Clinical Trial Details
— Status: Terminated
Administrative data
| NCT number |
NCT00299949 |
| Other study ID # |
HSC-MS-06-0012 |
| Secondary ID |
|
| Status |
Terminated |
| Phase |
N/A
|
| First received |
March 3, 2006 |
| Last updated |
February 6, 2013 |
| Start date |
October 2006 |
| Est. completion date |
December 2008 |
Study information
| Verified date |
February 2013 |
| Source |
The University of Texas Health Science Center, Houston |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
United States: Institutional Review Board |
| Study type |
Observational
|
Clinical Trial Summary
Sepsis is the 13th most common cause of death in the United States, causing approximately
210,000 deaths per year. Once DIC has developed, irreversible organ injury has already
occurred and the mortality rate is 70%. Inhibition of systemic coagulation with activated
protein C concentrate has been the only therapy for sepsis introduced in the past several
decades which has improved outcomes. Elucidation of the coagulopathic mechanisms early in
the development of DIC may give rise to targeted therapies and strategies for early
intervention. We hypothesize that an increase in endogenous thrombin potential precedes the
development of overt DIC by a clinically significant time period. Our primary objective is
to determine if endogenous thrombin potential (ETP) measured at first diagnosis of sepsis
prior to the onset of DIC and organ failure is predictive of overt DIC and/or poor outcome.
We will compare ETP to standard coagulation assays and the clinical assessment of DIC using
the ISTH criteria for overt DIC. A secondary objective of this study is to determine if host
coagulation variables predispose to the development of DIC and poor clinical outcome during
sepsis.
Description:
Activation of the coagulation system occurs early in patients with sepsis, although
clinically overt disseminated intravascular coagulation (DIC) is identified in only a
minority of patients with severe sepsis. Uncontrolled activation of the coagulation system
may contribute to the pathophysiology of multiple organ failure and the subsequent morbidity
and mortality of sepsis. Identification of risk factors predicting progression to severe
sepsis and DIC has been elusive. We propose that whole blood and cell-rich coagulation
assays will offer improved sensitivity to both the procoagulant and anti-coagulant changes
which occur early in sepsis and will improve recognition of non-overt DIC. Future studies
will address whether these assays have sufficiently high predictive value to identify
subgroups of patients who could benefit from early intervention.
Specific Aims:
1. We hypothesize that increased thrombin generation will precede development of overt DIC
by a clinically significant time period. Our primary objective is to determine if
endogenous thrombin potential measured at first diagnosis of sepsis prior to the onset
of DIC and organ failure is predictive of overt DIC.
2. There is significant individual variation among the healthy population in endogenous
thrombin generation due to known and unknown polymorphisms within coagulation proteins.
We predict that host variables in thrombin generation will contribute to susceptibility
to DIC and poor outcome during sepsis. A secondary objective of this study is to
determine if host coagulation variables predispose to the morbidity and mortality
associated with sepsis.
Experimental Design and Methods
The study design will be a prospective observational study of patients presenting to the
Memorial Hermann Hospital Emergency Department with sepsis. Criteria for sepsis include
evidence of systemic inflammatory response syndrome as defined by the ACCP/SCCM Consensus
Conference, and a known or suspected infection. Exclusion criteria include signs of severe
sepsis or septic shock, as defined by the ACCP/SCCM Consensus Conference, at presentation,
including: organ dysfunction, hypoperfusion and perfusion abnormalities. Chronic medical
conditions associated with immune suppression or coagulopathies, such as neutropenia and
sickle cell disease, and use of medications leading to immune dysfunction or coagulopathies,
such as chronic steroid use or anti-coagulation will also be reasons for exclusion. In
addition, because of the volume of blood required from each patient for laboratory studies,
only patients 25 kg body weight or more will be enrolled. Withdrawal from the study will be
at the discretion of the treating physician or subject. All efforts will be made to collect
clinical information from patients who have withdrawn.
Inclusion criteria
- Known or suspected infection as determined by the treating physician Patient to be
admitted to the hospital
- Systemic Inflammatory Response Syndrome: 3 of the following 4 criteria:
- Temperature > 38 C or < 35 C
- Heart rate > 90 beats/min, except in patients with a medical condition known to
increase the heart rate or those receiving treatment that would prevent tachycardia.
- Respiratory rate > 20 breaths/min or PaC02 < 32 mmHg, or on mechanical ventilation for
an acute respiratory process.
- White blood cell count > 12,000/mm3, < 4,000/mm3, or > 10% bands
Exclusion criteria
- - Use of the following medications: unfractionated heparin to treat an active
thrombotic event within 8 hours before the infusion; low-molecular-weight heparin at a
higher dose than recommended for prophylactic use within 12 hours before the infusion,
warfarin used within 7 days of study entry, aspirin use at a dose of more than 650
mg/day within 3 days before the study, thrombolytic therapy within 3 days before the
study, glycoprotein IIb/IIIa antagonists within 7 days before the study entry,
administration of activated protein C (Xigris ) in the 24 hours before study entry.
- Neutropenia
- Hemophilia
- Diabetic ketoacidosis
- Weight < 25 kg
Patients will be enrolled in the emergency department within 2 hours of meeting eligibility.
Written informed consent will be obtained from the patients or their authorized
representatives. Blood samples will be collected by peripheral venipuncture during the first
hour after enrollment and then once daily for 7 days (see Appendix A).
Patients will be withdrawn from the study if blood sampling is not performed within 2 hours
of obtaining informed consent.
Clinical data collection Clinical data forms (see Appendix B) will be completed at the time
of enrollment and daily for 7 days , at hospital discharge, and at 28 days. Clinicians will
be blinded to the results of the research laboratory tests.
Laboratory Methods
Blood and plasma Each patient will have 15 ml blood collected at enrollment. Specimens will
be obtained through antecubital venipuncture. Free flow or minimal suction will be employed;
vacuum containers will be avoided. Specimens for platelet-poor plasma (PPP) and whole blood
analysis will be collected into siliconized glass tubes with 0.105M tri-sodium citrate in
the ratio of 1 part anticoagulant to 9 parts whole blood. PPP will be separated within 60
minutes and analyzed immediately. Platelet-rich plasma (PRP) specimens will be separated
from the upper ¾ volume of plasma supernatant after centrifugation at 265g for 10 minutes at
room temperature. The platelets will be counted on a Beckman Coulter counter and adjusted to
150 X 109 platelets/l with autologous PPP. PRP will be used within 60 minutes. Cbc, PT/PTT,
Fibrinogen, d-dimer, Protein C activity, Protein S activity, ATIII activity, Factor V Leiden
mutation, Prothrombin G20210A mutation analysis will be performed in Memorial Herman
Hospital clinical laboratories.
RoTEG
Whole blood specimens will be drawn as described above. Measurements will be performed on
two roTEG Coagulation Analyzers from Pentapharm. RoTEG all-plastic reaction cups are
procured from the manufacturer. Polypropylene and polyethylene pipettes are used to handle
reagents and blood. Citrated whole blood will be re-calcified by 20 mcl 0.2 mol/L CaCl2 and
activated by 20 mcl solution of recombinant human TF (Innovin) diluted 1:1000 using a sodium
barbital buffer. The measured parameters have been defined by the manufacturer as follows:
The clotting time(CT) is the time in seconds from Ca2+ activation of coagulation and until
an increase in elasticity corresponding to 2 graphical mm is obtained on the ordinate. The
clot formation time (CFT) is the time in seconds passing while the elasticity increases from
2 mm to 20 mm on the ordinate. The maximum clot formation (MCF) expresses the maximum
strength in millimeters of the final clot. Several additional parameters representing the
continuous registration of clot formation have been defined by Sorensen et al 28: the
maximum velocity (MaxVel) of clot formation, the time to maximum velocity (T,MaxVel) of clot
formation, and the area under the velocity curve (AUC).
Thrombin Generation
Calibrated automated thrombin generation measurements will be performed using the Hemker
methodology. 29 Platelet rich plasma (PRP) will be prepared as described above. Fluorogenic
substrate and chromogenic thrombin will be purchased through Thermolabsystems, and
recombinant relipidated tissue factor(TF) through Dade Behring. alpha 2
macroglobulin-thrombin complex used as a calibrator will be purchased through
Thrombolabsystems. The thrombograms will be measured in a 96-well plate fluorometer (Ascent
reader, Thrombolabsystems) and analyzed with software purchased through Thrombinoscope.
Experiments will be carried out in quadruplicate and compared to a calibrator. To each well
80 mcl of plasma will be added, followed by the calibrator or buffer, then the "trigger": 20
mcl of 3 mM of TF. The plate will be placed in the fluorometer and allowed to warm to 37 C.
The instrument dispenses 20 mcl of Fluorogenic substrate 2.5 mM and CaCl2 100 mM (FluCa) to
all the wells to be measured, registers this as zero time, shakes them for 10 s and starts
reading. During the measurement, the program compares the readings from the TG and the CL,
calculates thrombin concentration and displays the thrombin concentration in time. The peak
thrombin is the highest thrombin concentration reached during the time course of thrombin
formation and inhibition. The thrombin potential is the amount of thrombin that is formed
within 60 minutes (Area under the curve). The lag phase and the peak time refer to the start
and velocity of thrombin formation, respectively.
Data Management Data will be collected on paper forms which will be designed by the GCRC
informatics core section. The GCRC informatics core will maintain data on a secure database
(Access). Each subject will be assigned a unique ID reflecting the order in which enrollment
took place.
Data Analysis and Presentation
This is a pilot study intended to provide the preliminary data for future clinical studies.
Descriptive statistics will be used to characterize ETP and roTEG at initial presentation of
sepsis. Means and ranges will be reported for each of the variables in the thrombin
generation assay (lag time, slope of rise, peak value, and area under the curve) and roTEG
(Clot formation time (CFT), maximum clot formation (MCF), maximum velocity (MaxVel) of clot
formation, time to maximum velocity (T,MaxVel) of clot formation, and area under the
velocity curve (AUC)). The primary objective of this study is to compare ETP at presentation
to the development of DIC, as defined by a positive ISTH DIC score. The secondary objective
will be to compare host coagulation variables, including ETP, roTEG, Pro C, Pro S, ATIII,
FVL, and prothrombin G20210A mutation at presentation, with the secondary outcome measures
of 28-day mortality and organ dysfunction. All statistics will be performed using NCSS/PASS.
Sample size determination: There are no published reports of thrombin generation assays or
thromboelastography in sepsis, or DIC. In our previous studies of patients taking an
anticoagulant (warfarin), there was a 400% decrement of ETP (1719 to 404). In order to
derive a mean ETP with a target width of 100 and 95% confidence interval, assuming a
standard deviation of 259, we will need to enroll 100 patients.
We will employ the following statistical methods for the analysis of data:
Specific Aim #1: The endogenous thrombin potential (ETP) is the area under the curve of the
thrombin generation assay. The values are continuous and range from 0 to 2,500. Maximum clot
formation (MCF) from the roTEG will also be used to approximate ETP. The DIC score will be
calculated and coded as a dichotomous variable: Yes (score > 5) or No (score < 5). A
receiver operating curve will be derived for ETP and MCT and its sensitivity and specificity
for predicting DIC. If the area under the curve is found to be significant, an optimal
cut-off value with the highest degree of accuracy will be chosen. This value will be used to
estimate the predictive value of the test. Positive predictive value will be calculated with
the formula: # patients with ETP or MCT above the cut-off and development of DIC / #
patients with positive DIC score. The predictive value of a negative DIC score will be
calculated using the formula: # patients with ETP or MCT below the cut-off and no
progression to DIC / # patients with negative DIC score.
Specific Aim #2: A multivariate analysis will be done to determine which of the predictor
variables (ETP, MCT, Pro C, Pro S, ATIII, FVL, ProG20210A, DIC) are associated with the
secondary dichotomous outcome measures: organ dysfunction at 28 days (Any/None), 28-day
mortality (Dead/Alive).
