The effect of multiple analysers on the biochemical diagnosis of myocardial infarction using a contemporary troponin-I assay.
Background The measurement of cardiac troponin is central for the diagnosis of myocardial infarction (MI). It is recommended that a coefficient of variation of ≤10% is achieved at the diagnostic threshold and significant change between serial measurements reported. Many modern laboratories use multiple analysers linked by automation where samples are randomly assigned to an analyser. It is therefore important to consider the combined effect of all analysers on the analytical performance of troponin measurement. Method The performance of a contemporary troponin-I (cTn-I) assay run on three analysers, linked by an automated track, was undertaken across a range of cTn-I concentrations. The data for the three analysers were aggregated to obtain the combined analytical coefficient of variation (CVA) and reference change values (RCVs). Results The CVAimproved with increasing concentration and calculated RCVs ranged from 67.2% (±13 ng/L) to 32% (±160 ng/L) between cTn-I values 20 ng/L and 500 ng/L. Although there were significant differences in cTn-I measurement between analysers around the diagnostic threshold ( P < 0.05), the CVAwas 13.6%. Conclusions We demonstrate that there are significant differences between the performances of analysers which can impact the biochemical criteria for the diagnosis of MI. We also show that the RCV varies according to baseline cTn-I values and that reporting a single RCV across the analytical range of cTn-I may not be appropriate.
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.
James
J
Pethick
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.|2 Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.|3 BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK.|4 NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, UK.
Prashanth
P
Patel
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.
Timothy
T
Davies
5 Department of Health Sciences, University of Leicester, Leicester, UK.
John
J
Thompson
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.
Madhavi
M
Nallagonda
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.
Alison
A
Beech
6 Departments of Clinical Blood Sciences and Cardiology, St George's Hospital and Medical School, London, UK.
Paul
P
Collinson
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.
Virginia
V
Lee
1 Department of Chemical Pathology and Metabolic Medicine, University Hospitals Leicester NHS Trust, Leicester, UK.|2 Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.|3 BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK.|4 NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, UK.
Pankaj
P
Gupta
D057205:Automation, Laboratory / Q000592:standards*; D001681:Biological Assay / Q000592:standards*; D015415:Biomarkers / Q000097:blood; D006801:Humans; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D015588:Observer Variation; D012016:Reference Values; D020107:Troponin T / Q000097:blood*
D015415:Biomarkers; D020107:Troponin T
Troponin; analytes; laboratory methods; statistics