The determination of the 99th centile level for troponin assays in an Australian reference population

Abstract

Depending on the selected reference population for troponin, there is likely to be variability in the 99th centile as shown in this study. Some differences in sample concordance at the 99th centile cut-off were observed between cTn methods and may result in different clinical classification.

The Global Need to Define Normality: The 99th Percentile Value of Cardiac Troponin

“…The most comprehensive 99th percentile study assessed a common set of results from presumably healthy individuals in 19 different cardiac tro-ponin assays (38 ). In this study as well as in a smaller study (25 ), differences in the determined 99th percentiles were observed for many assays when they were compared to the manufacturers' package insert 99th percentiles. Such findings would be expected with the assessment of nonuniformly defined normal groups of participants in the different studies.…”

“…However, the real-world pro-cess leading to the selection of "normal" subjects across different studies is highly variable, ranging from a failure to supply a detailed definition of how normal subjects were selected (10 -16 ), to primarily using health questionnaires or reviewing baseline clinical characteristics (17)(18)(19)(20)(21)(22)(23)(24), to more selective screening methods using surrogate blood biomarkers, electrocardiography, imaging, and/or physical examination in addition to assessment of known baseline clinical variables (25)(26)(27)(28)(29)(30)(31)(32)(33)(34). Several studies have relied exclusively on questionnaires to define reference individuals.…”

“…Various imaging methods have been applied, including stress echocardiography (25,28 ) and transthoracic echocardiograms to assess left ventricular ejection fraction (LVEF) and mass (29,(31)(32)34 ). For example, Tate et al excluded 3 out of 111 individuals who had cardiovascular abnormalities with stress echocardiography (25 ).…”

“…For example, Tate et al excluded 3 out of 111 individuals who had cardiovascular abnormalities with stress echocardiography (25 ). Logic suggests that a reference population should be free from structural heart disease, as determined by echocardiography, cardiac MRI, or computed tomography angiography (2,4,37 ).…”

“…Because 99th percentile values have been shown to vary by specimen type, it is important to clearly identify what specimen type was used in the methods section of a report (10,14,19,25 ). For example, Tate et al studied the 99th percentile in both plasma and serum among several cardiac troponin assays, finding concordant values for the 2 specimen types across the majority of assays.…”