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The true 99th percentile of high-sensitivity cardiac troponin for the hospital population: an observational cohort study - the CHARIOT Study

The true 99th percentile of high-sensitivity cardiac troponin for the hospital population: an observational cohort study - the CHARIOT Study
The true 99th percentile of high-sensitivity cardiac troponin for the hospital population: an observational cohort study - the CHARIOT Study
Objective: clinicians use the cardiac troponin (cTn) assay to aid in the diagnosis of an acute myocardial infarction (AMI). Each assay manufacturer provides the 99th percentile for cTn levels in a group of healthy individuals, and this level is taken as the upper limit of normal (ULN). The objective of this study was to determine the distribution, and specifically the true 99th percentile, for the whole hospital population, using the cTn assay currently employed routinely at our institution.

Design: prospective study of 20,000 consecutive patients undergoing blood sampling for any reason at a large teaching hospital. Hs-cTnI concentrations (Beckman Coulter Access AccuTnI+3 assay) were nested for analysis in all cases except those in whom the supervising physician had requested hs-cTnI for clinical reasons.

Setting: University Hospital Southampton NHS Trust (UHS).

Participants: 20,000 consecutive individuals, inpatient or outpatient, undergoing blood tests at UHS for any clinical reason.

Main outcome measures: distribution of hs-cTnI concentrations of all study patients, and specifically the 99th percentile.

Results: the 99th percentile of hs-cTnI for the whole population (n=20,000) was 296 ng/L, compared to a manufacturer quoted 99th percentile of 40 ng/L (currently used clinically as the ULN). In 1 in 20 (5.4%, n=1080) of the total population hs-cTnI concentrations were above 40 ng/L. After exclusion of individuals diagnosed with an acute myocardial infarction (AMI) (n=122), or those in whom troponin was requested (n=1707), the 99th percentile for the remainder (n=18,171) was 189 ng/L. The 99th percentile for inpatients (n=4759) and outpatients (n=9280) was 563 ng/L and 65 ng/L, respectively. Patients from the emergency department (n=3706) had a 99th percentile of 215 ng/L, with 6.1% (n=225) above the quoted ULN. 39.02% (n=48) of all individuals from the critical care units (n=123) and 14.16% (n=67) of all medical inpatients had a hs-cTnI concentration above the quoted ULN.

Conclusions: in 20,000 consecutive patients undergoing a blood test for any reason at this hospital 1 in 20 have a hs-cTnI above the supplied ULN. These data highlight the need for clinical staff to interpret hs-cTnI concentrations carefully, particularly when applying the supplied ULN to diagnose AMI. The use of hs- cTnI to diagnose AMI in any patient could lead to misdiagnosis in the absence of an appropriate clinical presentation.
0959-8138
Mariathas, Mark
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Allan, Rick
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Ramamoorthy, Sanjay
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Olechowski, Bartosz
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Hinton, Jonathan
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Azor, Martin
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Nicholas, Zoe
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Calver, Alison
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Corbett, Simon
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Mahmoudi, Michael
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Rawlins, John
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Simpson, Iain
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Wilkinson, James
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Shing Kwok, Chun
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Cook, Paul
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Mamas, Mamas A.
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Curzen, Nick
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Mariathas, Mark
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Allan, Rick
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Ramamoorthy, Sanjay
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Olechowski, Bartosz
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Hinton, Jonathan
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Azor, Martin
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Nicholas, Zoe
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Calver, Alison
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Corbett, Simon
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Mahmoudi, Michael
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Rawlins, John
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Simpson, Iain
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Wilkinson, James
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Shing Kwok, Chun
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Cook, Paul
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Mamas, Mamas A.
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Curzen, Nick
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Mariathas, Mark, Allan, Rick, Ramamoorthy, Sanjay, Olechowski, Bartosz, Hinton, Jonathan, Azor, Martin, Nicholas, Zoe, Calver, Alison, Corbett, Simon, Mahmoudi, Michael, Rawlins, John, Simpson, Iain, Wilkinson, James, Shing Kwok, Chun, Cook, Paul, Mamas, Mamas A. and Curzen, Nick (2019) The true 99th percentile of high-sensitivity cardiac troponin for the hospital population: an observational cohort study - the CHARIOT Study. British Medical Journal.

Record type: Article

Abstract

Objective: clinicians use the cardiac troponin (cTn) assay to aid in the diagnosis of an acute myocardial infarction (AMI). Each assay manufacturer provides the 99th percentile for cTn levels in a group of healthy individuals, and this level is taken as the upper limit of normal (ULN). The objective of this study was to determine the distribution, and specifically the true 99th percentile, for the whole hospital population, using the cTn assay currently employed routinely at our institution.

Design: prospective study of 20,000 consecutive patients undergoing blood sampling for any reason at a large teaching hospital. Hs-cTnI concentrations (Beckman Coulter Access AccuTnI+3 assay) were nested for analysis in all cases except those in whom the supervising physician had requested hs-cTnI for clinical reasons.

Setting: University Hospital Southampton NHS Trust (UHS).

Participants: 20,000 consecutive individuals, inpatient or outpatient, undergoing blood tests at UHS for any clinical reason.

Main outcome measures: distribution of hs-cTnI concentrations of all study patients, and specifically the 99th percentile.

Results: the 99th percentile of hs-cTnI for the whole population (n=20,000) was 296 ng/L, compared to a manufacturer quoted 99th percentile of 40 ng/L (currently used clinically as the ULN). In 1 in 20 (5.4%, n=1080) of the total population hs-cTnI concentrations were above 40 ng/L. After exclusion of individuals diagnosed with an acute myocardial infarction (AMI) (n=122), or those in whom troponin was requested (n=1707), the 99th percentile for the remainder (n=18,171) was 189 ng/L. The 99th percentile for inpatients (n=4759) and outpatients (n=9280) was 563 ng/L and 65 ng/L, respectively. Patients from the emergency department (n=3706) had a 99th percentile of 215 ng/L, with 6.1% (n=225) above the quoted ULN. 39.02% (n=48) of all individuals from the critical care units (n=123) and 14.16% (n=67) of all medical inpatients had a hs-cTnI concentration above the quoted ULN.

Conclusions: in 20,000 consecutive patients undergoing a blood test for any reason at this hospital 1 in 20 have a hs-cTnI above the supplied ULN. These data highlight the need for clinical staff to interpret hs-cTnI concentrations carefully, particularly when applying the supplied ULN to diagnose AMI. The use of hs- cTnI to diagnose AMI in any patient could lead to misdiagnosis in the absence of an appropriate clinical presentation.

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CHARIOT PAPER CLEAN 01 02 19 - Accepted Manuscript
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Accepted/In Press date: 8 February 2019
Published date: 2019

Identifiers

Local EPrints ID: 428331
URI: https://eprints.soton.ac.uk/id/eprint/428331
ISSN: 0959-8138
PURE UUID: ee05190a-f326-4bf0-b19b-416e0baae7ab
ORCID for Michael Mahmoudi: ORCID iD orcid.org/0000-0003-1293-8461

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Date deposited: 21 Feb 2019 17:30
Last modified: 09 May 2019 04:01

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Contributors

Author: Mark Mariathas
Author: Rick Allan
Author: Sanjay Ramamoorthy
Author: Bartosz Olechowski
Author: Jonathan Hinton
Author: Martin Azor
Author: Zoe Nicholas
Author: Alison Calver
Author: Simon Corbett
Author: John Rawlins
Author: Iain Simpson
Author: James Wilkinson
Author: Chun Shing Kwok
Author: Paul Cook
Author: Mamas A. Mamas
Author: Nick Curzen

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