coagulation testing
TRANSCRIPT
Coagulation TestingWhat is it?
Why do we need it POC?
Marcia L. Zucker, Ph.D.Director of Clinical Research
Educational Services, Edison, NJ
Coagulation Testing
Monitoring hemostasis
Bleeding Clotting
CLOT
Anticoagulants
Intrinsic Pathway
Extrinsic Pathway
Common PathwayX Xa
II IIa (thrombin)
HEPARIN
WARFARIN
LMWH
Hirudin & DTI
DXaI
Monitor with aPTT or ACT
Monitor with PT
Monitor with ?????
Coagulation is Complex
Picture from DiaPharma.com
Common(?) Coagulation Tests Laboratory
PT..
aPTT
TT..
Fib.– Anti Xa– Anti IIa– Factor Assays
Point of Care
– ACT» Celite®
» Kaolin» Glass beads» Silica» thromboplastin
Differences in test methods
Point of Care– Whole Blood
– No Added Anticoagulant
– No Dilution
– No Preanalytical Delay
Standard Laboratory– Platelet Poor Plasma
– Sodium Citrate Anticoagulant
– 1:9 Dilution
– Variable Preanalytical Delay
POC Coagulation Analyzers HEMOCHRON 401 / 801 / Response HEMOCHRON Jr. Signature / Signature + ProTime / 3 Medtronic HMS/HMS+/ HemoTec ACT II / ACTPlus CoaguChek / S / Pro / Pro DM i-STAT Helena Actalyke Hemosense INRatio Others?
POC Coag Analyzers Differ Test methodology
– Sample size and application» Microliters to milliliters
– Sample measurement» Manual vs automated
– Clot detection method» Enzyme detection method
Thrombin generation
– Reagent composition
– Results
Clinical ApplicationsOperating Room
– Cardiac Surgery– Interventional Cardiology and Radiology
Critical Care Satellite Sites
– Dialysis– ECMO– Emergency Room– Anticoagulation Clinic
History of the ACT Lee-White clotting time
– Manual
– No activator
– Very slow 1966 –Hattersley- Activated Clotting Time
– Diatomaceous earth activator
– Operator defined mixing and clot detection
– Global assay - Contact activation of cascade
Activated Clotting Time
Particulate Contact Activation Initiation of intrinsic coagulation cascade
– Factor XII (Hageman factor)– Prekallikrein (Fletcher factor)
Dramatically shortens contact activation period over Lee-White time
Proposed as both screening assay for coagulation defects and for heparin monitoring
ACT Automation - 1969
HEMOCHRON introduced– semi-automated
– less operator dependence
– two assays » CA510 (later FTCA510)
diatomaceous earth activated
» P214 glass bead activated
2 assays for separate applications
0
100
200
300
400
500
600
700
0 1 2 3 4 5
Heparin (units/ml)
Clo
ttin
g T
ime
(sec
)
C-ACT
P214
ECMO Dialysis
CATHPTCA CPB
1980’s HemoTec ACT Liquid kaolin activator Different technology
– Different results
ACT Differences Recognized in literature >20 years
– Clinical evaluations of Hemochron appeared in journals mid 1970’s
– By 1981, papers appeared showing little correlation between ACT and heparin level
– By 1988, papers clearly showed clinically different results between Hemochron and HemoTec
Differences ignored by clinicians
Why are there so many different ACTs?
0
100
200
300
400
500
600
700
0 1 2 3 4 5
Heparin (units/ml)
Clo
ttin
g T
ime
(sec
)
C-ACT
K-ACT
ACT+
P214
ACT-LR
CCUDialysis
CATHPTCA CPB
Monitoring - ACT Benefits
– Industry Standard Since 1970s– Recommended as primary method in
AmSECT guidelines (perfusion)– Easy to run
Disadvantages– Each system yields different numbers– High sensitivity to hypothermia and
hemodilution (with exceptions)– Little or no correlation to heparin level
» especially true for pediatric patients
475
500
525
550
575
600
625
650
675
700
PreCPB
15min
30min
45min
60min
75min
90min
105min
Seco
nds
Hemochron
Hemotec
TAS
HMS
Heparinized ACT - CPB
Data from Huffman, et.al. 1998 AmSECT meeting
Pharmaceutical Intervention
Amicar or Tranexamic Acid– No effect on standard celite ACT
Aprotinin– Significant elevation of celite ACT
– Two dosing regimens» Full or Half Hammersmith» Both independent of patient size
ACT Monitoring-Aprotinin Treatment Celite ACT
– Not recommended– Still used with target times of >750 seconds
Kaolin ACT– Unaffected by moderate doses of aprotinin– Used with target times of > 480 seconds
ACT+– Unaffected by ALL doses of aprotinin– Used with target times of > 400 seconds
Monitoring in CPB - Aprotinin
Data from clinical evaluation, on file, ITC
C-ACT
0
200
400
600
800
1000
1200
Baselin
e
PostB
olu
s
PostB
olu
s2
OnP
um
p
OnP
um
p2
OnP
um
p3
PostP
rot.
Trasylol
Placebo
ACT+
0
200
400
600
800
1000
1200
Baseline
PostB
olus
PostB
olus2
OnP
ump
OnP
ump2
OnP
ump3
PostP
rot.
Trasylol
Placebo
Other POC Coag in the OR aPTT / PT
– Pre- and post-procedural screening Fibrinogen
– Pre- and post-procedural screening Dosing Assays
– Customize heparin and protamine for each patient» HEMOCHRON HRT / PRT» Hepcon HMS
– Measure heparin level» Relationship to coagulation status unclear
Other POC Coag in the OR
Heparin neutralization verification– Ensure complete removal of circulating
heparin» aPTT» PDA-O - ACT based» TT / HNTT - Thrombin Time based» heparinase ACT
Outcome studies - POC in OR Reduced Blood Loss/Transfusion
– Use of HRT and PRT (RxDx System)
Reduced Cost Resulting from Use of POC Assays– RxDx combined with TT / HNTT
Reduced Complication Rates– TT / HNTT– Re-Exploration for Bleeding Reduced from 2.5% to
1.1%– Re-Exploration for Coagulopathy Reduced from
1.0% to 0.0.
Clinical ApplicationsOperating Room
– Cardiac Surgery– Interventional Cardiology and Radiology
Critical Care Satellite Sites
– Dialysis– ECMO– Emergency Room– Anticoagulation Clinic
Procedures Diagnostic
– Catheterization» locate and map vessel blockage(s)» determine need for interventional procedures
– Electrophysiology– Interventional Radiology
Interventional– Balloon angioplasty– Atherectomy (roto-rooter)
Diagnostic – Low dose heparin
Catheterization and Electrophysiology– 2500 - 5000 unit bolus dose
– frequently not monitored
– if monitored – » ACT» aPTT
Interventional – Moderate dose Angioplasty and Atherectomy
– Heparin» 10,000 unit bolus dose or
» 2 - 2.5 mg/kg
» target ACT 300 - 350 seconds 200 – 300 in presence of ReoPro
– Angiomax (bivalirudin)» ACT >300
Hemochron (ACT-LR or FTCA510) trials
» Measure post-bolus to ensure drug on board
» Required in patients with renal impairment
Why use platelet inhibitors? Angioplasty promotes aggregationAdhesion
•shape change • release
ADP release
Aggregation
Coagulation
•Fibrin formation
3 sec
10 sec
5 min
Need to inhibit restenosis / reocclusion
Platelet Inhibitors ReoPro
– elevates ACTs– target time = 250 sec with ReoPro
» determined using FTCA510 tube
Integrelin– No reported clinically significant
effects on ACT Aggrastat
– No reported effects on ACT
Clinical ApplicationsOperating Room
– Cardiac Surgery– Interventional Cardiology and Radiology
Critical Care Satellite Sites
– Dialysis– ECMO– Emergency Room– Anticoagulation Clinic
ACT or aPTT Determine when to pull the femoral sheath
– Premature sheath pull can lead to bleeding.
– Delayed removal can increase time in CCU.
– Target set at each site.» ACT targets range from 150 – 220 seconds» aPTT targets range from 40 – 70 seconds
Must be linked to heparin sensitivity of reagent used
ACT vs aPTT
y = 0.57x - 28.44R = 0.896
20
30
40
50
60
70
80
90
100
110
120
50 100 150 200 250FTCA510 (sec)
aP
TT
(J1
03)
(se
c)
Single site comparison, ACT tube vs HE Jr Sig aPTT
ACT or aPTT Monitor heparin therapy
– Target times determined by each facility
– APTT outcome study» Reduce time to result (112 vs <5 minute)» Reduce time to stabilization» Reduce dose adjustments» Reduce length of stay » By using POC aPTT instead of lab
Poster at AACC 2000 – Staikos, et.al.
Activated Partial Thromboplastin Time
Intrinsic Pathway
Extrinsic Pathway
Common Pathway
CLOT
APTT
NOT a PTT– PTT is the predecessor of the aPTT– Not used anymore
Laboratory or Point of Care High APTT values
– presence of heparin» treat by giving protamine
– underlying coagulopathy» treat by giving FFP
Monitor heparin / Coumadin® cross-over
Activated Partial Thromboplastin Time
Heparin versus Warfarin
Drug ActionMechan-
ismMoni-toring
Effective
HeparinDirect
Inhibition ofThrombin
ATIIIcofactor
APTTACT
Immediate
WarfarinDecreasesProductionof factors
Vitamin K PTDelay
3-5 days
Prothrombin Time
Intrinsic Pathway
Extrinsic Pathway
Common Pathway
CLOT
PT
Prothrombin Time Monitor warfarin therapy Monitor heparin/warfarin crossover Target times are set by
International Normalized Ratio (INR)
ISI = international Sensitivity Index– INR target ranges are specified by patient populations
» DVT, Afib, Atrial MHV: INR= 2.0 - 3.0
» Mitral mechanical heart valve: INR= 2.5 – 3.5
» Hypercoagulable disorders: INR= 1.5 – 2.5?
ISI
meannormal
patient
PT
PTINR
Will POC Results Match the Lab?
(Probably Not)
but it WILL Correlate
Correlate Does Not Mean Match
y = 0.737x + 22.2R = 0.920
0
20
40
60
80
100
120
140
0 50 100 150Lab APTT
Sig
na
ture
AP
TT
Coag is NOT Chemistry
y = 0.4493x + 17.898y = 0.4723x + 20.24y = 0.4374x + 22.173
IL C
Dade Actin / MLA
y = 0.72x + 11.5R = 0.883
20
30
40
50
60
70
20 30 40 50 60 70lab
Sig
na
ture
IL aPTT SP / ACL #2
y = 0.59x + 16.0R = 0.961
10.0
30.050.0
70.090.0
110.0130.0
150.0
10 30 50 70 90 110 130 150lab
Sig
na
ture
IL aPTT C / ACL #3y = 0.44x + 22.2
R = 0.9533
10.0
30.050.0
70.090.0
110.0130.0
150.0
10 30 50 70 90 110 130 150lab
Sig
na
ture
Organon Technika / MDA
y = 1.02x + 4.1R = 0.942
20
30
40
50
60
70
20 30 40 50 60 70lab
Sig
na
ture
y = 0.4493x + 17.898y = 0.4723x + 20.24y = 0.4374x + 22.173
IL C
IL SP
IL aPTT C /ACL #1
y = 0.45x + 17.9R = 0.929
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
IL aPTT SP / ACL #1
y = 0.35x + 22.1R = 0.928
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
IL aPTT C / ACL #2
y = 0.47x + 20.2R = 0.942
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
IL aPTT SP / ACL #3
y = 0.40x + 23.3R = 0.912
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
IL aPTT C / ACL #3
y = 0.44x + 22.2R = 0.953
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
IL aPTT SP / ACL #2
y = 0.59x + 16.0R = 0.961
0.0
20.0
40.0
60.0
80.0
100.0
0 50 100 150lab
Sig
na
ture
Compare for your site.
Same System / Multiple Sites
Are differences important?
Sometimes no - aPTT C
Signature site 1 site 2 site 330 27 21 1840 49 42 4150 71 63 6460 94 84 8770 116 105 10980 138 127 13290 160 148 155
Sometimes VERY - aPTT SPSignature site 1 site 2 site 3
30 23 24 3340 51 41 8250 80 57 13060 109 74 17970 138 91 >20080 167 108 >20090 196 125 >200
Lot to Lot ReproducibilitySignature
30405060708090
Cuvette Lot a
y = 1.35x - 14.2R=.909
20
30
40
50
60
70
80
20 40 60 80Signature
La
b
Cuvette Lot b
y = 1.39x - 12.8R=0.934
20
30
40
50
60
70
80
20 40 60 80Signature
La
b
Signature Lot a Lot b30 26 2940 40 4350 53 5760 67 7070 80 8480 93 9890 107 112
Clinical ApplicationsOperating Room
– Cardiac Surgery– Interventional Cardiology and Radiology
Critical Care Satellite Sites
– Dialysis– ECMO– Emergency Room– Anticoagulation Clinic
Dialysis / ECMO ACT (or nothing in dialysis)
– Majority use P214 glass activated ACT
– Some use ACT-LR; HemoTec LR ACT Better Control of Anticoagulation Leads to
Increased Dialyzer Reuse– Potential for Long Term Cost Savings
– No Compromise in Dialysis Efficacy (Kt/V)» Ouseph, R. et.al. Am J Kidney Dis 35:89-94; 2000
Emergency Room ACT; aPTT; PT; Fibrinogen Immediate Identification of Coagulopathies
– Optimization of Critical Decision Pathways ACT Allows Early Detection of Traumatic
Coagulopathy– Allows Early Treatment Decisions– Aids Damage Control Decisions
» Aucar, J. et.al. 1998 SW Surgeons Congress
Optimize Staffing During Off Hours
Anticoagulation Clinics Results Available While Patient is Present
– Improved Anticoagulation Management– Improved Standard of Care– Staff Efficiency
Immediate Retesting (if needed)– Fingerstick Sampling
Same System for Clinic and Home Bound Patients– Standardized ISI / PT normal
» Test System Specific
Anticoagulation Clinics
Potential for Self-Testing– High Risk Patients
– Patients Who Travel Frequently
– Home-Bound
– Patients in Rural Areas Far from Clinic Improved Outcomes Through More
Frequent Testing
Will POC Results Match the Lab?
(It will be a lot closer than for aPTT)
but it WILL Correlate
How to Compare INR Results
Lower dose? Keep same dose? Raise Dose?
Test Again? Test more often?
Lab to Lab Comparison
-1.5
-1
-0.5
0
0.5
1
1.5
0 1 2 3 4 5 6 7
Mean Innovin and TPC INR
Dif
fere
nce
(T
PC
- I
NN
)
Mean difference = 0.3 INR
INR Expectations
(values shown are ranges)AACC 2002
Pairs within 0.4 INR
Pairs within 0.7 INR
Lab to Lab 85.4 – 97.9 % 94.8 – 99.0 %
POC to Lab 74.7 – 89.9 % 87.9 – 99.0 %
POC to POC 89.9 – 94.9 % 97.0 – 99.5 %
INR within 0.4 of lab > 80%INR within 0.7 of lab > 90%INR within 1.0 of lab > 95%
Why Bother with POC Coag? Improved TAT - Turn Around Time
– Defined from the Clinician, not Lab view
– When is Turn Around Important» Emergency Room» ICU/CCU Dose Adjustments» Operating Room / Cath Lab
– STAT Testing Turn Around
STAT Testing TAT
Lab (min) Median
CPB (N=40)90.0
PVS (N=45)90.0
Mean 78.5 74.0Minimum 38.0 21.0
POC (min)Median
All Groups2.23
Minimum 0.33Maximum 6.97
Fitch, et.al, J. Clin Monit & Comput. 1999. 15:197-204
Standardized Clinical Interpretation
Defined Assay Sensitivity– Requires Lot to Lot Reproducibility
Defined Reagent Variability– Identical Instrumentation and Reagents at All
Testing Sites Defined Critical Clinical Decision Points
– No Change of Normal Ranges or Target Times Between Lots of Test Reagents or Testing Locations
What’s the catch?
1. Regulatory compliance
2. Connectivity
Regulatory compliance - Who sets the rules?– JCAHO
» Joint Commission on Accreditation of Health Care Orgs
– CAP » College of American Pathologists
– FDA» Food and Drug Administration» CDRH
Center for Devices and Radiological Health
– CMS» Centers for Medicare and Medicaid Services
– CDC» Centers for Disease Control
CLIA Applies to ALL Testing Areas
Central Laboratory Satellite Labs
– Critical Care
– Surgical Suite Clinics Bedside testing Doctor’s office
CLIA Regulations for Coagulation Central Laboratory can hold the CLIA license
– Satellites can have independent licensure Moderately Complex tests
– Except – ProTime, Coaguchek, INRatio are waived Requires
– Certified Laboratory Director– Record Keeping– Training– Quality Policy
Implementing POC coag requires: Method Validation - accuracy
– Comparison to current standard» NCCLS Guideline EP-09 recommends 40 samples
– Linearity may be used if no current standard– Is assay performance appropriate to clinical needs?
Precision– Controls may be used to establish within and between run
variability Training
– Document training of all personnel » high school equivalence or higher education level
– competency evaluations at predetermined intervals
Implementing POC coag requires:
Linearity NOT required for coag Calibration “does not apply to unit test systems that
cannot be adjusted” Calibration verification
• Current assumption:– Equivalent to CAP POC.05450
» If the laboratory has more than one method-system for performing tests for a given analyte, are they checked against each other at least twice a year for correlation of patient results?
– CLIA requires at least 3 point check
New CLIA Regulations Work in progress
– New rules published January 2003– Rules in effect March 23, 2003– Interpretive guidelines published Jan 2004– Inspections using new regulations now
» 2 year grace period to adapt new rules» Ends Jan 2005
Quality Assessment Program - Lab Responsibilities– Establish & follow policies/procedures addressing ongoing
QA activity. – Take corrective actions as necessary.
» Review their effectiveness.» Revise policies/procedures as necessary to prevent recurrence.
– Communicate to staff.– Document all assessment activities.
New CLIA Regulations Proficiency testing
– Changed consensus for PT program grading from 90% to 80%.
Quality Assessment replaces Quality Assurance.– Quality Assessment is interspersed throughout the regulation.
– Creates one set of nonwaived QC requirements.
Subpart K - Quality System for Nonwaived Testing– Laboratory is ultimately responsible for ensuring that all
components of the analytic process are monitored.
– Each laboratory that performs nonwaived testing must meet the applicable analytic systems requirements; unless HHS approves a procedure, specified in the Interpretive Guidelines, that provides equivalent quality testing
Equivalent Quality Testing Traditional:
– Testing two levels of external control materials each day of testing
– Except coag and blood gases» every 8 hours of use
Equivalent QC Options– #2 -Test systems with internal/procedural
controls that monitor a portion of the analytic components, and if the lab successfully completes a thirty day evaluation process, the lab may reduce the frequency of external quality control materials to once per calendar week.
Equivalent Quality Testing Option #2
– Perform the test system’s internal control procedure(s) in accordance with the manufacturer’s instructions (but not less frequently than once each day of testing) and test two levels of external control material daily for 30 consecutive days of testing.
EQC AND LQC daily (NOT every 8 hours) for 30 days– Then OK to use EQC daily, LQC weekly
» Unless manufacturer requires more
– Send comments to: Judith Yost» Director, Division of Laboratory Services, CMS
» (410) 786-3407
Routine Quality Control Instrument Performance Verification
– Electronic Quality Control with Numeric Output – Two levels per 8 hour shift (CLIA reg)
Assay Performance Verification– Wet QC as per Manufacturer’s Recommendation
» Varies by system No external QC required for ProTime / INRatio in
most States
» Within system may vary by waived or moderate complexity licensure
Ensuring Compliance Required identification
– Mandatory operator ID» Password control» Reuse IDs for some applications
– Mandatory patient ID» Reuse IDs for some applications
Lockout– Force QC at specific times
» QC must pass to run patient samples
– Lockout non-compliant or untrained operators– Disallow specific assays
Connectivity Multiple definitions
– Download to computer» To LIS or to HIS or to both or to data
management software» Real time and / or batch» QC data, patient data, or both
Connectivity Bidirectional communication
– Send data to instrument» Reset lockouts» Load configurations
Operator tables QC frequency QC ranges Reuse availability
» Vary configuration by clinical setting
Solutions System specific configuration
– e.g. HCM for Signature+ HRDM for Response
System specific data management– e.g. ReportMaker for Signature / + HRDM for Response RapidLink for Bayer RapidPoint DataCare for Roche CoaguChek / S / DM / Pro
Link to systems designed for glucose– Abbott and Roche state they will connect with any POC
instrumentation
Solutions
Manufacturer neutral interface– MAS RALS-plus– Telcor Quick Serv– Manufacturer works with interface supplier to
ensure compatibility– Interface supplier works with LIS / HIS
supplier to ensure compatibility– Likely more options as CIC guidelines
implemented (NCCLS POCT1-A)
Why Bother with POC Coag?
Once compliance issues addressed ––Improved Clinical Outcome
–Reduced LOS – Length of Stay
–Improved, timely patient care