 
website will include a summary of the results.  You can search this Web site at any time. 
Laboratory test results and other medical reports created as a result of your participation in the 
research study may be entered into the computer systems of Wake Forest University Health 
Sciences and North Carolina Baptist Hospital.  These will be kept secure, with access to this 
information limited to individuals with proper authority, but who may not be directly involved 
with this research study.
A North Carolina Baptist Hospital (NCBH) medical record will be created for all study 
participants. Information about your participation in the study will be placed in the NCBH 
medical record, along with any routine medical test results that were obtained at NCBH as part 
of this study. 
WHAT ARE MY RIGHTS AS A RESEARCH STUDY PARTICIPANT?
Taking part in this study is voluntary. You may choose not to take part or you may leave the 
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023


Page 8 of 8
Adult Consent Form
Version: 03/19/2020_____________
study at any time. Refusing to participate or leaving the study will not result in any penalty or 
loss of benefits to which you are entitled. If you decide to stop participating in the study we 
encourage you to talk to the investigators or study staff first to learn about any potential health or 
safety consequences. The investigators also have the right to stop your participation in the study 
at any time. This could be because it is in your best medical interest, your condition worsens or 
changes unexpectedly, you failed to follow the instructions related to the study, or the entire 
study was stopped.  
You will be given any new information we become aware of that would affect your willingness 
to continue to participate in the study.
WHOM DO I CALL IF I HAVE QUESTIONS OR PROBLEMS?
For questions about the study or in the event of a research-related injury, contact the study 
investigator, Daryl S. Henshaw, MD at 
.
The Institutional Review Board (IRB) is a group of people who review the research to protect 
your rights. If you have a question about your rights as a research participant, or you would like 
to discuss problems or concerns, have questions or want to offer input, or you want to obtain 
additional information, you should contact the Chairman of the IRB at 
.
You will be given a copy of this signed consent form. 
SIGNATURES
I agree to take part in this study. I authorize the use and disclosure of my health information as 
described in this consent and authorization form.  If I have not already received a copy of the 
Privacy Notice, I may request one or one will be made available to me.  I have had a chance to 
ask questions about being in this study and have those questions answered.   By signing this 
consent and authorization form, I am not releasing or agreeing to release the investigator, the 
sponsor, the institution or its agents from liability for negligence.
Subject Name (Printed):_____________________________
Subject Signature: _________________________________ Date: ________Time:_______ am pm 
Person Obtaining Consent (Printed):_____________________________
Person Obtaining Consent:___________________________ Date:_________ Time:________ am pm
WFU School of Medicine 
Institutional Review Board 
IRB Number:IRB00044503
Meeting Date Approved 2/1/2022          
Version Valid Until: 1/31/2023