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Sources of variability in measurements of cardiac troponin T in a community-based sample: the atherosclerosis risk in communities study.

TitleSources of variability in measurements of cardiac troponin T in a community-based sample: the atherosclerosis risk in communities study.
Publication TypeJournal Article
Year of Publication2011
AuthorsAgarwal SK, Avery CL, Ballantyne CM, Catellier D, Nambi V, Saunders J, A Sharrett R, Coresh J, Heiss G, Hoogeveen RC
JournalClin Chem
Volume57
Issue6
Pagination891-7
Date Published2011 Jun
ISSN1530-8561
KeywordsAged, Aged, 80 and over, Atherosclerosis, Biomarkers, Blood Specimen Collection, Female, Humans, Male, Middle Aged, Reproducibility of Results, Residence Characteristics, Risk Assessment, Temperature, Time Factors, Troponin T
Abstract

BACKGROUND: Application of cardiac troponin T (cTnT) as a marker of myocyte damage requires knowledge of its measurement variability. Using a highly sensitive assay for measurement, we evaluated the long-term storage stability of plasma cTnT at -70 °C and the sources of cTnT variability.

METHODS: Samples from the Atherosclerosis Risk in Communities study collected in 1996-1998 and 2005-2006 were assayed centrally to quantify variability in cTnT attributable to processing (replicates from same blood draw, n = 87), laboratory (replicates after freeze thaw, n = 29), short-term (n = 40) and long-term biological variation (repeat visit, n = 38), and degradation in frozen storage (n = 7677).

RESULTS: Approximately 30% of this population-based cohort had cTnT concentrations below the detection limit (3 ng/L). Reliability coefficients for all paired comparisons exceeded 0.93 except for samples drawn 8 years apart (r = 0.36). Sources of cTnT variation (as CVs) were: laboratory, 2.1% and 11.2% in those with and without heart failure, respectively; processing, 18.3%; biological, 16.6% at 6 weeks and 48.4% at 8 years. The reference change value at 6 weeks (68.5%) indicated that 4 samples are needed to determine a homeostatic set point within ±25%. The estimated cTnT degradation rate over the first year in long-term frozen storage was 0.36 ng/L per year.

CONCLUSIONS: cTnT was detectable in approximately 70% of community-dwelling middle-aged study participants and stable in -70 °C storage. The variability in cTnT attributable to 1 freeze-thaw cycle is of small magnitude. The observed high laboratory and intraindividual (biological) reliability of cTnT support its use for population-based research, and in clinical settings that rely on classification and serial measurements.

DOI10.1373/clinchem.2010.159350
Alternate JournalClin Chem
PubMed ID21519038
PubMed Central IDPMC4928588
Grant ListN01HC55020 / HL / NHLBI NIH HHS / United States
N01HC55018 / HL / NHLBI NIH HHS / United States
N01-HC-55022 / HC / NHLBI NIH HHS / United States
N01-HC-55016 / HC / NHLBI NIH HHS / United States
N01HC55022 / HL / NHLBI NIH HHS / United States
N01-HC-55021 / HC / NHLBI NIH HHS / United States
N01HC55015 / HL / NHLBI NIH HHS / United States
N01-HC-55019 / HC / NHLBI NIH HHS / United States
N01-HC-55015 / HC / NHLBI NIH HHS / United States
N01-HC-55020 / HC / NHLBI NIH HHS / United States
N01HC55016 / HL / NHLBI NIH HHS / United States
N01HC55019 / HL / NHLBI NIH HHS / United States
K99-HL-098458 / HL / NHLBI NIH HHS / United States
N01-HC-55018 / HC / NHLBI NIH HHS / United States
N01HC55021 / HL / NHLBI NIH HHS / United States