Alvaro Garcia-Osuna1, David Gaze2, Margarita Grau-Agramunt1, Thomas Morris3, Catarina Telha3, Amelita Bartolome4, Jeffrey J Bishop4, Luis Monsalve4, Richard Livingston4, Joel Estis4, Niamh Nolan4, Johanna Sandlund4, Jordi Ordonez-Llanos5. 1. Department of Clinical Biochemistry, IIB-Hospital de Sant Pau, Barcelona, Spain. 2. Department of Biomedical Sciences, University of Westminster, London, United Kingdom; Department of Clinical Blood Sciences, St George's University Hospitals NHS Foundation Trust, London, United Kingdom. 3. Department of Clinical Blood Sciences, St George's University Hospitals NHS Foundation Trust, London, United Kingdom. 4. Singulex, Inc., Alameda, CA, USA. 5. Department of Clinical Biochemistry, IIB-Hospital de Sant Pau, Barcelona, Spain; Department of Biochemistry and Molecular Biology, Universitat Autònoma, Barcelona, Spain. Electronic address: jordonez@santpau.es.
Abstract
AIM: To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology. METHODS: Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies. RESULTS: Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects. CONCLUSIONS: The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.
AIM: To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology. METHODS: Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies. RESULTS: Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects. CONCLUSIONS: The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.
Authors: Nils A Sörensen; Sebastian Ludwig; Nataliya Makarova; Johannes T Neumann; Jonas Lehmacher; Tau S Hartikainen; Paul M Haller; Till Keller; Stefan Blankenberg; Dirk Westermann; Tanja Zeller; Niklas Schofer Journal: Biomolecules Date: 2019-09-09