Point of care troponin tests
Professor Paul Collinson
MA MB BChir FRCPath MD FACB FESC
Consultant Chemical Pathologist and Professor of
Cardiovascular Biomarkers,
Departments of Chemical Pathology and Cardiology, St
George’s Hospital and Medical School, London
POCT testing
• Mentioned by Hippocrates and Galen
• Described in the 7th century by the Byzantine Theophilus
Protospatharios
POCT
• Codified in the UK
– Anon. Seynge of Urynes. London: R. Kele, 1552
• Techniques included tasting the urine
– no wonder the English make such awful wine
• Soon to be re-introduced as a cost saving alternative.
Rapid diagnostic protocols in the ED
• Increasing demand on ED facilities
• Chest pain is the largest single medical presenting
complaint
Overview
• The clinical problem
• The troponin paradighm
• The evolution of POCT
• The clinical and laboratory shift
• The state of the art
• The future state
The healthcare burden of chest pain – the patient paradox
• Chest pain and related complaints accounted for 6% of
adult emergency department attendances
• Two thirds were admitted, creating a substantial health
care burden
• A minority had diagnostic ECG changes. Approximately
one third of attendances and half of the admissions had a
clinical diagnosis of ACS without clear ECG changes.
• The majority have a final diagnosis that excludes an
acute coronary syndrome (ACS)Goodacre S et al. Heart 2005;91:229-30.
Rule out AMI
- role of troponin testing
• Studies have shown that rapid rule out of AMI within 2
hours in the ED is feasible.
– Than M et al Lancet 2011;377:1077-1084
– Than M et al J Am Coll Cardiol 2012;59:2091-2098.
– Cullen L et al Int J Cardiol 2013;168:2602-2608.
– Than M et al JAMA Intern Med 2014;174:51-58.
Advantages of cTn over other markers
• Cardiospecific
• Sensitive - diagnosis using CK or CK-MB is flawed.
Elevation of cTn in patients “without AMI”
– occurs in 33% of patients
– indicates myocardial damage
– predicts major adverse cardiac events (MACE)• death
• MI
• readmission with UAP
• need for urgent revascularisation
Evidence base
• Multiple publications showed that troponin could be used
as the single definitive test for acute myocardial
infarction for diagnosis and risk stratification
• Specific treatments could be related to troponin elevation
– Low molecular weight heparin
– Revascularisation
– GlycoproteinIIb/IIIa antagonists
• Sufficient publications to allow a meta-analysis and
subsequent HTA
The evolution of POCT
• Two tracks
– Hand held qualitative strip tests
– Instruments suitable for stat near to patient testing
Hand held qualitative strip tests
• Immunochromatography (GLORIA)– Spectral Cardiac Status
– CardiacT
Application
Zone
Reaction
Zone
Detection
Zone
TnT
wholeblood
gold gold
reagent fleeceGlass fibre fleece
plasma plasma
signalcontrol
membrane
synth.
peptide
Strept
avidin
Application Reaction Detection
MAB 2 MAB 1
biotin biotin
Instruments suitable for stat near to
patient testing• Dry chemistry analysers
– Seralyser (Serum)
– Kodak Ektachem DT-60 (Serum)
– Reflotron
Instruments suitable for stat near to
patient testing• Whole blood systems (Stat lab/POCT)
• Stratus CS
• First Medical AlphaDx
• AIO
• ISTAT
• RAMP
• Pathfast
• AQT90
The clinical and laboratory shift
- then• Diagnostic protocols were based on single measurements
at 10-12 hours from admission
• Laboratory assays were relatively insensitive
• POCT diagnostic performance was excellent
Diagnostic performance
• Troponin T
– CardiacT
• Diagnostic equivalence to CLT
– Hirschl MM et al Resuscitation 1996;32:193-98.
– (REACTT) Investigators Study Group. Acad Emerg Med
1997;4:1018-24.
• Prognostic risk stratification
– Antman EM et al. J Am Coll Cardiol 1998;31:326-30.
– Ohman EM et al. Am J Cardiol 1999;84:1281-86.
– Hamm CW et al, NEJM 1997;337:1648-53.
Survival without cardiac events (death/MI) during 30 days of follow-
up according to cTnT and cTnI status
Hamm et al. NEJM 1997;337:1648-53
Diagnostic performance
• Troponin I
– Cardiac STATus
• Prognostic risk stratification
Hamm CW et al.N.Engl.J.Med. 1997;337:1648-53.
• CK-MB/Myoglobin
– Cardiac STATus
• Diagnostic equivalence to CLT
Schwartz JG et al. Am.J.Emerg.Med. 1997;15:303-7.
Schouten Y et al. Clin.Chem.Lab Med. 1998;36:469-73.
Diagnosis
• Multiple markers
– Cardiac STATUS/CardiacT
• Diagnostic equivalence to CLT
Luscher MS et al. Cardiology 1998;89:222-8.
Sylven C et al.Am.Heart J. 1998;135:677-83.
– Biosite Triage
• Diagnostic equivalence to CLT
Ng SM et al. Am. J. Cardiol. 2001; 611-7
McCord J et al. Circulation 2001; 104; 1483-8
– Stratus CS
• Risk stratification
Newby LK et al. Circulation 2001;103:1832-7.
The clinical and laboratory shift
- now• Improved sensitivity of laboratory based assays
culminating in high sensitivity troponin assays
• Rapid diagnostic protocols based on very short time
intervals
Company/platform/ assay LOD 99th percentile ng/L 10% CV ng/L
Siemens Stratus CS 30 70 60
Abbott iStat 20 80 100
Alere Triage 50 NA NA
Alere Triage Cadio 3 10 22 37
AQT90 Flex 9.5 23 39
Respose RAMP 30 100 210
Roche cardiac reader 50 NA NA
Radiometer AQT90 cTnT 8 17 26
Radiometer AQT90 cTnI 9.5 23 39
Assay performance vs evidence base
Rule out AMI - assays used
• Studies have shown that rapid rule out of AMI within 2
hours in the ED is feasible.
– Than M et al Lancet 2011;377:1077-1084 (Triage)
– Than M et al J Am Coll Cardiol 2012;59:2091-2098 (Architect
99th 28 ng/L 10% CV 32 ng/L Beckman 99th centile 40ng/L
10% CV 60 ng/l).
– Cullen L et al Int J Cardiol 2013;168:2602-2608 (Beckman 99th
centile 40ng/L 10% CV 60 ng/l).
– Than M et al JAMA Intern Med 2014;174:51-58 (Architect 99th
28 ng/L 10% CV 32 ng/L).
Randomised Assessment of Treatment using
Panel Assays of Cardiac markers (RATPAC)
To measure the effect of PoC triple test on:
1. Proportion of patients successfully discharged home
after ED assessment
2. LoS and hospital bed use
3. Use of CCU and cardiac treatments
4. Major adverse events
5. Health and social care costs
Goodacre SW et al. Heart 2011;97:190-196.
Goodacre S et al. Health Technol Assess 2011;15:iii-102.
Study design
• Pragmatic randomised controlled trial comparing
diagnostic assessment with the PoC triple test to
conventional diagnostic assessment without the triple test
• Multi-centre (six hospitals)
Participants
• Patients presenting to the ED with chest pain due to
suspected but not proven AMI in whom a negative point-
of-care marker test could potentially rule out AMI and
allow discharge home
Intervention
• PoC triple test at baseline and 90 minutes
• Admission recommended if:
Troponin I greater than or equal to 0.03 ng/ml on either sample (changed to 0.07 ng/ml)
Sustained elevation in CK-MB
25% rise in myoglobin from baseline
• Discharge recommended if none of these and patient remains well
• Clinician is ultimately responsible for decision to admit or discharge
Control
• No PoC testing
• Normal access to laboratory testing
• Management at discretion of clinician, according to local
protocols
• Clinician is ultimately responsible for decision to admit
or discharge
Primary outcome
• The proportion of patients successfully discharged home
after ED assessment, defined as discharge with no
adverse event during the following three months
• Discharge defined as either having left hospital or in
hospital with a decision to discharge by 4 hours after
attendance
Secondary outcomes• LoS and use of hospital beds
• Proportion managed on CCU and receiving cardiac treatments
• Re-attendance or admissions over 3 months
• Adverse events (death, non-fatal AMI, life-threatening arrhythmia, emergency
revascularisation or hospitalisation for myocardial ischaemia)
• Proportion of admitted patients shown to have MI
• Health and social care resource use over 3 months
• Health utility (EQ-5D) at 1 and 3 months
Primary outcome
Successful discharge home:
• Either left hospital or a decision made to discharge by 4
hours
• No MAE during follow-up
Primary outcome
• Odds ratio for successful discharge with point-of-care
• Adjusted for age, gender and known CHD
• Odds ratio = 3.59
• 95% CI 2.86 to 4.52
• p<0.001
• Point-of-care testing increases successful discharge
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Point of Care Standard Care
Duration from arrival to discharge from hospital
Inpatient days
Number of days in hospital
706050403020100
Fre
qu
en
cy
700
600
500
400
300
200
100
0
Point-of-care
Number of days in hospital
706050403020100
Fre
qu
en
cy
700
600
500
400
300
200
100
0
Standard care
Major adverse events
Point of
care
Standard
Care
OR (95% CI) P-value
Death 6 (1%) 2 (<1%) 3.4
(0.7 to 17.3)
0.142
Non-fatal AMI 5 (<1%) 5 (<1%) 0.9
(0.3 to 3.2)
0.903
Hospitalisation for
ACS
18 (2%) 9 (1%) 1.8
(0.8 to 4.1)
0.149
Life threatening
arrhythmia
6 (1%) 2 (<1%) 3.2
(0.6 to 15.9)
0.160
Emergency
revascularisation
10 (1%) 14 (1%) 0.7
(0.3 to 1.5)
0.324
Proportion diagnosed with MI
Point of care Standard care P-value
All patients 82/1125
(7.3%)
76/1118
(6.8%)
0.650
Admitted
patients
82/763
(10.7%)
75/971
(7.7%)
0.029
Total costs
Point of care Standard care P-value
Barnsley £1058 £923 0.538
Derriford £1467 £1308 0.529
Edinburgh £1356 £710 0.025
Frenchay £1163 £1058 0.625
Leeds £785 £999 0.345
Leicester £1496 £1115 0.148
All hospitals £1217 £1006 0.047
RATPAC
summary of key findings
• POCT results in
– More rapid hospital discharge
– More accurate diagnosis (less missed AMI)
• Costs are slightly higher
• Patient satisfaction is higher
• Troponin alone is all that is required for diagnosis
– Collinson P et al. Heart 2012;98:312-8.
Other single centre trials
• ED trial – no impact on length of stay or outcome but
earlier initiation of anti-ischaemic therapy– Renaud et al Acad Emerg Med 2008; 15:216-24
Clinical assessment and
preliminary diagnosis
Test
requestBlood
takenSent to
laboratory
Sample receipt
Pre-analytical
processing
Analysis
Result
validation
Result
transmission
Result seen
by clinician
Clinical
action
taken
Patient
Turn
around
time
Clinician Therapeutic
turnaround time
Brain to
brain time
Clinical assessment and
preliminary diagnosis
Test
requestBlood
takenSent to
laboratory
Sample receipt
Pre-analytical
processing
Analysis
Result
validation
Result
transmission
Result seen
by clinician
Clinical
action
taken
Patient
Turn
around
time
Clinician Therapeutic
turnaround time
Brain to
brain time
The future state - requirements
• Hs Troponin by POCT
• Connectivity
• Integration with the EPR and care pathways
• Process rengineering
– A rapid result is not useful without action
Impact of process
• Unless process re-engineering accompanies test
introduction benefit will not occur
Management according to a pre-defined
protocol
Chest Pain - clinically stable
Meets ECG criteria for thrombolysis
Immediate assessment and thrombolysis
Admit to CCU
cTnT 12 h >0.2mg/L
STEMI confirmed
Cardiac Rehab
Follow up in post MI clinic
Does not meet criteria for thrombolysis
Chest pain ?cardiac or abnormal ECG
Trop T 12 h
cTnT <0.2 mg/LNo ECG changes
No further chest pain
Stress test
PositiveAngina
Appropriate investigation
NegativeDischarge or refer for OP
investigation of non-cardiac
chest pain as appropriate
cTnT < 0.2 mg/LECG changes
or further chest pain
UAP
Investigate
Trop T >=0.2 mg/L
NSTEMI confirmed
Investigate
Collinson et al Ann Clin Biochem 2004; 41 :397-404
Prospective RCT of POCT with CLT
CLT POCT Hospital stay 211.2 h 203.5 h ns
CCU stay rule out group 39.4 h 51.6 h ns
CCU stay rule out
group ITT
18.7 h 15.2 h 0.0269
Hospital stay rule out
group
209.3 h 149.9 h 0.0465
Cost per patient 1818.98 1532.93 286.06
Cost per annum (2825) 5182945.85 4420020.48 762925.38
Collinson et al Ann Clin Biochem 2004; 41 :397-404
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Barnsley
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Plymouth Derriford
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Edinburgh RI
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Bristol Frenchay
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Leeds General
0.00
0.25
0.50
0.75
1.00
Pro
port
ion
in h
ospi
tal
0 6 12 18 24 30 36 42 48Time to discharge (hours)
Leicester RI
Duration from arrival to discharge from hospital
Total costs
Point of care Standard care P-value
Barnsley £1058 £923 0.538
Derriford £1467 £1308 0.529
Edinburgh £1356 £710 0.025
Frenchay £1163 £1058 0.625
Leeds £785 £999 0.345
Leicester £1496 £1115 0.148
All hospitals £1217 £1006 0.047
Costs
• Costs were different between sites and only just achieved
statistical significance
• Economics depend on the healthcare system especially
the cost of low intensity beds
• Relief of pressure on ED beds is worth the small increase
in costs
• In subsequent economic modelling studies, rapid
troponin testing has been shown to be cost effective